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+*** START OF THE PROJECT GUTENBERG EBOOK 78368 ***
+
+
+                               THE NATURE
+                            OF LIVING MATTER
+
+
+                                   BY
+                             LANCELOT HOGBEN
+
+        _Professor of Social Biology in the University of London_
+
+
+            The mind that needs to know all things must needs
+       at last come to know its own limits, even its own nullity,
+                 beyond a certain point.--D. H. Lawrence
+
+
+                                 LONDON
+                 KEGAN PAUL, TRENCH, TRUBNER & CO., LTD.
+                 BROADWAY HOUSE: 68-74 CARTER LANE, E.C.
+                                  1930
+
+
+                  Made and Printed in Great Britain by
+                 Butler & Tanner Ltd., Frome and London
+
+
+                                   To
+                            BERTRAND RUSSELL
+
+
+
+
+FOREWORD
+
+
+In the summer of 1929 I was asked to speak for thirty-five minutes
+in a symposium on the Nature of Life arranged by the officers of the
+Physiological Section of the British Association. I soon discovered
+that there are many ways of filling up thirty-five minutes devoted to
+the consideration of so formidable a topic. Eventually I decided to
+make my contribution in the form which appears almost unchanged in the
+fourth essay of this book. By that time I had written a volume without
+intending to break my silence before attaining my sixtieth year. With
+the insertion of some material to elaborate the point of view I had
+developed this collection might be described as the rejected addresses.
+I owe to my friend Mr. Sewell, who has adopted the same standpoint in a
+criticism of æsthetics in course of preparation, the suggestion of the
+word _public_ in contradistinction to the _external_ world of Professor
+Eddington.
+
+Four contributors to the Symposium on the Nature of Life, General
+Smuts, Dr. Haldane, Dr. Wildon Carr and Professor Eddington, had
+already published their philosophical views in book form. General
+Smuts and Dr. Haldane courteously wrote to me, expressing the hope
+that I would criticize their views destructively. I found the time
+at my disposal insufficient for stating my own point of view. I have
+responded to their invitation in these essays. If certain passages
+seem to some of my readers unduly polemical, I have the assurance that
+my fellow-contributors will regard this collection as the continuation
+of what was a very friendly argument.
+
+I wish to acknowledge my indebtedness to my friend Professor Levy for
+criticism and assistance in seeing this book through the press.
+
+                                                              L. T. H.
+
+  Cape Town,
+      _April, 1930._
+
+
+
+
+                                CONTENTS
+
+
+                                 PART I
+
+                         VITALISM AND MECHANISM
+
+        Summary                                                     1
+        Introduction                                                3
+     I: The Mechanization of Consciousness                         33
+    II: The Atomistic View of Parenthood                           56
+   III: The Nature of Life--an Introduction to the Theory
+          of a Public World                                        80
+    IV: The Concept of Adaptation                                 102
+
+                                PART II
+
+       DARWINISM AND THE ATOMISTIC INTERPRETATION OF INHERITANCE
+
+        Summary                                                   127
+     V: The Methodology of Evolution                              129
+    VI: The Problem of Species                                    151
+   VII: Natural Selection and Experimental Research               170
+  VIII: The Survival of the Eugenist                              193
+
+                                PART III
+
+           HOLISM AND THE PUBLICIST STANDPOINT IN PHILOSOPHY
+
+     Summary                                                      217
+    IX: Biology and Humanism                                      219
+     X: Publicity, Reality, and Religion                          245
+    XI: Privacy, Publicity, and Education                         266
+   XII: The Publicist Standpoint and Holism                       289
+
+
+
+
+PART I
+
+VITALISM AND MECHANISM
+
+SUMMARY
+
+
+An uneasy recognition of the conflict between science and common sense
+in our generation has rekindled interest in the relation of science to
+moral philosophy. In this awakening the physicists have assumed the
+leading part. It will not be possible to predict the outcome, until the
+contribution of contemporary biology to natural philosophy is taken
+into consideration. Some writers have expressed the hope that the
+influence of biological concepts may assist to a reconciliation of the
+claims of natural science and moral philosophy. This hope is based on a
+failure to recognize that modern experimental biology is an ethically
+neutral body of enquiry. The merits of a mechanistic or vitalistic
+outlook in biology have been too often discussed from an ontological
+rather than an epistemological standpoint. Our estimate of the
+influence of biological concepts on the future of natural philosophy
+must be guided by a recognition of the essential similarity of method
+in biology and physics. This similarity is nowhere more evident than
+in those branches of physiology which lie most conspicuously outside
+the realm of applicability of physico-chemical hypotheses. Traditional
+mechanistic physiology has accepted the Cartesian dualism of mind and
+matter. The modern physiology of the conditioned reflex has undermined
+the distinction between reflex and voluntary behaviour. There is thus
+no nicely defined boundary at which physiology ends and philosophy
+begins. Biology is annexing regions of enquiry which have hitherto
+remained the province of moral philosophy. As a concept of biology
+_Mind_ is replaced by _Behaviour_. Since modern biology claims to
+interpret the characteristics of conscious behaviour as properties of
+physical objects, the advance of biological science cannot be expected
+to reinforce the claims of moral philosophy. How far it is possible
+to reduce the interpretation of behaviour to purely physico-chemical
+hypotheses, we have no means of predicting. At present we can foresee
+no limit to progress in that direction. The significant issue is not
+the completeness of the mechanistic solution, but whether there exists
+any definable method of arriving at a more complete solution than the
+mechanistic outlook permits.
+
+                   *       *       *       *       *
+
+“It is our happiness to live in one of those eventful periods of
+intellectual and moral history when the fast-closed gates of discovery
+and reform stand open at their widest. How long these good days may
+last we cannot tell. It may be that the increasing power and range of
+scientific method with its stringency of argument and constant check
+of fact may start the world in a more steady and continuous course of
+progress than it has moved on heretofore. But if history is to repeat
+itself according to precedent, we must look forward to stiffer, duller
+ages of traditionalists and commentators, when the great thinkers of
+our time will be appealed to by men who slavishly accept their tenets,
+yet cannot or dare not follow their methods through better evidence
+to higher ends. In either case it is for those among us whose minds
+are set on the advancement of civilization to make the most of present
+opportunities that, even when in future years progress is arrested, it
+may be arrested at a higher level.”
+
+                                         Tylor’s _Primitive Culture_
+
+
+
+
+INTRODUCTION
+
+
+§1
+
+No one who is familiar with contemporary thought can have failed to
+recognize two characteristics which have emerged into prominence during
+the past two decades. With increasing elaboration of its logical
+technique, science has been brought into apparently irreconcilable
+conflict with common sense. The result is that scientists, uneasy
+in the realization of this conflict, are seeking to establish a new
+working relation between science and philosophy. This _rapprochement_
+has been brought about especially through recent progress in physics.
+It will not be possible to predict its outcome so long as the physicist
+claims to speak for science as a whole. In this introductory essay I
+propose to discuss in a somewhat discursive and preliminary way how far
+the conflict between science and common sense is apparent rather than
+real, and to indicate the special need for reviewing the progress of
+modern biology in its philosophical bearings.
+
+At the present time few biologists are anxious to court publicity
+in the field of philosophic controversy. Those who do so are rarely
+numbered among the ranks of those who are still actively contributing
+to contemporary progress in biological enquiry. Those who are actively
+contributing to the advancement of biological knowledge show little
+disposition to commit themselves to far-reaching generalizations.
+There has emerged from the morass of speculation associated with the
+rise of the evolutionary hypothesis a recognition of the paramount
+importance of painstaking quantitative study of limited aspects of
+vital phenomena. This attitude is a salutary one. It does not signify
+that biology is passing through a phase of stagnation. On the contrary
+current biological discoveries contain the germ of philosophical issues
+which may prove to be as revolutionary as Relativity and as repugnant
+to common sense. In the essays which follow I shall confine myself
+to accredited experimental data. I do not pretend that all or even
+a majority of biologists will agree with my interpretation of their
+philosophic significance.
+
+There is no novelty in asserting the need for incorporating the
+contribution of biological science in a modern philosophical outlook.
+Herbert Spencer and the Evolutionists prepared the ground fifty years
+ago; but they failed to lay emphasis on the methodological aspect of
+biological enquiry. The methods and not the results of biological
+science are specially significant to philosophical discussion. In
+putting forward my own views upon the nature of life, it is not the
+results of biological enquiry, but the methods which I propose to
+discuss in the first series of essays in this volume. In contrasting
+the methods and concepts of physical and biological science, I shall
+sometimes draw inferences which will not commend themselves to the
+judgment of biologists for whose contributions I entertain a lively
+respect. I shall not be surprised to be told that my forecast of the
+outcome of biological enquiry is pretentious, and that my philosophical
+conclusions are in conflict with common sense.
+
+At an early age I abandoned the conviction that scientific hypotheses
+must conform to the requirements of common sense. When I was a boy,
+there used to be in Portsmouth, the town of my nativity, a public
+figure by name Ebenezer Breach. Mr. Breach was a philosopher. To be
+precise he described himself as “Natural Astronomer and Poet.” In that
+he belittled his gifts. Of his poetry I shall say nothing, save that he
+stated the qualification “poet by Royal Patronage” in his fascinating
+brochure _Twenty Reasons against Newtonianism or The Universal
+Challenge to Unnatural Science_. This was sold for the modest price
+of twopence sterling. As his contribution to modern thought may be
+unfamiliar to many cultivated people who were not born in Portsmouth, I
+propose to quote the first of his twenty reasons as representative of
+the system he develops:
+
+  “Because the earth has no axis, therefore nothing on which to
+  revolve, an imaginary mathematical line is substituted. But no
+  solid body could revolve on an imaginary axis or line. It is an
+  imaginary cause which can only produce an imaginary effect, so all
+  that follows the cause must be imaginary. If anything be placed on
+  the top of a revolving body it will fly off at a tangent.”
+
+From this you might infer, wrongly it happens, that Mr. Ebenezer
+Breach earned a comfortable livelihood as Regius Professor of Moral
+Philosophy in an authentic University. He had in fact chosen to bear
+witness to the hope that was in him by the only alternative which a
+harsher economic destiny had imposed. Every Saturday night he addressed
+a handful of half-intoxicated seamen, tired commercial travellers,
+adventurous nursery maids and irreverent pupil teachers foregathered
+on the sea-front. There he occasionally succeeded in selling a copy
+of the _Twenty Reasons_, and beyond this obtained, as far as I am
+aware, no reward in the life that now is. In spite of his erudition and
+distinction of person, Mr. Breach, the prophet of common sense, did
+not make many converts. He was less successful in his popular appeal
+than an evangelical competitor who used to minister to Portsmouth beach
+before a banner whose legend stated, “the wages of sin is death.”
+This banner I can still recall as, in its way, a work of art. On the
+foreground were displayed the theatre, race-course, public-house,
+dancing saloon and gaming tables along the edge of a precipice over
+which poor folk in a semi-incandescent condition were tumbling into a
+lake of brimstone and fire. It invariably drew a large crowd. I had
+early imbibed the notion that science like Sunday travelling, whist and
+dramatic entertainment is worldly, so that the gospel of Mr. Breach,
+who condemned science on account of its essential unworldliness,
+presented a new and arresting point of view. On the whole the
+inhabitants of Portsmouth were more interested in their souls and what
+would become of them after death. Mr. Breach had another competitor
+with more peculiar views about the soul and about life. As far as I
+can remember he held that the brain secretes consciousness in much the
+same way as the liver secretes bile, and he asserted that the soul
+was the shadow cast by the machine. My nurse held very definite views
+about his domestic life. He was a materialist, and in all probability a
+polygamist, if not worse. Mr. Breach who was a bachelor, the evangelist
+who was certainly not a polygamist, and the Secularist who was
+undoubtedly a bad man all agreed in one particular. Each believed that
+the gospel he proclaimed was common sense.
+
+Of the Flat Earth faith Mr. Ebenezer Breach is the only Confessor and,
+financially speaking, Martyr I have been privileged to encounter. I
+cherish the recollection of his secular ministrations for a reason
+which is eminently relevant to everything which I propose to say about
+the bearing of current biological concepts on philosophical discussion.
+At an age when, to my way of thinking, Punch and Judy were the only
+serious rivals to the magnetism of his stupendous intellectual
+gifts Mr. Breach stands out in the sharp relief of retrospect as the
+Forerunner of the coming conflict between science and common sense.
+I have already remarked that the uneasy recognition that science
+conflicts with common sense has been the keynote of philosophical
+controversy during the past decade. Curiously enough some scientists
+seem to regard this as a grave disability on the part of science.
+They feel compelled in consequence to adopt an apologetic attitude
+to the claims of traditional philosophy. Perhaps this is because the
+protagonists of science in the nineteenth century made it their proud
+boast that science is nothing more than organized common sense. They
+therefore felt that they had the man in the crowd on their side. Even
+Herbert Spencer, prophet of evolution, when evolution was still a
+subversive doctrine, could soberly declare that “the ultimate truth of
+a proposition is the inconceivableness of its negation.”
+
+Neitzsche includes this quotation in the _Will to Power_ as one of his
+“inscriptions over the porch of a modern lunatic asylum.” It is only
+necessary to mention the word Relativity to indicate how impossible it
+would be for a natural philosopher to express himself in similar terms
+to-day. The situation which has been created by progress in modern
+physics is not without parallel in human history. It is true that
+the new theories have employed an immensely elaborate and difficult
+logical technique. How far they can be simplified it is at present
+impossible to predict. Newton’s fluxions were unfamiliar to his
+contemporaries. The author of the _Principia_ devoted a good deal of
+time to a geometrical presentation of his ideas, in order to make them
+accessible to his generation. For more than a century after Newton’s
+death the calculus remained a preserve for mathematical specialists.
+To-day a knowledge of the calculus requisite to an elementary
+understanding of the theory of elliptical orbits lies within the scope
+of the first year’s work at a university, if it has not been acquired
+in the higher forms of a good school. It is conceivable that the
+mathematical development of modern physical theories will be simplified
+in the course of time. In that sense the esoteric stage through which
+physics is now passing may be a temporary phase. The essential feature
+of the conflict between common sense and physical science in this
+generation lies in the unfamiliarity of the new concepts. The conflict
+between common sense and the new biological concepts shares the same
+characteristic.
+
+In Bernard Shaw’s _St. Joan_, La Tremouille asks: “Who the deuce was
+Pythagoras?” “A sage,” replies the Archbishop, “who held that the earth
+is round and that it moves round the sun.” “What an utter fool,” says
+La Tremouille, “couldn’t he use his eyes?” La Tremouille here calls
+attention to a fact that was overlooked by Herbert Spencer, by Mr.
+Ebenezer Breach and by those Relativist philosophers, who, being unable
+to convince the man in the crowd, indulge in the luxury of wondering
+whether the claims of scientific method have been pushed too far.
+Common sense is another name for what good citizens are prepared to
+accept without argument. Scientific ideas only conflict with common
+sense so long as they are still new and unfamiliar. Mr. Breach was in
+advance of his time in daring to criticize the Newtonian system. He was
+behind his time in thinking that Newton’s position could be assailed
+successfully with the weapons of common sense. The essential rightness
+of the Newtonian system had already become incorporated in British
+middle-class respectability. To the rising generation suckled on Mr.
+Wells’ _Outlines_ evolution is common sense. Two generations have
+elapsed since, as La Tremouille would say, any fool who used his eyes
+could see that a bishop was a product of special creation. The man in
+the crowd has no clearer notion of the logical status of the doctrine
+of descent than had his grandfathers who implicitly accepted the story
+of the Fall.
+
+The phenomenal success of those who set out to popularize the Theory
+of Evolution makes it easy to overlook the circumstance that evolution
+was wholly repugnant to common sense within the memory of those who
+are still living. The outburst of public controversy which greeted its
+announcement has no parallel in this generation. In consequence its
+impact upon traditional philosophy has been far less apparent than
+its influence upon religious dogma and social theory. The younger
+generation of biologists cannot recapture the first fine raptures of
+enthusiasm which their elders experienced. The prevailing attitude is
+to welcome a return to the complacent dualism of pre-Darwinian days,
+when scientists did not meddle with philosophy and metaphysicians
+conceded to scientists the right to go to the devil in their own
+way. Although this view is widely held, I do not believe that the
+philosophical implications of evolution have ever been thoroughly
+explored; or that it was possible to do so, while the study of animal
+behaviour was still dominated by the language of introspective
+psychology. By explaining the secular origin of philosophers Darwin
+bequeathed to us the task of elucidating the anatomy of philosophy.
+
+In the opening years of the present century, science had already
+lost that truculence which one associates with the generation of
+Huxley and Tyndall. It had surrendered its tradition of fearlessness
+and candour. Academic philosophy, liberal theology and utilitarian
+science went their placid ways without mutual interference. Bergson,
+a philosopher more widely known than Mr. Ebenezer Breach, had cast
+a pebble of _belles lettres_ into the mill-pond of compromise. The
+indifference with which it was greeted by those engaged in the task
+of placing the evolutionary problem upon a secure foundation of
+experimental data is a measure of the esteem which they entertained
+for it. It has been interpreted as assent by some contemporary writers
+who are not themselves biologists. In _Science and the Modern World_
+Dr. Whitehead even speaks of Bergson’s “instinctive grasp of modern
+biology.” A modern biologist engaged in the study of behaviour would
+refer with greater caution to Madame Blavatsky’s instinctive grasp
+of modern astronomy or Mahatma Gandhi’s instinctive grasp of modern
+economics. He would regard the instinctive grasp of any branch of
+scientific knowledge with more suspicion than approval. No biologist
+has undertaken the task of examining the philosophical implications
+of Darwin’s doctrine in the light of contemporary progress in the
+experimental analysis of living matter.
+
+
+§2
+
+Under the influence of Hegel, academic philosophy left the scientist
+to his own devices. To-day the physicist has again driven the idealist
+philosopher out of his retreat. He has compelled him to take account of
+a conceptual world which we all recognize whenever we consult a railway
+time-table or book a passage in an ocean liner. Secure in the prospect
+of fresh philosophical victories, the astronomer surveys the world with
+a blind eye to the microscope, and magnanimously dictates the new
+territorial frontiers of science and moral philosophy to the advantage
+of the latter. It has been customary in the past, and therefore common
+sense, to assume that the issues with which moral philosophy deals are
+more fundamental than those which fall within the scope of natural
+science. It is an assumption which, whatever its meaning, does not
+hamper the advance of pure physics; but the biologist is not bound to
+accept this convention when it restricts his own field of enquiry. A
+philosopher is a particular kind of organism. Philosophy itself might
+therefore be regarded as an aspect of the behaviour of a piece of
+living matter. The study of the properties of living matter is the
+province of the biologist. From this point of view the study of biology
+is more fundamental than the pursuit of moral philosophy.
+
+The physicist brings to the discussion of philosophy the discipline
+of an older branch of enquiry with a more elaborate logical technique
+than that of biology. His claim to speak for the whole field of science
+should be scrutinized with a critical eye. I am sure that Professor
+Eddington will agree with me, when I say that the biologist has a
+specific contribution to make to what he has aptly called the “world
+symposium.” I am also confident that many biologists will agree with
+me, when I state that the contributions of the Relativist philosophers
+rarely display a profound understanding of the kind of problems
+biologists are now attempting to solve, and the way in which the modern
+biologist sets about his task. A quotation from Mr. Sullivan’s _Bases
+of Modern Science_, a stimulating and provocative book, will illustrate
+my meaning. Mr. Sullivan, whose physics I do not venture to criticize,
+states: “The primary concepts in terms of which the science of physics
+is constructed... have to be supplemented by others in the science of
+chemistry, and for the sciences of life and mind, are so far from being
+sufficient, that they have hardly yet been found to be relevant.” Half
+a century has passed since the concept of chemical affinity was annexed
+by thermodynamics, and the most conservative physiologist could hardly
+refrain from ridiculing the latter part of this quotation. Professor
+Eddington himself has adopted the “Principle of Indeterminacy” as an
+_ad hoc_ hypothesis in a limited field of enquiry. From it he proceeds
+to draw conclusions about human responsibility and the doctrine of free
+will. These are topics which lie nearer to the province of biology than
+physics. It would be well to await the verdict of biological science
+before accepting inferences of so far reaching a character as those
+which Professor Eddington has advanced.
+
+By emphasizing the conflict between science and common sense Relativity
+has engendered a new interest in the relation of science to moral
+philosophy. To view that relation in its proper perspective the
+concepts of modern biology must supplement the concepts of modern
+physics. I am not suggesting that this need is overlooked by those
+who are not biologists. Dr. Whitehead has gone so far as to advocate
+replacing the traditional physical idea of matter by the biological
+concept of organism, or as a modern biologist might prefer to say,
+behaviour. When he expresses the hope that this will assist to “end
+the divorce of science from the affirmations of æsthetic and ethical
+experiences,” it is clear that his conception of the nature of
+biological enquiry dates from Herbert Spencer and differs from that
+which contemporary biologists would generally be willing to accept.
+Owing to the separation of descriptive from experimental biology, a
+separation for which the evolutionists were pre-eminently to blame,
+a well-informed interest in the study of living matter is more rare
+among physicists of our period than it was in the days of Robert Hooke
+and Boyle or of Euler, Lavoisier, and Laplace. I am convinced that
+very few scientists who are not biologists--perhaps no professional
+philosophers--possess a clear notion of the way in which the modern
+experimental biologist approaches the study of the organism and the
+results at which he aims.
+
+I have already suggested that there are special reasons why the
+concepts of biology stand in a more intimate relation to the scope of
+moral philosophy than do those of physical science in the restricted
+sense. It is difficult to define the meaning of philosophy without
+implying a particular point of view about the limitations of human
+knowledge. There are as many different definitions of philosophy as
+there are different schools of philosophical opinion. From the point of
+view of the materialist a Hegelian is a sea lawyer. From the point of
+view of the subjective idealist a materialist is not a philosopher at
+all. If there is anything which all the two and seventy jarring sects
+would agree to regard as a problem of philosophy, it is the Nature of
+Life. If we are to avoid making any unjustifiable assumptions about the
+nature of knowledge, we must for the present define a philosophical
+discussion of the Nature of Life as the most comprehensive treatment of
+the problem. It does not necessarily follow that there is any essential
+difference between a scientific and a philosophic enquiry in this sense.
+
+When people first hear their own voices recorded by a gramophone, it
+is well known that they are often--like myself--a little humiliated,
+and generally somewhat surprised. I once had occasion to witness an
+instructive incident which occurred in the phonetics department of
+the University of Cape Town. A gramophone record of three men engaged
+in a conversation was prepared. None of the three participants had
+previously listened to a record of his own voice. When the record
+was completed each man agreed that the voices of the other two were
+faithfully recorded. Each man denied that his own voice had any
+semblance to its representation by the recording instrument. This
+simple experiment in human behaviour illustrates what I shall later
+call the distinction between the _private worlds_ and the _public
+world_. It also illustrates a fundamental divergence of outlook which
+distinguishes two tendencies in philosophical discussion, and makes
+it difficult to give any definition of philosophy satisfactory to all
+parties. One school of philosophers defines a good record as a record
+which on the whole faithfully conveys the impression of human voices.
+The philosopher of the opposing school feels that it ought to be
+possible to manufacture a record which will faithfully represent the
+voice of his opponent, while at the same time registering his own voice
+as he hears it himself, when he is speaking, and would prefer other
+people to hear it.
+
+This distinction has an interesting history which will be discussed in
+the third series of essays in this volume. Greek speculative philosophy
+had its first beginnings in a secular curiosity about Nature.
+Science and philosophy were thus one and the same thing to Thales,
+to Empedocles or to Democritus. In Greek thought speculation was not
+sufficiently disciplined by sustained observation of Nature. For that
+reason it gave birth to innumerable conflicting hypotheses which could
+never be made the subject of decisive tests. Out of this confusion of
+conflicting ideas was born a reaction against science. Philosophy
+turned from the slow and tedious task of examining the actual world
+to the more facile and pretentious pursuit of an ideal world. In
+the person of Plato it forfeited its secular temper. Science was
+introduced into modern Europe by the Arabs, who assimilated the secular
+curiosity of the Greeks. Ecclesiasticism seized upon the speculations
+of the later Greek philosophers to provide a rational basis for
+theological dogma. Since mediæval times scientists have submitted
+to an arrangement which gives to those who have not studied Nature
+the right to supervise the logical status of their conclusions. The
+stability of this arrangement has been maintained by the circumstance
+that human beings are far more interested in themselves than in any
+other material objects. Greek materialism declined, because it could
+not satisfy man’s curiosity about himself. The success of its rival
+was not due to its ability to settle the problems of human nature and
+social conduct. It succeeded because human nature demands a forum for
+the ventilation of its grievances. Science has been most successful
+in the past in dealing with inanimate things. Only in comparatively
+recent times has the phenomenal success of scientific method, fortified
+by the secular influence of Darwin’s teaching, encouraged the belief
+that it might be applied to the study of man’s behaviour and social
+organization. The belief that a philosophical discussion of the Nature
+of Life lies beyond the province of the biologist is due to centuries
+of subservience to a tradition which has identified philosophy with
+the interests of statesmanship and ecclesiasticism. If the method of
+science is applicable to the study of how statesmen and theologians
+behave, it is legitimate to undertake a discussion of the nature
+of life without assuming that the biological standpoint must be
+reinforced by the discipline of scholastic philosophy.
+
+There is a further assumption which we need not make in our enquiries
+into the Nature of Life. We need not presume like Socrates that all
+questions about life are permissible. A proper respect for our own
+limitations is as essential to philosophy as to sanity and modesty in
+everyday life. It is only possible to formulate questions in the right
+way when we already have at our disposal a good deal of information
+relevant to the correct answer. This was not recognized by the
+materialists of the nineteenth century when they attempted to give a
+common-sense solution of the Riddle of Life. To-day it is customary to
+refer to materialism as an exploded fallacy. If instead of looking at
+the way in which the materialist attempted to answer the man in the
+crowd, we examine the way in which he attempted to answer the questions
+which he himself propounded, the explosion of the fallacy is not so
+encouraging to traditional beliefs. The term materialism, when it is
+not employed like Bolshevism as a term of abuse, is loosely applied to
+a constellation of beliefs, some of which concern the Nature of Life
+and some of which concern the Nature of Knowledge. In the latter sense
+materialism implies the conviction that the only genuine knowledge is
+that which can be gained by pursuing the method devised by scientists
+for the study of what are ordinarily called material objects. If this
+conviction is carried to its logical conclusion, a discussion of the
+Nature of Life in language which is intelligible to the audience of
+Mr. Breach or his Secularist competitor is impossible. The materialist
+who attempts a common-sense solution of the Riddle of Life is
+inconsistent with his materialism. It is his inconsistency and not his
+materialism which is an exploded fallacy. Common-sense materialism,
+the materialism which is an exploded fallacy to-day, was based on the
+belief that a plain answer to a plain question is the inalienable
+birthright of the plain man. Secularist rationalism was the offspring
+of Protestant democracy. Protestant democracy is suspicious of the
+expert, who is the person who knows that there is a technique of asking
+questions in the right way as well as a technique of answering them
+in the right way. Perhaps Xanthippe, who has become the symbol of a
+nagging wife, realized this profound truth more clearly than Socrates.
+Perhaps her short way with introspective philosophers was based on a
+considered recognition of human frailty, and experience of children.
+
+An intelligent child of three once asked me to tell her the colour of
+Wednesday. To the more sophisticated adult the question is ridiculous,
+though I suppose the theosophist would regard it as permissible.
+Metaphorically speaking, the habit of asking the colour of Wednesday
+is not exclusively confined to children. Thousands of years ago human
+beings began to associate particular sounds with objects around them,
+so that these sounds became signals for activities. These activities
+became increasingly more complex as articulate speech became more
+elaborate. Gradually human beings ceased to employ a separate symbol
+for every object around them. They began to condense and economize,
+abstracting separate properties. It became no longer necessary to
+have separate words for white cow, black cow, white horse and black
+horse. In effecting this economy it was inevitable that new words with
+no clear relation to experience were often invented. Common language
+the world over is burdened with words which effect no economy of
+discourse. Anyone who has not realized this may perform the simple
+experiment of asking six educated people to define in writing on a
+folded slip of paper the meaning of the word _sincerity_. With the
+coming of civilization man invented a new form of symbolism, the
+language of science. In spite of immense social inertia this symbolism
+has become more and more important, because of the tremendous power
+for controlling nature which it has given us. In the invention of this
+new language not only sustained observation of nature, but active
+interference with nature, or experiment, is enlisted in the process of
+abstraction.
+
+Because common language and the language of science are not the same
+thing, there never can be a plain answer for the plain question of the
+man in the crowd. There can only be a familiar one. In any restricted
+field of scientific enquiry confusion of thought is avoided by the
+introduction of new symbols to denote new experience, or a preliminary
+re-definition of old symbols, if these are employed. So long as the
+chemist is only concerned with the reducing power of a particular
+sugar, it is sufficient for him to describe it as dextrose. When he
+directs his attention to the optical properties of the sugars he finds
+this symbol no longer adequate to define a homogeneous class, and
+distinguishes between α dextrose, β dextrose and so forth. When
+scientific hypothesis so broadens its channels as to merge into the
+general current of human thought, the scientist finds himself dealing
+with matters for which there already exists a vocabulary, but one that
+has none of the precision of scientific nomenclature, one called into
+being by an approach to experience which has none of the disciplined
+restraint which scientific method imposes. That is why the practising
+scientist is sometimes compelled to treat the conundrums of humanistic
+philosophers like the question of the child who wanted to know the
+colour of Wednesday. Concerning those things about which we talk most
+our language is apt to be least definite.
+
+
+§3
+
+One of the things about which we talk most is life itself. A discussion
+of the Nature of Life presupposes that we mean something quite
+definite, when we use the term life. The familiar lines of Mr. Belloc
+suggest a helpful analogy to illustrate the nature of a scientific
+definition:
+
+  “Here you may put with critical felicity
+  The following question, ‘What is Electricity?’
+  ‘Molecular activity,’ say some.
+  Others remain silent or are dumb.”
+
+What is electricity?--is a plain question. It is only possible to
+give it an intelligible answer when we translate it into the form,
+what conditions determine electrical phenomena? A scientific concept
+is a label for a class of properties which can be investigated
+scientifically. Though this happens to be a cardinal doctrine of
+modern logicians, it is also a commonplace of scientific thought,
+when undisturbed by ulterior considerations. It is a commonplace
+which is constantly overlooked by biologists as well as laymen in a
+discussion concerning the nature of life. The temptation to overlook
+it is assisted by the custom of spelling nature and life with capital
+letters, a practice to which what the Melanesians call _mana_ adheres.
+The only intelligible significance of the word Life in scientific
+discussion is to denote collectively the properties of living[1] things.
+
+The word life is variously employed in common language. To Mr.
+Mantalini life is one demmed {sic} thing after another. Every
+biological student is familiar with the experiment of removing a
+frog’s heart from its body, maintaining its beat by perfusing it
+with a suitable saline medium, arresting its rhythm and restarting
+it by changing the constituents of the medium. This can be performed
+repeatedly for many hours after the owner of the heart is, legally
+speaking, dead. The layman confronted with this commonplace of the
+laboratory invariably asks with some show of bewilderment, “Is it
+alive?” It is extremely difficult to answer him in words he will
+understand. He has been accustomed to think of an organism as a whole,
+just as we think of solid matter as a whole. Unaided common sense
+does not easily grasp the notion that the frog’s heart displays the
+characteristic properties of living matter, after the frog, considered
+as a whole, has ceased to display those characteristics of living
+matter which we associate with whole frogs, when we say that they are
+alive.
+
+In biological discussion the nature of life can only be understood
+to mean the characteristic properties of living things, how they are
+related to one another and to the properties of non-living matter, how
+they have come into being. To those who are accustomed to thinking in
+abstract nouns and capital letters this way of defining life will seem
+rather like the well-known definition of an archdeacon as a man who
+discharges archidiaconal functions; but if life is only a convenient
+label for the properties of living matter, we have foreshadowed an
+important conclusion. Those who declare that materialism is an exploded
+fallacy are usually those who deplore the judicial separation of
+science and moral philosophy. If they entertain the hope that biology
+is likely to effect a restitution of conjugal rights, they evidently
+imply that life to the biologist means something more than the
+properties of living matter. They assume that a biological concept of
+life contains other implications of its use in common language.
+
+The source of this confusion is easy to understand. The biologist
+can no more avoid using the word life than the physicist can avoid
+using the word matter in a loose and arbitrary sense in everyday
+conversation. Whatever meaning the biologist may attach to the term
+life, when he is exercising his domestic and political activities,
+there is only one legitimate manner in which he can employ it in
+his capacity as a scientist. Much discussion between the opposing
+schools of vitalists and mechanists is utterly barren, because this
+fundamental issue is not clearly defined at the outset. The vitalist
+can legitimately attack the mechanist by pointing out that living
+things have characteristic properties other than those which the
+mechanist attempts to analyse. If he does so, he must specify what such
+properties are. In the laboratory the biologist carries out his work
+on the same lines, whether he calls himself a vitalist or a mechanist.
+On the platform he may, and frequently does, overlook this. The layman
+may thus acquire a disproportionate estimate of the extent to which
+biologists differ among themselves about fundamental issues.
+
+That biologists are still less unanimous than chemists in the hope of
+resolving, in more universal terms, concepts traditionally restricted
+to their own fields of enquiry, may be attributed to the complexity of
+their subject matter. Biology is a younger science, and a vast amount
+of purely descriptive work was necessary, before it was possible to
+formulate the mechanical problems which living matter presents. This
+task requiring considerable specialization in the descriptive study
+of the exclusively geometrical aspects of the configuration of living
+systems unhappily became divorced from the more fundamental issue of
+biological enquiry. The physical analysis of the properties of living
+matter is a problem necessarily spatio-temporal in its extension,
+experimental in its method, and quantitative in its grammar. The
+spectacular success of evolutionary speculation during the nineteenth
+century preceded the birth of quantitative and experimental researches
+on inheritance and variation, giving descriptive biology a reflected
+glory on account of the far-reaching cosmological consequences of the
+doctrine of descent.
+
+By encouraging the hope of reconstructing the pedigree of mankind,
+Natural Selection widened the gulf between descriptive and experimental
+enquiry; and provided a satisfactory modus vivendi for two diverging
+and independent schools of research. Anatomy claimed the relation of
+one type of living being to another. Physiology concerned itself with
+the relation of living matter to inanimate objects. During the present
+generation evolutionary problems have emerged to the forefront of
+experimental enquiry. Heredity and variation are no longer axioms with
+which the taxidermist and the osteologist can conjure unchallenged.
+Experimental biologists are grateful to those who have compiled
+the Who’s Who of the Animal Kingdom. They refuse to concede that
+the execution of this task implies a profound understanding of the
+principles of political economy. Naturally the anatomist and the field
+naturalist view the change with a jealous and suspicious eye.
+
+Biologists agree among themselves in recognizing that the approach to
+the organism as a physical object has led to many valuable discoveries;
+and that the application of physical methods to the study of the
+organism permits us to make many predictions about the behaviour
+of living systems with as much confidence as we have in predicting
+other secular events. In so far as recent investigation has probed
+into phenomena which it has been customary to place beyond the limit
+of applicability of physical methods and concepts to the analysis
+of the properties of living matter, it is not surprising that many
+biologists have failed to take stock of the situation. They may simply
+deny that certain aspects of the behaviour of organisms can be treated
+successfully by the traditional methods of experimental physiology. If
+they do, it should be sufficient to set forth the new evidence at our
+disposal. When they go further and assert that certain characteristics
+of living things properly belong to the sphere of traditional
+philosophy, it is permissible to entertain the suspicion that they
+share the all too human desire to be _certain_ rather than to _know_.
+
+The chief source of disagreement between different schools of opinion
+in any discussion of the Nature of Life arises from the difficulty
+of defining another concept which is intimately connected, but not
+necessarily co-extensive with, that of life itself. It has been
+customary in the past to assume that the concept of _consciousness_
+defines a field in which the methods of experimental physiology break
+down and require to be supplemented by the method of introspection. In
+so far as it bears on the Nature of Life this implies the possibility
+of identifying and specifying in living systems characteristics to
+which the term consciousness directs attention. It is impossible to
+avoid disagreement in connexion with this concept without recognizing a
+fruitful source of confusion. The statement “I (N or M) am a conscious
+being” has a formal relation to the statement “All men are conscious
+beings” like the analogous statement “Mr. Bertrand Russell is a
+conscious being,” so long as it is understood that I and Mr. Bertrand
+Russell are both single valued and members of the class “men.” From
+this it follows that any implication of the first proposition which is
+not implicit in the second defies logical analysis and therefore eludes
+philosophical enquiry. For the purpose of philosophical discussion “I
+am a conscious being” contains nothing that is not implied by saying
+that “all men are conscious beings.” I shall use the term _public_
+to signify this way of looking at the concept of consciousness. Any
+residuum of the first proposition which cannot be formally identified
+with the third and shown like it to be included in the second and
+more general proposition is a _private_ affair of the individual.
+If we find that modern physiology has undertaken to investigate
+those characteristics of the behaviour of living systems associated
+with the term consciousness in its public sense, a new horizon of
+philosophical discussion is unfolded. If physiology is more successful
+than introspective philosophy in defining predictable conclusions about
+living behaviour, we have no need to go outside the data of physiology
+for the materials of a comprehensive discussion of the Nature of Life.
+A philosophical discussion of the Nature of Life will only be more
+comprehensive than a biological discussion of the Nature of Life in
+the sense that more attention will be paid to the methods of enquiry
+adopted.
+
+Between two extreme schools of opinion existing at the present day the
+issue, in so far as it is a tangible one to the practising biologist,
+is thus defined by Dr. Haldane in his recent Gifford Lectures.
+
+  “We can of course leave the characteristic peculiarities of
+  conscious behaviour out of account, and regard persons from a
+  purely physical and chemical point, as weighing so much, as
+  yielding certain amounts of various proteins and other chemical
+  substances, distributed in a certain way, and as in various ways
+  continually converting potential into kinetic energy. This mode
+  of regarding persons is of great practical use for engineering
+  and other purposes, _but tells us nothing, however far we may
+  extend it, regarding the distinctive_ characters of conscious
+  behaviour...” (italics inserted).
+
+In this passage Dr. Haldane is perfectly definite in stating where,
+as he believes, the methods of traditional physiology cease to
+be applicable. It is peculiarly felicitous that he uses the term
+conscious behaviour rather than consciousness in this connexion. If
+we find reason to believe that “conscious behaviour” can be analysed
+with reference to a space-time framework by the methods of physical
+science, Dr. Haldane’s attack on the mechanistic position falls to
+the ground except in so far as he can refuse to capitulate until the
+problem has been reduced to a question of pure physical chemistry. In
+the succeeding essay on The Mechanization of Consciousness I shall
+endeavour to show that in our generation the work of Pavlov’s school
+has successfully tackled, for the first time in history, the problem of
+what Dr. Haldane calls “conscious behaviour” in non-teleological terms.
+It has reduced it to the investigation of the conditions under which
+new reflex systems are brought into being.
+
+In _Science and the Modern World_ Professor Whitehead states that
+the “effect of physiology” on philosophical discussion has been
+“to put mind back into nature.” I presume that he is referring to
+the traditional distinction between reflex activity and voluntary
+behaviour. It is true that physiology has accepted this distinction
+which it inherited from the dualism of Descartes; but traditional
+physiology never attempted to probe deeply into the nature of
+voluntary behaviour. It was content to investigate reflex activity,
+and concede the prerogative of discussing the characteristics of
+conscious behaviour to moral philosophy. _Experimental physiology
+like experimental physics is an ethically neutral science._ If Pavlov
+has reduced the problem of conscious behaviour to the same level
+of discussion as the problems of reflex behaviour, the traditional
+distinction between reflex and voluntary activity has ceased to define
+the boundary at which physiology ends and moral philosophy begins. If
+the investigation of the characteristics of conscious behaviour can
+be brought within the scope of an ethically neutral method, we must
+abandon any hope that biology can assist to end “the divorce of science
+from the affirmations of æsthetic and ethical experiences.” If the
+Relativists can say that modern physics has given materialism its death
+blow by referring solid matter to an atomic nexus of conceptual fields
+of force which only exist in our consciousness, the physiologist can
+add that modern biological enquiry is disintegrating consciousness into
+an atomic nexus of reflex arcs. If modern physics has shown that we
+can no longer think profitably of solid matter as existing in the way
+in which it presents itself to common sense, modern biology is showing
+that for the purpose of profitable discourse mind itself does not exist
+as the essential unity which it assumes to common sense. If the advance
+of science has disposed of the older forms of materialism, it is also
+disposing of the traditional forms of idealism and dualism at the same
+time.
+
+Biological science no less than physics is opening up new fields
+for exploration in philosophy. The new approach to the problem
+of “conscious behaviour” involves an intellectual effort no less
+repugnant than the non-Euclidean space of the relativist. The new,
+in preference to the traditional biological standpoint, owes its
+sanction to the same test as that by which relativistic theories must
+in the last resort be assayed. A disinclination to discuss “conscious
+behaviour” and a tendency to assert dogmatically the possibility of
+reducing it to purely chemical concepts has been characteristic of the
+mechanistic standpoint in the past. It would seem that to emphasize the
+applicability of physical methods to living matter in all its aspects,
+a new term, free from this taint, is now needed. _Behaviourist_ has
+already acquired certain restricted implications, and for reasons which
+will be set forth in a succeeding essay I shall sometimes speak of
+the _publicist_ in preference to the mechanistic standpoint. Unlike
+the Flat Earth doctrine of Mr. Breach the publicist standpoint in
+philosophy is not based on an appeal to common sense.
+
+I began these introductory remarks by calling attention to two
+characteristic features of contemporary thought, the uneasy recognition
+of the opposition of science to common sense and the renewed search
+for a working agreement between the claims of science and of moral
+philosophy. In concluding, I would add a third to which I have not
+explicitly referred. The scientist brought into collision with common
+sense has for the time being lost his former air of self-confidence.
+We are told that science does not deal with reality, that the external
+world of physics is a shadow world, that the laws of physics are only
+statistical generalizations, that scientific hypotheses are no more
+than convenient devices to aid us in the practical business of living.
+I cannot but feel that the solemnity of these assertions is out of all
+proportion to their novelty. I cannot discover why recent developments
+in physics constitute a specially cogent reason for reiterating them
+at the present moment. I am disposed to believe that some of the
+younger generation who have been familiar with the writings of Mach,
+of Pearson, of William James and of Bergson, since they first began to
+think about the nature of scientific knowledge, must share with me a
+sentiment of surprise, when told that living scientists ever seriously
+put forward those extravagant claims which, as we are now assured,
+received their death blow from the theory of a relativity and the new
+quantum mechanics. The apologetic attitude so prevalent in science
+to-day is not a logical outcome of the introduction of new concepts. It
+is based upon the hope of reinstating traditional beliefs with which
+science was at one time in open conflict. This hope is not a by-product
+of scientific discovery. It has its roots in the social temper of
+the period. For half a decade the nations of Europe abandoned the
+exercise of reason in their relations with one another. Intellectual
+detachment was disloyalty. Criticism of traditional belief was treason.
+Philosophers and men of science bowed to the inexorable decree of herd
+suggestion. Compromise to traditional belief became the hall-mark of
+good citizenship. Contemporary philosophy has yet to find a way out of
+the intellectual discouragement which is the heritage of a World War.
+
+The physicist has abandoned teleology in his own field. He has banished
+the spiritual values from the domain of his enquiries. He now looks
+to the biologist to shoulder the task of proving that the universe is
+consonant with our notions of ethical propriety. I shall endeavour to
+show that the progress of modern biology gives no justification for
+the belief that such a compromise is possible. In approaching this
+task my aim is not primarily to advocate the mechanistic conception of
+life or to criticise the vitalistic standpoint. Controversy between
+writers of the mechanistic and vitalistic schools has too often focused
+attention on whether a complete solution of the Nature of Life can be
+found within the mechanistic framework. The more significant question
+is whether any solution can be obtained outside the mechanistic
+framework. It may be interesting to know how far the biologist has
+progressed in his enquiry into the Nature of Life. Philosophically it
+is more significant to understand what methods of investigation have
+permitted him to advance towards an admittedly partial solution of his
+problem. To show that the mechanistic conception of life is inadequate
+is one thing. To show that any alternative and more comprehensive view
+can be gained by pursuing methods other than the traditional methods
+of experimental biology is a more difficult task. It appears to me
+that the mechanist can admit every criticism which the vitalist brings
+to bear upon his case without weakening its essential strength. If
+we commence our enquiries with the assumption that it is possible to
+know everything, we shall be disappointed to find that the mechanistic
+conception of life does not--and probably never will--find an answer
+to every question which we may be tempted to propound. In that
+disappointment lies the false security of the vitalistic standpoint.
+It was the peculiar merit of Hume’s philosophy that he rejected the
+necessity of making this assumption.
+
+In assessing the respective contributions of the biological and
+physical sciences to the construction of a Public World, we are
+investigating the existence of certain characteristics common to all
+branches of natural science. The method of science is not static. It
+is ever growing and expanding, incorporating new territories within
+its empire. For this reason formal definitions unfortified by an
+examination of the historic past tend to be superficial and barren.
+The origins of even the most exact sciences are deeply rooted in
+the soil of magic. At any stage in the progress of human knowledge
+particular features may be evident in more than one branch of enquiry.
+As time goes on fresh similarities present themselves. The exact line
+of demarcation between the already scientific and what is not as yet
+scientific is therefore somewhat arbitrary. No definition of scientific
+method is adequate unless it implies the recognition of a developmental
+sequence in which new characteristics emerge successively into
+prominence.
+
+In the natural sciences, as customarily defined, it is essential that
+the data shall be publicly accredited by the testimony of independent
+observers. The observation and recording of publicly accredited data
+is not in itself regarded as an adequate criterion of scientific
+study, unless the data are arranged or classified in a particular way.
+Such classification makes it possible to draw inferences which extend
+beyond the range of the original data. The validity of the relations
+implied in a particular classification is referred to their capacity
+to permit us to predict verifiable conclusions. In practice it is
+necessary to classify the data of a problem in a variety of ways before
+it is possible to arrive at the type of classification which yields
+relations satisfying this criterion of validity. This circumstance
+assists us to draw a rough distinction between a type of enquiry
+which is maturely scientific and one which is in process of becoming
+scientific. In the older and more firmly established branches of
+science, it is evident that severe economy in the initial assumptions
+promotes the construction of hypotheses which are valid in the sense
+defined. Ethical values have been eliminated altogether. The same
+characteristics are increasingly recognized in newer departments of
+scientific investigation.
+
+When every criticism of the limitations of scientific method has been
+accepted, the belief that philosophy can provide a means of solving
+the problems which lie outside the realm of scientific enquiry still
+remains to be proved. In the essays which form the third series of this
+volume, I shall endeavour to discuss whether an enquiry into the nature
+of reality has any intelligible meaning. With Hume I doubt whether it
+is possible to attach any significance to deciding whether scientific
+beliefs are a faithful representation of “reality.” Scientific beliefs
+are specially characterized by their communicability, or, to use the
+term which I shall employ more frequently, their _publicity_. The
+fundamental problem of a philosophy which does not presuppose what
+it sets out to establish is to find what characteristics of beliefs
+make them communicable. It is by examining these characteristics
+that we can hope to decide whether the discussion of our ethical and
+æsthetic predilections can yield conclusions which have the same kind
+of communicability as scientific beliefs, and, if that is possible,
+in what manner such discussion must be conducted. I shall endeavour
+to show that there is a confusion of meaning involved in discussing
+whether the experiences with which science deals are more or less real
+than the experiences which moral philosophy has claimed for its parish.
+The more modest task of deciding whether the conclusions of science
+have more or less communicability than ethical and æsthetic beliefs is
+not a problem which necessarily eludes unprejudiced investigation.
+
+I have indicated that an enquiry into the nature of life and the
+nature of consciousness presupposes the necessity of formulating the
+problem in the right way. This task is a necessary preliminary to
+the analogous question, what is philosophy? The firefly emits light.
+When we say that we understand what animal light is, we mean that we
+understand what processes are involved in the production of animal
+light. The method of science can lay bare the structures in which
+luminescent materials are secreted and the physical transformation
+of their chemical energy into visible radiation. Animal light is an
+unusual characteristic of a species of insect known as the firefly.
+The light of reason is a peculiar characteristic of certain human
+beings known as philosophers. We can only say that we truly understand
+philosophy or the light of reason, if we understand the processes which
+confer upon philosophers their unusual characteristics. A philosopher
+brought into being by the process of natural generation develops in an
+environment which includes inanimate objects and other human beings.
+He reacts to his physical environment by growth and to his social
+environment by learning. If the method of science can assist us to
+elucidate the processes of growth, learning and natural generation,
+science can assist us to understand what philosophy is. The anatomy
+of philosophy and the physiology of philosophers are inseparable. We
+need not be discouraged in pursuing this line of enquiry, because the
+answer which science can give us at present is incomplete. It is the
+chief glory of science that its answers are always incomplete. The
+pitiful failure of introspective philosophy resides in the finality of
+its answers. Perhaps the most permanent influence of Relativity in the
+history of philosophy will prove to be the challenge it issued to the
+finality with which Kant enunciated the concepts of space and time.
+
+
+
+
+I. THE MECHANIZATION OF CONSCIOUSNESS
+
+  “Now, in conclusion, the Method which teaches adherence to the
+  true order and an exact enumeration of the conditions of the
+  thing sought includes all that gives certitude to the rules of
+  arithmetic.”--Descartes, _Discourse on Method_
+
+
+§1
+
+The onus of proving that all the properties of living matter can be
+reduced eventually to problems in physical chemistry or, on the other
+hand, of denying that such will ever be accomplished, may be laid on
+the shoulders of those who commit themselves to rash affirmations and
+denials. If this were the only matter to decide, a discussion of the
+merits of the mechanistic conception of life could reveal nothing more
+than a temperamental difference between the disputants. A temperamental
+difference does exist. The mechanist has a cheerful attitude to
+knowledge and refuses to capitulate to the fear of the Unknown: the
+vitalist, a sadder but not necessarily wiser type, finds balm in the
+limitations and failures of human effort. The average biologist, who
+has little sympathy either for the heroic or the desperate point of
+view, maintains a detached scepticism.
+
+Such scepticism has much to commend it; but scepticism no less than
+piety can be employed as an excuse for mere intellectual laziness.
+Between those who advocate the mechanistic conception of life and those
+who reject it, there is a divergence of outlook more fundamental than
+usually appears in the course of controversy. Whether the same set of
+hypotheses will ultimately serve to interpret the properties of living
+and non-living matter may be left to the arbitrament of time. For
+practical purposes a decision one way or the other makes very little
+difference to the course of biological enquiry. The fundamental unity
+of scientific method in chemistry and physics is not invalidated by
+the fact that some phenomena can only be dealt with successfully in
+thermodynamical terms, while yet others yield only to treatment with
+the aid of kinetic and molecular hypotheses. It is less important to
+know how far the properties of living matter can be reduced to physical
+chemistry than to decide whether the logical structure of biological
+enquiry is essentially similar to or different from that of physical
+science. This is an issue of the most far-reaching consequences, not
+merely for philosophy but for biology as well. Though rarely stated
+explicitly, it represents the basic divergence of standpoint between
+the mechanist and the vitalist or holist. It is not merely a matter of
+taste or temperament: it is profoundly relevant to the way in which
+biological enquiry continues to develop. In this matter scepticism can
+only be justified by disinclination to face uncomfortable conclusions.
+
+If the logical structure of biological enquiry is essentially similar
+to that of physical science, we must entertain the possibility of
+interpreting the whole domain of living matter without departing
+from the principle of ethical neutrality. This is not a pleasant
+possibility to admit; and it is hardly surprising that few biologists
+are enthusiastic in committing themselves with regard to it. If we
+find that there is no fundamental difference between the logical
+structure of biological and physical science, we cannot follow Dr.
+Whitehead in reviving the hope that scientific enquiry will eventually
+yield conclusions about the universe in conformity with our ethical
+predilections. If, without modifying the structure of its logic,
+biological science is capable of annexing as its parish the entire
+survey of living matter, there remains no nicely defined boundary
+at which science ends and philosophy begins. Philosophical enquiry
+must then abandon its pretensions to arrive at conclusions about
+the universe unaided by scientific discovery. It must restrict its
+operations to an examination of the logical structure of beliefs. It is
+therefore remarkable that the biological standpoint has been so little
+explored in contemporary criticism of traditional philosophy.
+
+During the past two decades there have been three outstanding
+developments in biological research, the work of A. V. Hill and
+Meyerhof on the chemical mechanics of muscle, the extension of Mendel’s
+hypothesis by Morgan and his colleagues at Columbia, and the study of
+the conditioned reflex by Pavlov’s school. Of these the first alone
+represents an advance in the actual reduction of vital processes to
+physical chemistry. Yet no aspect of biology could be selected more
+appropriately than Morgan’s hypothesis to illustrate its logical unity
+with the study of chemistry. The study of the conditioned reflex
+has not as yet enlisted the resources of physical chemistry to any
+noticeable extent. Nor does it employ a logical technique as elaborate
+as that of the modern chromosome hypothesis. Its importance lies in
+the fact that it has emancipated biological study from the Cartesian
+dualism with its implicit assumption that method of enquiry applicable
+to one aspect of the properties of living matter is of a totally
+different kind from that employed in dealing with the remainder.
+
+To estimate the significance of this advance it is necessary to start
+with a clear statement about the meaning of a word. The term _reflex_
+is used by dentists, politicians and faith healers with a variety of
+implications irrelevant to the biologist. To exclude these irrelevant
+associations it is best to be concrete. Suppose that we decapitate
+or destroy the brain of a frog, and suspend it, legs downwards, in a
+vertical position. On raising a vessel of warm--about 40° C.--water,
+until the tips of the toes touch the surface, the legs of the animal
+are withdrawn after a short interval. This event takes place regularly
+and similarly under the same conditions. It is as definite and
+predictable a property of secular objects as is the precipitation of
+barium sulphate on mixing a solution of barium chloride with a solution
+of sodium sulphate. It is, if you care to express it in that way, a
+physical reaction between warm water and frog toes. In biological
+nomenclature it is a reflex.
+
+The word reflex is not used in biology to denote every change that
+occurs in living matter. To clarify its meaning further we must
+consider how such a phenomenon can be studied more intimately. To the
+biologist it presents two types of problem. One is that of analysing
+the constituent parts of the reaction, and is analogous to what the
+chemist does, when he determines the solubility and dissociation
+constants of barium sulphate, barium chloride, sodium sulphate and
+sodium chloride to define more precisely what occurs during the
+reaction with a view to elucidating conditions under which it may be
+expected to occur. In the biological example that we have taken the
+first stage involves the purely spatial (or anatomical) examination of
+the reaction. It may be noted in this connexion that anatomy in its
+initial phase was an experimental science, and only became a catalogue
+in its dotage. We observe that we are dealing with a localized response
+to a localized agent involving a spatially localized structure the
+nervous system. We can in fact obtain the reaction from a preparation
+from which every structure but the skin of the toe, the nervous system
+and the muscles of the leg have been removed. From this point we
+proceed by a study of the temporal relations of the phenomenon, first
+undertaken by Helmholtz, to show that a disturbance is propagated
+at a measurable, predictable and modifiable rate from the seat of
+application of the agent to the seat of the visible reaction. The
+further analysis of the problem from the physico-chemical standpoint,
+an essentially modern development, will be referred to in a subsequent
+essay. We have now obtained the current definition of a reflex as a
+localized response to a localized stimulus, involving the intervention
+of the propagated disturbance known as the _nervous impulse_. Erroneous
+ideas implied in the common use of the term reflex arise chiefly in
+connexion with the second aspect of the study of reflex phenomena. This
+is not readily comparable with the investigation of a simple reaction
+like the precipitation of barium chloride. It might be compared with
+the interpretation of a more complex system such as the oxidation of
+oxalic acid in the presence of potassium permanganate and sulphuric
+acid, when the behaviour of any two reactants towards one another is
+already known. Frogs lift their legs from time to time in civil life,
+when they enjoy the use of a head. We may therefore ask what part
+do such reflexes, as we can study in the headless frog, play in the
+behaviour of the intact animal.
+
+In any reflex displayed by the pithed frog the nervous impulse
+traverses a characteristic path. From the skin, the receptive area
+affected, it passes by one of numerous fibres of microscopic thickness
+to the spinal cord. Such fibres together with others carrying impulses
+from the cord to the muscles or glands collectively constitute the
+visible nerves. Fibres carrying impulses into the cord divide into very
+fine branches in the inner core or grey matter. These fine branches
+are intertwined with the ramifications of other fibres passing up
+and down the length of the cord. The latter branch at their other
+extremities around the fine endings of fibres which pass from the cord
+to the glands and muscles. An impulse entering the spinal cord first
+therefore passes across the junction or _synapse_ between the fibre
+along which it enters the cord and some other fibre running up or down
+the cord. Having traversed the latter, it passes across the junction or
+synapse between its branched ending and that of some fibre connecting
+the spinal cord with a muscle or gland. Reflex action depends upon the
+fact that an impulse travelling along a particular fibre can traverse
+some synapses more readily than others. This is a physical process,
+occupying a measurable time. By the use of certain physical reagents it
+is possible to increase the conductivity of the synapses, so that an
+impulse entering the cord irradiates to all the muscles of the body.
+Strychnine is such a reagent.
+
+The familiar fact that the moth flies towards the candle will serve
+to illustrate how the study of a simple reflex, like the withdrawal
+of the toes of the pithed frog from warm water, makes it possible to
+make predictable conclusions about the normal behaviour of animals.
+If the nerves of the frog’s leg are severed, the leg hangs limply.
+Normally the muscles of the leg are never completely relaxed. They
+are maintained in a state of partial contraction or _tone_, reflexly
+determined by a number of agencies which for our present purpose it
+is unnecessary to specify. The nerve fibres which run up and down the
+length of the spinal cord in the frog cross from one side to the other
+at some level, and on this account most reflexes obtained in the pithed
+frog, when only one side is stimulated, involve muscular response of
+both sides of the body. Insects which move towards the light become
+noticeably more limp in darkness. Light reflexly increases the tone of
+their muscles. In insects there is little crossing of fibres from one
+side of the central nervous system to the other. It follows that, if
+light reflexly increases tone, the muscles of that side will be more
+contracted, when one eye is illuminated more strongly than its fellow.
+This will have the effect of bending the body round in the direction of
+the incident beam, until the head is brought into such a position that
+both sides are equally illuminated. Having attained this position the
+body will continue to move along the direction of the incident beam. If
+it swerves to the right or left, it is automatically readjusted.
+
+This interpretation of the proverbial flight of the moth towards the
+candle permits us to make a very large number of easily verifiable
+predictions. One simple consequence repeatedly confirmed by experiment
+on a variety of insects which fly towards the light is the fact that,
+when one eye is blinded, they fly in circles. There is no need to
+mention the variety of predictable positions which such insects occupy,
+when allowed to crawl up rotating cylinders illuminated in various
+ways. One other rather interesting result of the experimental analysis
+of this phenomenon is worth mentioning. According to the common sense
+view the insect moves towards the candle, because it likes the
+light. There is one and only one fairly evident inference from the
+teleological way of looking at the matter. It implies that the moth
+should always fly from the darker to the brighter situation. Now the
+interpretation of its movement in terms of reflex action signifies that
+it is the direction of the light rays and not primarily the intensity
+of illumination which determines the direction of its movement. In
+Nature moving along the direction of the rays towards the source of
+light usually involves progression from a darker to a brighter region.
+In the laboratory it is easy to arrange conditions so that an insect
+crawling along the direction of an obliquely incident beam, moves from
+a brighter to a darker area, as it approaches the source. In doing so
+it behaves, as it would be predicted to behave in such a situation
+on the assumption that its behaviour is determined by reflex action.
+According to the teleological view it should do the opposite.
+
+Even in the behaviour of so capricious an animal as man himself, it
+is possible to isolate units of behaviour to which the term _reflex_
+is appropriate. The entire behaviour of a pithed frog or of a dog
+deprived of its brain can be regarded as the summation of a number
+of discrete reflexes compounded according to ascertainable laws. The
+problem is not a simple one; but the way in which the operation of
+one reflex affects the exercise of another has been elucidated with
+considerable success by Sherrington and his co-workers. Sherrington has
+paid special attention to what occurs in the simultaneous application
+of two stimuli whose appropriate responses involve the propagation
+of impulses along common fibres within the central nervous system.
+A further complication is introduced by the existence of inhibitory
+reflexes, responses which involve the cessation or the diminution of
+activity already in progress before the application of the stimulus.
+The work of Magnus and his colleagues, who have solved the riddle of
+how a cat falls on all fours, demonstrates to a very large extent the
+possibility of interpreting balancing movements of the body as the
+summation of such reflexes as are readily exhibited in the brainless
+or “spinal” animal. Yet few physiologists have ventured to entertain
+the likelihood that the entire behaviour of even such an animal as a
+cat, still less man himself, could be treated successfully in this
+way. Hence has arisen the traditional distinction between reflex and
+voluntary activity. So long as that distinction was a valid one,
+biology admitted a fundamental dualism in its subject matter and in its
+method. The vitalist was in a position to claim that there is a group
+of properties of living matter in dealing with which we must adopt
+introspective rather than physical methods of enquiry. The mechanist
+might reply epigrammatically that physiology deals with what we know
+about the central nervous system, psychology with what we do not know.
+The distinction still remained.
+
+There are certain fairly evident reasons why the behaviour of a frog
+deprived of its brain should be simpler than that of the intact animal.
+One is that the number of possible paths along which nervous impulses
+can pass is much smaller. Another is the fact that the brain receives
+the nerves which bring in impulses from the three great receptor
+organs, or, in the older terminology, sense organs of the head. The eye
+and the ear bring the organism within the range of physical influence
+of innumerable events remotely situated in space. When we have allowed
+for all such differences there remains a perfectly tangible distinction
+between the behaviour of the spinal and that of the intact animal.
+The response that we have hitherto called a reflex is such that for a
+given agency under the same external conditions we may expect the same
+result. There are the best of reasons, based not on any introspective
+ideas but upon the study of behaviour to make us think that however
+much we standardize the external conditions at the moment, when the
+stimulus is applied, we can never predict from that alone exactly
+what will happen as the result of the application of certain types of
+stimuli. The performance of “learning” justifies this conclusion, and
+it has been customary in the past to refer this property of living
+matter to essentially non-physical concepts such as _memory_. By
+defining in this way the distinction between reflex behaviour in the
+traditional sense and voluntary or conscious behaviour, a new problem
+has emerged. This may be stated in the following way. If instead of
+concentrating exclusively on what is happening at the moment, we take
+into consideration the way in which a given stimulus has been presented
+to an organism on previous occasions, is it possible to establish any
+relation between the effect it now produces and the events associated
+with its application antecedently? In so stating the issue we have
+introduced no new and introspective concepts foreign to the traditional
+physiology of the reflex. We have simply envisaged the possibility of
+studying conditions under which new reflex systems may be brought into
+being.
+
+
+§2
+
+It is this problem which the Russian physiologist Pavlov and his
+co-workers have attacked with such conspicuous success during the
+past two decades. For some time their researches remained little known
+in this country, but two translations of Pavlov’s lectures are now
+accessible to the English-speaking reader. There is therefore no need
+to go into details concerning the experimental technique which is
+formidable. The more significant developments of the subject may be
+dealt with by considering how aspects of behaviour which were formerly
+referred to the introspective concepts of memory, attention and
+sensation can now be investigated without departing from the language
+adopted by physiologists, when describing the properties of simple
+reflex action.
+
+Pavlov’s investigations commenced with the study of salivary secretion
+in dogs. A dog which has been deprived of the forebrain secretes
+saliva, when food is introduced into the mouth. The intact animal also
+secretes saliva, when food is brought within the range of its eyes or
+nostrils. In the adult the sight or smell of food is an appropriate
+stimulus for reflex salivary secretion. The ringing of a bell is
+ordinarily without effect on the secretion of saliva; but the ringing
+of a bell if repeated a certain number of times, when food is also
+presented, eventually comes to evoke salivary secretion, when food
+does not accompany it. In general it is found that, in the intact
+animal, a previously indifferent stimulus applied at suitable intervals
+simultaneously with the application of a stimulus which unconditionally
+evokes a reflex response is found to acquire the property of evoking
+the same reflex response, when unaccompanied by the original or
+“unconditioned” stimulus. A new reflex has been built up. Such reflexes
+are called by Pavlov _conditioned_ reflexes, and the previously
+indifferent stimulus is called the conditioned stimulus. Any event in
+the external world which affects a receptor organ may in the intact
+animal become a conditioned stimulus, provided external conditions
+are rigidly standardized in other respects, provided also that it
+accompanies the unconditioned stimulus a sufficient number of times
+depending on whether the application is precisely simultaneous, whether
+the conditioned stimulus begins to operate before the unconditioned,
+overlapping it in duration or separated from it by a short interval.
+The task of defining the facility with which a conditioned reflex is
+built up involves a study of the significance of the interval between
+successive applications of both stimuli and of the juxtaposition of
+conditioned and unconditioned stimulus. In defining the conditions
+which determine the bringing into being of a new reflex system by this
+method, we are investigating a class of phenomena which would formerly
+have been attributed to “memory.” At no point is it necessary to depart
+from the conventions of scientific nomenclature; and in place of a
+descriptive epithet, we arrive at a definite specification regarding
+when and whether an event will occur.
+
+What it has been the custom to denote by the term memory is only one
+aspect of the problem of “conscious” or “voluntary” behaviour, that
+is to say those aspects of behaviour which are spatially referable to
+reflex paths in the fore brain. An animal is constantly subject to
+the simultaneous application of many indifferent and unconditioned
+stimuli, but its behaviour is selective. This introduces the problem
+of _attention_. To ascertain the conditions which prevent new reflex
+systems from coming into being, or extinguish them when they have
+become established, was perhaps the most important aspect of Pavlov’s
+work, because an understanding of this part of the problem underlies
+the successful control of experimental procedure. The possibility of
+isolating a conditioned reflex for study implies the existence of
+some inhibitory agencies which prevent the normal surroundings of the
+laboratory from exerting a significant influence on the course of
+the experiment. The inhibition of conditioned reflexes is a complex
+question; and its complexity emphasizes how broad a basis they offer
+for the interpretation of “conscious” behaviour in general and the
+interpretation of _attention_ in particular.
+
+From this standpoint two important types of inhibition are called
+by Pavlov inhibition by extinction and conditional inhibition. The
+first term refers to the fact that, when an indifferent stimulus has
+been converted into a conditioned stimulus, and is then allowed to
+act repeatedly without the unconditioned stimulus, it gradually loses
+its potency, regaining it after an interval of rest. Conditional
+inhibition is the extinction which occurs, when a new indifferent
+stimulus is superimposed upon the effective phase of a conditioned
+stimulus. A third and especially important form of inhibition is the
+extinction of a state of inhibition by conditional inhibition, or as
+Pavlov calls it, inhibition of inhibition. Let us suppose that an
+organ note of one thousand vibrations per second has been made the
+signal for salivary secretion by repeated application of the stimulus,
+when food is administered to the animal. If it is now administered
+repeatedly without the accompaniment of food, it suffers inhibition
+by extinction, but recovers its efficacy after a period of rest. If,
+during the indifferent period, the experimenter superimposes on the
+now ineffective sound stimulus another indifferent agent such as the
+flash of a lamp before the dog’s eyes, secretion of saliva ensues.
+The sound regains its efficacy as a conditioned stimulus. One other
+type of inhibition which can be studied experimentally is “generalized
+inhibition” or elimination of the activity of the fore brain, which can
+be brought about in the dog by local warming or cooling of an area of
+the skin. This has an intimate bearing on the phenomena of sleep and
+hypnotic trance, as also on the advantages of summer time.
+
+Perhaps the most radical consequence of the line of work which we
+are now considering lies in the possibilities which it presents for
+inverting our traditional attitude to the discussion of “sensation.”
+When we can isolate some simple unconditioned response to a particular
+stimulus, we can investigate the extent to which the efficacy of
+the stimulus is localized with reference to some receptive area,
+and discuss the sense organ in the same way as a piece of physical
+apparatus. We know for instance that a frog does not respond to white
+or black background by the appropriate change in colour of the skin, if
+its eyes are removed. The influence of the earth’s gravitational field
+on the way in which a frog maintains its normal balance in swimming
+provides another illustration of the way in which the experimental
+biologist deals with the phenomenon of receptivity, when it is possible
+to isolate a type of response which invariably accompanies a particular
+type of stimulation. In this instance the receptor is that part of the
+internal ear known as the labyrinthine organ. After destruction of the
+labyrinthine organ on one side only, a frog swims in a spiral path. If
+the internal ear of both sides is removed, it swims hither and thither,
+as likely as not upside down or sideways without any sign of its normal
+maintenance of balance. The inner ear of the frog or man with its
+three semicircular canals in the three Cartesian planes is a rather
+elaborate example of a type of receptor organ represented in shrimps
+by two little sacs called statocysts at the base of the feelers.
+These sacs contain concretions of sand known as the statoliths.
+Experimentally the sand can be replaced by iron filings. If this is
+done, the shrimp swims upside down, when a strong electromagnet is
+placed above it. The position occupied by the statolith in its sac is
+determined by the pull of gravity in ordinary circumstances. When the
+body is bent, the statocyst comes into contact with a new portion of
+the wall of the sac, thus stimulating a different set of nerve fibres,
+and initiating appropriate muscular reflexes. The balancing movements
+of a shrimp in swimming also depend on the eyes. With both feelers
+removed a shrimp swims normally in daylight. It loses its balance
+completely in a dark room; and swims on its back if illuminated from
+below. Removal of one eye or one statocyst does not affect its balance
+in daylight, unless the two operations are performed on the same
+animal. It then swims in spirals.
+
+A modern biologist adopts to the statocyst and the eye the same
+attitude which he would adopt to the self starter of a motor car, if he
+were quite ignorant of its mechanism. Sometimes his problem is further
+complicated by the necessity of turning on the switch before the engine
+will start, adjusting the spark or cutting down the air. In an animal
+whose behaviour is largely conditioned behaviour, it is not so easy to
+isolate simple invariable responses to particular types of external
+agency. We lapse into the language of introspective psychology. Pavlov
+has shown that this is unnecessary. By employing the method of building
+up conditioned reflexes to define the limits of discrimination, the
+analysis of sensation can be carried out without departing from the
+attitude which we adopt to a motor car. Let us suppose that the sound
+of a tuning fork of 256 vibrations per second, i.e. middle C, is
+accompanied by electrical stimulation of the paw of the dog, until the
+note itself becomes an effective stimulus for withdrawal of the paw.
+A tuning fork of 264 vibrations will also evoke the withdrawal of the
+paw; but the application of the second stimulus suffers inhibition by
+extinction before the original (middle C), as can be shown by applying
+the latter after response to the tuning fork of 264 vibrations has
+been extinguished. Applying series of tuning forks in such experiments
+it is found that the limits of discrimination in dogs is a fraction
+of a tone. The delicacy of this method of testing discrimination or
+selective receptivity to a given range of stimuli depends on the fact
+that it is possible not merely to show whether one stimulus can be
+substituted for another in a conditioned reflex but to measure the
+extent to which a given stimulus can replace another. Judged from this
+standpoint dogs and cats are colour blind, as far as such a statement
+can have any tangible meaning. That is to say, differences of light
+intensity but not of wave length in the effective range determine the
+reactions of these animals to photic stimuli.
+
+
+§3
+
+In the light of Pavlov’s work the problem of conscious behaviour, or
+as we should now say conditioned behaviour, no longer presents itself
+to biological enquiry as a domain in which the methods of traditional
+physiology must be abandoned in favour of introspective speculation.
+It becomes the problem of defining how new reflex systems can be
+built up. The possibility of a further analysis of the process on
+mechanistic lines will be discussed elsewhere. Whatever success attends
+such an attempt, the fact remains that the controversy between the
+mechanistic and vitalistic schools must now be conducted on a new
+basis. Mechanistic biology could not claim to take a comprehensive view
+of the properties of living matter, so long as it failed to indicate
+how “voluntary” activity, as it was almost universally denoted by
+physiologists, differs from reflex activity. It is true that some of
+the more radical mechanists like Loeb preferred to speak of associative
+behaviour as having a more objective flavour. But Loeb’s own use of the
+concept of “brain images” emphasizes how fundamental is the innovation
+which the work of Pavlov’s school has introduced into philosophical
+discussion. The mechanist never legitimately claimed more than the
+right to investigate the properties of living matter in its simpler
+manifestations by those methods whose success had been justified in
+the domain of physics and chemistry. If the mechanist ventured to
+speculate beyond those limits he transgressed his terms of reference.
+Until the publication of the work of Pavlov’s school physiology was
+tied hand and foot to the traditional distinction between reflex and
+voluntary behaviour. Thus the author of a standard work on human
+physiology with a distinctly mechanistic tendency writes on the
+functions of the cerebellum: “... the degree of consciousness, if any,
+exhibited by the cerebellum is of a much lower order than that shown
+by the cerebrum. All observers agree that there is no apparent loss of
+sensation after removal of the cerebellum, but Luciani, Russell and
+others state their belief that in some indefinable way it is affected
+by such operations. Whatever functions of this kind are present we can
+define only by the unsatisfactory terms of subconscious rather than
+unconscious...” What Howell wrote in 1905 might have been written by
+any mechanist of that period. The physiologist inevitably lapsed into
+introspective terminology, when dealing with brain physiology; and it
+is this restricted mechanistic outlook which Dr. Haldane has attacked
+in his recent Gifford Lectures. It is not difficult to show that the
+mechanist, as that term is used by Dr. Haldane, accepted implicitly the
+Cartesian compromise. It is surprising that, although Pavlov’s work
+has been generally accepted by contemporary biologists, Dr. Haldane
+completely refrains from considering its bearing on the present status
+of the mechanistic conception of life.
+
+Dr. Haldane’s statement that the method of traditional, i.e.
+mechanistic, physiology “tells us nothing, however far we may extend
+it, regarding the distinctive characters of conscious behaviour” is
+especially remarkable. Although few writers have hitherto ventured to
+formulate the far-reaching philosophical consequences of Pavlov’s work,
+more than fifteen years have passed since the veteran physiologist Sir
+William Bayliss made the following pronouncement:
+
+  “Pavlov states that he was struck by the fact that when the
+  physiologist leaves the study of the simpler parts of the central
+  nervous system which he has investigated by the observation of
+  reflexes, and proceeds to the higher parts, his methods suddenly
+  change. He gives up the observation of the relation between
+  external phenomena and the reaction of the organism to them and
+  introduces psychological ideas, derived from his own internal
+  consciousness. To extend to the higher centres the method of
+  observing what changes in the organism are correlated with external
+  changes might appear too difficult, but Pavlov has succeeded in
+  doing so to a remarkable degree” (_General Principles_, 1914, p.
+  502).
+
+In denouncing the mechanistic view of life as set forth by Professor
+Donnan at the meeting of the British Association in 1928, Dr. Haldane
+states:
+
+  “I regard this view as now entirely obsolete, since it ignores
+  the facts, and this is far more evident now than it was a few
+  years ago, before physiology had become to so large an extent a
+  _quantitative science_” (italics inserted) “... The fact that
+  Professor Donnan, though his work in physical chemistry commands
+  universal respect among those who know it, is not a physiologist,
+  may partly account for his opinions.”
+
+Perhaps also the fact that Dr. Haldane, whose work on the physiology
+of respiration and excretion commands universal respect among those
+who know it, neglects in his Gifford Lectures to make any reference to
+the work of Pavlov may partly account for his belief that “a biologist
+interprets his observations in a different manner from a physicist”
+(p. 97). It is certainly permissible to state that Dr. Haldane is not
+speaking for biologists as a whole, when he denies that the problem
+of conscious behaviour can ever be attacked successfully by the
+traditional method of the physiologist.
+
+Biologists may be expected to differ in the hopes they may entertain
+as to the progress of further investigation. We can at least envisage
+the possibility that biology will advance towards a comprehensive
+account of the properties of living matter without interpreting its
+observations in a manner different from that adopted in physics. The
+work of Pavlov’s school shows that it is not necessary to introduce
+concepts foreign to other parts of biology in dealing with conscious
+behaviour. Of late years the notion of matter which is so fundamental
+to common sense has been disintegrated by the advance of the physical
+sciences. The notion of mind or consciousness so fundamental to common
+sense is being disintegrated by contemporary biology in an analogous
+way. If materialism in the traditional sense is dead, idealism in
+its traditional form is dead. Like traditional dualism they are dead
+because they never contained within themselves the capacity for
+growth. The success of biology in attacking the problem of “conscious
+behaviour” in Haldane’s terminology has been consistent with the
+attitude of treating _conditioned behaviour_ as an aspect of the
+properties of a peculiar kind of matter, living matter. In that sense
+the new philosophical outlook which emerges from Pavlov’s work is a
+materialistic one.
+
+Physiology has at length discovered a neutral ground for the
+investigation of the problem of learning. If it is too early to
+predict the final outcome of this advance, it is permissible to
+proffer some tentative suggestions concerning its influence on the
+future of philosophical discussion. From Plato to modern times
+philosophical enquiry has mainly occupied itself with what Kant calls
+“the problems of mere pure reason.” Of these Kant enumerates God,
+Freedom and Immortality as the three principal objects of philosophical
+enquiry. For the final solution of these problems, Kant asserted that
+“philosophy stands in need of a science which shall determine the
+possibility, principles and extent of human knowledge _a priori_.”
+Introspective psychology was the “science” to which he assigned this
+task. Introspective psychology has failed to fulfil the expectations
+which Kant entertained, when he concluded the _Critique_ by expressing
+the hope that it “would bring reason to perfect contentment in
+regard to that which has always, but without permanent results,
+occupied her powers and engaged her ardent desire for knowledge.”
+The type of psychology which Kant promoted had already begun to
+sever its connexion with moral philosophy before the emergence of
+the Behaviourist tendency in an explicit form. Kant did not refute
+Hume’s arguments when he proposed the question, “whence could our
+experience acquire certainty, if all the rules on which it depends were
+themselves empirical and fortuitous”? He stated a problem. For its
+solution he lacked a method. For its discussion he lacked a vocabulary.
+If the physiology of human learning continues to progress under the
+Behaviourist influence to which Pavlov’s work has given birth, Kant’s
+solution of the problem, which he himself propounded, must eventually
+be relegated to the same status as astrology and palmistry in the
+history of human knowledge.
+
+The strength of Kant’s case against Hume’s empiricism lay in the
+immature state of physiological knowledge, when the _Critique of
+Pure Reason_ was published. Kant’s views on Space and Time were
+circumscribed by the biological limitations of his period. The Kantian
+conception of experience was defined by the influence of light, sound,
+chemical stimuli, mechanical pressure and temperature affecting the
+eye, the ear, the nose, the mouth and the skin--the only receptor
+organs recognized by the physiologists of the eighteenth century. Two
+of the most important instruments of receptivity in the human body, the
+labyrinthine organ and the proprioceptors which respond to the state
+of tone of the muscles, were not studied till the nineteenth century.
+If Kant had been familiar with the physiology of the labyrinthine
+organ, he would not have argued with the same cogency that the concept
+of space is essentially different from the concept of weight. The
+_a priori_ necessity of the proposition that “space has only three
+dimensions” was determined, according to Kant, by the existence of an
+“external sense” which is “a property of the mind.” If he had lived
+fifty years later he would have realized that the “necessity” of the
+Cartesian frame work is a material consequence of the structure of the
+internal ear. If Kant had been familiar with Sherrington’s work on
+the proprioceptor organs, he would have seen a deeper significance in
+the experiment which Galileo performed, when he used his own pulse to
+measure the period of a swinging lamp. Kant was compelled to attribute
+the “_a priori_ necessity” of the proposition that “time has only
+one dimension” to “the internal sense by which the mind contemplates
+itself.” The time conditioned reflexes which Pavlov has demonstrated
+are intelligible to modern physiology without recourse to a “faculty
+of pure _a priori_ cognition.” The human body is itself a clock from
+whose tickings we can never escape. Periodic changes in tone of the
+body muscles influence the proprioceptor organs in a manner essentially
+analogous to the way in which light exerts its effect on the eye.[2]
+
+Kant’s physiology calls for more detailed treatment elsewhere. In
+concluding this essay, I must remove one source of misunderstanding. I
+do not assert that all aspects of conscious behaviour will eventually
+be explained in terms of Pavlov’s conditioned reflexes. I do affirm
+that Pavlov has successfully applied the methods of traditional
+physiology to the study of processes presumably included in Dr.
+Haldane’s definition of conscious behaviour. The strength of Dr.
+Haldane’s position lies in the fact that behaviour ceases to be called
+conscious so soon as it is possible to bring it within the range of
+scientific prediction. I can well believe that the vitalists of fifty
+years hence will be assuring their opponents that they never regarded
+the process of learning, the phenomenon of attention or sensory
+discrimination as characteristics of the conscious state.
+
+
+
+
+II. THE ATOMISTIC VIEW OF PARENTHOOD
+
+  “When you can measure what you are talking about, and express
+  it in numbers, you know something about it; but when you cannot
+  measure it, when you cannot express it in numbers, your knowledge
+  is of a meagre and unsatisfactory kind; it may be the beginning
+  of knowledge, but you have scarcely in your thoughts advanced to
+  the stage of science whatever the matter may be...”--Lord Kelvin,
+  _Addresses_
+
+
+§1
+
+The future progress of biological science depends upon a large number
+of unpredictable contingencies, some political, others meteorological.
+The collision of the earth with a comet may leave the fate of the
+argument between the mechanist and the vitalist for ever unsettled.
+There is therefore no justification for a dogmatic assertion that
+all the properties of living matter will eventually be reduced to
+the same hypotheses as are adopted in physical chemistry. But it is
+doubtful whether any biologists of the mechanistic persuasion have on
+any occasion explicitly committed themselves to so rash a statement.
+The vitalistic Sarah Gamp has invented a mechanistic Mrs. Harris with
+the express object of giving her a piece of her mind. As a polemical
+device this is most valuable, especially in political propaganda. It
+does not help the mechanist to understand what vitalism can offer as a
+guide to further biological enquiry. His perplexity is increased by the
+circumstance that so many vitalists of the platform behave themselves
+with mechanistic propriety in the laboratory. Dogmatism is at least as
+frequent among those who call themselves vitalists as among mechanists.
+The vitalist does not qualify his denial that a complete solution
+of the riddle of life can be obtained in physico-chemical terms. The
+mechanist is usually content to state that he knows of no other terms
+in which an intelligible solution could be found. The vitalist even
+goes further, and, quite inconsistently with his laboratory practice,
+if he is a competent biologist, asserts, that in its very methodology,
+biology is an _independent_ science. A biologist, says Dr. Haldane
+in his Gifford Lectures, “interprets his observations in a different
+manner from that of the physicist.”
+
+This I think is the main bone of contention between the two attitudes
+which are generically denoted by the terms mechanistic and vitalistic.
+The real issue has shifted from deciding whether the hypotheses
+of physics and chemistry suffice for the interpretation of vital
+phenomena to deciding whether there is an essential difference between
+the logical structure of those branches of science that deal with
+living matter and those which deal with inanimate objects. This is a
+welcome change, because it presents a much more genuine and concrete
+problem for solution. It is somewhat surprising that the controversy
+should undergo such a metamorphosis at the present moment. The recent
+development of evolutionary biology is especially calculated to
+reinforce the belief that biological theory only progresses, when the
+biologist adopts towards the subject matter of his investigations the
+same attitude as that which the chemist and physicist adopt towards the
+objects which they study. In our generation it is possible to find in
+those aspects of biology which are most recalcitrant to the application
+of physico-chemical hypotheses the most conspicuous examples of a
+fundamental similarity in the logical procedure which the biologist
+on the one hand and the physicist or chemist on the other employ in
+constructing their hypotheses. It would not be possible to select from
+the whole field of biological science a more striking illustration of
+the success of quantitative and experimental methods than the recent
+extension of Mendel’s hypothesis by Morgan’s school. This advance
+has entailed an extensive elimination of teleological concepts in
+the interpretation of the evolutionary process. Yet the phenomena of
+heredity and variation at present lie completely outside the scope of
+physico-chemical analysis in the ordinary sense of the term; and any
+attempt to formulate the problems of genetics in physico-chemical terms
+is still a matter of pure conjecture.
+
+In this sense we may agree with one writer of the vitalistic school in
+saying that to speak of the “mechanism of heredity” is a meaningless
+collocation of words. But if our interest is primarily directed not
+to the end product itself but towards the way in which the scientist
+proceeds to elaborate his hypotheses, the study of heredity provides
+a particularly clear example of how a hypothesis developed without
+any departure from the _principle of mechanism_ can yield verifiable
+conclusions about the behaviour of living systems. From this point of
+view it is both legitimate and intelligible to speak of the mechanisms
+of heredity and variation; and the expression is as permissible as the
+analogous phrase, the mechanism of chemical reaction. A comparison
+of the growth of the Mendelian principle with Dalton’s atomic theory
+of the structure of matter will help us to see whether the biologist
+does actually interpret his observations in a manner different from
+that adopted by the student of non-living matter, and whether the
+biologist has recourse to a kind of logic which is different from
+the logic which the physicist and chemist employ in framing their own
+generalizations.
+
+When Mendel took up the problem of hybridization, the nature of
+fertilization in plants was known in a general way. Just a century
+before Mendel began his work Kolreuter by painting pollen from one
+individual on to the stigmas of another variety, and vice versa, had
+shown that hybrids inherit equally from the pollen and seed plant. At
+the end of the eighteenth century and the beginning of the nineteenth,
+Knight and Goss in England had made further progress in crossing pure
+bred varieties by calling attention to the “splitting” of hybrids, or
+reappearance of parental types when intercrossing hybrid offspring.
+Contemporaneously with Mendel, Naudin in France studied this phenomenon
+more closely, and came very near to formulating Mendel’s principle.
+His results were published in 1862. These pioneers in hybridization
+laid down the necessity of working with what to the geneticist is like
+pure chemicals to the chemist, pure breeding stock. They fell short of
+arriving at far-reaching results, because their attitude to heredity
+was dominated by the holistic standpoint. They could only think of
+the plant in terms of a preconceived notion of individuality. They
+refrained from focusing their attention on the separate parts, and
+following out the fate of discrete characteristics in their crosses.
+
+We must not overlook the debt which Mendel owed to the pioneers of
+hybridization. There would have been no modern chemistry if the
+Arabs and alchemists had not devoted years of laborious study to the
+clarification of our idea of a pure substance; and there would have
+been no genetics, if the idea of pure breeding stock had not been laid
+down by Mendel’s predecessors. Chemistry failed to progress beyond
+the stage of describing new compounds so long as it remained entangled
+in the vitalistic “phlogiston” concept; and genetics, the study of
+heredity and variation, remained purely descriptive, until it was
+emancipated by Mendel from the holistic tendency to concentrate upon
+the organism as a whole. Naudin did in fact envisage less definitely
+than Mendel the atomistic concept of heredity, just as William Higgins
+had partly visualized the chemical possibilities of atoms before Dalton
+published his theory.
+
+Mendel used in his researches pure breeding stocks differing only in
+well-defined particulars, employing single characteristics as units
+of study, and recording the progeny of every cross separately for
+comparative observation. In his original work Mendel chiefly dealt
+with the common pea, which possesses two advantages which recommend
+it for such experimentation, namely, that its flowers are capable
+of self fertilization (i.e., the pistil can be pollinated from the
+stamens of the same flower) and that it has a number of well-marked
+varieties distinguished by tangible characteristics such as the shape
+(round or wrinkled) and colour (green or yellow) of the seeds, or the
+stature (tall or dwarf) of the shoot, etc. In all his crosses involving
+a single difference of this kind he found that the first generation
+of the cross resembled one of the parents. When these crossbreeds
+were self fertilized, they produced offspring resembling the original
+parents in the constant ratio of three to one. One-quarter of the
+offspring of the crossbreeds resembled one parent and bred true;
+one-quarter resembled the other parent and bred true; and the remaining
+half being like the “dominant” parent, which the first generation
+of hybrids resembled, behaved exactly like the latter, when self
+fertilized.
+
+An investigator who had not the attitude which makes a capable chemist
+might have been distracted by the peculiar circumstance of dominance,
+or the resemblance of the impure individuals to one of the parents
+exclusively. Mendel rightly judged this to be insignificant. A chemical
+analogy will perhaps assist to make this clear. Sodium and potassium
+yield colourless salts with most common acids, but the permanganates
+of both are purple in solution. The salts of copper are generally of
+a bluish or greenish tint in solution. In the one case the anion, in
+the other case the kation, is the dominant factor in determining the
+physical property of colour; but in both cases the other component
+behaves in any reaction with no less characteristic efficacy, because
+its presence is seemingly masked. So likewise Mendel looked beyond the
+bodily resemblance of the dominant parental and hybrid individuals
+to their hereditary makeup; and recognized in his experimental data
+two general conclusions which prompted special consideration. One
+was the fact that the original parental types can be recovered in
+all their purity. The other was the fact that the various hereditary
+types produced by hybridization regularly appear in the same numerical
+ratios. Both conclusions are of universal validity, though Mendel had
+the very good fortune to select materials which yield the simplest
+type of numerical results which occur in crosses between pure strains.
+When Dalton formulated the atomic hypothesis two fundamental empirical
+generalisations of chemistry were fully accredited. The law of the
+conservation of matter and the law of constant proportions had been
+established. Mendel found in his data the proof of what we might call
+the principle of the conservation of genetic materials and the law of
+constant genetic proportions. To the recognition of these empirical
+generalizations he added a conceptualization of the basis of their
+existence in terms of discrete factors. These factors were according
+to Mendel’s hypothesis (or Mendel’s “first law”) units of hereditary
+combination, just as Dalton’s atoms were units of chemical combination.
+
+Each character involved in his crosses was regarded by Mendel as
+determined by a factor derived from the maternal and one derived from
+the paternal parent. A pure individual was thus represented by _aa_
+or _bb_, and an impure individual by _ab_. Mendel assumed that _a_
+and _b_ are atoms of heredity in the sense that they retain their
+separate entities through the whole course of development. Having
+introduced this conception, he showed that all his numerical data
+followed from the laws of chance, if the maternal and paternal factors
+which determine a particular character separate in the formation
+of the gametes (pollen and ovules) so that one-half of the gametes
+contain only the maternal and one-half only the paternal factor for the
+character considered. The combinations which may occur as the result of
+fertilization are compatible with the assumption that any given male
+gamete (pollen or sperm) may fertilize any given female gamete (ovule
+or egg cell). Mendel’s first law may then be stated thus: characters
+distinguishing different hereditary strains depend upon factors which
+are inherited from both parents and _segregate_ in the formation of
+the gametes, so that one-half contain the paternal and one-half the
+maternal factor. Mendel tested the implications of this hypothesis by
+crossing his hybrids to pure types with verifiable results. He then
+proceeded to make crosses involving two or three character differences.
+This led him to enunciate a second law which might be compared with the
+law of multiple proportions in chemistry, for its validity is of less
+general significance than the first law. It served eventually to direct
+attention to the much more complicated numerical results which arise in
+dealing with character differences attributable not to one but several
+pairs of factors. The analysis of such cases was left to Mendel’s
+successors.
+
+There is internal evidence in Mendel’s writings to support the
+view that Mendel himself realized that the atomistic conception of
+inheritance would demand a drastic revision of the prevailing notion
+of variation. To Mendel’s generation, to Darwin and the pioneers of
+Natural Selection, variation and heredity were co-extensive terms.
+Offspring were always on the whole like their parents, but always on
+the other hand a little different. So the species in conformity with
+sound liberal principles broadened down from precedent to precedent.
+But on the atomistic view heredity is essentially conservative, and
+variation essentially revolutionary. For an indefinite number of
+generations the atoms of heredity remain unchanged. But times come,
+when the political barometer falls, and the change when it happens is
+a discontinuous one. Something new has been brought into being, as
+when lead is produced from the disintegration of radium or another
+allotropic modification of an element is formed. The full implications
+of this were not destined to be realized till forty years had elapsed.
+Meanwhile the evolutionary ship drifted upon an uncharted ocean of
+speculation without the compass of experiment to direct its course.
+
+
+§2
+
+Mendel’s work published in an obscure horticultural journal
+remained neglected for forty years, till in 1900 his principle
+was independently rediscovered by three continental workers--de
+Vries, Tschermak, and Correns. During that period the study of the
+reproductive process had progressed rapidly. The way was being paved
+for new and spectacular developments of the atomistic standpoint
+in heredity. To appreciate the subsequent elaboration of Mendel’s
+hypothesis in its historical perspective a brief digression into the
+anatomy of the cell is necessary.
+
+Mendel’s researches were confined to plants. When he started his work
+the nature of fertilization in animals was still obscure. The bodies of
+animals like plants were known to be built up of microscopic bricks, or
+_cells_ as Robert Hooke had called them. With the use of more powerful
+microscopes this had gained general recognition during the thirties
+and forties. Two centuries had elapsed, since Leeuwenhoek with the
+first microscope had seen seminal fluid teeming with minute vibratile
+bodies, the _spermatozoa_. At the end of the eighteenth century
+that inquisitive ecclesiastic Spallanzani had shown that the sperm
+is the essential constituent of the seminal fluid. By 1841 Kolliker
+had traced the development of the spermatozoa from single cells of
+the testis. It was not until 1875-9 that Hertwig and Fol working on
+sea urchins independently observed for the first time in history the
+penetration of the egg by the sperm, and established the universal
+rule that fertilization involves the union of a single sperm with a
+single egg cell. All modern discussion of genetic differences takes its
+starting point from the fact that anything which is implied by the word
+inheritance has its material basis in the microscopic sperm contributed
+by the father or in the egg cell with which it unites.
+
+In all animals the sperm is a microscopic entity. In all animals
+from the jellyfish to Man with very few exceptions its appearance is
+extraordinarily similar. It consists of a thicker portion to which is
+attached a long vibratile process, or flagellum. The eggs of different
+animals are of very different dimensions. Sometimes they contain
+immense stores of food material (yolk). Sometimes as they pass to the
+exterior by the female generative tract they are invested with an
+additional slimy coat and a leathery or calcareous shell, secreted by
+special glands. The immature egg of all animals is essentially similar.
+In the living condition it is a spherical or ellipsoidal body in
+which a clear spherical vesicle is seen; this vesicle present in all
+cells is called the _nucleus_. The thicker part or body of the sperm
+consists mainly of the nucleus of the cell from which it is derived. At
+fertilization it swells up and unites with the nucleus of the egg. The
+fertilized egg then divides into two separate segments or cells, and
+the process of dividing is repeated an indefinite number of times. The
+cells or segments into which the fertilized egg divides each contain a
+nucleus, and the process of segmentation which involves the division of
+cells into two is accompanied by the division of the nucleus of each
+dividing cell. Like the testis or ovary the substance of all the organs
+of the animal body is built up of the microscopic bricks which we
+have called cells. In some tissues like bone and cartilage the bricks
+are separated by a good deal of mortar. Others, such as the lining
+membranes of the body, consist simply of cells packed tightly together.
+At the beginning of embryonic existence all the cells are very much
+alike. In the course of development the cells of different tissues
+are considerably differentiated. Throughout all stages the process of
+cell division always involves the partition of the nucleus in a highly
+characteristic manner.
+
+The details of this peculiar process, first elucidated by Flemming
+and others during the seventies, has proved to be of astonishing
+significance for the further understanding of Mendel’s hypothesis.
+When a cell is about to divide, the nucleus looks like a tangle of
+fine threads; and this tangle of fine threads resolves itself into a
+number of readily distinguishable filaments which become progressively
+shorter, assuming the appearance of stout rods staining deeply
+with basic dyes. These rods, visible only with high powers of the
+microscope, are the _chromosomes_, whose behaviour has provided us
+with a tangible basis for Mendel’s conception of inheritance, and have
+thereby permitted an extensive clarification and amplification of the
+original hypothesis. From one point of view they might be said to have
+done as much for the Mendelian conception of heredity as the discovery
+of alpha particles has done for our belief in the atomic structure
+of matter. As the dividing cell begins to constrict, the chromosomes
+arrange themselves at its equator, and split longitudinally into
+halves, each half travelling to opposite poles, where they spin out
+again into fine threads from which the nuclei of the daughter cells are
+built up. Thus each of the chromosomes in the nucleus of any cell in
+the body is structurally equivalent to a corresponding chromosome in
+the preceding or succeeding cell generation. About the year 1875 it was
+recognized that this numerical constancy extends beyond the life of a
+single individual. In every species of animal or plant the number of
+chromosomes which can be counted in dividing nuclei is a constant for
+the species.
+
+With the discovery of this fact a new problem arose so soon as the
+essential features of fertilization were appreciated. How is this
+constancy maintained from generation to generation of new individuals?
+Two investigators, Van Beneden and Boveri (1881-3), who worked on
+the horse threadworm, a form which has only four chromosomes in the
+dividing cells of the segmenting egg, showed that the egg and sperm
+each contain only half the number of chromosomes characteristic of
+the cells of the embryo. This conclusion turned out to be a perfectly
+general one. Attention was immediately directed to the nuclear changes
+which happen in the formation of the gametes. Innumerable cell
+divisions occur in the testis or ovary of an animal. These are at first
+similar in all respects to those which occur in the segmentation of the
+developing embryo; but cell division goes on in the testis or ovary
+throughout life. If we trace backwards the history of an individual
+sperm or egg in the testis or ovary in which it originates, we find
+a reduction of the number of chromosomes effected during the last
+division but one, leading up to the formation of a sperm or ripe egg.
+This penultimate division of the germ nuclei is preceded by the fusion
+of the chromosomes lengthwise in pairs. When the division actually
+takes place, each pair behaves like a single chromosome, splitting in
+such a way that one member of each pair goes to form each daughter
+nucleus. The succeeding division being normal, each gamete receives
+half the number of chromosomes present in ordinary cell division. At
+fertilization the normal number is restored. Thus each ordinary cell of
+the body has a chromosome set of which half the components are paternal
+and half maternal in origin.
+
+In many animals and plants the chromosomes are very distinctly of
+different sizes and shapes, and can be sorted out into corresponding
+pairs. Such arrangements are constant for the species, and could only
+be maintained constant, if each gamete contains one representative of
+each pair. This means that the maternal and paternal constituents of
+a pair are distributed in the reduction division to different cells.
+The chromosomes therefore exist in pairs of which one element is of
+maternal origin and one of paternal origin. Each gamete receives
+one element of each pair, just as Mendel supposed that each gamete
+contained either the paternal or maternal element of his paired
+“factors.” By a curious coincidence this far-reaching conclusion was
+first established in the very year which witnessed the application of
+Mendel’s principles to animals by Bateson in England and Cuenot in
+France (1902). Its recognition accompanied the elucidation of another
+peculiarity of nuclear division, also destined to have important
+theoretical consequences. In many animals there is found to be an
+unequally mated pair of chromosomes, the XY pair. When this occurs, it
+occurs in one sex only. In the alternate sex there is a corresponding
+equal pair (XX). In birds and moths the female is the XY, the male
+the XX individual. In other animals the male is usually found with
+sufficiently careful measurement to have an unequal (XY) pair which
+is equally mated in the female (XX). During the nineties it was found
+that some animals had in one sex an odd number of chromosomes, a fact
+which at first sight seemed to conflict with the numerical constancy
+of the chromosomes. In the early years of the present century American
+zoologists provided the key to an understanding of the discrepancy.
+In all such cases the alternate sex has one more chromosome. The case
+of the large cockroach will serve as an illustration. The male of
+_Periplaneta americana_ (its technical name) has 33, the female 34
+chromosomes. The eggs will all have 17 chromosomes. One-half of the
+sperm will have 17, the other half 16 chromosomes. If a sperm of the
+former class fertilizes an egg, the individual produced will be a
+female (17 + 17 = 34); and if a sperm of the second type fertilizes
+an egg, the individual produced will be a male (17 + 16 = 33). In an
+animal with an unequally mated (XY) pair of chromosomes in the male
+reduction will result in one-half of the sperm carrying the X and
+one-half the Y chromosome. The eggs will all have the X, since this
+chromosome is equally paired in the female. Thus an egg fertilized by
+a Y-bearing sperm will become a male, while an egg fertilized by an
+X-bearing sperm will develop into a female.
+
+
+§3
+
+By statistical reasoning Mendel had deduced from his experimental
+data the existence of entities which behave just as the chromosomes
+do. He had no direct evidence that his factors had any material basis
+in the architecture of the germ cells. The new cell anatomy provided
+independent confirmation of his predictions from an unexpected quarter;
+but it was not immediately recognized that this was so. Antagonism to
+the belief that the chromosomes fulfilled the requirements of Mendel’s
+hypothesis is easily explicable. To Mendel’s first disciples his second
+and first laws were equally sacrosanct. Mendel’s second law implies
+that different pairs of hereditary factors behave quite independently
+of one another. On such an assumption one of two deductions is
+inevitable. Either the applicability of Mendel’s first law is extremely
+restricted; or the number of factors is too large to permit of their
+localization in the chromosomes. The sweet-pea, for instance, has only
+seven pairs of chromosomes. If Mendel’s second law were as general as
+the first, only seven pairs of factors could be accounted for by the
+behaviour of the chromosomes. From this dilemma further development
+of the atomistic view of heredity was rescued, when it was discovered
+that Mendel’s second law is only a particular case of the possibilities
+inherent in the first.
+
+In 1910 Bateson and Punnet first discovered in the sweet-pea what they
+then called “coupling and repulsion,” or as we now say, _linkage_.
+Without going into the experimental data, we may define the phenomenon
+of linkage in the following way. Suppose that these are two varieties
+A and B which obey Mendel’s first law and two other varieties C and
+D which likewise conform to its requirements, when crossed with one
+another. Mendel’s second law stated that in a cross between AC and BD
+the second generation will consist of the types AC, AD, BC and BD in
+numerical proportions agreeable to the assumption that it is equally
+likely that the factor determining A will be present in the same gamete
+as the factor determining C or the factor determining D. Bateson
+and Punnet found that this does not always happen. There is another
+category of cases in which the factor which determines A sticks more
+or less completely to the factor for C in preference to the factor for
+D. The detailed analysis of these cases was at first made difficult
+by Mendel’s literal symbolism, and his way of thinking of factors in
+_pairs_. But the discovery of linkage at once led Lock to formulate the
+fruitful suggestion that factors located on the same chromosome pair
+would satisfy the requirements of linkage, while factors located on
+different pairs of chromosomes would fit in with Mendel’s second law.
+
+From this point onwards the most spectacular development came from
+the study of inheritance in animals, and the significance of the
+chromosomes was immensely reinforced by newly gained knowledge of sex
+determination. Almost contemporaneously with the discovery of the sex
+chromosomes or XY mechanism, as we now say, Leonard Doncaster had
+elucidated in moths the phenomenon of sex-linked inheritance. This was
+soon found to be of common occurrence in animals. Till this discovery,
+which was made in 1905, the same results had always been obtained
+in crosses of pure-bred varieties, whether the male or the female
+parent displayed one or the other characteristic distinguishing them.
+Doncaster’s work on the currant moth showed that there is a category of
+cases which at first sight obey Mendel’s first law in its simplest form
+when the cross is made in one way, but yield a different type of result
+when the cross is carried out reciprocally with respect to the sex of
+the parents. In such cases one sex is only able to transmit certain
+characters to its offspring of the opposite sex. It was already known
+that the XY sex (male in Man and most animals) can only transmit its X
+chromosome to the XX type. The facts did not dovetail at first sight,
+because sex-linked inheritance was originally elucidated in birds and
+moths of which the female is the XY type. There was still an attitude
+of hesitancy towards accepting Lock’s hypothesis, strengthened by the
+persistence of an incorrect interpretation of the process of reduction
+which had been made the basis of Weismann’s metaphysical speculations
+concerning “germinal selection.”
+
+When in 1914 Doncaster summed up the case for regarding the chromosomes
+as the material basis of Mendel’s first law, a new era had already
+dawned. Thomas Hunt Morgan, the central figure of a group of ardent
+investigators at Columbia, had initiated a body of enquiries which
+within half a decade eclipsed all other achievements that had
+succeeded Mendel’s pioneer labours. About the time when Bateson first
+encountered the phenomenon of linked inheritance Morgan began to rear
+the fruit-fly Drosophila for breeding experiments. Till then genetic
+experiment had been held in check by the slow rate at which most
+convenient animals and plants reproduce and the expense entailed in
+breeding them in sufficiently large numbers to permit statistical
+inference. The fruit-fly completes its life cycle, if kept in warm
+laboratory conditions, in a period of ten days. It is prolific. It
+feeds on rotten banana skins. It therefore costs little to breed. To
+these immense advantages it adds two others of supreme importance.
+It has only four pairs of chromosomes readily distinguishable from
+one another by size and shape; and it has produced in the laboratory
+a crop of several hundreds of sports or _mutants_. Each mutant type
+differs from the wild parent stock in some well-defined characteristic
+inherited in crosses with the wild type in accordance with Mendel’s
+first law. The mutant characters are extremely varied. One is
+distinguished from the red-eyed parent by having white eyes, another
+by having purple eyes, another by having no eyes at all. One is
+distinguished by having wings that are practically vestiges, another
+by wings that turn up at the tips, another by wings that are truncated
+at their extremities. From the wild type which has a greyish body, one
+mutant is distinguished by a deep black, another by yellow coloration.
+The mutant characters are thus in general clear-cut differences
+lending themselves to easy identification. With an animal that breeds
+so rapidly and prolifically information accumulated with astonishing
+rapidity. From data based on the study of a large assemblage of mutant
+characters there soon emerged the precise requirements of Lock’s
+hypothesis. All the mutant characters of Drosophila fall into four
+groups. Members of the same group always tend to stick together in
+hereditary transmission. Members of different groups like Mendel’s
+dihybrids behave independently of one another. Of several hundred
+mutant characters in Drosophila every one belongs to one of these four
+linkage groups; and the number of chromosome pairs in Drosophila is
+four.
+
+This discovery was only the beginning of what might well be called
+one of the faery tales of modern scientific research. In the way of
+accepting Lock’s hypothesis there were still difficulties. It was in
+evading the principal difficulty that Morgan’s school extended the
+atomistic concept of heredity much further than his predecessors had
+done. Till then the main outcome of experiments on breeding had been
+to show that Mendel’s principle was of vastly wider applicability
+than was at first supposed, and to engender the suspicion that the
+patient unravelling of difficult and elusive cases would establish its
+universal validity. As yet the world of Mendel’s atoms was without
+form. Morgan and his colleagues gave it a map. Not content with
+showing that Mendel’s atoms of heredity have their material basis in
+the chromosomes, nor with actually identifying which chromosome is
+significantly associated with a particular mutant character, Morgan
+went further and localized the region of an individual chromosome in
+which a particular Mendelian factor resides. He thus gave to Mendel’s
+factors spatial co-ordinates in the living cell.
+
+At the outset the study of linkage upon which the chromosome map is
+based was facilitated in the case of Drosophila, because the varieties
+dealt with were all known to be mutants from a fixed wild type. Thus
+it was possible to break away from Mendel’s conception of “pairs”
+of hybridizing characters. The Mendelian factor was replaced by the
+mutant _gene_, by saying which is implied that a mutant arises because
+at some point on a particular chromosome a physical change has taken
+place. The gene is the Mendelian factor for the mutant condition, but
+no assumptions are made about what determines the wild-type condition.
+The inter-relationship of different characters is greatly simplified
+by thinking only of the relation of one _mutant_ gene to another. The
+discovery that all the genes fall into four groups corresponding to the
+four groups of chromosomes presented one stumbling-block. Members of
+the same group in general do not invariably stick together. When two
+mutants are crossed the numerical proportions of the various types of
+offspring give a definite value for the probability that the gene A and
+the gene B will stick together or separate apart. This is a constant
+for A and B. The constant used in practice is the tendency for A and B
+to separate. Expressed as a percentage, it is called the _cross-over
+value_. Some additional information was necessary to explain why A
+and B do not always stick together, if they are associated with the
+same chromosome. It was from the solution of this problem that the
+chromosome map took shape.
+
+Here the sex chromosomes came to the rescue. One very interesting
+type of sport which has turned up in breeding the fruit-fly is not
+recognizable by any discrete bodily peculiarity but merely by an
+abnormality in the number of chromosomes. Of these the first to be
+discovered was a type of female which has in addition to its usual
+four pairs of chromosomes an additional Y chromosome. The XXY females
+yield very extraordinary numerical results both as regards the sex
+ratio and other characteristics, when used in making crosses involving
+mutant characters. There is a class of mutant characters in Drosophila,
+more than a hundred in all, distinguished by the fact that they are
+not inherited symmetrically with regard to sex. They display linkage
+_inter se_. They behave as “sex-linked” characters. The introduction of
+XXY females into crosses involving such mutant characters results in
+numerical ratios which are inexplicable on any assumption other than
+the view that the sex-linked gene is referable to the X chromosome
+alone. Yet, although the sex-linked genes are all borne on the same
+chromosome, they do not invariably stick together in crossing. The
+holistic chromosome clearly would not do. An atomistic chromosome had
+to be put in its place.
+
+The clue to this was provided by studying more closely the extent
+to which the different genes stick together. Taking all the genes
+located on the X chromosome this remarkable generalization emerged
+from Morgan’s researches. If A, B, and C are three sex-linked genes;
+if the probability that A and B will not stick together is _x_, and
+the probability that B and C will not stick together is _y_, the
+probability that A and C will not stick together is either the sum
+or the difference of _x_ and _y_. The correspondence here stated is,
+of course, subject to the margin of error permitted by the theory of
+probability. To interpret this new _law of the linear alignment of the
+genes_ Morgan made use of a structural peculiarity of the reduction
+process. When the chromosomes pair in the reduction division, they
+appear to become twisted. The appearance suggests that in the ensuing
+split corresponding lengths of the original pair are interchanged. It
+is very natural to assume that the likelihood that two points will be
+separated from one another in such a manner is proportional to their
+distance apart. So if the sex-linked genes are arranged in a series
+along the length of the chromosome, the probability that A and C will
+not stick together must be the sum of the probabilities that A and B
+and B and C will be separated. This is just what experiment had shown
+to be true. Thus all the genes on the X chromosome can be arranged in a
+linear series. The intervals between consecutive genes in such a series
+represents a space dimension.
+
+The law of the linear alignment of the genes was soon found to apply
+to the other groups of linked characters. Abnormalities in the
+number of chromosomes have made it possible to identify each of the
+remaining three linkage groups of the fruit-fly with its corresponding
+pair of chromosomes. The first chromosome map of Drosophila was
+constructed in 1916. It revealed the suggestive coincidence that the
+number of ascertained points on each pair of chromosomes is roughly
+proportional to its size. There is now very little doubt that the
+work of the Columbia school has revealed an aspect of inheritance
+which is of general significance. After years of patient work with the
+relatively slow breeding sweet-pea, Punnet has at length elucidated
+seven linkage groups corresponding to its seven pairs of chromosomes.
+He has constructed a chromosome map of a seed plant on the basis of
+the principle first established for the fruit-fly. A law which holds
+good for two organisms so far apart in the evolutionary scale can
+hardly be supposed to be lacking in universal validity. The chromosome
+hypothesis may now take its place as one of the major generalizations
+of biological science. The law of linear alignment has transformed
+Mendel’s original conception of inheritance in a way which might
+be compared with the elaboration of Dalton’s hypothesis after the
+discovery of the law of combination of gases by volume. Mendel’s
+atoms of heredity are now units spatially localized in larger units
+of microscopically visible dimensions. These supermolecules are the
+chromosomes.
+
+Being a portion of living matter the chromosome is constantly
+undergoing chemical change. Some critics of the chromosome hypothesis
+have based objections upon this circumstance. The difficulty is more
+apparent than real. Like the individuality of the modern atom the
+individuality of the chromosome must be conceived in statistical terms.
+For the discussion of the more familiar chemical reactions the statical
+atom of traditional chemistry is adequate. For the interpretation of
+hybridization experiments the diagrammatic chromosome of the text-book
+suffices. In the field of radioactivity the statical atom makes way for
+a dynamical model. So also in the domain of cell physiology we conceive
+the chromosome as an ever-changing entity. The logical situation is
+analogous in the two cases. Those who hold with Dr. Haldane that the
+biologist must interpret his data in a manner different from that in
+which the chemist or physicist interpret theirs have now to fall back
+on the contention that the Mendelian view is only a partial picture of
+heredity transmission. Anything which might have been said in favour
+of this contention ten years ago has been weakened by recent work on
+the inheritance of size. The pioneers of Mendelism selected clear-cut
+hereditary differences which ordinarily manifest themselves in any
+environment in which the animal or plant can live. They succeeded
+in showing that a vast number of hereditary differences involving
+a great variety of anatomical and physiological features conform to
+the requirements of Mendel’s hypothesis. There was one category of
+phenomena which remained obscure till quite recently. Differences in
+size, height, body weight and the like vary greatly with environmental
+conditions. Two stocks may be distinguished from one another by the
+fact that the average member of one is measurably different from the
+average member of another; but any given individual of one stock may
+be indistinguishable from another individual of the other, because,
+even when the environment is standardized as much as is practicable,
+the range of variability of the two stocks overlaps. The analysis of
+such cases cannot be undertaken by the ordinary technique of Mendelian
+experiments; but certain statistical requirements of Mendel’s laws may
+nevertheless be verified. By elementary statistical reasoning we can
+deduce that the coefficient of variability of the progeny of a cross
+between two inbred stocks must be a minimum in the first generation and
+a maximum in the second. This has been shown to be true in a number of
+crosses in which it is impossible to distinguish individual genetic
+types by direct observation.
+
+There is no longer any adequate reason to support the contention that
+Mendel’s atomistic concept leads us to an incomplete understanding of
+biparental inheritance in animals and plants. Those who assert that it
+is so are now forced to fall back upon the last resort of obscurantism
+by appealing to the magnitude of our ignorance. The modern theory of
+the gene is a statistical construction consistently developed by a
+logical interpretation similar to that adopted in elaborating the great
+generalizations of physical science. The mechanist is often accused of
+attributing vital processes to “chance” combinations of phenomena.
+If the word chance is used to imply that we do not know the precise
+conditions which determine such combinations, the statement is hardly
+exceptionable. It might also imply that the phenomena which biologists
+study can be successfully interpreted in terms of the mathematical
+laws of chance. The history of Mendelism shows that these laws provide
+a fruitful basis for predicting the behaviour of living systems, even
+where physico-chemical hypotheses at present fail to throw light on
+the phenomena which the biologist studies. The biologist is able to
+progress to greater certainty of prediction only when he interprets his
+data with the same logical method employed by the chemist and physicist
+to deduce physical “laws.” Whatever the future holds in store for
+further interpretation of heredity and variation on physico-chemical
+lines, the progress already achieved has at every stage involved
+elimination of holistic concepts by the ruthless application of
+mechanistic logic. To the application of physico-chemical hypotheses no
+branch of physiology has proved more recalcitrant than the physiology
+of inheritance. No branch of physiology might more suitably be chosen
+to cast doubt on Dr. Haldane’s recent statement that “anything which
+can properly be called scientific physiology is impossible apart from
+the assumption of _holism_.”
+
+
+
+
+III. THE NATURE OF LIFE
+
+  “I am sorry then, I have pretended to be a philosopher: for I find
+  your questions very perplexing; and am in danger, if my answer be
+  too rigid and severe, of passing for a pedant and scholastic: if
+  it be too easy and free, of being taken for a preacher of vice and
+  immorality. However, to satisfy you, I shall deliver my opinion
+  upon the matter, and shall only desire you to esteem it of as
+  little consequence as I do myself. By that means you will neither
+  think it worthy of your ridicule nor your anger.”--David Hume, _The
+  Sceptic_
+
+
+§1
+
+Since a man must needs live before he can be a philosopher, no problem
+of philosophy is more fundamental than the nature of life. There
+is also no issue which provides more scope for vague, barren and
+undisciplined discussion. A Regius Professor of Moral Philosophy,
+whether he accepts the fact with resignation or refuses to do so, is a
+piece of living matter. Perhaps this is why physicists are more vocal
+than biologists in promoting a pacific solution of the territorial
+dispute between science and traditional philosophy. At the present
+moment it is the fashion among those who are writing on scientific
+philosophy either to neglect the contribution of the biologist to
+the world symposium, or to assume that the biologist in dealing
+with living matter operates with different methods and different
+concepts from those employed in physics. No phase in the history of
+biology is more fitted than the present to illustrate the fundamental
+unity of scientific method. In no branch of science is the limit of
+applicability of scientific method a more significant issue.
+
+Since a scientific concept is only a way of describing a class of
+properties, the nature of life cannot refer to anything but the nature
+of the properties of living things. Having arrived at some general
+classification of the characteristic properties of living things, a
+discussion of the nature of life in the light of modern biological
+science presents two issues of pre-eminent interest. One is how far
+the _methods_ employed in physical science have been successful
+and are likely to continue to prove successful in dealing with the
+properties of living matter. The other is how the increasing measure of
+success which attends the utilization of purely physical _concepts_ to
+interpret the properties of living matter is calculated to influence
+our evaluation of the place of science in human thought. Whatever
+differences of interpretation may exist among biologists on matters of
+detail, it should at least be possible to infer from a survey of the
+progress of biology whether the study of living matter is progressing
+satisfactorily along the lines of quantitative analysis of experimental
+data towards greater certainty of prediction, and whether there is good
+reason to believe that the preservation of the teleological standpoint
+in dealing with living matter is likely to ensure conspicuous success
+in the same direction.
+
+It may be admitted that there exists among biologists more unanimity
+with reference to the first than towards the second issue. Every infant
+science makes use of notions peculiar to its own province. Chemistry
+has but lately passed beyond the stage when the concept of _affinity_
+first became amenable to interpretation in thermodynamical quantities.
+There are still many biologists who would assert that the concept of
+_adaptation_ demarcates the province of biology from that of physics
+and chemistry by an impassable gulf. There are others, fewer in
+number, who, surveying the teleological growing pains of the more exact
+sciences and bearing in mind that only 300 years have passed since the
+properties of familiar chemical compounds were literally personified as
+spirits of wood, spirits of salt and the like, do not feel compelled to
+regard the concept of adaptation as final. They are able to entertain
+the possibility that those properties which enable an organism to
+maintain its continued existence as an organism are not permanently
+more incapable of physical interpretation than the polarization of a
+voltaic battery, a phenomenon which the consistent teleologist would
+presumably regard as an attempt on the part of the latter to save its
+own life. Clearly the onus of defining what precisely is implied in the
+concept of adaptation lies on those who assert its uniqueness. Until
+the vitalist is more definite on this issue, the mechanist is under no
+obligation to refrain from classifying the properties of living matter
+in the light of his own experience. The mechanist denies that anything
+is to be gained by clinging to the teleological standpoint with its
+implication of some extra- or intra-mundane purpose which has been
+abandoned in all branches of science that lay claim to exactitude. He
+refuses to deal with living matter except in as far as it is considered
+as a series of “events” whose characteristics must be interpreted with
+rigid economy of hypothesis.
+
+In approaching any lump of living matter, let us say the author of
+these essays, as an object of the external world, the maintenance of
+economy of hypothesis compels the enquirer to seek as far as possible a
+common basis for the characteristic properties of living and non-living
+systems. This necessitates a clear definition of the distinction
+between the two. Taking a comparatively complex organism, as, for
+instance, the common frog, a distinction might be attempted along the
+following lines. In the first place, its possibilities of behaviour
+are more varied than those of any machine which can be manufactured
+by man; yet, while possessing a greater range of reversible response
+than any non-living system, it would be difficult to specify in a
+living system any single activity which could not be reproduced by a
+mechanical system. Apart from this diversity, which we may refer to
+under the generic term _reactivity_, living matter is characterized
+in general by the wide range of external influences which are
+significant in determining its characteristic reversible responses.
+This peculiarity, in view of the subjective preconceptions implicit
+in the older terms irritability, sensation, etc., may be denoted by
+the term _receptivity_. Here again it is impossible to isolate any
+single agency (or “_stimulus_”) capable of evoking reversible change
+in any living system and incapable of evoking reversible change in
+any non-living system. Finally--and at first sight--a more diagnostic
+difference between living and non-living matter is seen in the property
+of _reproduction_ (taken in the broader sense of the term, to include
+growth). A given piece of living matter comes into being in our
+experience only through the agency of other pieces of living matter
+closely resembling itself.
+
+
+§2
+
+Were the more obscure process of sexual reproduction universally
+characteristic of living matter, this distinction would appear
+especially fundamental. Experimental biology is far from the
+achievement of a complete physico-chemical analysis of asexual
+reproduction in any type of organism. On the other hand, in the life
+cycles of those multitudes of micro-organisms which multiply by simple
+fission after attaining a certain limit of growth, there is nothing
+which compels an unprejudiced investigator to regard the process as
+more intrinsically incapable of physical interpretation than the
+splitting into two of a liquid drop. Although our knowledge of the
+nature of sexual reproduction is fragmentary, in this very field some
+particularly spectacular advances have been registered in substituting
+physical agencies as effective instruments for initiating processes
+which at one time were only amenable to the influences of living matter
+itself. Thirty years have now passed since Loeb’s discovery that
+changes in the osmotic pressure of the external medium or alteration
+of the permeability of the egg itself, leading to changes in its own
+internal osmotic pressure, can initiate without any assistance from the
+sperm the development of the ovum into a new and complete organism.
+That discovery was the starting-point of a body of investigations whose
+influence has radiated into many other fields of biological enquiry.
+Especially noteworthy in this connexion is the work of Warburg during
+the last decade. Warburg was able to show that sea-urchin eggs, and
+later animal cells in general, if rapidly dehydrated and ground to
+a powder, will, like the intact cell, absorb oxygen for some time
+when moistened. He showed also that this property, like respiration
+in the intact cell, can be abolished by the action of cyanides and
+other classes of tissue poisons. By doing so, Warburg has taken a
+characteristic and highly complex property of living matter out of
+the realm of vitalism into that of physical chemistry. His analysis
+went further. Experiment showed that three classes of poisons which
+inhibit tissue respiration can be distinguished by their quantitative
+relations. Of these, the efficacy of one class, the cyanides, was
+shown by Warburg to be correlated with the iron content of the
+cell. On the hypothesis that iron catalysis is the main factor in
+the oxidation of organic material in the cell, Warburg manufactured
+suspensions of charcoal with a high iron content capable of catalysing
+the auto-oxidation of sugars, fats, etc. The catalytic activity of
+these suspensions was found to be related quantitatively to the three
+categories of respiratory poisons in a manner closely parallel to the
+action of the latter on tissue respiration.
+
+Though reproduction is, in some respects, to the biologist at least,
+the most fundamental of all the three features which I have defined
+above, the ever-changing reactivity and manifold receptivity to
+external influences so characteristic of living matter pre-eminently
+engage our attention in connexion with the more intimate and subtle
+issues of a field of enquiry which biology may yet claim. I refer to
+the analysis of human behaviour. In this connexion I shall mention
+progress in three directions as illustrating the transition from
+teleological to quantitative treatment during the last half century;
+namely, the physical analysis of the events which constitute an
+isolated unit of response or reflex, the integration of reflexes in the
+normal behaviour of animals, and the determination of new behaviour
+patterns along the lines laid down by Pavlov’s school. With regard to
+the first, we will consider the effect of flashing a bright light upon
+an animal that has been previously kept in the dark. The characteristic
+response, let us say, blinking of the eyelids, and the intervening
+events involved are, first, a physical change in a receptive area,
+namely, the retina; secondly, the propagation of the disturbance
+there set up along a certain path, the nervous system; thirdly, the
+liberation of a considerable quantity of energy at the seat of response
+or effector organ, that is to say, the muscles of the eyelid.
+
+Our knowledge of the nature of receptivity is least complete. That it
+is a measurable physical event is beyond dispute. When light impinges
+upon a given area of the retina there follows a characteristic series
+of changes in electrical potential of the excited area with reference
+to a non-excited area. Through the work of Jolly, Adrian and others
+the sequence, the time relations and the magnitude of these changes
+are being related to the intensity and duration of the stimulus
+within predictable limits for a given species. These events initiate
+the propagation of the disturbance known as the nervous impulse. The
+nervous impulse is a physical event whose space-time relations can be
+defined as concretely as the passage of an electric current through a
+wire. Three-quarters of a century ago Helmholtz showed that the time
+which elapses between the application of a stimulus to a nerve and
+contraction of its attached muscle is a linear function of the distance
+between the latter and the point of application of the stimulus. The
+conception of the nervous impulse as a physical event had been, till
+this discovery, entirely repugnant to scientific thought. We now know
+not only, as Helmholtz showed, that the nervous impulse has definite
+space-time co-ordinates, but that it has the dimensions of energy. Its
+passage corresponds to the rate of propagation of an electrical change
+of an analogous character to the electrical response of the excited
+retina. The total energy of its propagation has been recently measured
+by Gerrard and A. V. Hill from determinations of heat production during
+its passage. Its mass relations are attested by a measurable increase
+in the carbon dioxide production of stimulated nerve. The rate of
+propagation of the nervous impulse varies like all chemical reactions
+in a characteristic way with increase in temperature. The goal of the
+nervous impulse after it has traversed one or more synapses in the
+central nervous system is the effecter organ itself--in the case of
+blinking of the eyelids, a muscle fibre. During the past two decades
+a series of brilliant researches based on calorimetric methods have
+revolutionized our knowledge of the final component of the reflex.
+A. V. Hill and Meyerhof have correlated the chemical and energetic
+changes accompanying muscular contraction with a precision of the order
+expected in purely physico-chemical determinations. They have shown
+that the total energy of muscular contraction can be quantitatively
+related to the energy liberated _in vitro_ by the breakdown into lactic
+acid of an amount of glycogen equivalent to that which is converted
+into lactic acid in the actual contractile process.
+
+Passing from the analysis of the constituent events of the reflex to
+the integration of reflexes in normal behaviour, we are faced with a
+striking change in the attitude of enquiry adopted in the study of
+those aspects of behaviour determined by generalized stimuli such as
+light and gravity and denoted by the term _tropisms_. Three-quarters
+of a century ago, after Helmholtz had dispelled the belief that
+identified the nervous impulse with an imponderable psychical
+principle, biologists like Lubbock were content for the most part with
+the statement that the moth flies towards the candle because it likes
+the light. The work of Loeb and others has shown that the state of
+contraction of particular groups of muscles is reflexly determined by
+the stimulation of particular areas of the retina. It is a mechanical
+necessity that when different areas are unequally stimulated,
+differences in tension of different groups of muscles will bring the
+body into such a position that symmetrically opposite areas will be
+equally illuminated. The animal must move, as in fact it does, along
+the path of the incident beam, whether by so doing it brings itself
+into a brighter, or, as can easily be arranged experimentally, a darker
+situation. Whereas the older and purely teleological attitude permits
+us to predict nothing of consequence, the objective interpretation of
+tropisms by experimental methods permits us to make many verifiable
+predictions, as, for instance, the fact that the moth will move in
+circles, if one eye is blackened, owing to the fact that the muscles on
+that side will be more relaxed.
+
+By the end of the nineteenth century, experimental biologists were
+generally disposed to the belief that the analysis of the reflex and
+the integration of reflex systems were problems not of apologetics but
+of energetics. Investigation had been confined to those aspects of
+behaviour which are for practical purposes invariable responses to a
+particular situation. From the human standpoint the most fascinating
+feature of the behaviour of an organism is, after all, the extent
+to which its behaviour is conditioned not by the immediate but by
+the antecedent situation. In the opening years of this century the
+researches of Sherrington were elucidating the integration of reflexes
+in normal behaviour. Restricted as they were to the decerebrate
+animal, the traditional distinction between reflex and voluntary
+activity remained as a defeatist formula in biological nomenclature.
+The distinction was not a gratuitous olive branch to introspective
+philosophy. It had its objective basis in the domain of behaviour
+which is not uniquely determined by the immediate stimulus, when all
+synchronous conditions have been standardized. That distinction has
+been superseded to-day by the work of Pavlov’s school, which has shown,
+first, that in the higher animals with the cerebrum intact, new reflex
+systems can be built up experimentally under perfectly definable and
+reproducible conditions; that the relations between such conditioned
+reflexes can be defined in the language of space and time; and that the
+concept of sensation can be externalized by reference to the ability of
+a given stimulus to become a specific agent in the building up of a new
+reflex system. In short, it is legitimate to anticipate the possibility
+of giving a complete specification of how such an animal as a dog
+will behave in a given situation without recourse to the traditional
+nomenclature of memory, consciousness, sensation, etc.
+
+Pavlov’s work is now accessible to the English reader through two
+translations of the Russian physiologist’s own writings and several
+excellent résumés, such as the one given in Lovatt Evans’ _Recent
+Advances in Physiology_. How far-reaching are its consequences has not
+been widely recognized even by biologists themselves. Experimental
+biology, during its brief career, has attempted to accommodate itself
+to the introspective temper of traditional philosophy by a compromise
+explicitly formulated in the writings of Descartes, who bequeathed
+to physiology the dualism of mind and matter. In conformity with the
+Chaldæan mythos, many philosophers, Descartes among them, have endowed
+Man alone with soulfulness. The coming of the Evolutionary hypothesis
+has broken down so inflexible a distinction between Man and other
+forms of living matter. Evolutionists in the nineteenth century, like
+Haeckel, were prepared to equip the Amœba with a soul. In our time
+the Cartesian compromise has again shifted its boundaries. By the
+beginning of this century the moth once more had gone to join the
+candle. Still Man stood with a little family of mammals around him,
+each with one leg on either side of the frontier that separates the
+universe of space and time from the Platonic world of universals.
+Pavlov has taken those aspects of behaviour which would have been
+referred twenty years ago to exclusively introspective concepts, and
+has treated them successfully as predictable configurations in a
+space-time framework. The little family of mammals has been let through
+the tollgate of the Cartesian compromise. A new school of psychologists
+has come into being with the express object of making psychology a
+physical science, relieving Man, the celestial pilgrim, of his burden
+of soul.
+
+Philosophers have always had a legitimate cause for complaint that
+biologists were unable to deal with those aspects of human life
+which interest people most. The distinction between reflex and
+voluntary activity provided the fullest absolution for that amiable
+libertarianism which we all entertain under the influence of alcohol
+and love. Because that distinction was implicit in the outlook of the
+most radical mechanists of the last generation, Loeb among them, Dr.
+Haldane finds it so easy to point out the inadequacy of the mechanistic
+outlook. In the light of Pavlov’s work we can now envisage the
+possibility that the methods of physical science will one day claim the
+whole field of what can be properly called knowledge. If I am right in
+cherishing such an opinion, it would thus appear that the investigation
+of the conditioned reflex initiates a new epoch in biology, pregnant
+with more far-reaching philosophical implications than the evolutionary
+speculations of the nineteenth century. The fact that no reference to
+the conditioned reflex is contained in Dr. Haldane’s Gifford Lectures
+may in part account for the fact that he can so easily dispose of the
+mechanistic position. The modern mechanist does not say that thought
+and love and heroism do not exist. He says, show me behaviour to
+which you apply the adjectives thoughtful or loving or heroic, and we
+will, one fine day, endeavour to arrive at predictable conclusions
+with reference to it by following the only method of enquiry which
+we have learned by experience to trust. When Dr. Haldane goes out of
+his way to dispose of the puerile formula that thought is a secretion
+of the brain, as bile is a secretion of the liver, and does so, I
+gather, under the impression that mechanists either believe it to mean
+something or alternatively shut their eyes to the major problems of
+existence, I can only respectfully suggest that he is flogging a dead
+horse, while the living ones are getting out of the vitalistic stables.
+
+I have endeavoured so far to indicate the increasing measure of
+success that has crowned the application of physical methods and the
+use of physical concepts in modern biological investigation. I have
+attempted to illustrate the continuous retreat from teleological
+concepts that has accompanied this advance. In asking what progress
+may be anticipated from encouraging the teleological attitude to the
+nature of life, I wish now to urge that the important advances of
+biological science during the last hundred years have not only involved
+continual abandonment of teleological concepts, but have consistently
+been made in the teeth of opposition from the vitalists, organicists
+and holists of their time. A century ago, in the same year that
+witnessed Wöhler’s announcement of the successful synthesis of Urea,
+the great chemist Henry wrote (1827) concerning organic compounds:
+“It is not probable that we shall ever attain the power of imitating
+Nature in these operations. For in the functions of a living plant a
+directing principle appears to be concerned peculiar to animated bodies
+and superior to and differing from the cause which has been termed
+chemical affinity.” Only six years before Helmholtz’s determination
+of the velocity of the nervous impulse in 1851, Johannes Müller had
+declared that to measure the propagation of that imponderable psychical
+principle was a theoretical absurdity.
+
+It is not unlikely that before another celebration of the centenary
+of Wöhler’s achievement, Fischer’s synthesis of an octadecapeptide
+will have been surpassed by the manufacture of complex proteins in the
+laboratory. Looking forward a little in the light of what success has
+crowned the construction of physical models of vital processes, it
+is, as Sir Edward Sharpey Schafer scandalously suggested at a meeting
+of the British Association some years ago, perfectly legitimate to
+entertain the possibility, even the likelihood, that scientists will
+one day construct from artificially synthesized organic materials,
+systems with so wide a range of reversible reactivity and receptivity
+to external influences that they would be called organisms, if met with
+in Nature. While taking a more hopeful view in this matter than some
+biologists, I would remark that the validity of the mechanistic outlook
+is quite independent of this possibility. The security of any dynamical
+system of treating the motions of the heavenly bodies is independent of
+the possibility that human effort could manufacture a new satellite for
+Jupiter.
+
+
+§3
+
+If we can assert that the present phase of biological enquiry is
+a peculiarly fruitful one, and that there is no reason to see any
+immediate cessation of progress in the use of physical concepts as
+the basis of our analysis of the properties of living matter, can we
+not go further and state that we have absolutely no encouragement
+for entertaining the hope that any deeper knowledge will accrue from
+apostrophizing under the sobriquets of entelechy, life force, élan
+vital that elusive entity to which, perhaps, the poet William Blake
+referred as Old Nobodaddy? It is doubtful whether we shall see a
+recrudescence of such frankly animistic devices as these. As biology
+becomes more technical and more exact, an aptitude for rehabilitating
+oriental mysticism in somewhat unusual verbiage will be regarded
+as an insufficient equipment for entering the field of biological
+controversy. The investigator who abandons physics for the pursuit
+of biology will contribute new ideas. Fruitful contributions need no
+longer be expected from those who combine the pursuit of literature
+with an amiable interest in natural history. The days of Butler and
+Bergson are passed.
+
+Dr. Haldane, the most vigorous contemporary critic of the mechanistic
+standpoint, is very anxious to avoid any suspicion of being tainted
+with the cruder forms of vitalism. He disowns any allegiance to the
+life force, élan vital et hoc genus omne, except in so far as he,
+somewhat mysteriously, contrives to introduce an adventitious deity
+into the latter portion of his Gifford Lectures. This does not make
+its appearance until his major thesis is complete. Anxious as is Dr.
+Haldane to disclaim adherence to the tenets of vitalism, he is very
+definite in denying the possibility that atomistic concepts will
+ever successfully deal with the problem of what he calls “conscious
+behaviour.” In the light of Pavlov’s work we see that the problem of
+what is usually called conscious behaviour, or as we should rather say
+_conditioned behaviour_, can now be approached as a problem in the
+study of those conditions which determine whether a new reflex will,
+or will not, be brought into being. We may state this in other words
+by enquiring how the passage of impulses along particular tracts in
+the central nervous system _influences the facility with which the
+nervous impulse will pass across a particular type of synapse_. Since
+the problem of the conductivity of the synapse is, as we have seen,
+an essentially physical problem, it is not overstating the case to
+say that the work of Pavlov’s school has brought the study of what
+Dr. Haldane calls “conscious behaviour” within the realm of physical
+enquiry. Once this is fully grasped it no longer seems incredible
+that the interpretation of conditioned behaviour will eventually come
+within the scope of physico-chemical analysis. Contrary to the holistic
+standpoint, we are thus led to an atomistic concept of individuality.
+This I shall venture to formulate as _the statistical probability
+that in an immensely elaborate system of reversible reactions a
+certain number of states characteristic of any given moment will be
+reproducible at another moment_.
+
+In his Lowell lectures Professor A. V. Hill lays down two general
+conclusions derived from the extension of modern biological enquiry.
+First, as I have endeavoured to show, there is no limit to the extent
+to which the mechanisms of life can be elucidated with the aid of
+physical methods and concepts. Second, that, however far we get, we
+shall still find function, adaptation, organization and purpose in
+the processes we explore. I would venture to suggest that, however
+alluring such a compromise between vitalism and mechanism may appear,
+these two conclusions, though formally in nowise inconsistent, are,
+nevertheless, in practice incompatible. As Henderson points out in his
+_Fitness of the Environment_, if we wish to indulge in teleological
+phantasies, we can find as much scope in physics and chemistry as in
+biology. We do not dismiss the hypothesis that thunderstorms occur when
+a blue unicorn sneezes on Uranus, because it is actually possible to
+disprove so engaging a fancy, but simply because other ways of treating
+thunderstorms lead to more useful conclusions.
+
+Hence it seems to me that as we come to understand more and more about
+the mechanics of living systems by using methods of which Professor
+Hill is so brilliant an exponent, we shall inevitably find ourselves
+talking less and less about purpose and function. In consequence many
+of the problems which now engage the attention of philosophers will be
+relegated to the same status as the philosopher’s stone. No doubt such
+a change will come very gradually, so gradually that we shall hardly
+notice it. Nevertheless, one may venture to predict that philosophers,
+already forced by the developments of modern physics to divert their
+attention from the pretentious crossword puzzles of the Hegelian
+tradition, will sooner or later be driven to take account of the
+post-evolutionary developments in biology, and more especially those
+which have their starting-point in Pavlov’s researches.
+
+By undertaking the analysis of the characteristics of conscious
+behaviour without departing from the methods of the traditional
+physiology of reflex action, biological science in our generation has
+shown that there is no nicely defined boundary at which physiology
+ends and moral philosophy begins. Hitherto physiology and academic
+philosophy have developed independently, because physiologists
+themselves have accepted the common sense dualism of mind and matter.
+Moral philosophy can no longer claim that there is any distinctive
+aspect of the Nature of Life, which lies beyond the province of
+physiological enquiry. If any fundamental distinction between mind
+and matter remains, that distinction henceforth defines the antinomy
+of a _public world_ of common beliefs which all can share, the
+conceptual world of science in which ethical neutrality and economy
+of hypothesis reign supreme, and, in contradistinction to that public
+world, many _private_ worlds which for the present remain impenetrable
+through the medium of discourse. Biological science is continually
+socializing our beliefs. What seems irrevocably part of the private
+worlds of one generation becomes irrevocably part of the public world
+of its grandchildren. Thus the new pluralism will not be, like the
+Cartesian system, static, but dynamic. It is ever tending towards a
+monistic outlook as a limiting case. Such a monism, unlike traditional
+materialism and traditional idealism will be regarded not as a formula
+but as an asymptote. It is evidently immaterial to _public_ discourse
+whether we _privately_ entertain the view that _the_ public world is
+more or less _real_ than _our_ private worlds. It would thus seem that
+as biological science invades the province of human behaviour the
+concept of _publicity_, as I venture to call the communicability of
+beliefs, will come to occupy the status of importance which _reality_
+has held in the systems of egocentric philosophers.
+
+The public world, as I have conceived it, is a construction based on
+the continuous extension of the principle of mechanism. The principle
+of mechanism, that a complex system is interpretable only by reference
+to the properties of its constituent parts, is not urged in the spirit
+of dogmatic assertion, but because it has served us well in the past.
+We still await any single verifiable conclusion that is uniquely
+developed from any alternative principle. Holism, the newest form
+of Vitalism, claims to have found an alternative or supplementary
+principle that is essentially teleological. The holist does not specify
+by reference to any single concrete situation how he proposes to use
+his principle. It is admitted even by the mechanist that we are not
+in a position to construct a symbolic relation which will completely
+describe the vagaries of a Ford car in terms of the field equations
+of the proton and electron. Does the holist wish us to believe that
+we can help anyone to drive a car by assuring him that at every level
+of complexity between the internal structure of the atom and the
+newly licensed automobile there emerges an ever-increasing urge to a
+wholeness or unity which is somehow indefinably different from the
+interaction of the parts? Verily the mechanist of all people knows that
+we know in part and we prophesy in part. For this very reason, because
+he is prepared to await with patience the slow advance of science, he
+refuses to subscribe to high-sounding pseudonyms for ignorance and
+principles that are never seriously intended to be put into practice.
+
+In the recent symposium on _The Nature of Life_ before the British
+Association both General Smuts in his exposition of the holistic
+standpoint and Dr. Haldane who supported him dwelt upon the supposed
+collapse of mechanistic principles in physics itself. The former
+cited in support of his point a somewhat rhetorical remark by Dr.
+Whitehead in this sense. It is of course evident that if our mechanical
+principles undergo modification our biological interpretations must
+share in the general change of outlook. It is, therefore, beside the
+point to criticize the mechanistic standpoint on the ground that our
+mechanical principles are undergoing revision. Let us examine this
+objection a little more closely. Experimental biology, we are told,
+has been directed towards the attempt to describe the properties
+of living matter in terms of the traditional physical concepts of
+mass, length, time, energy, etc. Since these concepts now appear to
+be less fundamental than we once believed, the hope that a complete
+mathematical description of the universe is realizable, has, as
+Mr. Sullivan asserts with triumphant _naïveté_, “no longer any
+plausibility.” Surely it is evident that a signal advance towards
+a more monistic interpretation of nature has been made, when the
+analysis of any biological phenomenon has been achieved with the aid
+of traditional physical concepts, and when concepts once peculiar
+to biology, as affinity was once peculiar to chemistry, have been
+translated into the traditional language of physics. Physics to-day
+is seeking a new synthesis to take into one system of equations all
+the old data, and many new ones which have lately accumulated. This
+is not a new situation. The old mechanics remains as valid as ever
+for the realm in which it was developed to operate. To effect a more
+comprehensive scheme it has been necessary to examine many of the
+old postulates. In the meantime we have to recognize that we are not
+so near to a single unifying hypothesis as the rise of energetics
+led the physicists of Kelvin’s generation to hope. What does this
+signify? Certainly not that mechanics has abandoned the principles
+of mechanism. Is it not rather a fact that the modern physicist is
+complaining that the inadequacy of Newtonian principles is in part
+attributable to teleological implications insufficiently recognized
+till now? The very hope of finality which Kelvin’s generation
+entertained seems from the new mechanistic standpoint, as I have stated
+it, to savour of scholasticism.
+
+In taking this line General Smuts and Dr. Haldane seem to me to have
+laid bare the source of a misunderstanding that lies at the root of
+most of the criticism which vitalists old or new direct against the
+new or the old mechanistic standpoint. Those who have the scholastic
+predilection for finality and the scholastic predilection for the
+abstract noun, do not seem to be able to believe in the existence of
+people who are not like themselves. They cannot, it appears, understand
+that unless one starts off with the obsession that the universe can
+be summed up in a monosyllable, one is under no imperative necessity
+on the one hand to be resentful towards or disappointed with science
+because it lays no claim to the finality of religious dogma, nor
+on the other to make the assumption that such finality ought to be
+obtainable. The mechanist does not claim that his system is, or ever
+will be, complete in the sense that science will one day find an answer
+for all the conundrums which the scholastic temperament dictates. On
+the contrary, it is the essence of the mechanistic position that there
+is a technique of asking questions profitably as well as a way of
+answering them satisfactorily. All the mechanist claims is that as far
+as we can see at present his way of dealing with things leads to the
+most complete unanimity which it is possible to attain. Against the
+old vitalism, that of Dr. Haldane, who denies that the principle of
+mechanism can ever deal with conscious behaviour the older mechanistic
+outlook was secure in the assurance that, if the principle of
+mechanism failed at such a level, no other principle led to verifiable
+predictions in the same field. Against the new vitalism or holistic
+standpoint of General Smuts which no longer asserts dogmatically that
+the principle of mechanism is inapplicable at any specific level of
+existence, but contends that it does not anywhere give a complete
+account, the new mechanistic or _publicist_ standpoint which I have
+outlined contends that if the principle of mechanism fails to give a
+complete account at any level no alternative or supplementary principle
+has been discovered. The reply of the mechanist old or new to the
+vitalist old or new is that of Mr. W. B. Yeats’ faeries:
+
+  “Is anything better, anything better
+  Tell us it then...”
+
+It follows that, in any discussion between the two, the combatants
+are generally at cross-purposes. The mechanist is primarily concerned
+with an epistemological issue. His critic has always an ontological
+axe to grind. The mechanist is concerned with how to proceed to a
+construction which will represent as much about the universe as human
+beings with their limited range of receptor organs can agree to accept.
+The vitalist or holist has an incorrigible urge to get behind the
+limitations of our receptor organs and discover what the universe is
+_really_ like. What we mean by _really_ in this connexion evidently
+depends upon whether we view the question socially or individually. In
+our relation to other human beings the nearest approach to what the
+universe is really like is found in the schematization of our common
+experiences. If there is any other reality its sanction is non-social.
+Thus in contradistinction to the _reality_ of traditional philosophy
+which is an individualistic concept, the concept of _publicity_, which
+it is proposed to substitute as the goal of synthetic philosophy, is an
+essentially social one.
+
+
+
+
+IV. THE CONCEPT OF ADAPTATION
+
+  “No philosopher who is rational and modest has ever pretended to
+  assign the ultimate cause of any natural operation, or to show
+  distinctly the action of that power which produces single effect
+  in the universe. It is confessed that the utmost effort of human
+  reason is to reduce the principles productive of natural phenomena
+  to a greater simplicity.... The most perfect philosophy of the
+  natural kind only staves off our ignorance a little longer, as
+  perhaps the most perfect philosophy of the moral or metaphysical
+  kind serves only to discover larger portions of it.”--David Hume,
+  _Sceptical Doubts_
+
+
+§1
+
+By those who hesitate to commit themselves to an explicit advocacy of
+either the vitalistic or mechanistic views about the Nature of Life it
+has often been urged that the concept of adaptation is fundamental to
+biological science. Professor A. V. Hill is perhaps the most brilliant
+physiologist now living. He adopts a hopeful attitude to the progress
+which awaits further analysis of the properties of living matter in
+physico-chemical terms. He also thinks that, however far mechanistic
+principles are extended, the biologist will always encounter
+“adaptation” in the phenomena which he studies. Another distinguished
+physiologist, Professor Lovatt Evans has expressed himself in rather
+more emphatic terms.
+
+  “Physiologists,” he states, “in attempting to know what life is,
+  have in my opinion attempted too much, and I think that a new point
+  of view is essential.... The idea of adaptation, urged by Claude
+  Bernard, should be adopted by physiology as its basal principle, as
+  the chemist accepts the conservation of matter or the physicist
+  the conservation of energy. We need not seek to know why it is so,
+  that is the province of the philosopher.... It is not a definition
+  of what life is, but a brief statement of its way.... Life is
+  conserved by adaptation.”
+
+When I first read these words I was not sure that I agreed with them.
+I was not quite certain that I knew what they meant. I had already
+come to the conclusion that the word adaptation is frequently used
+by biologists without a very clear agreement as to its content. I
+cannot subscribe to the view that there is a sort of trade union of
+philosophers to which physiologists are ineligible, unless they can
+show their articles of apprenticeship. Nor can I conceive what is meant
+by a concept of life except such as is implied in a statement of _its
+way_. A scientific concept defines a class of properties. A scientific
+concept of life or adaptation must conform to this requirement. In
+this essay my object is not to criticize Professor Lovatt Evans for
+whose breadth of view I entertain a very sincere respect. I have
+quoted his words, because they focus attention on some significant and
+controversial issues. They serve to reveal how imperative it has become
+that biologists should agree about the sense in which they intend to
+use the word _adaptation_.
+
+The quotation given above might be interpreted to mean two very
+different things. If the term adaptation is used to define certain
+very general characteristics of living systems, it becomes almost
+co-extensive with a scientific concept of life itself. If we use
+_principle_ in a somewhat archaic sense to indicate a field for
+investigation, like the principle of affinity or the active principle
+of the thyroid gland, there can be no question that the idea of
+adaptation is the basic principle of physiology. The comparison of the
+biologist with the chemist or physicist seems to go beyond this, and
+imply that adaptation is not something to be explored and interpreted,
+but part of the logical procedure of biology, something by the aid of
+which we can predict conclusions of universal validity in the field
+of biological enquiry. I do not think that Professor Lovatt Evans
+really means this. I do urge that biologists continually confuse within
+the compass of the concept of adaptation the notion of a problem for
+solution and of a _vera causa_. This in everything but verbiage is
+precisely what the cruder type of vitalist does, when he invokes the
+vital principle. He first introduces a term to describe a large number
+of things about which we are ignorant and wish that we knew more. He
+then falls into the trap of imagining that the invention of a new term
+has solved the problem.
+
+Quite apart from this difference which, if it is to define the scope
+of our scientific enquiries, cannot be dismissed as metaphysics,
+biologists differ a good deal concerning the extent of the phenomena
+and the kinds of phenomena they are dealing with, when they speak
+of adaptation. The physiologist--in the restricted sense of the
+term--is usually referring to something which might be called
+the self-regulating characteristic of the body. The evolutionary
+biologist--who to-day is a physiologist in the broader sense of the
+term--is usually thinking of “a change in the structure, and by
+implication also in the habits of an animal which render it better
+fitted” for life. I here quote Professor D. M. S. Watson’s suggestive
+address on adaptation from the evolutionary standpoint.[3] Sometimes
+the word adaptation has a more comprehensive significance and includes
+both definitions which I have distinguished. It then amounts to saying
+that living systems are self-regulating and self-propagating, which
+is one way of defining the nature of life as a scientific concept.
+None of these technical uses of the word adaptation imply anything
+that the most dogmatic mechanist could decry. If we define adaptation
+as the self-regulating processes by which living matter retains its
+recognizable characteristics, it is a truism to say that life is
+preserved by adaptation. In that case, if adaptation is to be made
+the paramount issue for biological enquiry, we can hardly upbraid our
+predecessors for presumptuously seeking to know what life is. If we are
+to reach any agreement about the use of the word adaptation we must
+therefore retrace our steps, and examine more closely what are the
+characteristics of a living system. It is useless to define the goal
+of biological enquiry in terms of a concept which is as vague as life
+itself. I suggest that when, in its various uses, the term adaptation
+has any objective utility, it refers to these two more or less
+distinct categories of characteristics which living beings display,
+i.e. self-regulating and self-propagating. They are separable issues
+inasmuch as a worker bee and a Dominican friar are self-regulating but
+not self-propagating systems. There is no particular reason to object
+to the use of the prefix, so long as no personalistic implications of
+the word self are imposed upon it without further discussion.
+
+
+§2
+
+Of the two ways in which the word adaptation is used in biological
+discussion, that which implies the notion of self-regulation is
+most fundamental. A living organism is an extremely complex system
+in dynamic equilibrium with its environment. The idea of dynamical
+equilibrium is not peculiar to biology. The atom, which for traditional
+chemistry was a statical concept, is no longer regarded in that way
+by the modern physicist. What is more peculiar about living matter
+is its amazing complexity, and the idea of adaptation in the sense
+of self-regulation calls attention to the fact that a system of such
+extreme complexity, a system with so many characteristics, continues
+to maintain its individuality, i.e., its manifold characteristics,
+in spite of all the changes that are taking place within it and
+without. The recognition of this complexity is common ground. If the
+mechanist underrates the difficulty of the problem, he is certainly
+to be discouraged, except in so far as the scientist in attacking any
+problem must always focus his attention on a limited range of data
+and rule out certain things as insignificant for his present purpose.
+It may be true, as Professor Lovatt Evans opines, that mechanistic
+interpretations tend to become arrogant and superficial. Is he on surer
+ground in holding that “it is unthinkable that a chance encounter
+of physico-chemical phenomena can be the explanation”? Might we not
+reflect with David Hume that “our own mind being narrow and contracted,
+we cannot extend our conception to the variety and extent of nature,
+but imagine that she is as much bounded in her operations, as we are in
+our speculation”?
+
+Scientific hypotheses are not always thinkable, if by that we mean
+pleasant, easy or conformable to common sense. Our grandfathers
+thought it “inconceivable” that her Gracious Majesty, Queen of Great
+Britain and Ireland, Empress of India and Defender of the Faith,
+could be descended from an ape. The atomic structure of matter was
+unthinkable to many people little more than a century ago. To-day the
+quantum atomic model is unthinkable; but we think it is the best way
+of interpreting the data. Given this amazingly complex system in
+dynamically stable equilibrium with its environment, we have to decide
+consistently with the fullest requirements of the problems what is the
+most economical way in which we can envisage its existence. Seeing that
+a mechanistic interpretation is evidently the most economical one, the
+real issue is to decide whether there are any characteristics of the
+complex which are inconsistent with such an attitude.
+
+From the modern standpoint the individuality of the atom is a
+statistical concept. The atom is in dynamically stable equilibrium
+with its surroundings. It might, therefore, be argued that a Ford car
+is an example of a complex mechanism which is in dynamical equilibrium
+with its environment. This would be a superficial analogy for the
+order of complexity which we encounter in living matter. The molecular
+constitution of the parts of a Ford car is comparatively static. In
+the minutest parts of an organism new molecules are being built up and
+replacing others that have been broken down. Nevertheless, in all this
+astonishing panorama of microscopic revolutions which underlie the
+microscopic continuity of the organism we know of no events which are
+in conflict with the great generalizations of physical science.
+
+On this point Professor Hill speaks with special authority, when he
+declares:
+
+  “Fortunately for physiology several of the generalizations of
+  science appear to be fairly strictly true, even when applied
+  to the living organism. Although such exact experiments are
+  not possible on man, or animals, or plants, as may be made on
+  non-living objects, there is little evidence--indeed, I would be
+  bold and say there is no evidence--that such living creatures can,
+  in any manner or degree, evade the ordinary laws of mechanics,
+  chemistry and physics, the principles of the Conservation of Energy
+  and Mass.... There really is _no_ evidence that momentum and
+  kinetic energy, that chemical transformations, that electrical and
+  magnetic phenomena, occur in the living body in any manner, or to
+  any extent, which differs from that obtaining in the more readily
+  investigated non-living world.”
+
+In the same lecture Professor Hill replies to a statement which has
+been frequently reiterated by vitalistic writers including General
+Smuts and Professor Julian Huxley. Referring to the Second Law of
+Thermodynamics, he says:
+
+  “Philosophically speaking, the Second Law of Thermodynamics,
+  dealing with the limitations of the availability of Energy, is
+  more liable to doubt. It is known to rest on a statistical basis,
+  and when we are dealing with units, complete, self-producing,
+  yet as invisible and intangible as the filter-passing or other
+  micro-organisms, it is, theoretically speaking, possible that some
+  means may be available of evading the statistical relations which
+  govern the behaviour of larger systems. But here again we must ask
+  for evidence--and there is none of a precise or definite character
+  which suggests, in the least degree, that the living cell can
+  escape the jurisdiction of the Second Law.”
+
+We are thus forced to consider the order of complexity of the living
+system maintained in dynamical equilibrium with its surroundings as
+the essential feature which distinguishes it from non-living things.
+This complexity can be arbitrarily divided into many levels; but for
+convenience we may confine ourselves to two, the macroscopic and the
+microscopic. Let us be explicit about the meaning of this distinction.
+In the more familiar animals, we are accustomed to recognize a variety
+of responses to a variety of external agencies. Generally speaking
+in the more complex animals each kind of reactivity and each kind of
+receptivity is spatially localized. For instance, light impinging upon
+the retina evokes contraction of the pigment cells in the toes of a
+frog. From this macroscopic complexity of the gross architecture of
+the animal body arise two types of problems: first, the problems of
+co-ordination dealing with the way in which a disturbance recurring in
+some receptive area is propagated to an effector organ (gland, muscle,
+etc.) in some other region; and second, the problems of metabolic
+exchange, dealing with how the supply and distribution of sources
+of energy for all this display of activity is maintained. The first
+involves the study of the nervous impulse along the peripheral nerve
+fibres and through the central nervous system; it also involves the
+study of the internal secretions. The second involves the study of
+digestion and assimilation of foodstuffs, the intake of oxygen to burn
+up the waste products of chemical activity, and the removal of carbon
+dioxide, water and other products of oxidation. In contradistinction
+to the gross complexity of organs or populations of cells, we have to
+take into account the microscopic complexity of the cell itself. This
+presents a more general issue, because there exist many organisms whose
+complexity is of the same order as that of the separate cells which
+make up the bodies of familiar animals of visible dimensions. Two of
+the major problems of cell physiology concern the way in which the cell
+maintains its semi-permeability, and the way in which it maintains
+a constant renewal of chemical materials by utilizing the energy
+liberated in certain organic oxidations.
+
+If we remove the magneto from a car, we can keep it intact for an
+indefinite period: it is fundamental to our idea of a mechanism that it
+can be taken to pieces and put together again. We are so accustomed to
+think of a leg or an arm as dependent for their activity on the rest
+of the body, that the conception of a living mechanism is repugnant to
+common sense. In the laboratory it is possible to study properties
+of nerve, muscle, the cell membrane, absorption of food in the gut,
+oxidation of nitrogenous materials in the liver, etc., as isolated
+events. A person who is not a biologist almost invariably expresses
+bewilderment when he sees the isolated heart of an animal beating
+regularly in a perfusion apparatus. There exists the idea that the
+living organism differs from a mechanical system in that the parts
+cannot persist without the whole.[4] Behind this illusion of common
+sense the holistic concept of adaptation stands securely entrenched.
+The holistic conception implies that for living systems the part must
+be interpreted in relation to the whole, and not the whole from the
+interaction of parts. We have seen that the ultimate non-biological
+constituents of living matter, molecules, atoms, etc., do not behave
+differently when united to form a living system. In transcending this
+level of organization we are faced with an equally striking conclusion.
+The contraction of an isolated muscle preparation is essentially the
+same as the contraction of a muscle considered as an isolated aspect
+of the behaviour of the intact organism. The passage of the nervous
+impulse along an isolated nerve is not fundamentally different from the
+passage of the nervous impulse in the normal animal. The conversion
+of sugar into alcohol by the isolated enzyme zymase obtained from
+crushed yeast cells is a process like that of the conversion of sugar
+into alcohol by the living yeast fungus. The whole development of
+physiology, from the time when Haller first made an isolated muscle
+preparation and Spallanzani produced animal light by moistening a
+dessicated powder of luminescent jelly fishes, bears witness to the
+conclusion that the separated constituents of a living whole do not
+at any level of complexity behave differently from the way in which
+they behave as parts of a more complex order. Thus, when the fullest
+recognition is given to the extreme complexity of living systems, the
+problem of self-regulation submitted to experimental analysis does not
+bring forward any confirmation for the holistic view of adaptation as
+the creative interpolation of new irreducible properties at different
+levels of complexity. The holist may reply that it is one thing to take
+the living machine to pieces, and another thing to put it together
+again. Even here the analogy with the machine holds good. To graft the
+eye of one salamander tadpole on to the head of another individual
+is now a commonplace of experimental embryology. Five-legged and
+two-headed newts are now manufactured in the laboratory.
+
+Self-regulation, the way in which an organism maintains a seeming
+continuity of arrangement in spite of the uninterrupted and ubiquitous
+flux of macroscopic and microscopic changes which its existence
+implies, defines the sense in which the term adaptation is ordinarily
+used by the physiologist. In contradistinction to this physiological
+and individual use, adaptation is employed in biological discussion
+in a morphological and specific sense, when we consider how one
+animal comes to be distinguished from another by some architectural
+arrangement appropriate to a particular kind of environment. In this
+sense the problem of adaptation has played a prominent part in the
+evolutionary speculations of the past century. Given the fact that
+organisms are not only self-regulating but self-propagating, the
+evolutionary theory sets out to explain how living systems come to
+exist in so many specific forms, and how it is that these specific
+forms are on the whole _fitted_ or _adapted_ to their respective
+surroundings. The qualification _on the whole_ is highly significant.
+Organisms display many peculiarities of architecture which by no
+stretch of imagination can be regarded as necessarily fitting them
+better for their conditions of life. To assume that every peculiarity
+of structure in an animal is useful to it in the struggle for existence
+is a pure assumption unfounded on anything but teleological prejudice.
+
+Adaptation in the morphological sense really includes two ideas which
+to some extent coalesce, and are therefore all the more readily
+confused. At times the word implies nothing more than _viability_.
+In this sense adaptation is the whole problem of evolution. Up to
+a certain point an organism must be “suited” to its environment in
+order to live at all. At other times adaptation is extended to mean an
+essential utility in every detail of the structure of an organism. This
+is a mischievous implication which, as will be seen later, has hindered
+the formation of a clear conception of the evolutionary process.
+Even if we could justify the belief that female peafowl are as much
+impressed by peacocks as are some male biologists, we have still failed
+to supply a criterion of survival value which has any satisfactory
+significance. The enthusiast who describes an adaptation is often like
+the advertizing manager who tells us how many customers we shall get,
+if we advertize with him, but is inclined to be reticent about whether
+the profit derived from more customers is commensurate with the fees
+he proposes to exact for his services. Bateson, who first applied
+Mendel’s principles to animals, wrote five years before the Mendelian
+Renaissance in terms which may still be commended to the thoughtful
+examination of every student of the evolutionary problems:
+
+  “Whereas the only possible test of the utility of a structure is
+  a quantitative one, such a quantitative method of assessment is
+  entirely beyond our powers. To know that the presence of a certain
+  organ may lead to the preservation of the race is useless, if we
+  cannot tell how much preservation it can effect... unless we know
+  also the degree to which its presence is harmful, unless, in fact,
+  we know how its presence affects the profit and loss account of the
+  organism.” (_Materials for the Study of Variation_).
+
+That animals do in fact display many structural characteristics which
+are in no sense useful to them is generally admitted to-day. It
+thus becomes as much the function of any theory of the evolutionary
+process to explain the origin of useless as to explain the origin
+of useful devices. There is a practical limit to the use of the
+concept of adaptation in morphology. There is a no less obvious limit
+to the use of the concept of adaptation in physiology. An animal
+is a self-regulating system up to a point; but it cannot in every
+contingency take arms against a sea of troubles and by opposing end
+them. If we could define in some general terms where this limit lies,
+we should be justified in speaking of a principle of adaptation in
+the sense that we speak of a principle of conservation of matter.
+The ideally self-regulating unit of living matter endowed with the
+secret of perpetual youth is as imaginary as the Economic Man. At
+present the fact that organisms cease to regulate themselves and die
+is as fundamental a problem of biology as the converse fact that they
+regulate themselves and thereby continue to live. The fact that the
+organism has a good deal of useless anatomical equipment seems to be
+as true as the fact that on the whole its anatomy is suited to the
+requirements of its surroundings. In whichever way we employ the term
+adaptation we are forced to the conclusion that it is only legitimate
+to speak of a principle of adaptation in the sense in which we speak
+of the active principle of the thyroid gland. Adaptation defines a
+field of problems which await solution. In that sense the concept of
+adaptation is as fundamental to mechanistic as to any other theories of
+the organism.
+
+
+§3
+
+This is not what is generally meant when it is said that adaptation
+is a fundamental principle of biological enquiry. I believe that it
+is the only legitimate sense in which it can be said that there is
+a biological principle of adaptation. It seems to me that, when we
+go further and put more than this into our concept of adaptation, we
+are driven to formulating the problems of biology in a wrong way. By
+inventing hypotheses to explain facts which do not exist, we then
+proceed to give false interpretations of the significance of facts that
+do exist.
+
+When the principle of adaptation is treated as a principle which
+enables us to predict conclusions, it constantly leads us to fantastic
+distortions of what really happens. If I wished to illustrate this in
+connexion with the self-regulating aspect of the concept of adaptation,
+I could not do better than refer to current speculations about the rôle
+of the ductless glands in the economy of the organism. The physiologist
+who interprets his field of observation in a manner analogous to
+that of the physicist and chemist realizes that we have no reason
+to believe that every chemical entity found in the animal body is
+necessary or even useful to its owner. He will not therefore draw any
+conclusions of a far-reaching nature from the discovery that a certain
+tissue extract has highly specific physiological properties, unless
+he can show that the removal of the tissue itself produces effects
+of an opposite nature to those which ensue on injecting its active
+constituent. The student of ductless glands who regards adaptation as
+a principle to be applied rather than as field to be explored will
+not be held back by such restraint. We must thank the “principle” of
+adaptation in endocrinology for the romantic guess-work of that school
+which undertakes to interpret the whole of human history in terms of a
+glandular explanation of temperament. Most speculations on which the
+glandular theory of temperament are based have their only experimental
+basis in the presence of supposedly specific active substances in one
+or other tissue extract. A “principle of adaptation” does not assist
+us to understand why the pituitary gland of a fish should contain one
+specific constituent which produces expansion of the black pigment
+cells in the skin of a frog, another specific constituent which causes
+the uterus of the mammal to contract, and yet a third which produces
+a specific fall of blood pressure in the bird and a specific rise of
+blood pressure in the mammal.
+
+It is especially in the field of evolutionary biology that we must look
+for most guidance, because the concept of adaptation has occupied such
+a prominent part in the evolutionary controversy. As an example of how
+“the principle of adaptation” leads to incorrect conclusions I need
+cite only one example from an exceedingly able and provocative address
+of Professor D. M. S. Watson.
+
+  “It is not unusual for a student of fossils to discuss the habits
+  of an extinct animal on the basis of a structural resemblance of
+  its ‘adaptive features’ with those of a living animal and then to
+  pass on to make use of his conclusions as if they were facts in
+  the discussion of an evolutionary history or of the mode of origin
+  of a series of sediments. In extreme cases such evidence may be
+  absolutely reliable: no man faced with an ichthyosaur so perfectly
+  preserved that the outlines of its fins are visible can possibly
+  doubt that it is an aquatic animal, and such a conclusion based on
+  structure is supported by the entire absence of ichthyosaurs in
+  continental deposits of appropriate ages and their abundance in
+  marine beds. But if extremes give good evidence, ordinary cases are
+  always disputable. For example, there is, so far as I know, not the
+  least evidence in the post-cranial skeleton that the hippopotamus
+  is aquatic; its limbs show no swimming modification whatsoever, and
+  the dorsal position of the eyes would be a small point on which to
+  base assumptions. Most palæontologists believe that the dentition
+  of a mammal, and by inference also that of a reptile or fish, is
+  highly adaptive, that its character will be closely correlated with
+  the animal’s food, and that from it the habits of an extinct animal
+  can be inferred with safety. Here again the extreme cases are
+  justified, the flesh-eating teeth of a cat and the grinding battery
+  of the horse are clearly related to diet. Crushing dentitions, with
+  the modification of skull and jaw shape and of musculature which
+  go with them, seem equally characteristic. I had always believed
+  that the horny plates and the jaws of Platypus were adapted to
+  hard food, and that that animal possessed them, whilst the closely
+  allied Echidna was toothless, because it was aquatic and lived in
+  rivers which might be expected to have a rich molluscan fauna which
+  could serve as food. But the half-dozen specimens whose stomachs I
+  have opened contained no molluscs whatsoever, and seem to have fed
+  on insect larvæ, the ordinary soft bottom fauna of a stream.” (_Op.
+  cit._)
+
+We are now beginning to see that the evolutionists of the nineteenth
+century focused their attention far too exclusively on adaptation. In
+other words, they regarded adaptation as a principle like the principle
+of conservation of matter, one of universal validity within the field
+of biology. Any theory of evolution has to explain why non-adaptive,
+as well as adaptive, features arise. In that sense the fundamental
+problem of evolution is not the origin of adaptation but the origin of
+species. Both the theories of Lamarck and Darwin implicitly assumed
+that the differences between species, in the traditional, i.e. Linnæan
+sense, are mainly utilitarian. Having started with an incorrect
+apprehension of the facts they proceeded to elaborate hypotheses to
+account for them. Thence inevitably they drew from these hypotheses an
+unsatisfactory account of the way in which new species do arise. From
+the modern standpoint analysis of the species problem does not demand a
+recognition that species differences are even in the main utilitarian,
+though such a statement would probably be true of differences between
+larger units such as genera. Nor from the modern standpoint do the
+hypotheses of either Lamarck or Darwin give us any clue to the way in
+which the species barrier, i.e. inability to breed with other species
+successfully, can have arisen. Anything which remains of the Lamarckian
+principle in the light of modern research has no special relevance
+to the origin of adaptations. Whatever remains of the theory of
+natural selection has been completely divested of the implication that
+non-adaptive characters were necessarily adaptive at their inception.
+
+A discussion of the fate of the Lamarckian and Darwinian theories must
+be undertaken elsewhere. Here it is sufficient to point out that both,
+more particularly the latter, had a peculiarly sterilizing influence
+on the growth of experimental biology. Obsessed with the principle of
+universal adaptation which Natural Selection had secularized, zoology,
+from the publication of the _Origin of Species_ to the rediscovery of
+Mendel’s Laws, wandered for forty years in a wilderness of phylogenetic
+speculation. Biological research in the words of Professor Punnett
+became
+
+  “devoted to the construction of hypothetical pedigrees suggesting
+  the various tracks of evolution.... The result of such work may be
+  said to have shown that the diverse forms under which living things
+  exist to-day, and have existed in the past, so far as palæontology
+  can tell us, are consistent with the view that they are all
+  related by the community of descent.... It is obvious that all this
+  work has little or nothing to do with the manner in which species
+  are formed.”
+
+According to the Selectionist doctrine in its original form, characters
+originated and persisted in virtue of their utility and what Darwin
+somewhat vaguely called “the strong principle of inheritance.” To
+explain any peculiarity of structure or habit, it became necessary
+only to show one of two things, either it was useful to its owner or
+was once useful to an ancestor of its owner. Everything was or had
+been an adaptation. This resulted in a complete divorce of comparative
+anatomy from comparative physiology. The morphologist and systematic
+zoologist regarded it as an impertinence of the physiologist to seek
+for experimental evidence, where a perfectly good case of adaptation
+was evident to anyone who would accept their premisses.
+
+I will illustrate this from a field in which I have myself carried out
+experimental investigations for twelve years. Writing of colour change
+in frogs Dr. Hans Gadow makes the following remarks in the _Cambridge
+Natural History_ (_Amphibia and Reptiles_, p. 36):
+
+  “Biedermann concludes that the chromatic function of frogs in
+  general depends chiefly upon the sensory impressions received by
+  the skin, while that of fishes depends upon the eye. All this
+  sounds very well, but the observations and experiments are such
+  as are usual in physiological laboratories, and the frogs, when
+  absorbed in their native haunts, or even when kept under proper
+  conditions, do not always behave as the physiologist thinks they
+  should. There is no doubt that in many cases the changes of colour
+  are not voluntary but reflex actions. It is quite conceivable that
+  the sensation of sitting on a rough surface starts a whole train of
+  processes: roughness means bark, bark is brown, change into brown;
+  but one and the same tree frog does not always assume the colour of
+  the bark, when it rests or when it sleeps upon such a piece. He
+  will if it suits him remain grass green on a yellow stone or on a
+  white window frame.... The sensory impression received through the
+  skin of the belly is the same, no matter if the board be painted
+  white, black or green, and how does it then come to pass that the
+  frog adjusts its colour to a nicety to the general hue or tone of
+  its surroundings.”
+
+It is safe to say that no one, unless at the outset prejudiced by the
+principle of adaptation, could be led to entertain the view that frogs
+as a rule are able to adjust themselves “to a nicety” to the general
+hue and tone of their surroundings. The state of the pigment cells in
+the skin is influenced independently by a number of diverse factors,
+including moisture, temperature, diffuse light acting on the skin
+and reflected light acting on the retina of the eye in the opposite
+sense. Individual frogs differ in basic pattern, but the range of hue
+between the dark and pale condition for any frog is fixed, as is also
+true of the proverbial chameleon. When the conditions affecting colour
+change in a frog are defined, it is possible to predict the pigmentary
+response of a frog and its time relations with as much confidence as
+any other physical event in nature. It is, on the other hand, quite
+impossible to draw any far-reaching conclusions about colour change
+from uncontrolled observation of the frog in its native haunts, because
+the number of significant variables is far too numerous to handle
+in this way. I have quoted this passage to show the attitude which
+zoologists under the influence of the post-Darwinian tradition adopted
+towards experimental enquiry of any description. Dr. Gadow applies
+the “principle of adaptation,” as it was then used in morphology, to
+the self-regulating aspect of the organism with results which show
+what might well happen to physiology if the physiologist employed
+the principle of adaptation as the chemist employs the principle of
+conservation of matter.
+
+Ecology, or the study of the relation of species to particular types
+of environment, provides a clear illustration of the progress that
+has been achieved by detailed study of physiological mechanisms in
+place of the speculative application of the principle of “adaptation.”
+Krogh and his pupils have made a special study of the physico-chemical
+properties of the blood pigments of the lower organisms, and have
+thereby thrown a good deal of light on the conditions which determine
+their ecological distribution. Let us take the case of two common bony
+fishes, the carp and the trout. It is a matter of common experience
+that in nature the trout will only live in running streams. It can
+be kept with great difficulty in aquaria, if special precautions for
+aerating the water are taken. The carp will live in still water, where
+the oxygen content is low, and like its ally the goldfish accommodates
+itself to the aquarium with great ease. The difference between the two
+types is at once understood, when we know that the hæmoglobin of the
+carp has a much higher affinity for oxygen than the hæmoglobin of the
+trout. In consequence the blood of the carp is completely saturated
+with oxygen when the oxygen content of the water in which it swims is
+far below that which is in equilibrium with the oxygen pressure of the
+atmosphere. The blood of the trout on the other hand is only fully
+saturated with oxygen when the water is itself nearly saturated.
+
+The concentration of salts in the blood of fishes like the trout
+and carp is kept constant at a level below that of sea water. The
+concentration of dissolved substances in the blood of sharks and
+dogfishes which are all marine is in equilibrium with the osmotic
+pressure of the sea. The respiratory centre of the wrasse is
+paralysed at 60° C. {sic}, while the heart of the English dogfish
+shows irreversible changes above 18° C. Taking these facts together
+we can deduce a good deal about the viability of a species in a given
+locality. A fish like the skate placed near the estuary of a large
+river is forced to remain where the salt concentration is above a
+certain level. A salmon is not subject to this restraint. Assuming that
+the fish can pass the estuarine boundary and proceed upstream, two
+alternatives present themselves. He can remain in the swiftly moving
+main stream or take to backwaters and stagnant lakes connected with
+it. If he has the hæmoglobin of a trout, he is committed irretrievably
+to the former alternative. Being compelled to remain in the swiftly
+running part of the river bed, he might stay in the lowlands or make
+for the source, which in general will be much colder. In the case of
+a fish like the wrasse, whose respiratory centre is paralysed at a
+temperature of 6° C., the latter course is impossible, if the river
+rises in a high range. Thus in place of vaguely speculating about how
+an organism is specially “adapted” to live in some particular place,
+experimental biology is gathering clearly defined ideas about why an
+organism cannot live in any place other than that in which it does live.
+
+The idea that a problem can be solved by invoking the principle of
+adaptation assumes its most grotesque form in Haeckel’s discussion of
+Recapitulation. The classical example of what is called recapitulation
+is provided by the gill clefts of vertebrates. All vertebrate
+embryos have pits or clefts at the sides of the throat, supplied by
+a characteristic arrangement of blood-vessels. In fishes the clefts
+acquire filaments richly supplied with blood-vessels, and act as
+gills. Both the gill clefts and the characteristic arrangement of
+blood-vessels associated with them persist throughout life. In frogs
+and salamanders gill filaments are developed in the tadpole stage, but
+the clefts disappear in adult life and the characteristic arrangement
+of their blood supply becomes profoundly changed. In Man and most land
+vertebrates the gill clefts are never used as respiratory organs, and
+with their blood-vessels disappear at an early stage in development.
+During the first half of the last century Van Baer, the pioneer
+embryologist, propounded a generalization which may be stated thus:
+embryos of different species of animals of the same group are more
+alike than the adults, and the younger the embryo the greater are the
+resemblances. This generalization, well illustrated by the gill clefts,
+was later extended by Haeckel with the sonorous title “Biogenetische
+Grundgesetz.” It is thus defined by its author: “The history of the
+fœtus is a recapitulation of the history of the race, or in other
+words, ontogeny is a recapitulation of phylogeny.”
+
+The way in which the modern geneticist handles the problem of
+development offers a striking contrast to the attitude of Haeckel and
+a generation of zoologists unduly preoccupied with the concept of
+adaptation. A recent investigation from the laboratory of Professor
+Julian Huxley will illustrate the difference. In the little crustacean
+_Gammarus_ there are a number of varieties distinguished by the colour
+of their eyes. All coloured eyes are at an early stage of development
+colourless. They then become scarlet owing to the formation of a red
+pigment. They may subsequently darken owing to the deposition of the
+black substance known as melanin. Varieties with eye colour from a
+dark red through various grades of chocolate to dark brown and black
+are distinguished by the time at which the deposition of melanin
+begins and the rate at which it occurs. Here there is no difficulty in
+seeing what conditions must be fulfilled in order that a new variety
+should or should not recapitulate the characteristic of the ancestral
+stock from which it arises. If a red-eyed variety of Gammarus arose
+from a white-eyed stock, it would necessarily exhibit the ancestral
+condition at the beginning of development, because all eyes are at
+first colourless. If a black-eyed form arose as a sport from a red-eyed
+stock, it would also recapitulate the ancestral characteristic, because
+all black eyes are at first red. If a white-eyed form arose as a sport
+in a red-eyed stock, or a red-eyed form emerged from a black-eyed
+stock, in neither case would the ancestral condition be manifest at any
+stage of development. There is no question of the intrinsic usefulness
+of a new character involved in this. Whether recapitulation does or
+does not occur here depends upon whether the Mendelian factor which
+distinguishes a new variety hastens or retards some feature of the
+developmental process.
+
+Now Haeckel’s “Grundgesetz” implies an additional statement to that
+contained in Van Baer’s Law. It signifies that the embryonic stages of
+one form are to be compared with adult rather than embryonic stages
+of another. This in fact is not correct, as the classical cases of
+recapitulatory phenomena demonstrate most clearly. The mammalian
+embryo never possesses true gills. It goes through a stage at which it
+has the characteristic clefts and arterial arches which in the _fish
+embryo_ precede the development of functional gills. This is also
+true of crustacean larvæ. _Sacculina_, the crab gall, passes through
+the two characteristic larval forms of the true _barnacles_. It has
+no resemblance to an adult barnacle in any stage. A more serious
+objection to Haeckel’s way of stating the idea of recapitulation in
+development is the vagueness it assumes when brought face to face with
+the exceptions that are as numerous as the applications of the rule. An
+illustration of the exceptions is provided by eye colour in the human
+species. It is fairly certain that the blue-eyed condition has arisen
+as a mutant in a brown-eyed stock; yet the eyes of brown-eyed adults
+are often blue in the newly born.
+
+It is not difficult to discover in Haeckel’s own writings the train of
+reasoning which led him to distort the facts of development in stating
+the law which is often associated with his name.
+
+  “The evolution of the fœtus (or ontogenesis),” states Haeckel, “is
+  a condensed and abbreviated recapitulation of the evolution of the
+  stem (or phylogenesis); is preserved by a constant heredity; on the
+  other hand, it becomes less complete in proportion as a varying
+  adaptation to new conditions increases the disturbing factors in
+  the development (or cenogenesis). The cenogenetic alterations or
+  distortions of the original paligenetic course of development take
+  the form, as a rule, of a gradual displacement of the phenomena,
+  which is slowly effected by adaptation to the changed conditions
+  of embryonic existence during the course of thousands of years.
+  This displacement may take place as regards either the locality or
+  the time of the phenomenon. The first is called heterotopism, the
+  second heterochronism.”
+
+So naïve a combination of garrulous teleology and self-contradiction
+is characteristic of the hopeless confusion of thought which existed
+in evolutionary biology, while it remained dominated by the principle
+of adaptation. The larval “adaptations” should on the face of it
+recapitulate their ancestral story--and so on in endless regression.
+There is no intelligible meaning in Haeckel’s explanation of the
+admittedly ubiquitous exceptions to his rule.
+
+Haeckel’s so-called Biogenetische Grundgesetz exerted a profound
+influence on biology during the second half of the nineteenth
+century, and perhaps did more than anything else to divert zoologists
+from the study of activity to the pursuit of insignificant details
+of no conceivable physiological interest. Instead of furthering
+the development of zoology as an exact science, it substituted
+the construction of architectural mnemonics for the search after
+quantitative laws. With Haeckel’s law is associated an interesting
+logical fallacy in the development of the argument for evolution.
+Huxley made a good debating point when he disclosed the embarrassing
+information that a bishop at one stage of the episcopal life cycle
+has gill structures like those of a fish. From the standpoint of
+formal logic the point is worthless. Only the atmosphere of religious
+propaganda which surrounds the birth of the evolutionary doctrine
+can explain the perennial reappearance of the contention that
+recapitulation constitutes an argument _sui generis_ in favour of the
+doctrine of descent. If experimental breeding taught us that mutant
+forms recapitulate the characteristics of the stock from which they
+originate, the resemblance of developmental stages of present-day
+forms to adult organisms which existed in the geological past would
+constitute a special consideration in favour of regarding fossil
+remains as ancestral to contemporary animals. As yet experimental
+breeding teaches us no such thing. We do not find that a white-eyed fly
+originating as a sport in a red-eyed stock invariably has red eyes at
+any prior stage of development. Recapitulatory phenomena are difficult
+to explain on a theological basis, but they do not constitute a special
+argument in favour of the evolutionary alternative. To-day biologists
+are beginning to realize that evolution must furnish an explanation
+of specific differences which are not adaptive as much as specific
+differences which are adaptive. With this change of outlook it is
+becoming possible to discuss the logical status of the evolutionary
+hypothesis without recourse to arguments which belong more properly to
+propaganda than to science.
+
+
+
+
+PART II
+
+DARWINISM AND THE ATOMISTIC INTERPRETATION OF INHERITANCE
+
+SUMMARY
+
+
+The failure to recognize that biology no less than physics is
+an ethically neutral science is a heritage of the evolutionary
+controversy. The doctrine of organic evolution evoked intense religious
+hostility in the middle of the nineteenth century. Biologists were
+compelled to fight for their right to speculate on their own lines.
+Forced into the forum as a propagandist the biologist gave less
+attention to the logical structure of the new theory than to its
+apparent implications for social philosophy. The ethical concept of
+progress became entangled in the evolutionary idea. In the writings of
+Herbert Spencer and the evolutionist philosophers Darwinism has left a
+lasting impress upon contemporary thought. Experimental biology in this
+generation has undertaken the task of reducing the problems of organic
+evolution to an exact science. This must necessitate a re-examination
+of many traditional biological concepts and many philosophical and
+sociological inferences which have been extracted from an earlier phase
+in the development of the evolutionary doctrine.
+
+
+
+
+V. THE METHODOLOGY OF EVOLUTION
+
+  “Chemistry is not so far from physics as the generation before ours
+  thought. Biology, through bio-physics and bio-chemistry, no longer
+  stands aloof from the methods and procedures of physical science.
+  And these new alliances cannot be made without modifications in
+  the logical construction of the separate concepts upon which these
+  various sciences previously took their stands. This is a task which
+  laboratory practice alone cannot undertake.”--_Dorothy Wrinch_
+
+
+§1
+
+From Aristotle to our own time biologists have been too preoccupied
+with collecting information about the extremely complex phenomena which
+they study to pay very much attention to the logical structure of the
+hypotheses they adopt. This not only tends to make controversy between
+the mechanist and vitalist barren, but also explains why much that has
+recently been written and said about evolution is both unsatisfactory
+and perplexing to the intelligent layman. Many of the views which
+gained well-nigh universal assent among biologists in the latter half
+of the nineteenth century have been undermined by the discoveries of
+the Mendelian renaissance. When the onlooker asks the biologist for a
+straightforward exposition of the present status of the evolutionary
+hypothesis, he is frequently met with the guarded statement that
+biologists are no longer so sure that they know _how_ evolution
+occurred, but are more certain than ever that it _has_ occurred. Such
+a statement might conceivably have a logically admissible meaning,
+though if so, it belongs to the category of things which were better
+said otherwise. On the face of it, the layman has very good reason for
+wondering whether it means anything at all. It is logically permissible
+to say we know that common salt is soluble, but we do not know how it
+happens that common salt should possess this property. But evolution is
+not a simple property. It is a process. We cannot very well know of the
+existence of a process unless we can say in what the process consists.
+
+The doctrine of evolution which deals with the way in which living
+matter has come to exist in the manifold forms which biologists call
+species is one which can only be placed on the same footing as the
+great generalizations of physics and chemistry, when it is examined
+from the experimental standpoint. From that standpoint the particular
+phase in the growth of the evolutionary hypothesis associated with the
+names of Darwin and Wallace has less significance than is customarily
+attached to it. From a purely experimental point of view Darwin and
+Wallace brought to bear on the discussion of the evolutionary doctrine
+nothing which their predecessors Buffon, Erasmus Darwin, Lamarck, St.
+Hilaire, Goethe and Oken lacked. The importance of their work lies in
+the history of the controversy. Under Cuvier’s influence biology had
+turned away from premature speculation to industrious study of the
+nature of species differences from every available standpoint. Darwin
+and Wallace brought together the fruits of the progress resulting
+from a generation of intensive research on such lines, and formulated
+the evolutionary problem in a much more explicit form than _les
+philosophes_ were in a position to do. The particular answer that they
+gave to the problem they formulated is the least significant part of
+the contribution which Darwin and Wallace made to biological science.
+The biological world did not begin to examine the experimental
+implications of the selectionist solution until the rediscovery of
+Mendel’s laws by Correns, de Vries and Tschermak, and their extension
+to animals by Bateson and Cuenot in the opening years of the present
+century. The Mendelian renaissance provoked considerable hostility from
+a generation of biologists untrained in experimental methods. It is
+only now becoming possible to re-examine the selectionist doctrine with
+detachment and candour.
+
+It must not be implied that antagonism to the new movement was a mere
+disinclination to face the effort of learning new methods of attacking
+the problem. In the nineteenth century biologists had to fight for
+their right to speculate freely in their own field. The generation in
+whose memory the struggles of that period were fresh not unnaturally
+resented the suggestion that biologists were no longer unanimous among
+themselves. It was heresy to betray the policy of a united front. If
+such schisms were permitted, and the truth were allowed to leak out
+to the general public, the church somnolent might again become the
+church militant. The recently published biography of the late William
+Bateson shows how keenly this was felt. In the end hostility towards
+the new movement which followed the rediscovery of Mendel’s work gave
+place to a comfortable compromise, based on the attractive device of
+inventing a word for human ignorance. This device is not peculiar
+to biological science. There were from the start physicists who
+entertained the most profound suspicion of the ether on that account.
+It was agreed to state that inheritance in animals and plants is of
+two kinds, Mendelian and non-Mendelian. Study of the former was to be
+encouraged because it was useful to stock breeders, horticulturalists,
+and pigeon fanciers. The latter was the peculiar speciality of the
+evolutionist. Apart from that, the impenitent selectionist did not
+attempt to define exactly what non-Mendelian inheritance was. Its
+sphere was progressively encroached upon by the Mendelian variety,
+until nothing was left of it but a comfortable corner for those highly
+variable characters which were somewhat vaguely referred to under the
+term “quantitative inheritance,” i.e. hereditary differences in size so
+subject to fluctuating variability in response to external conditions
+that they are only definable by reference to a statistical average for
+a particular inbred stock. Naturally experiment first turned to the
+analysis of clear-cut hereditary differences such as colour, where
+little trouble is requisite in standardizing external conditions, so
+that an hereditary difference will be apparent in the individual. Since
+mathematical analysis has been brought to bear on the study of size
+inheritance in such work as that of East and Jones, there can no longer
+be any justification for doubting that the atomistic conception of
+heredity which Mendel formulated covers the whole domain of biparental
+inheritance.
+
+While experimental analysis was progressing towards a recognition of
+the universal validity of the Mendelian conception, the brilliant
+work of Morgan’s school was leading to an exact theory of the
+inter-relation of genetical factors based on the observed behaviour
+of the chromosomes. Experiment now equipped with a definite criterion
+of genetic purity could assert that new forms do come into existence
+discontinuously in nature. It could state the conditions which
+determine whether a new genetic character will persist. When chromosome
+maps of several allied species of the fruit-fly were constructed by
+Metz and Sturtevant seven years ago the whole discussion of the problem
+of species formation entered on an entirely new phase. To-day we must
+approach the discussion of evolution on the assumption that in Mendel’s
+atomistic conception of the hereditary process must be sought the
+correct interpretation of how new characters, having come into being,
+may be transmitted to future generations.
+
+
+§2
+
+To appreciate at once the greatness and the limitations of Darwin’s
+contribution to evolutionary thought it is essential to see the
+question in its historical perspective. Many of the steps which have
+led to the construction of the evolutionary hypothesis are now only
+of historical interest. Only with an understanding of the history
+of the doctrine is it possible to gain a clear idea of the logical
+status it occupies in scientific thought. In approaching it, one has
+to remember that the discussion of organic evolution aroused a good
+deal of prejudice from religious quarters, and that in consequence
+many issues, e.g. Recapitulation, which were not strictly relevant to
+a straightforward presentation of the problem occupied a prominent
+place in the controversies that raged around it. In forming an estimate
+of the present status of the evolutionary hypothesis, let us, as far
+as possible, eliminate these irrelevant questions, and deal only with
+the steps which have made a definite constructive contribution to the
+present state of knowledge. These may be treated under four headings:
+(_a_) The Principle of Biogenesis, (_b_) The Principle of Unity of
+Type, (_c_) The Principle of Succession, and (_d_) The Principle of
+Genetic Variation.
+
+_The Principle of Biogenesis_ is simply the recognition that animals
+and plants only arise in our immediate experience from other animals
+and plants through the process of reproduction. Linnæus accepted
+it in his doctrine of the fixity of species as generally true with
+regard to animals in the ordinary sense. Not until the middle of the
+nineteenth century did the work of Pasteur demonstrate its validity
+for micro-organisms. Linnæus and Ray were among the first to recognize
+the general truth of the commonplace that “like begets like.” The
+Aristotelian influence which predominated during the Renaissance
+had lingered on until the beginning of the seventeenth century. The
+fascinating legend of the goose barnacle contained in the concluding
+passage of Gerrard’s _Herbal_ (1594) is illustrated by an actual
+woodcut of the Goose and its Barnacle Progenitor. The passage reads:
+
+  “But what our eyes have seene; and hands have touched we shall
+  declare. There is a small Island in Lancashire called the Pile of
+  Foulders, wherein are found the broken pieces of old and bruised
+  ships, some whereof have beene cast thither by shipwracke, and also
+  the trunks and bodies with the branches of old and rotten trees,
+  cast up there likewise, whereon is found a certain spume or froth
+  that in time breedith unto certain shells, in shape like those of
+  the Muskle, but sharper pointed, and of whitish colour, wherein is
+  contained a thing in forme like lace of silke finely woven as it
+  were together, of a whitish colour, one end whereof is fastened
+  unto the inside of the shell, even as the fish of Oisters and
+  Muskels are; the other end is made fast unto the belly of a rude
+  masse or lumpe which in time commeth to the shape of a Bird; when
+  it is perfectly formed the shell gapeth open, and the first thing
+  that appeareth is the foresaid lace or string; next come the legs
+  of the bird hanging out, and as it groweth greater it openeth the
+  shell by degrees, til at length it is all come forth and hangeth
+  onely by the bill: in short space after it cometh to full maturitie
+  and falleth unto the sea, where it gathereth feathers, and groweth
+  to a fowle bigger than a Mallard and less than a goose having
+  blacke legs and bill or beak, and feathers blacke and white,
+  spotted in such manner as is our magpie.... For the truth thereof
+  if any doubt, may it please them to repaire unto me, and I shall
+  satisfie them by the testimonie of good witnesses.... The bordes
+  and rotten planks whereon are found these shells breeding the
+  Barnacle are taken up on a small Island adjoyning Lancashier, halfe
+  a mile from the main land, called the Pile of Foulders. They spawn
+  as it were in March and April; the Geese are formed in May and
+  June, and come to fulnesse of feathers in the month after. And thus
+  having through God’s assistance discoursed somewhat at large of
+  Grasses, herbs, Shrubs, trees and Mosses, and certain Excrescences
+  of the earth, with other things moe, incident to the historie
+  thereof, we conclude and end our present Volume, with this Wonder
+  of England. For the which God’s Name be ever honoured and praised.”
+
+The legend of the goose and the barnacle died a slow death, and many
+diverting citations might be added. That canny Scot, Sir Robert Moray,
+wrote concerning the mystery surrounding the reproductive habits of
+geese and barnacles so late as 1678 in the following words, which occur
+in a paper actually published in the _Royal Society’s Transactions_.
+After describing the barnacle shells washed up on the coast of
+Scotland, he refers to their “little bill like that of a goose, the
+eyes marked, the head, neck, breast, wings, tail and feet formed, the
+feathers everywhere perfectly shaped and blackish coloured, and the
+feet like those of other water fowl to my best remembrance.”
+
+Writing in the middle of the seventeenth century Sir Thomas Browne
+states (_Vulgar Errors_, bk. 3):
+
+  “Concerning the generation of frogs we shall briefly deliver that
+  account which observation hath taught us. By frogs I understand
+  not such, as arising from putrefaction are bred without copulation
+  and because they subsist not long are called temporariæ (Rana
+  temporaria, the common frog), nor do I mean the little frog of an
+  excellent parrot green that usually sits on trees and bushes, and
+  is therefore called Rananculus viridis (the tree frog) but hereby I
+  understand the aquatile or water frog, whereof, we may behold many
+  millions every spring in England.”
+
+Referring to the doubt expressed by the author of _Vulgar Errors_
+concerning Aristotle’s belief that mice arise from putrefaction,
+Alexander Ross commented:
+
+  “So may one doubt whether in cheese and timber worms are generated;
+  or if beetles and wasps in cow’s dung; or if butterflies, locusts,
+  grasshoppers, shell fish, snails, eels and such like be procreated
+  of putrefied matter which is apt to receive the form of that
+  creature to which it is by formative powers disposed. To question
+  this is to question reason, sense, and experience. If he doubt
+  of this let him go to Egypt, and there he will find the fields
+  swarming with mice, begot of the mud of Nylus, to the great
+  calamity of the inhabitants.”
+
+During the sixteenth century under the influence of Vesalius, Fallopius
+and Servetus experimental investigation liberated medicine from the
+paralysing tradition of Galenic teleology. The effect of this change
+of outlook became evident in the revival of natural history in the
+seventeenth century. Redi (1688) turns to experiment to decide whether
+maggots can be produced from putrescent meat, if flies are prevented
+from depositing their eggs on it. “Reason, sense and experience” were
+at length forced to capitulate to experiment. The comparative study of
+animal life after centuries of stagnation following the publication
+of Aristotle’s Natural History entered on a new phase. So long as
+innumerable _ad hoc_ accounts of the origin of species existed the
+general problem with which the evolutionary hypothesis deals could not
+be envisaged. Thus the work of Linnæus is the starting-point of the
+modern theory of evolution.
+
+More than a century elapsed before the essential features common to
+sexual reproduction in all animals were understood. Leeuwenhoek,
+a Hollander, in 1668 had first seen the minute spermatozoa in the
+seminal fluid. A little over a century later the ingenious Abbot
+Spallanzani gave experimental proof that it is to the spermatozoan
+that the seminal fluid owes its fertilizing power. Only in 1879 did
+Hertwig and Fol independently observe beneath the microscope that
+only one sperm normally fertilizes one egg. Their observations were
+made on sea-urchins, but we now know that their conclusions are true
+for all animals. Thus the recognition that everything implied in the
+term inheritance has reference to the material substance of the egg
+and sperm, a concept fundamental to any exact theory of hereditary
+transmission, did not emerge with clarity till more than fifteen years
+after the _Origin of Species_ was published.
+
+The formal classification of organisms codified by Linnæus introduced
+a new era of intensive investigation into the character of species
+differences and so ushered in the great age of comparative anatomy.
+Thus we come to the second step in the historical development of the
+Evolution theory, the _Principle of Unity of Type_. This generalization
+was the special contribution of the school of French and German
+comparative anatomists whose foremost exponent was Georges Cuvier. The
+work of Linnæus gave a great impetus to the study of the structural
+differences between animals, at a time when anatomy like any young
+branch of knowledge was still dominated by teleology. Some instructive
+examples of the happy combination of piety and anatomy are given in the
+_Speculum Mundi_ published by John Swan in 1635. In an old translation
+of Pliny the Elder there occurs the following information about the
+elephant:
+
+  “Their skin is covered with haire or bristle, no, not so much as in
+  their taile, which might serve them in good steade to drive away
+  the busie and troublesome flies (for as vast and huge a beast as he
+  is, the flie haunteth and stingeth him), but full their skin is of
+  crosse wrinckles lattiswise; and besides that, the smell thereof
+  is able to draw and allure such vermine to it, and therefore when
+  they are laid stretched along, and perceive the flies by whole
+  swarmes settled on their skin, sodainly they draw those cranies
+  and crevices together close, and so crush them all to death. This
+  serves them instead of taile, maine and long hairs....”
+
+This citation is not an isolated instance of the way in which a
+pagan philosopher could employ the study of natural history to
+justify the ways of God to men. During the Middle Ages the influence
+of ecclesiasticism reinforced the teleological attitude from which
+Aristotle’s Natural History is comparatively speaking free. At a
+later date Deism had its scientific complement in a tradition which
+identified the pursuit of Natural History with Natural Religion. The
+first classifications were based on comparatively superficial points
+of resemblance. As the study of animal structure progressed in the two
+generations that followed the labours of Ray and Linnæus, it became
+increasingly evident that the teleological standpoint in comparative
+anatomy is inadequate. If animals had been specially designed to suit
+their conditions of life, it would be expected that the greatest degree
+of similarity would be found in animals pursuing a similar mode of
+existence. This is not what is actually found. On the contrary, as
+we make the greatest degree of similarity in structure the basis of
+our attempts to classify animals, our units of classification resolve
+themselves into collections of forms which show the greatest diversity
+of habit, locality, diet, means of progression or anything else
+which might be significant from a purposive standpoint. Animals can
+be classified in groups based on striking similarity in architecture
+and development involving complex constellations of physiological
+units. Within these groups the utmost variety of habitat, climate,
+locomotion, nutrition, etc., are encountered. The underlying similarity
+of the bones of the limb and its musculature in a whale, a bird and an
+elephant, as contrasted with the limb structures of a beetle, a fish
+or a squid illustrate this conclusion. The whole study of systematic
+zoology bears witness to it. Van Baer extended the principle of Unity
+of Type to embryonic forms in 1834.
+
+The importance of the principle of Unity of Type to the Evolutionary
+hypothesis lies in the attitude which it promoted. By discouraging the
+teleological approach to the diversity of animal life, it paved the
+way for a naturalistic investigation of the problem. The net result
+of the intensive study of comparative anatomy which progressed under
+the influence of Cuvier in France and Johannes Müller in Germany was
+also to show that the task of classifying animals in hard and fast
+categories is at all turns embarrassed by the existence of anomalous
+intermediate forms like the duck-billed platypus or the worm-like
+arthropod Peripatus. Thus biological thought was becoming more and more
+sympathetic towards the existence of a process of species modification.
+This tendency became more sharply defined as biology took the third
+great step in the development of the modern theory of evolution.
+
+This step has been called the _Principle of Succession_. When the Law
+of Unity of Type first obtained recognition, many fossils were known,
+but geologists had not arrived at a general agreement concerning
+the order in which the various strata had been deposited nor the
+magnitude of the time which their formation occupied. By the middle of
+the nineteenth century the modern doctrine (“Uniformitarianism”) had
+gained assent. It now became apparent from studying the distribution
+of animals in space and time, that divergent forms which exist on
+the earth’s surface to-day were preceded by widely distributed forms
+of a more generalized type in the past. The further we go back in
+the history of any group of animals, the less do we find the same
+pronounced differences as are displayed by existing members of the same
+assemblage. The differentiation of species is inferred from the record
+of the rocks to have been a continuous process in space and time. This
+doctrine in its modern form was explicitly put forward in 1855 by
+Wallace.
+
+The masterly way in which Darwin marshalled the facts at his disposal
+in presenting this aspect of the case constitutes his chief claim to
+have made an enduring contribution to the Doctrine of descent. From
+ancient times, but more especially from the end of the seventeenth
+century onwards, the hard remains of animals were discovered and
+described. Shells of molluscs which only live in water were found far
+inland remote from lake, river or sea. Such relics were attributed
+by the current mythology of Christian countries to the deluge that
+overwhelmed the contemporaries of the Noah family. Sceptics like
+Voltaire, who ventured to offer more naturalistic hypotheses, were
+not more felicitous in their speculations. An exception must be made
+in favour of Xenophanes (B.C. _circa_ 500) and the Arab physician
+Avicenna, who, it appears, recognized fossils as remains of animals
+formerly alive, and saw in them evidence of the existence of oceans
+where there is now only land. A giant fossil salamander which occurs
+abundantly in the Upper Miocene of Switzerland, closely related to
+the Japanese salamander _Cryptobranchus japonicus_, was unearthed by
+Scheuchzer in 1726, and named _Homo diluvii testis_. The motto attached
+to the figure reads:
+
+  Betrübtes Beingerust von einem alten Sünder
+  Erweiche Herz und Sinn der neuen Bösheitskinder.
+
+This has been translated:
+
+  Oh sad remains of bone, frame of poor Man of Sin,
+  Soften the heart and mind of recent sinful kin.
+
+After the Renaissance it seems that priority in the recognition of
+fossils as remains of what were once living animals is due to Steno
+(1699), a Danish anatomist who taught at Padua. More than a century
+later, Cuvier’s monograph on fossil remains initiated the epoch
+of systematic palæontology. The effect of the researches which it
+initiated was not felt till the Uniformitarian doctrine, i.e. the view
+that successive strata have been deposited by a continuous process,
+was generally accepted, mainly through the work of Lyell (1830).
+The impiety of this new geology promoted violent controversy. In
+the minutes of a meeting of the Geological Society of Great Britain
+in 1840, we are told that the retiring president, Dr. Buckland,
+“with a look and tone of triumph pronounced upon his opponents who
+dared to question the orthodoxy of the scratches and grooves of the
+glacial mountains the pains of eternal itch without the privilege
+of scratching” (_Hist. Geol. Soc. Lond._, p. 142). By the middle of
+the nineteenth century geologists were universally convinced that
+the various strata of which the earth’s crust is composed have been
+laid down in orderly succession during periods of time compared with
+which that occupied by the history of human society is of negligible
+duration. Once this conclusion was accepted, the study of fossils
+received a new impetus and progressed rapidly under the leadership of
+men like Owen, Cope and his contemporaries. Students of fossils now
+began to compare the characteristics of animals in different geological
+epochs, and to elucidate evidences of a continuous succession of new
+forms of life transmitted to posterity in the record of the rocks. Out
+of their studies the principle of succession took shape.
+
+The geological succession of animal and plant life is demonstrated by
+two features of the record. Many of the more highly specialized and
+successful groups of the present day are not found to have existed at
+earlier periods of the earth’s history, and were preceded by forms
+which are intermediate between them and representatives of surviving
+groups that were already existent before them. It is also found that
+the earliest members of the great groups are usually found to be of
+a more generalized type of structure than existing types. Adequate
+material for drawing these conclusions is provided only by forms which
+have resistant structures, such as the vertebrates, shellfish and
+vascular plants.
+
+Before we can fully appreciate the continuity of the geological record,
+we have to take into account the fact that the same animals are not
+found in all the different parts of the globe. One group of animals
+may be confined, like the kangaroos, to Australia; one group, like the
+monotypic order, in which the ant-bear is placed, to South Africa. If,
+then, we know that there existed in, let us say, the Chalk Age, a small
+mammal which was of a type so generalized as to form a link between the
+kangaroo and the ant bear, it is most important to know whether the
+barriers of ocean that now separate Australia and South Africa were as
+impassable in those times as they are now; or whether this architypal
+mammal lived in a situation from which it could have access to both of
+these promising lands of settlement for its family. We are thus led to
+ask if the process of geological succession was a continuous one both
+in time and space.
+
+To answer this question demanded a comprehensive survey of the existing
+distribution of animal life on the earth, perhaps the most significant
+contribution that Darwin and Wallace made to the evolutionary doctrine.
+In their writings the facts of geographical distribution, facts which
+were very largely based on their own first-hand observations, and not
+like their erroneous views upon heredity collected from the testimony
+of other persons, first received critical examination. They were forced
+to conclude that no amount of ingenuity could successfully interpret
+the geographical distribution of animals on a purely teleological
+basis. The habitat of different kinds of animals is not uniquely
+determined by their special suitability for the locality in which they
+occur. This statement is attested by many species that were at one
+time restricted to a very definite area. When introduced into other
+parts by man they have flourished phenomenally. A familiar instance
+is the introduction of rabbits into Australia. The facts about the
+geographical distribution of living and fossil species collected
+by Darwin and Wallace resulted in an extension of the principle of
+geological succession. This is especially associated with the name of
+Wallace. Wallace’s law (1855) is stated briefly at the conclusion of
+the memoir entitled _On the Law which has Regulated the Introduction of
+New Species_. “Every species has come into existence coincident both
+in space and time with a pre-existing closely allied species.”
+
+With the statement of this law and its confirmation by more carefully
+sifted and comprehensive data the positive contribution of the
+nineteenth century to the development of the modern theory of evolution
+ended. The picture of a progressive gradual differentiation of animal
+life, as it spread over different parts of the earth in successive
+geological epochs became a commonplace of the naturalistic outlook. It
+remained for the Mendelian renaissance to clarify the conception of
+this gradual differentiation as an outcome of the agency of natural
+generation. It must be remembered that the Principle of Succession
+is still only a step in the formulation of a theory of Evolution.
+We have still to ascertain what is the natural process by which
+this progressive differentiation has been effected. The principle
+of Biogenesis forces us to look to the reproductive process for the
+answer; but only experiment can arbitrate in this field. The weaving
+together of principles derived from anatomy, embryology and geology
+in the light that experiment throws on the nature of the reproductive
+process is necessary to the completion of the evolutionary argument.
+
+Let us now examine how much we have proved up to this point. We have
+seen that animals only come into being in our immediate experience
+through the agency of natural generation. We have also seen that
+similarity which animals display in their hereditable properties
+must be interpreted primarily in terms of the hereditability of the
+properties themselves, and not in terms of a purposive agency. Finally
+we have found evidence of a gradual and accumulative divergence in the
+hereditable properties of animals continuing over vast geological
+epochs. We have still to interpret this divergence in terms of the
+only agency through which living matter in our experience is brought
+into being. We are thus led to the fourth step in our argument, the
+enunciation of the _Principle of Genetic Variation_.
+
+This states the experimental fact that units of living matter with
+new hereditable properties do actually come into being in the normal
+operations of the process of natural generation. In using the word
+_experimental_ in this connexion we lay bare a sharp divergence of
+standpoint between Darwin’s generation and our own. Darwin collected
+a good deal of information about the origin of domesticated plants
+and animals. This seemed to his immediate successors to constitute
+sufficient evidence for believing that new hereditable properties arise
+in nature. The development of Mendelian analysis has shown that this
+is far from certain. Unless we have studied the parent stock under
+experimental conditions which safeguard its purity, we cannot be sure
+that a new domesticated variety is anything more than a new combination
+of genetical characters already present in pre-existing varieties. In
+other words it may only have arisen through hybridization. We have now
+at our disposal a clear concept of genetical purity and well-defined
+methods for establishing the purity of a stock. The whole question has
+been placed on a new foundation during the past three years by the
+_artificial_ production of _mutants_ or sports by X-rays in pure stocks
+of the fruit-fly Drosophila reared under experimental conditions.
+
+A further discussion of the Principle of Genetical Variation with
+special reference to the Selection doctrine will be undertaken in a
+subsequent essay, when the possibility of building up new varieties
+into the units which biologists call species will be dealt with
+more fully. To return to the discussion of the logical status of the
+evolutionary doctrine, we may assume that the Principle of Genetical
+Variation is established. On this assumption we may state the
+conclusion of the foregoing survey in the following terms. Animals with
+new hereditable properties have appeared successively with increasing
+divergence of type in the past history of the earth. Animals only arise
+in our experience by reproduction from pre-existing animals. Animals
+with new hereditable properties can arise in our immediate experience
+by reproduction from pre-existing animals with different hereditable
+properties. It is therefore natural to conclude that the existing
+divergence of specific characteristics is the outcome of a natural
+process of generation operating over long periods of geological time.
+
+
+§3
+
+Darwin’s generation was in the main satisfied with the evidence
+derived from domestication. This was embodied as an _argumentum ad
+hominem_ in the Selection hypothesis. The immediate effect of Darwin’s
+influence was thus, as Punnett has remarked, “to divert interest from
+the study of the origin of species” as an experimental issue. Zoology
+and physiology became divorced in Great Britain. One resolved itself
+into a Somerset House for the Animal Kingdom, tracing pedigrees on a
+purely armorial basis. The other tended to develop in association with
+narrowly clinical objectives, till the rise of modern experimental
+zoology in the twentieth century. In the light of modern research the
+Selection hypothesis presents some interesting methodological aspects
+discussed elsewhere. Let us here confine ourselves to the evolutionary
+hypothesis in broad outline.
+
+There are two fundamental results of the present enquiry which must
+be emphasized in any discussion of the logical structure of the
+evolutionary doctrine. One is the necessity of distinguishing between
+the Principle of Succession and the evolutionary hypothesis itself.
+The other is the recognition that in the last resort the validity
+of the evolutionary hypothesis rests on the issue of experiment.
+The first of these may sound like a platitude. It is frequently
+overlooked. Presumably when a biologist says we are more certain
+than ever to-day that evolution has occurred, but less certain about
+_how_ it has occurred, he really means that the enormous extension
+of our knowledge of fossils has placed the Principle of Succession
+on a much firmer foundation than it enjoyed in Darwin’s time. The
+mass of new information about comparative anatomy now available is
+more than ever inexplicable on a crudely teleological basis and more
+than ever consistent with an evolutionary interpretation, if such an
+interpretation is permissible. But evolution is more than succession.
+It is the interpretation of succession in terms of genetical variation.
+If experiment does not justify this interpretation, in other words if
+we do not know _how_ evolution occurred, it is evident that we cannot
+be more certain that it has occurred.
+
+The critique of evolution is not exhausted by a logical analysis of
+the experimental postulates of the hypothesis, because the doctrine
+of succession is more than a question of fact. It also implies the
+validity of current geological doctrines, whose logical status
+lies outside our present enquiry.[5] What are ordinarily called
+scientific hypotheses may be classified in two categories according
+to the test of validity which is applied to them. They might be
+called respectively _prospective_ and _interpretative_ for lack of
+existing terminology which makes the distinction which is relevant
+to our present object. If the consequences of one or other of a set
+of hypotheses each capable of accounting for a given series of data
+are uniquely capable of yielding verifiable conclusions about other
+realms of our experience, we accept the hypothesis which leads us
+to the new and previously undiscovered fact. We do this even if, in
+the absence of the new fact, the hypothesis so verified is a _less
+economical_ one than others which satisfied the original data but
+do not account for the new one. By _prospective_ hypotheses I mean
+hypotheses to which this test is applicable. They are such as permit
+us to make verifiable predictions in other fields of experience. In
+everyday language they assist us to prophesy correctly about future
+events. They constitute a hierarchy of socialized beliefs. By their
+aid mankind has been permitted to construct modern civilization. They
+possess to a pre-eminent degree the quality of _publicity_ defined in
+an earlier essay. Mendel’s hypothesis and the kinetic theory of gases
+belong to this category. Some writers, among others William James, have
+tended to imply that all so-called scientific hypotheses are of this
+type. This is not so. There are hypotheses whose justification resides
+only in the fact that they conform to the requirements of economy of
+thought. Such hypotheses are accepted because alternative hypotheses
+are less economical. They are incapable of yielding any verifiable
+consequences which follow uniquely from them. It is these to which I
+refer by the term _interpretative_ hypotheses. We construct them, not
+because they are practically serviceable to us, but because they are
+conformable with the intellectual requirements of a civilization which
+is the practical outcome of the application of science. They share
+two pre-eminent characteristics of the prospective type, economy of
+hypothesis and ethical neutrality. The need for them resides in our
+curiosity. They represent one aspect of the secularization of human
+life and the obsolescence of animistic ideas. We construct them for
+their _philosophic_ interest alone. The evolutionary doctrine belongs
+to this category.
+
+Few biologists would admit so heretical a conclusion. They would
+argue that every new missing link whose discovery is almost daily
+announced in the press provides verification of the predictions of the
+evolutionary hypothesis. But there is a fallacy in this contention.
+The discovery of missing links is not a unique consequence of the
+evolutionary doctrine. It might be inferred from the Principle of
+Succession, even if the evolutionary interpretation of the Principle
+of Succession turned out to be incorrect. Given the experimental
+postulates of the evolutionary hypothesis as established facts, the
+evolutionary hypothesis does not belong to the same hierarchy of
+scientific generalizations as the kinetic theory of gases or Mendel’s
+Law, because as yet we are not able to predict with the aid of it any
+unique consequences which can be made the issue of decisive tests.
+
+There is an interesting consequence of these considerations, and one
+which has a more comprehensive significance. Biology deals with two
+kinds of relations: relations between living and non-living matter and
+relations between different kinds of living matter. The Mechanistic
+Conception of Life is a secular extension of experimental analysis of
+the former, just as the evolutionary hypothesis is a secular extension
+of experimental study of the latter. Both belong to the category of
+interpretative hypotheses in the sense defined above. Why is it then
+that so many prefer the luxury of scepticism concerning the first
+issue, and resent the exercise of a suspicion of scepticism concerning
+the second? Perhaps the answer is that evolution has already become
+incorporated in the apparatus of what Robert Briffault calls custom
+thought. I do not think that the physiologist who adopts the attitude
+of Gallio towards the mechanistic conception of life, affecting to
+despise all mere philosophy, is consistent, unless he is prepared to
+dismiss the doctrine of Organic Descent in the same manner. I have yet
+to meet one who does. Evolution is a philosophy.
+
+
+
+
+VI. THE PROBLEM OF SPECIES
+
+  “The effect of Darwin’s _Origin of Species_ was to divert attention
+  from the way in which species originate.”--R. C. Punnett,
+  _Mendelism_
+
+
+§1
+
+In a letter to H. de Varigny dated November 25, 1891, Thomas Henry
+Huxley wrote: “I shall be very glad to have your book on Experimental
+Evolution. I insisted on the necessity of obtaining experimental proof
+of the possibility of obtaining virtually infertile breeds from a
+common stock in 1860.... From the first I told Darwin this was the
+weak point of his case from the point of view of scientific logic.
+But in this matter we are just where we were thirty years ago.” In
+this passage Huxley explicitly draws attention to the fact that
+Darwin never came to grips with the historic problem of the Origin of
+Species, as it had been propounded by Linnæus. Three years later he
+is writing to acknowledge the receipt of Bateson’s _Materials for the
+Study of Variation_, a book which laid the philosophical foundations
+of the present era of experimental enquiry into evolutionary problems.
+“I see,” he notes, “you are inclined to advocate the possibility of
+considerable _saltus_ on the part of Dame Nature in her variations.
+I always took the same view, much to Darwin’s disgust, and we used
+often to debate it.” Another thirty years passed by, and Bateson
+ventured to appeal to his contemporaries for a reconsideration of the
+traditional species problem in the light of the accumulated results
+of investigation based on Mendel’s methods. He was rebuffed by a
+veritable storm of criticism from Huxley’s followers. Evolution had
+become Darwin, as geometry has become Euclid. Had Huxley been living,
+it hardly seems likely that he would have taken the same side as his
+devoted disciples in the controversy which ensued.
+
+During the latter half of the eighteenth and the beginning of the
+nineteenth century biological science progressed towards a clear
+definition of the problem of Man’s secular origin. This progress
+involved the rejection of many of the teleological concepts which had
+been current since the Middle Ages. In the light of recent advances
+in the study of inheritance and variation, we know that much of the
+evidence which seemed adequate for an understanding of the evolutionary
+process fifty years ago must be re-examined to-day and supplemented
+from other sources. The final court of appeal in the case for an
+evolutionary interpretation of the origin of species is experiment.
+Only experiment can place the Principle of Genetic Variation, i.e.
+the origin of new genetic types in the normal course of procreation,
+on a sure foundation. A detailed examination of the evidence for this
+conclusion is essential to a satisfactory examination of the logical
+status of evolution in the light of modern knowledge. Four separate
+issues suggest themselves for discussion in a critical enquiry into
+the experimental evidence for the Principle of Genetic Variation.
+We must first ask whether the origin of new hereditable types under
+experimentally controlled conditions is an established fact. We must
+then decide what natural agency ensures that new types having so arisen
+will be preserved. This leads us to ask if the appearance of new types
+is an occurrence of sufficient frequency to have accounted for all the
+divergency of specific form that has come about in the interval of
+time which geology places at our disposal. Finally we are faced with
+the task of deciding how new genetic types can be segregated into the
+units which biologists call species.
+
+First let us consider the origin of new hereditable types. Thirty years
+of controlled experiment on the lines suggested by Mendel’s work has
+given abundant proof that from time to time there do arise in pure
+stocks individuals which have entirely new hereditable properties. Such
+individuals are called _mutants_ or sports, a term used synonymously
+by some writers with the alternative word mutations. The word mutation
+was originally employed by De Vries in a somewhat different sense from
+that in which the term mutant is now used. It is preferable to avoid
+perpetuating this confusion.[6] A new phase in this aspect of the
+evolutionary problem has been initiated by the recent work of Müller. A
+controllable agency, exposure of parents to X-rays, has been shown to
+produce mutants in the fruit-fly Drosophila.
+
+Darwin and Wallace are usually given the credit of first emphasizing
+the fact of genetical variation. A careful study of their works shows
+that they did not clearly apprehend the essential aspect of the
+problem or realize the imperative necessity of subjecting the issue to
+direct experimental test. When they spoke of variation they included
+both genetical variation, i.e. the production of mutants as defined
+above, and differences between parents and offspring which result from
+the influence of external agencies in early development. The small
+differences of which Darwin was thinking were mainly of bodily rather
+than germinal origin. As such they have nothing to do with the problem
+of evolution unless, as Darwin himself did, we accept the Lamarckian
+doctrine. In the Introduction to the _Origin of Species_ Darwin states
+his position thus: “Any being, if it vary in any manner profitable to
+itself, under the complex and sometimes varying conditions on life,
+will have a better chance of surviving, and thus be naturally selected.
+From the strong principle of inheritance, any selected variety will
+tend to propagate its new and modified form.” What he meant by the
+strong principle of inheritance Darwin never states in exact terms.
+Experimental knowledge was not ripe. Biology was still in the phase of
+_a priori_ reasoning from “common-sense” principles. That he did not
+distinguish between bodily and germinal differences is shown by the
+following passage from Chapter 3 of the _Origin of Species_:
+
+  “_Variations, however slight, and from whatever cause_ proceeding,
+  if they be in any degree profitable to the individuals of a
+  species, in their infinitely complex relations to the individuals
+  of a species... will tend to the preservation of such individuals
+  and will generally be inherited by the offspring. The offspring
+  also will have a better chance of surviving, for of the many
+  individuals of a species which are periodically born, but a small
+  number can survive. _I have called this principle, by which each
+  slight variation if useful is preserved, by the term Natural
+  Selection._”--(Italics inserted.)
+
+
+§2
+
+The second aspect of the problem of genetical variation, formulated
+above, is the special issue raised by the selection hypothesis of
+Darwin and Wallace. Mendel might perhaps more justly be given priority
+for clearly envisaging the essence of the problem.
+
+  “Those,” wrote Mendel, “who survey the work done in this department
+  will arrive at the conviction that among all the numerous
+  experiments made not one has been carried out to such an extent
+  and in such a way as to make it possible to determine the number
+  of different forms under which the offspring of hybrids appear, or
+  to arrange these forms with certainty according to their separate
+  generations or definitely to ascertain their statistical relations.
+  It requires indeed some courage to undertake a labour of such
+  far-reaching extent. This appears, however, to be _the only right
+  way by which we can finally_ reach the solution of a question the
+  importance of which cannot be overestimated in connexion with the
+  history of _the evolution of organic forms_.”
+
+Mendel’s method shows us that so long as they attain sexual maturity
+and bear offspring, new forms having once arisen, transmit their
+hereditable properties unchanged. The new hereditary type will sooner
+or later appear among subsequent generations in its original purity.
+
+This prompts us to ask what chance a given mutant has of surviving to
+sexual maturity. The question demands serious consideration. We know
+that a very small percentage of animals that are born into the world
+do actually survive till the age at which reproduction is possible. It
+has been calculated that if all the progeny of a single female aphis
+(the green plant louse) survived in every generation the total of
+individuals produced in twelve generations would be 10^{22}. Since a
+single aphis is about a tenth of an inch long, this number would cover
+the face of the globe. Twelve generations in a family of aphids would
+appear in less than three years. Evidently the chance that a given
+mutant will survive depends on two things. One is whether it possesses
+any characteristics which favour its survival in preference to the
+parent form. The other is whether it appears once or many times in the
+same stock. We now know that the same mutants appear again and again.
+There seem to be definite _loci of instability_ on the chromosomes.
+Which of these two considerations is of greater importance is at
+present problematical. Most biologists incline with good reason to
+regard the former as more significant. The significance of the second
+is increasingly realized.
+
+Many contemporary authors use the term Natural Selection to imply
+that competition for the means of existence permits some mutants to
+live, and weeds out others. On grounds of priority this can hardly be
+regarded as justified by the writings of the Selectionist writers of
+the nineteenth century. It is not supported by the actual words Darwin
+used to define the term Natural Selection which he himself introduced.
+Goodrich in his admirable book entitled _Living Organisms_, makes the
+following statement with regard to Darwin’s position:
+
+  “It is often said that of late years Darwinism has lost ground,
+  and that natural selection cannot be regarded as a satisfying
+  explanation of, or even as an important factor in, the process of
+  evolution. Doubtless there is some truth in the saying, at all
+  events in so far as it appears that the doctrine is not what some
+  misguided enthusiasts may have represented it to be, that it does
+  not explain everything, that many problems remain unsolved. Yet
+  the Darwinian theory still stands unassailable as the one and only
+  rational scientific explanation of evolution by ‘natural’ forces
+  whose action can be observed, tested and measured. Nevertheless,
+  the critics are quite right in demanding convincing evidence for
+  every step in the argument. The modern developments of the study of
+  hereditary and variation on Mendelian lines, far from weakening the
+  case for natural selection, seem to have definitely disposed of the
+  only rival theory, the doctrine of Lamarck, founded on the supposed
+  ‘inheritance of acquired characters.’ Fortuitous changes in the
+  inherited organization, in the complex of factors transmitted, are
+  left as the only elements of primary importance, the only stones of
+  which the edifice is built.”
+
+These remarks imply that Darwin’s successors went much further than
+Darwin in asserting the creative, preservative, accumulative and
+continuous character of the selection process. This is true; but Darwin
+himself, in the _Origin of Species_, expressly stated what he meant
+by Natural Selection in two quotations which have already been given;
+and neither of these agree with what Goodrich or any modern geneticist
+means when he says that he believes in natural selection. Since Darwin
+introduced the term he has priority in defining its meaning. If later
+biologists mean something different, when they speak of natural
+selection, it would avoid confusion to coin a new term. Elsewhere
+Goodrich says: “What selection alone can do is to preserve variations;”
+and he quotes Darwin’s words in support. Darwin meant by _preserving_
+variations something different from what a modern geneticist believes.
+The modern geneticist believes that _individuals_ who possess certain
+advantageous characters will survive in virtue of these advantages.
+Darwin and Wallace meant that _hereditary characteristics could only
+survive_ if the supposed tendency to dilution of characters by crossing
+were counteracted by the elimination of individuals at the other end of
+the scale of variability.
+
+Apart from what Darwin himself said on the subject we owe some
+consideration to the sense in which his contemporaries understood his
+argument. Since I may be accused of tilting with a lance of straw at
+a windmill of my own construction, let us refer to the section on
+swamping in Wallace’s _Darwinism_. “He (Darwin) had always considered
+that the chief part and, latterly, the whole of the materials with
+which natural selection works was afforded by individual variations
+or that amount of ever-fluctuating variability which exists in all
+organisms and in all their parts...” Wallace then proceeds to quote
+Romanes as saying that “if a sufficient number of individuals were thus
+simultaneously and similarly modified, there need no longer be any
+danger of the variety becoming _swamped by inter-crossing_.” Wallace
+himself wrote as follows:
+
+  “I have already shown that every part of an organism in common
+  species does vary to a very considerable amount in a large number
+  of individuals and in the same locality; the only point that
+  remains to be discussed is whether any or most of these variations
+  are ‘beneficial.’ But every one of these consists either in
+  increase or diminution of size or power of the organ or faculty,
+  that varies.... If less size of body would be beneficial, then as
+  half the variations in size are above and half below the mean or
+  existing standard of the species, there would be ample beneficial
+  variations.”
+
+The implication is that natural selection by cutting off the other
+half--the ample non-beneficial variations--prevents the swamping of the
+beneficial ones out of existence. We know to-day that the traditional
+belief in the swamping effects of intercrossing is false. With its
+rejection the _argumentum ad hominem_ which made the struggle for
+existence an essential agency for preserving new hereditary properties
+becomes unnecessary.
+
+However much importance Darwin himself attributed to this aspect
+of his theory of Natural Selection, he makes clear his attitude in
+several passages. It cannot be doubted that the assent which he
+received from his contemporaries was in large measure due to it.
+Accepting the prevailing misconceptions about swamping, he showed how
+an evolutionary process could and, as it then appeared, must operate.
+Experimental evidence for the hereditability of the kind of variations
+on which Darwin seems to have relied was not brought forward. We now
+know that the kind of variations which Darwin regarded as the raw
+materials for the selective process are not generally hereditable.
+The wisdom of retaining the term Natural Selection may therefore be
+questioned. In all probability there is another reason which in part
+explains the popularity of Darwin’s theory as contrasted with the
+neglect of Mendel’s pioneer labours. Natural selection was suggested
+by the analogy of industrial conditions in the nineteenth century.
+Once formulated as a universal principle of nature it appealed to
+the dominant political theories of the period. The Origin of Species
+became the bible of _laissez faire_. It triumphed as classical humanism
+triumphed during the Middle Ages in part at least for reasons which
+were primarily political. The idea that the struggle for existence is a
+constructive process played a prominent part in the social theories of
+the Selectionist School.
+
+A great deal of confusion can be dispelled if we recognize that Darwin
+never clearly distinguished between two distinct issues. His herculean
+labours in the field of geographical distribution urged him to seek a
+reason for the circumstance that different species of animals exist in
+different parts of the world. The struggle for existence does explain
+why some species have died out in one place while others have died
+out in other places. From that point Darwin went on to generalize
+about the Origin of Species, i.e. how species come into being. It is
+unfortunate that, though most of his earlier and enduring contributions
+to science are concerned with how certain species have ceased to
+exist, the title of his work laid emphasis on the process by which
+species are brought into being. It was naturally this part of his
+theory which made the greatest appeal to his contemporaries. Possibly
+it was not the one which was most significant to Darwin himself.
+Darwin used the term Natural Selection in connexion with both problems.
+With regard to the former his theory is as acceptable as ever. With
+regard to the latter it has now been superseded by exact experimental
+enquiry into the mechanism involved in the production and preservation
+of new hereditable types. The work of Gregor Mendel is the proper
+starting-point of such enquiry.
+
+A third aspect of the Principle of Genetic Variation concerns the
+adequacy of geological time. It will only be touched on briefly. When
+the evolutionary theory was introduced to the biological world, it
+had to encounter a difficulty that no longer presents itself as a
+formidable objection. Kelvin had calculated the possible period of time
+during which life can have existed from considerations derived from the
+rate of cooling of the earth. The allowance which Kelvin conceded was
+subject to the qualification that no factors at that time undiscovered
+enter into the question significantly. Since that time the discovery of
+radio activity has removed the necessity to place any such restriction
+on the period of geological time, as Kelvin was led to deduce. To-day
+we have no reason for believing that geological time is too short to
+permit us to ascribe the faunistic changes of successive generations to
+the operations of the natural process of genetical variation. At the
+same time the Evolution Theory will not stand side by side with the
+retrospective hypotheses of astronomy in the hierarchy of scientific
+generalizations, until the frequency of genetical variation and the
+conditions which determine it have been correlated with more exact
+knowledge of the duration and climatic features of the intervals
+corresponding to geological strata.
+
+
+§3
+
+There remains another aspect of the Principle of Genetic Variation.
+This is of paramount importance in connexion with the evolutionary
+hypothesis. It is the Origin of Species _sensu stricto_. A good deal
+of confusion has arisen in the discussion of the species problem on
+account of the equivocal usage of the word _species_. It is therefore
+best to begin with a clear definition of the species problem. It is a
+universal experience that any dog resembles its father and mother in
+more respects than it resembles any cat or any fish; any cat resembles
+its father and mother in more respects than it resembles any dog or
+any fish; any fish resembles its father and mother more closely than
+it resembles any cat or any dog. We may express this by saying that
+cats, dogs and fish have certain specific hereditable properties. If
+we examine these hereditable properties we find that a cat has more
+hereditable properties in common with any dog than those which it
+shares with any fish. Thus organisms can be arranged or classified
+in groups expressing the extent of resemblance in their hereditable
+properties. The work of Ray and Linnæus in the early half of the
+eighteenth century led to the general belief that “like begets like,”
+and the publication of the _Systema Naturæ_ (1757) by the latter author
+marks the beginning of a century and a half of detailed anatomical
+studies directed to classification of this kind. According to the
+degree of resemblance of organisms with respect to their hereditary
+properties they are customarily grouped in phyla, classes, orders,
+families, genera and species. To illustrate the meaning of these
+terms let us consider the reader of this essay. He or she is said to
+belong to the species _sapiens_ of the genus _Homo_, which includes
+all living races of man. The genus _Homo_ includes in addition _H.
+Neanderthalensis_, the early stone-age heavy-browed first men, and is
+grouped with the genera _Pithecanthropus_ and _Eoanthropus_ (the fossil
+ape man of Java and Pilt Down man) in a family _Hominidæ_, within the
+order _Primates_, that comprises apes, monkeys and marmosets. The order
+_Primates_ is one of many orders of forms within the class _Mammalia_
+that includes hairy animals that suckle their young. The _Mammalia_,
+along with birds, reptiles, amphibia (frogs, toads salamanders) and
+fishes, is placed in the phylum _Vertebrata_, which includes all forms
+with a backbone.
+
+The degree of similarity implied by placing two species in the same
+genus, order, class, etc., is an arbitrary one defined by convenience
+and general consent. The degree of similarity implied in placing two
+individuals in the same species in the sense in which the term was
+defined by Linnæus implies something more than convenience. Linnæus
+placed within the same species all individuals which breed readily with
+one another. The structural difference between two Linnæan species
+of animals and plants may be negligible compared with the immense
+structural differences that distinguish varieties within a single
+Linnæan species, as for instance the difference between White Leghorns,
+Yokohamas, Silkies, Partridge Cochins, etc., which are all members of
+the species _Gallus domesticus_.
+
+Though this definition of the species as a unit is the one sanctioned
+by priority, it is insufficiently emphasized by those who discuss
+evolution that the creation of new species in the daily routine of a
+large museum has very little to do with the Linnæan test. Preserved
+animals are sent by collectors to the taxonomist, who proceeds
+to classify them in new species, varieties or genera in the vast
+majority of cases without any experimental knowledge as to their
+breeding habits. Hence the terms species and variety are in practice
+used to a large extent interchangeably, though not deliberately. The
+historic problem of the origin of species is not that of the origin of
+museum species but of Linnæan species. If we can show that discrete
+hereditable properties arise, as we know that they do, discontinuously
+in the normal course of generation, we have all the materials we
+need to interpret the origin of varieties, genera, orders, families,
+classes, phyla. Whereas all these are arbitrary groups defined in terms
+of similarity and difference of the hereditable anatomical properties
+of animals and plants, the species, as defined by Linnæus, is a group
+limited not merely by the anatomical resemblance of its individual
+members but also by _their inability to breed successfully with other
+forms_.
+
+What has been said so far about the origin of new hereditable
+properties bears directly upon the way in which new varieties arise.
+New varieties will only retain their characteristics if some external
+agency is employed to prevent them from hybridizing and thereby giving
+rise to an indefinite number of new combinations of characters. The
+Yokohama can be made to retain those characteristic differences which
+distinguish it from a White Leghorn by the mechanical device of
+separating the two strains with a partition of wire netting. No wire
+netting is required to prevent a White Leghorn and a turkey from losing
+their genetic individualities, when they are placed in propinquity to
+one another as are closely allied species in Nature. There is therefore
+in addition to the problem of the origin of new varieties a problem
+of the origin of species incompatibility. This cannot be dismissed as
+of no importance, so long as our experimental knowledge of the origin
+of varieties fails to suggest in what way this incompatibility may
+arise. If we can solve this new problem the evolutionary hypothesis
+presents no ulterior difficulties in the way of explaining the origin
+of differences which separate the larger systematic groups. The
+differences employed in distinguishing genera from varieties, and
+orders from genera or classes from orders are differences of degree.
+Between species, superficially at least, there seems to be a difference
+in kind. On this account the origin of species has always been taken to
+signify the core of the evolutionary problem.
+
+In a somewhat panegyric vein Mr. H. G. Wells replying to Hilaire Belloc
+makes the following remark: “Darwin’s book upon the subject was called
+_The Origin of Species_. It was a very modest and sufficient title. He
+did not even go to the length of calling it the origin of genera or
+orders or classes.” Surely Darwin might much more appropriately have
+employed the latter. How types which are structurally different arise
+may or may not be accounted for by the selection hypothesis. How types
+which will not breed with one another arise within the same stock is
+not relevant to it. It is true that Darwin and Wallace vaguely referred
+in their writings to a natural tendency to infertility as forms become
+more sharply differentiated. This does not meet the difficulties of the
+case, even if it is a sound experimental doctrine. Bateson has used
+the following illustration to emphasize the irrelevance of Natural
+Selection to the species problem in the strict sense of the term:
+
+  “Sometimes specific difference (anatomical differences between
+  species) is to be seen in a character which we can believe to
+  be important in the struggle, but at least as often it is some
+  little detail that we cannot but regard as trivial which suffices
+  to differentiate the two species. Even when the diagnostic point
+  is of such a nature that we can imagine it to make a serious
+  difference in the economy, we are absolutely at a loss to explain
+  why this feature should be necessary to species A, and unnecessary
+  to species B, its nearest ally. The house sparrow (_Passer
+  domesticus_) is in general structure very like the tree sparrow
+  (_P. Montanus_)... They differ in small point of colour... The two
+  species therefore, apart from any difference that we can suppose
+  to be related to respective habits, are characterized by small
+  fixed distinctions in colour-markings, by a striking difference in
+  secondary sexual characters and by a difference in variability. In
+  all these respects we can form no surmise as to any economic reason
+  why the one species should be differentiated in one way and the
+  other in another way, and I believe it is mere self-deception which
+  suggests the hope that with fuller knowledge reasons of this nature
+  would be discovered.”
+
+It is permissible to argue that the final justification of the
+evolutionary argument will be achieved when intersterile mutants have
+been shown to appear under experimental conditions. We shall then
+be able to state that new types which display not only anatomical
+but specific discontinuity have arisen in the ordinary course of
+generation. At present it is only possible to say that we have very
+good reason to believe they can do so. Bateson overemphasized the
+difficulty of the species problem when he said “the production of an
+indubitably sterile hybrid from completely fertile parents, which
+have arisen under critical observation from a common origin... is the
+event for which we wait.” Although the origin of the species barrier
+does introduce a novel issue into the discussion of the evolutionary
+problem, its novelty is not so fundamental as it appears to be at first
+sight. Morgan remarks with justice:
+
+  “The necessity of putting the mutation theory to the test that
+  Bateson calls for seems to me very doubtful, for while this is one
+  of the possible ways in which a mutant might split off at once from
+  the parent type, it is by no means the only way or even, I think,
+  the most probable way in which species have become separated....
+  There is no one problem of infertility of species and no one
+  problem of the sterility of hybrids, but many problems, each due to
+  differences that have arisen in the germinal material. One or more
+  of these differences may affect the mechanism of fertilization or
+  the process of development, producing some incompatibility.”
+
+Bateson performed a most important task in emphasizing that the problem
+of species discontinuity exists. He made its solution assume more
+formidable proportions than the facts merit. There is no mysterious
+wholeness about the concept of the species barrier. Like other
+scientific concepts it defines a class of properties. When we examine
+the characteristics of species barriers, we at once see that they
+constitute a very heterogeneous assemblage of hereditable properties,
+many of which are recognizably similar to hereditable properties which
+we know to arise as mutants in genetic experiments. An individual may
+be placed in a different species from another individual because of
+some merely anatomical difference in the structures associated with the
+copulative act. Owing to the respective absence of neck hackles and
+tail feathers in two strains known as the Barbadoes and Rumpies, the
+male of the latter cannot successfully tread the female of the former,
+though each is interfertile with other breeds of domestic fowls. The
+origin of such differences does not constitute a problem of a different
+class from the origin of other varieties. High and low fertility are
+hereditable properties that can be studied as varieties within the
+species group. They have arisen as mutant characters in experiment.
+If there arose within a stock mutants with complementary genes for
+infertility either type would be infertile with respect to the other.
+They would constitute separate species in the Linnæan sense, when the
+parent stock died out. In the case of the donkey and the horse, we
+can go further and identify the complementary sterility factors in
+the structure of the chromosomes. Difference of size and shape in the
+chromosomes of the donkey and horse prevent them from pairing in the
+reduction division, so that no ripe sperm is formed in the testis of
+the mule. Mutants differing with respect to chromosome numbers and
+sizes arising by fragmentation or fusion are known both in plants and
+animals to have arisen under experimental conditions. In many plants
+they have been perpetuated by self-fertilization. Plough has raised a
+mutant strain of Drosophila which is more fertile _inter se_ than with
+the wild stock. The genetic basis of interspecific sterility, while
+worthy of much more extensive research, is now reaching a precision
+which places the experimental data of evolutionary theory beyond the
+plane of Malthusian speculation.
+
+The foregoing illustrations do not exhaust the variety of biological
+characteristics which separate one individual from another as a member
+of a different Linnæan species. Nor do they exhaust the types which can
+be brought within the realm of experimental treatment. Other cases are
+discussed at length in Crew’s _Animal Genetics_. The species barrier is
+not one thing but many things. In the light of modern research there is
+no reason to regard the origin of species barriers as an essentially
+different problem from the origin of varieties. Nevertheless the two
+issues are superficially distinct. No discussion of the present status
+of the evolutionary hypothesis is complete unless the distinction is
+submitted to critical examination in the light of experiment.
+
+In the opening years of the twentieth century it had become the
+fashion among biologists to treat evolution as a dogma. The growth of
+experimental study of inheritance and variation tends rather to make us
+value it as a hypothesis suggestive of further enquiry. The difference
+between the two attitudes is akin to a difference of method which
+mankind has adopted throughout the ages in the pursuit of knowledge.
+One method rationalized in its most rigid form in the philosophy of
+Hegel is to seek for some proposition to which every one is agreed and
+proceed by deduction to whatever conclusions may be reached from the
+starting-point. This method has proved invaluable to politicians and
+members of the legal profession in the discharge of their vocational
+activities. It is essentially like that of the schoolmen who would
+exhaust themselves in untiring search into the writings of the ancients
+for some authoritative statement regarding the number of teeth which
+the horse possesses, a statement that no one would dare to question.
+The scientific method is irreconcilably opposed to the Hegelian
+method. With no aspirations to good breeding it prefers to look the
+gift horse in the mouth. It is just those propositions which every
+one accepts that the scientist is most anxious to examine in the hard
+light of experience. In attempting to envisage a natural mechanism by
+which the graded differentiation of animal structure could have been
+brought about, Lamarck was content to employ the generally accepted
+belief in the inheritance of acquired characters without bringing
+it to experimental test. Darwin, fortified with newer knowledge of
+the historical succession of animals and plants as recorded in the
+rocks, sought to show that evolution was a necessary consequence of
+competition and the “strong principle of inheritance.” Darwin did
+not undertake the task of enquiring into the nature of the “strong
+principle of inheritance.” It was to him like one of Euclid’s axioms.
+Mendel alone at this time saw the necessity for an experimental study
+of inheritance, and pointed the way to a non-dialectical treatment of
+the problem.
+
+
+
+
+VII. NATURAL SELECTION AND EXPERIMENTAL RESEARCH
+
+  “Heredity as something quite incomprehensible cannot be used as an
+  explanation, but only as a designation for the identification of a
+  problem. And the same holds good of adaptability.”--Nietzsche, _The
+  Will to Power_
+
+
+§1
+
+To large numbers of people evolution is Darwinism, just as to our
+fathers geometry was Euclid. In one of his writings Morgan has remarked
+that “it is not so important to find out whether Darwin’s ideas were
+as clear as our own, as to make sure that our own ideas are clear.”
+This is true; but an interest in the history of scientific thought
+is a blameless pursuit for its own sake; and there are ulterior
+reasons which justify an historical discussion of the criticisms which
+experimental discovery has brought to bear on the Selection doctrine
+in its original form. During the latter half of the nineteenth century
+the evolutionary hypothesis became entangled with the idea of a moral
+progress of mankind. On this account some philosophers, who are not
+biologists themselves, fail to recognize the ethical neutrality of
+biological enquiry. It is doubtful whether the promulgation of any
+scientific hypothesis has ever had so profound and, at the same time,
+so immediate an effect on the attitude of educated people towards
+personal responsibility and social obligations. The fate of Darwinism
+is as much the concern of the layman as of academic biologists.
+
+Nor is it easy for those who are not biologists to gain definite
+enlightenment concerning the extent of the change that has taken
+place. With the rise of experimental method the discussion of evolution
+has become more technical owing to the accumulation of new data and on
+account of the introduction of a more intricate form of logic. It is
+a quantitative branch of science. There was a time when the biologist
+thought it worth his while to read and to reply to Samuel Butler.
+To-day there are biologists who read--and like the present writer
+enjoy--the works of Mr. Bernard Shaw. They do not feel it necessary to
+defend their philosophy against the arguments advanced in the preface
+to _Back to Methuselah_. Popular expositions of evolution are still
+written. More often than not one suspects that they are rather too
+popular to answer the questions which an intelligent reader who is not
+a biologist is most anxious to hear discussed.
+
+As an exact science biology is still very young. Evolution is in its
+infancy. Only in our generation has it become the nucleus of a growing
+body of experimental research. It may be that when the history of the
+evolutionary hypothesis is written two centuries hence, Bateson’s
+_Materials for the Study of Variation_ will assume a more prominent
+place than _The Origin of Species_. It may be that the name of Thomas
+Hunt Morgan will be mentioned in its pages more often than that of
+Charles Darwin. We are too near the footlights to view the matter
+in its correct historical perspective. It is at least permissible
+to entertain such a possibility. Ancestor worship has no place in
+the ritual of science. If any display of sentiment is appropriate in
+scientific discussion, it might be said that the only fit way in which
+to honour the memory of a Darwin and a Newton is to press forward in
+exploring the fields which their labours have fertilized.
+
+Without entering into technicalities I shall make the attempt in this
+essay to contrast the use of the term Natural Selection in Morgan’s
+writings with the Darwinian doctrine in its original form. My aim will
+be neither to justify in the one case nor exculpate in the other, but
+to discover whether a difference exists, wherein the difference lies,
+and how the difference has arisen. In contrasting the views held by
+two men of science it is of the utmost importance to lay emphasis on
+the type of data which they have respectively studied most. Morgan is
+an experimental geneticist. Darwin was pre-eminently a geographical
+naturalist. Morgan’s most brilliant contributions to the advance of
+science have been focused on the study of those conditions which
+are significant to the origin and transmission of new hereditable
+properties in animals. Before the publication of _The Origin of
+Species_ Darwin’s scientific labours had concentrated more especially
+on amassing a wealth of information about the way in which species are
+distributed in different parts of the world. In his long itineraries,
+it is not difficult to surmise what aspect of the species problem was
+constantly uppermost in Darwin’s thought. I think it is necessary to
+appreciate this bias in any attempt to understand the way in which the
+Selection hypothesis developed. Though Darwin spoke of the Origin of
+Species, he was interested primarily in why some species happen to be
+found in one place and other species in different places. Darwin had
+two distinct problems in view when he set out to write _The Origin of
+Species_. In the course of writing it he sometimes lost sight of the
+distinction between them. One was how different types of animals have
+come to persist in different parts of the world. The other was how
+an evolutionary process could take place at all. That the struggle
+for existence is the key to the former is highly plausible. No facts
+are known which contradict such a view. It is not really an issue
+with which the modern experimentalist concerns himself. Up to this
+point there is no divergence between the Darwinian and the Mendelian
+standpoint. But Darwin in very unequivocal language committed himself
+to the view that in building up new specific forms the struggle for
+existence makes use of all differences between parent and offspring
+of “whatsoever” origin. He thus implicitly encouraged the view that
+natural selection is a creative agency. Herein lies a fundamental
+difference between the standpoint adopted by Morgan and the Darwinian
+doctrine. Darwin really believed in the Origin of Species by natural
+selection. Morgan believes in the Origin of Gaps by natural selection.
+
+It is perfectly true that Darwin did not formulate this deduction so
+explicitly or so prominently as did some of his followers. But it was
+logically implicit in his earlier writings and very definitely set
+forth in his later. It was in virtue of this aspect of the Natural
+Selection hypothesis that evolution captured the support of Darwin’s
+contemporaries. Till Darwin’s book appeared, biologists did not for
+the most part believe that evolution could take place. Darwin’s
+hypothesis demonstrated that evolution must take place in a world in
+which organisms had to struggle for their existence. The experimental
+data which Morgan employs as the basis for his conception of the
+evolutionary process imply that the reasons which led the pre-Darwinian
+biologist to think that evolution could not take place are unfounded.
+They also imply that the reasons which Darwin advanced to show that
+evolution _must_ take place are wrong.
+
+It is easier to make this distinction clear at a later stage with the
+aid of a concrete example than by stating general propositions. This
+is because one result of experimental progress has been a change in
+our use of the concept of “variation.” Darwin used the term variation
+for any difference between parent and offspring. In affirming that the
+struggle for existence makes use of all variations for building up
+species differences, he logically implied one of two things. Either
+all differences between parents and offspring are genetic in origin,
+that is to say, referable to differences in the egg or sperm; or
+alternatively bodily modifications which occur during the lifetime of
+an individual influence the genetic structure of the offspring so as
+to produce an analogous result. This principle, usually associated
+with the name of Lamarck, was accepted by every one in Darwin’s time.
+Darwin himself, while ridiculing Lamarck’s idea of the _modus operandi_
+of evolution, accepted the inheritance of acquired characters. There
+was therefore no need for him to make a distinction between the
+two alternatives. Neither the one nor the other is in harmony with
+the standpoint of a modern geneticist of Morgan’s school; but the
+difference between the Darwinian standpoint and that of Morgan concerns
+not only the question of fact but the deductions drawn from it.
+
+The difference between either of these alternatives on the one hand and
+the Mendelian standpoint on the other can be illustrated by reference
+to one of Mendel’s original experiments on the hybridization of peas.
+In crossing pure-bred peas of the variety characterized by a dwarf
+shoot with the normal tall variety, Mendel obtained only tall types
+on the first generation, and in the second generation derived from
+crossing the latter _inter se_ one-quarter were dwarf and the remaining
+three-quarters tall. Now the individuals of either the tall or the
+dwarf class are not all alike. Any dwarf shoot grown under ordinary
+conditions is distinctly smaller than a tall shoot, so that the two
+classes are discontinuous and quite easily distinguishable; but when
+the conditions are standardized as much as possible small differences
+of light, moisture, soil-content, temperature or proximity exert their
+influence, so that no two dwarf plants are of exactly the same size.
+What is transmitted through the gametes is something which determines
+the extent to which an individual is capable of growing under
+appropriate conditions. This distinction greatly clarifies our thought
+about the so-called inheritance of acquired characters.
+
+A criticism of the Lamarckian doctrine is irrelevant at this juncture.
+It is referred to in this connexion because it was only in the
+eighties, after the Lamarckian view was challenged by Weismann, that
+the full force of the logical implications of Darwin’s teaching was
+felt. It is true that his followers were far more definite than the
+author of _The Origin of Species_ in emphasizing the creative rôle of
+selection. It is true that the discredit into which the Lamarckian
+principle fell after the discovery of the nature of fertilization
+led the Selectionist writers to exaggerate this aspect of Darwin’s
+hypothesis. Nevertheless Darwin did express himself in unmistakable
+language with regard to this issue. His followers, forced to be more
+specific concerning the nature of differences between parents and
+offspring, made the bold, and, it transpired, unwarranted assumption
+that all those small differences between parent and offspring now
+referred to as fluctuating variability are in the main genetic in
+origin. The Selectionist doctrine thus assumed that hard outline which
+produced its first vigorous reaction in Bateson’s _Materials for the
+Study of Variation_ (1894), a work which laid down the main lines of
+investigation which have been elucidated by the Mendelian renaissance.
+
+To avoid vagueness concerning what Darwin actually did say I shall
+quote once more from _The Origin of Species_:
+
+  “Any being, if it vary in any manner profitable to itself, under
+  the complex and sometimes varying conditions of life, will have a
+  better chance of surviving, and thus be naturally selected. From
+  the strong principle of inheritance, any selected variety will tend
+  to propagate its new and modified form.” (Introduction.)
+
+  “Each of the endless variations which we see in the plumage of
+  fowls must have had some efficient cause; and if the same cause
+  were to act uniformly during a long series of generations on many
+  individuals, all probably would be modified in the same manner.”
+  (Chap. 1.)
+
+  “A high degree of variability is obviously favourable as giving
+  the materials for selection to work upon, not that mere individual
+  differences are not amply sufficient, with extreme care, to allow
+  of the accumulation of a large amount of modification in almost any
+  desired direction.” (Chap. 1.)
+
+  “Over all these _causes_ of change, the accumulative action
+  of selection, whether applied methodically and quickly, or
+  unconsciously and slowly but more efficiently, seems to have been
+  the predominant power.” (Chap. 1.)
+
+  “Variations, _however slight, and from whatever cause_ proceeding,
+  if they be in any degree profitable to the individuals of a
+  species, in their infinitely complex relations to the individuals
+  of a species... will tend to the preservation of such individuals
+  and will generally be inherited by the offspring. The offspring
+  also will have a better chance of surviving, for of the many
+  individuals of a species which are periodically born, but a small
+  number can survive. _I have called this principle, by which each
+  slight variation if useful is preserved, by the term Natural
+  Selection._” (Chap. 3.) (Italics inserted.)
+
+If, as Darwin believed, it were true, that variation occurs in every
+generation, the evolutionary process would be a continuous one. To
+Morgan the production of mutants is a discontinuous break in a
+normal routine of stability. To Darwin variation and heredity were
+co-extensive terms. The offspring are always on the whole like their
+parents. That resemblance constitutes inheritance. On the other hand
+they are never quite the same. The difference was what Darwin called
+variation. To Morgan heredity and variation are not co-extensive terms.
+The structure of the chromosomes is fundamentally stable. From time
+to time there occur disturbances of this normally stable equilibrium.
+New hereditable properties emerge into being in a quite discontinuous
+fashion. There is no self-evident reason why a particular stock should
+not remain indefinitely in a phase of stability. To the experimental
+geneticist there thus exists no difficulty in interpreting the fact
+that some animals have remained unchanged since the earliest rocks.
+
+To the generation in which Darwin lived there seemed to be only one
+logical outcome of the view that variation is a continuous process
+involving all the individuals of every generation. This deduction
+was never stated very explicitly by Darwin himself, though it was
+definitely asserted by Wallace. There can be no doubt that this
+deduction gave the Selection hypothesis such a strong appeal to
+Darwin’s contemporaries, and contributed largely to the success of
+the hypothesis of Natural Selection. Before Mendel, investigators
+in hybridization had treated the individual as the unit for study.
+From this arose the belief that hybrids are intermediate between the
+parents. This belief in its turn gave rise to the notion that on
+crossing a new type back to the parent stock there would be a dilution
+of the new character, culminating after a number of generations in
+swamping it out of existence altogether. Evolutionists of the Darwinian
+period therefore introduced a variety of devices, such as geographical
+isolation and, above all, the survival of the fittest, to counteract
+the effect of this swamping and account for the persistence of new
+types. To Darwin’s generation it seemed that without selection there
+could be no evolution. The new type would always be swamped out in the
+long run. In the struggle for existence the less viable variations
+would tend to be eliminated, and since there would always be less of
+them on that account, the swamping process would favour the gradual
+moulding of the species in the direction of more favourable variation.
+On this view the struggle for existence is the agency which makes
+species change. Evolution becomes a necessity.
+
+From Morgan’s standpoint evolution is only a necessity in so far as
+it happens that mutants do from time to time appear. The struggle for
+existence though eliminating the less viable types has no creative
+rôle in the Darwinian sense. Mendelian analysis shows that though
+the first generation of a cross between pure-bred parents may be
+intermediate between the parental types, both parental types appear
+in their original purity in the next generation, and will continue
+to breed true to type, whenever they mate with other individuals
+similarly constituted. The modern geneticist feels no necessity for
+an _argumentum ad hominem_ to explain how evolution can occur in
+spite of a supposed swamping process. To him the swamping process is
+an illusion based on imperfect knowledge of the facts of hereditary
+transmission. The importance of this difference in standpoint lies in
+the fact that the idea of natural selection would never have assumed so
+powerful an influence over biological thought, unless it had provided
+the evolutionist with train of reasoning which seemed to prove that
+evolution must be going on all the time.
+
+This interpretation of the Darwinian standpoint is not a caricature
+drawn by the pen of an adverse critic. An enthusiastic contemporary
+exponent of Natural Selection, Mr. H. G. Wells, thus defines the
+selection theory in his _Outline of History_:
+
+  “the young which a living thing produces... are like the parent
+  living thing. But they are _never exactly like it_ or like each
+  other.... Suppose, for example, there is some little furry
+  whitey-brown animal living in a bitterly cold land which is usually
+  under snow. Such individuals as have the thickest, whitest fur will
+  be least hurt by the cold, less seen by their enemies and less
+  conspicuous as they seek their prey. The fur of this species will
+  thicken and its whiteness increase _with every generation_, until
+  there is no advantage in carrying any more fur.” (Italics inserted.)
+
+Having cited the above, it is somewhat surprising to note that in
+replying to Mr. Belloc’s strictures, Mr. Wells makes the following
+statement with reference to the Natural Selection theory:
+
+  “Among questions bearing upon it but not directly attacking it
+  has been the discussion of the individual difference.... What
+  rôle is played by what one might call normal relatively slight
+  differences and what by the sports. Can differences establish
+  themselves while outer necessity remains natural? Can variations
+  amounting to specific differences... be tolerated rather than
+  selected by Nature?... What happens to differences in cases of
+  hybridization?... None of these subsidiary questions affect the
+  stability of this main generalization of biology.”
+
+In explaining the Natural Selection theory, as quoted above, Mr. Wells
+himself states or implies every one of these “subsidiary” questions,
+and answers them in his own way.
+
+Let us now see how a modern geneticist would interpret the evolutionary
+process by taking an analogous concrete example. He would argue
+somewhat as follows. Supposing a single white mutant hare arises in a
+grey parent stock, the behaviour of the chromosomes leads us to infer
+that eventually other white hares, pure for the white gene or genes,
+will reappear. These mated _inter se_ will breed true to type. On the
+assumption (not conclusively proved) that it is advantageous for a hare
+in temperate climates to be grey and in arctic regions to be white,
+there will be more white hares in the long run in northern countries
+and more grey ones in temperate countries. If there were no competitive
+struggle at all, there would in the long run be grey and white hares in
+northern and grey and white hares in temperate countries. There would
+have been the same amount of evolution. The only difference that the
+struggle for existence introduces is that the final picture presents
+a more discontinuous aspect. This was not at all what Darwin meant by
+Natural Selection. He would have said that a single mutant would be
+swamped out of existence by intercrossing. He would have formulated the
+problem in the following terms. Of all hares born to grey parents some
+are lighter and others darker. In a region where it is advantageous,
+the half that are lighter than the mean will have more chance of
+surviving to maturity. In any given generation there will therefore be
+more lighter than darker parents. The result of this will be that in
+every generation the swamping process will always be on the side of
+the lighter individuals. Darwin postulated that, if this process went
+on long enough, a white hare would eventually be produced. Such a race
+would only be produced in the region where natural selection favoured
+its survival. On this view natural selection is the creative agency,
+or at least a paramount creative agency in the evolutionary process.
+Without the struggle for existence hares everywhere would remain grey.
+In every generation the half that are lighter than their parents would
+always be swamped by the half that are darker.
+
+To Darwin and more especially to Darwin’s followers selection was the
+agency which preserved not merely new individuals but new characters,
+since characters would otherwise be diluted out of existence. For
+Morgan the preservation of new characters ultimately resides in
+Mendel’s law of segregation. It has its material basis in the behaviour
+of the chromosomes. The contrast between the alternatives is at once
+made clear when we consider what would happen in a universe so large
+and so abundantly supplied with the necessities of life that no
+struggle for existence intervenes. Given unlimited time in a Mendelian
+universe in which natural selection did not operate, all the species
+we know to-day would be present, and many more besides. Evolution
+would have occurred; but the pageant of life would present to the
+taxonomist a more continuous appearance, and the striking gaps which
+we now see would be filled not by fossil relics but by living forms.
+Except in so far as he was prepared to invoke the Lamarckian principle
+to circumvent difficulties inherent in his own hypothesis, natural
+selection was to Darwin the necessary condition not merely for gaps but
+for any evolution to take place at all. In a Darwinian universe without
+natural selection there would be no progressive differentiation of new
+characters.
+
+
+§2
+
+When, out of deference to Darwin’s contribution to biological thought,
+the experimentalist of Morgan’s school asserts his belief in Natural
+Selection, he is in fact referring to something very different from
+Darwin’s Natural Selection, indeed to a view of the process which
+Darwin would have rejected emphatically. Of course it is admitted that
+all scientific hypotheses become modified as new data accumulate; and
+phrases imperceptibly change their meaning in the course of time.
+But the natural selection of Morgan’s school is not a continuous
+development from the original concept. Within two decades of the
+publication of _The Origin of Species_ the selection hypothesis had
+assumed a clarity of outline which had an influence on subsequent
+developments in biological thought, persisting till the present day,
+and not likely to disappear for some time. In 1881 Weismann challenged
+the prevailing belief in the inheritance of acquired characters.
+Thenceforth in the hands of the Selectionists environment became merely
+an agency by which the hereditary materials are preserved or rejected.
+As an aspect of the problem of development it faded into the background
+of the picture. To question the almightiness of heredity became
+equivalent to defending the Lamarckian principle, though the two issues
+are logically independent.
+
+Educated people frequently use the words environment and heredity in
+a very different sense from that in which they are employed by the
+biologist. Unless we are accustomed to the study of embryonic and
+larval life, we are apt to think of an organism as a finished product.
+The rôle of environment and of heredity as seen through the eyes of
+a contemporary biologist can be made explicit by reference to recent
+work on the metamorphosis of tadpoles. We know to-day that the thyroid
+gland of all vertebrates contains a high percentage of iodine. Barger
+and Harrington have now prepared in pure crystalline form an iodine
+compound which has the same therapeutic properties as extracts of
+the thyroid gland. A few years ago the discovery that frog tadpoles
+will change very rapidly into adults if fed with thyroid gland, was
+followed up by the development of a successful technique for removing
+the rudiment of the thyroid gland in frog embryos. Thyroidless tadpoles
+never undergo metamorphosis. They continue to grow as tadpoles when
+the normal tadpole would change into a frog. The change into the adult
+in the normal tadpole is initiated by the liberation of the thyroid
+secretion into the circulation. It has also been shown that tadpoles
+reared on an iodine-free diet in water containing no trace of iodine
+remain permanently in the larval state. This clarifies what is meant by
+an _environmental_ factor in development. In contradistinction to the
+influence of environment the influence of inheritance in development
+may be illustrated by reference to an American salamander, _Amblystoma
+tigrinum_, which has a characteristic larval form. In the lakes around
+Mexico city there is a local race of this species which never undergoes
+metamorphosis in nature, reproducing in the larval form. It can be
+made to develop into the land-dwelling adult in a few weeks, if fed
+with thyroid gland in the laboratory. Addition of iodine salts to the
+water in which it lives or to its food will not induce metamorphosis.
+Its permanent fixation in the larval stage is due to the fact that it
+_inherits_ from one generation to another a deficient thyroid gland,
+which cannot make use of the iodine in its surroundings. Absence of
+iodine in minute quantities from the water, a purely environmental
+agency, or on the other hand a hereditary difference between two races
+with respect to the efficiency of thyroid secretion, may either of
+them be _independently_ instrumental in deciding whether a particular
+individual shall attain sexual maturity in the form of an air-breathing
+land-dwelling salamander, or an aquatic half-way house between a
+salamander and a fish. A geological epoch, if you like to put it in
+that way, is thus summed up in a mutant gene or in a trace of iodine.
+
+In the attempt to understand the tenacity with which belief in the
+Lamarckian view persisted in biological thought, it must be borne
+in mind that embryology is the most recently developed branch of
+anatomical science. Until the classical researches of von Baer and
+Meckel were published in the first half of the nineteenth century, the
+prevailing idea about development was the teleological doctrine that
+an animal is from the very first complete in all its parts and only
+needs growth to make its minute structure manifest to the eye. Caspar
+Wolff in 1759 made observations on the hen’s egg, and was led to state
+the “epigenetic” as opposed to the prevailing “evolutionary” view. He
+sought to show that the hen’s egg is at the beginning without any gross
+anatomical organization and that structural organization within the
+egg is a gradual development. His work failed to attract attention.
+Von Baer’s researches on the same subject were published synchronously
+with the formulation of the Cell doctrine (1832). One might say that
+until the middle of the nineteenth century, the current conception of
+inheritance in biology was closely analogous to the legal notion. The
+parent was supposed to hand on its anatomy to its offspring in the same
+sense as the well-to-do hand on their belongings. With so erroneous
+a conception of the nature of development prevailing, it is little
+wonder that the idea of the inheritance of acquired characters seemed
+a perfectly reasonable one. It is not surprising that the doctrine of
+Lamarck should have been first challenged during the decade in which
+the nature of fertilization and the process of maturation of the germ
+cells were elucidated.
+
+As stated by its author the Lamarckian principle implied that any
+reaction of the organism to its environment is carried over to
+subsequent generations. It was especially _adaptive_ reactions such
+as the effect of use and disuse which Lamarck emphasized in his
+evolutionary speculations. When the Lamarckian principle was first
+challenged, prominent scientists like Cope were willing to assert such
+fables as the story that a cock deprived of one eye transmitted eye
+defects to all his offspring. When it was conclusively proved that
+mutilations effected through several generations left no impress on
+the hereditable characters of the stock, the Lamarckians fell back
+on the gratuitous postulate that only “adaptive” changes could be
+transmitted. The precise meaning of this adjective was never defined,
+nor was any reason forthcoming to suggest the existence of a mechanism
+that could discriminate between mutilations and bodily changes that are
+“adaptive.” This is yet another example of the perils of introducing
+teleological preoccupations into the construction of biological
+hypotheses. If recent experimental research conserves any element
+of truth in the Lamarckian idea, it has robbed it of any special
+significance to the way in which adaptive structures originate.
+
+Structural changes may arise in the course of development from two
+conceivable sources. The chromosomes which represent the hereditary
+materials may find themselves reacting to a different type of “internal
+environment.” The majority of modifications in the normal course of
+development undoubtedly come within this category. Modifications of
+this type, including in all probability relative sizes of organs, all
+mutilations and habits are clearly not hereditable. Belief in their
+hereditability was only possible so long as biology was dominated
+by teleology and the essential features of the reproductive cycle
+were undiscovered. There is another possibility which was entirely
+disregarded by Weismann in his Theory of the Germ Plasm. It is a
+possibility that has no bearing on the problem of adaptation. If
+environmental agencies can produce mutations by a structural change
+in the chromosome itself, there is no reason why such structural
+changes should be confined to the chromosomes of the germ cells. We
+must therefore preserve an open mind with regard to the possibility
+of encountering phenomena having a superficial similarity to what
+is implied in Lamarck’s doctrine. The exposure of young larvæ of
+the fruit-fly to X-rays has led to the production of individuals
+which show bodily resemblances to forms which have arisen in the
+ordinary course of events as mutants. The effect of X-rays may be
+to change the environment in which the chromosomes operate. But
+the recent investigations of Patterson indicate the likelihood
+that the modification is due to the action of the X-rays on the
+chromosome itself. We know that X-rays will produce mutant changes
+in the chromosomes of the germ cells. If Patterson’s interpretation
+is correct, it may well be found that X-rays can simultaneously
+effect mutant changes in all the chromosomes of the body. If applied
+sufficiently early in the course of development, radiation with
+X-rays would then produce bodily changes of a transmissible nature.
+This possibility resides in the fact that the agent is capable of
+acting on all the cells of the body in the same way at the same time.
+There is no inherent unlikelihood that temperature and the chemical
+constituents of an animal’s food may simultaneously produce bodily
+and germinal mutations. Strictly speaking this is not the same as the
+traditional belief in the “inheritance of acquired characters.” The
+Lamarckian principle completely disregards the distinction between
+modifications which arise from a change in the internal environment of
+the chromosomes and a physical change in the chromosomes themselves. It
+takes no account of the possibility that the environmental agent can
+act in the same way simultaneously on all the cells of the body.
+
+There are still students of fossil forms who claim that the
+traditional Lamarckian view is necessary to explain the historic
+succession of animals by continuous generation. There seems to be no
+satisfactory reason to justify the statement that evolution can only
+be satisfactorily explained by assuming the inheritance of acquired
+characters. If there were, it would not be an argument in favour of
+the Lamarckian principle. It would be as an argument against the
+evolution theory. It would imply that the truth of evolution depends on
+assuming a mechanism whose existence is most unlikely. What is often
+called the neo-Lamarckian standpoint, the view that acquired characters
+only gradually become impressed on the hereditary constitution after
+countless generations, transfers the issue from the plane of verifiable
+experience to one of pure surmise, rendering further discussion
+profitless. In such a matter as this when experiment is silent, the
+student of fossils must also be silent.
+
+The objection rests in fact on a misapprehension. The earlier phase of
+experimental enquiry along the lines laid down by Mendel was confined
+to the analysis of simple clear-cut hereditary differences which
+present themselves in almost any environment in which the animal can
+live. They were also largely concerned with differences that could be
+resolved into the simplest arithmetical ratios, or as Morgan would say
+with mutants that have arisen through a change at a single point on
+one pair of chromosomes. It is only as technique has progressed that
+it has been possible to analyse the more complex cases in which single
+characteristics depend on numerous Mendelian factors, or where the
+character differences are so variable that they can only be defined in
+statistical terms. The palæontologist being occupied very largely with
+size differences is sometimes disappointed, because such phenomena lie
+outside the scope of the simpler problems, which were once thought to
+define the scope of the Mendelian hypothesis. Recent progress which has
+led to the recognition that Mendel’s principle of segregation underlies
+the inheritance of size is therefore of no little significance to
+evolutionary theory. As we come to recognize the dependence of
+hereditary transmission on discrete particles which maintain their
+entities uncontaminated through all the cell divisions of the body,
+segregating in their entirety in the formation of the gametes, the
+unlikelihood of the Lamarckian principle in its traditional form
+becomes more and more evident.
+
+If the Lamarckian principle in its traditional form was undoubtedly
+based on a confusion of ideas and an ignorance of fact, the Theory
+of the Germ Plasm put forward by Weismann shows how facts may be
+distorted to fit in with preconceived ideas which are in themselves
+logically flawless. The discredit into which the Lamarckian principle
+fell, almost as soon as the elementary facts about the nature of
+fertilization became known, led Darwin’s successors to assume that
+all those differences between parent and offspring which Darwin had
+referred to under the term variations are genetic in origin. The
+assumption was gratuitous, as later experimental analysis has shown.
+Without that assumption the Selection doctrine would have been
+robbed of the immense importance it had already begun to assume. From
+a complete misapprehension of the true rôle of the environment in
+relation to inheritance, the biological pendulum swung in the opposite
+direction to a complete disregard of the influence of the environment
+in relation to development. It is from Weismann’s writings that we
+can best appreciate the fundamental dissimilarity of Darwin’s Natural
+Selection and Morgan’s views. For Weismann’s “germinal selection” is
+the logical outcome of Darwin’s selectionism, once it had been purged
+of the Lamarckian principle. It is a triumph of Hegelian reasoning
+applied to biology. There is nothing wrong with it but its premises.
+Weismann’s theory embodied an atomistic conception of heredity.
+Unlike Mendel’s it had no connexion with experimental data. Weismann
+identified his hereditary determinants with the substance of the
+chromosomes. Unlike Morgan’s hypothesis, Weismann’s speculations were
+based on incorrect observations about the way in which the chromosomes
+behave. In the long run the influence of Weismann’s teaching has
+probably been more sterilizing than the Lamarckian doctrine which he
+challenged.
+
+Weismann imagined that his atoms of heredity or “determinants” multiply
+in the cell and in some rather abstract way compete with one another
+for survival. Hence the hereditary constitution of the individual
+is never quite the same in two successive generations. Heredity
+and variation are thus co-extensive, as Darwin’s Natural Selection
+postulates. Weismann also thought wrongly, it transpired, that the
+reduction division of the germ cells takes place in such a way that
+each cell receives half a maternal and half a paternal chromosome
+of each pair and not, as we now know, a whole paternal or a whole
+maternal element. Hence he argued that the formation of the germ cells
+involves not, as Mendel proved by experiment, a segregation but a
+closer intermingling of the germinal materials. From this the swamping
+of new characters on crossing became an absolute necessity. To Weismann
+selection alone could prevent this swamping. Selection must act in
+every generation, because the mingling of the hereditary materials
+becomes more intimate with every generation. Only under the influence
+of continuous selection could any change be brought about. Without it
+universal stagnation would exist. In short Selection was the creator
+and the preserver of the benefits of variation. In all this Weismann,
+with the support of Wallace, went much further than Darwin himself.
+But the Selectionist doctrine in its main features was implicit in
+the Origin of Species. The sociological exploits of biologists belong
+especially to the period in which the Selection doctrine assumed this
+doctrinaire aspect. Doctrinaire Selectionism has persisted in our own
+generation in the writings of many eugenists.
+
+
+§3
+
+We set out in the first place to contrast the views of the modern
+geneticist with the Selection hypothesis in its original form. The
+main differences arise in connexion with two issues. One concerns
+Darwin’s own view that evolution is a continuous process. Darwin
+believed that selection operates on all the individuals of every
+generation. This implies either that acquired characters are inherited
+or alternatively that all differences between parent and offspring are
+hereditary differences in the modern sense. The views to which modern
+geneticists have been led by their experiments are diametrically
+opposed to both conclusions. The other question concerns the creative
+rôle of selection. This belief arose from ideas about hybridization
+and artificial selection current among those biologists to whom Darwin
+addressed his argument. Darwin himself did not stress the point; but
+it was this corollary of his theory which accounts for the successful
+appeal which Natural Selection made to Darwin’s contemporaries. They
+were satisfied that, if a struggle for existence occurs, evolution must
+be taking place. This was because all biologists before Mendel confused
+the characters which do blend with the genes that do not. To the modern
+geneticist this corollary has no significance, because experiment has
+forced him to reject views about hybridization prevalent before the
+publication of Mendel’s researches. To Morgan, as to Darwin, selection
+through the survival of the fitter is essentially like artificial
+selection. Morgan differs radically from Darwin in his understanding
+of the way in which artificial selection itself operates. According
+to Morgan selection has no creative significance. “Selection has not
+produced anything new, but only more of certain kinds of individuals;
+Evolution however means producing new things, not more of what already
+exists.”
+
+Thus from the standpoint of Morgan the status of evolution is more
+satisfactory in the light of modern research. For there is no need to
+advance any special device to explain why new types are not swamped
+out of existence through the blending of characters on crossing. From
+the point of view of the Darwinians, if they were still with us, the
+outlook would be disconcerting. The modern geneticist no longer regards
+evolution as an imperative consequence of the struggle for existence.
+On the other hand the modern view presents no greater difficulty than
+the former one in explaining the tendency towards greater adaptation.
+It is free from the objection that it proves too much. New hereditary
+types would persist even if there were no struggle for existence. Since
+there is one, the chance that a given mutant will reach the age at
+which it can produce offspring will be greater if the mutant character
+has “survival value.” At present there are insufficient experimental
+data to make profitable the discussion of the amount of advantage
+necessary to ensure survival. At the same time it is of interest to
+record that the application of Mendelian method furnishes materials
+for a precise statement of what selection can achieve and the rate at
+which it works, when the extent of differential fertility or mortality
+in a population is known. The mathematical theory of selection has been
+made the subject of some illuminating researches by J. B. S. Haldane
+and by Fisher. Haldane’s calculations have led him to conclusions very
+different from the dialectical deductions which some eugenists have
+drawn from the recent decline of the European birth rate.[7]
+
+
+
+
+VIII. THE SURVIVAL OF THE EUGENIST
+
+  “I am that ancient hunter of the plains,
+  That raked the shaggy flitches of the bison:
+  Pass, world: I am the dreamer that remains,
+  The Man, clear-cut against the last horizon.”
+              Roy Campbell, _Flaming Terrapin_
+
+
+Concerning Vesalius one of his biographers has said: “in dissecting
+monkeys he became convinced that the many discrepancies between the
+Galenic teaching and his own observations on the human body were due
+to the circumstance that Galen had derived most of his knowledge from
+dissecting monkeys, and had not thought it necessary to mention the
+fact.” Perhaps the biographer of a future Vesalius who succeeds in
+laying the foundations of social anatomy will record that “in studying
+the writings of the Eugenists he became strengthened in the conclusion
+that they were discussing the habits of fruit flies rather than human
+beings, but had not thought it necessary to mention the fact.”
+
+I have called this essay _The Survival of the Eugenist_; but I wish
+to make it clear that I entertain no lack of sympathy for _Eugenics_
+as defined in general terms by Galton, the Galen of social biology. I
+have chosen this title to lay emphasis on the part which eugenists have
+played in perpetuating a certain attitude towards human society. This
+attitude starts from an examination of those characteristics which man
+shares with all other animals, but neglects the equally important task
+of defining those characteristics which distinguish man from all other
+animals. The weakness of all mechanistic systems hitherto proposed
+lies in their refusal to recognize the existence of anything which does
+not yet come within the province of scientific method. A mechanistic
+philosopher can legitimately entertain the hope that the study of
+human society will become an ethically neutral science, and that the
+methods of biology will fertilize sociological enquiry, as the methods
+of physics and chemistry have fertilized biological investigation. He
+is not entitled to pretend that biology can at present provide a key
+to the interpretation of human history. I am well aware that there are
+eugenists who would repudiate any such pretensions. At the same time
+the general tendency of eugenic propaganda has been to exaggerate, and
+grossly exaggerate, the applicability of genetic principles to the
+analysis of human society. This tendency is a legacy of the period in
+which Eugenic ideas had their origin.
+
+Whatever disadvantages the Christian cosmogony imposed upon the study
+of human society, it possessed the merit of emphasizing that the proper
+study of mankind is man. The immediate influence of the evolutionary
+controversy was a reversion to the Galenic practice in social anatomy.
+There is nothing surprising in this reaction. To Huxley and Spencer the
+important fact was that Man is a brute. It was necessary for them to
+emphasize man’s genetic similarity to other animals in opposition to
+the traditional view which placed man in a special category apart from
+other natural objects. How strongly the need to emphasize Man’s new
+status was felt can be inferred by a well-known dictum in _Man’s Place
+in Nature_. “Whatever systems of organs be studied,” wrote Huxley, “the
+comparison of their modification in the ape series leads to one and the
+same result--that the structural differences which separate man from
+the gorilla and the chimpanzee are not so great as those which separate
+the gorilla from the lower apes.” In his dispute with Owen, Huxley went
+much further than any modern anatomist would be prepared to follow him.
+If like Cuvier he had based his objections on the structure of the
+human foot instead of the hippocampus major, Owen might have made a
+stronger case. His opponents were too busy disposing of man’s Cartesian
+spirit to devote much attention to his Cuvierian sole.
+
+The evolution of Thomas Henry Huxley, of Herbert Spencer and of Francis
+Galton was a precocious baby. Its parents and relatives entertained
+high hopes of its future career. In that tradition it has been nursed
+by their loyal disciples who have encouraged it to discourse upon
+sociology before it has learned to read and write. Huxley, Spencer and
+Galton were fundamentally right in recognizing that any theory of the
+development of human society implies certain biological assumptions.
+Their anticipations of immediate progress in the biological treatment
+of human society was inevitably coloured by the issues which made the
+first claim on their attention. Those issues are no longer topical.
+The experimental biologist of to-day cannot approach the structure of
+human society from quite the same angle. The pioneers of evolution
+were goaded by theological opposition to adopt an attitude which is
+easy to condone but unnecessary to emulate. To justify their right
+to speculate, they found it necessary to convince the non-scientific
+public that their speculations were correct. To do so they were driven
+to minimize the gap between man and the apes and make the best of
+any evidence pointing to the missing link which popular imagination
+demanded.
+
+The missing link provided the occasion for one of the first
+sociological exploits of anatomical science. There is an account of the
+incident given in Dr. Haddon’s _History of Anthropology_. Three years
+after _The Origin of Species_ was published Dr. James Hunt, President
+of the Anthropological Society, read his paper on “The Negro’s Place in
+Nature.” In it he maintained that “the analogies are far more numerous
+between the ape and the negro than between the ape and the European.”
+In 1866 he recorded a further contribution to the detection of the
+missing link by asserting that “there is as good reason for classifying
+the negro as a distinct species from the European as there is for
+making the ass a distinct species from the zebra.” In this discussion
+Huxley gave the exponents of the missing link a half-hearted support
+tempered somewhat by his humane and sceptical disposition. An obituary
+notice of Dr. Hunt in a New York paper announced in 1870 the “Death of
+the Best Man in England.” Sixty years after the publication of Hunt’s
+first communication, a leading American anthropologist, Professor
+Kroeber, summed up the present state of knowledge in the following
+terms:
+
+  “The only way in which a decision could be arrived at along this
+  line of consideration would be to count all features to see whether
+  the Negro or the Caucasian was the most unape-like in the plurality
+  of cases. It is possible that in such a reckoning the Caucasian
+  would emerge with a lead. But it is even more clear that which ever
+  way the majority fell, it would be a well-divided count.”
+
+Speculation upon the ancestry of man has continued with unabated
+vigour to the present time. Huxley’s generation had one good excuse
+for confusing the process of social and organic evolution. It cannot
+be pleaded by our own. Modern men were known to be associated with
+the later palæolithic cultures. The Mousterian artefacts had been
+associated with the Neanderthal type. There was much to encourage
+the hope that further research would reveal a close parallelism
+between the physical differentiation of specific or racial types
+and successive stages of cultural development. It now appears that
+Mousterian artefacts were also fashioned by types who, as Sir Arthur
+Keith puts it, “would excite no comment, if dressed in modern
+garb in any assemblage of modern Europeans.” Our own species has
+served a long apprenticeship in a much earlier phase of cultural
+development than that which was at one time attributed specifically
+to the Neanderthalers. The data presented in Sir Arthur Keith’s
+book _The Antiquity of Man_ show that it is not easy to press blood
+relationships out of stone implements. There are already signs of a
+reaction against the extravagant claims which have been put forward
+by some physical anthropologists. The most recent hypothesis of the
+origin of civilization completely breaks with the earlier tradition to
+harp on the racial aspect of the problem. Professor Elliott Smith is
+distinguished both as a physical and cultural anthropologist, and it is
+therefore noteworthy that his theory emphasizes the characteristics of
+man’s physical environment as the significant factors in the appearance
+of the first civilized communities of the Nilotic region.
+
+Under Weismann’s influence environment as an aspect of the problem of
+development assumed a nebulous outline. For a generation biologists
+were hypnotized by the discredit of the Lamarckian teaching. Eventually
+the progress of experimental embryology and cell anatomy relegated
+Weismann’s theory of germinal selection to the same limbo as the
+Lamarckian hypothesis. In Weismann’s hands the Selection doctrine
+had assumed a particularly rigid form. Evolution was necessarily a
+continuous process. All differences between parents and offspring were
+genetic. Heredity and variation were coextensive processes. From this
+it followed that a continuous evolutionary process had accompanied
+the development of social institutions. It was a natural step to
+confuse the two. The conviction that eugenic legislation is a matter
+of overwhelming urgency arose as a direct outcome of that step. That
+the same confusion still dominates eugenic propaganda is illustrated
+by a statement made by Mr. Lidbetter, a prominent eugenist, in his
+paper at the World Population Congress of 1927, “It is a platitude,”
+Mr. Lidbetter stated, “in these days to speak of natural selection as
+the essential agent in human progress.” It may be a platitude. It is
+not a truism. It is simply a misuse of terms. Social development is
+the communication of social tradition and social accomplishment from
+one generation to another, with the addition of new ingredients in
+each. Organic evolution is brought about by the transmission through
+the gametes of new hereditable properties. The mechanism of one is
+education. The mechanism of the other is sexual reproduction. It is
+possible that they react upon one another, but the extent to which they
+do so cannot be ascertained by _a priori_ reasoning. The experimental
+study of genetic variation has made it abundantly clear that evolution
+is not a continuous process. At present we do not know the precise
+conditions relevant to the production of mutant types; consequently
+it is unjustifiable to make any general assumptions about genetic
+variation in human societies without recourse to direct experimental
+inquiry.
+
+That is the task which now lies before the social biologist. Its
+successful accomplishment will not be facilitated by under-estimating
+the difficulties inherent in the problem. The study of human
+inheritance is beset by innumerable obstacles. Man is a slow-breeding
+animal of low fertility. His chromosomes are numerous. The geneticist
+cannot control his matings. In spite of these drawbacks some insight
+into the nature of hereditary transmission within the human species
+can be gained by formulating the results of random mating on certain
+hypothetical assumptions. Familial studies of colour blindness,
+brachydactyly and the blood groups provide clear illustrations of
+Mendelian phenomena. So long as family pedigrees are employed to
+demonstrate the inheritance of physical characteristics, it is not
+difficult to recognize the nature of the environmental influences
+with which the hereditary materials react, and to make allowance for
+them. The geneticist is on familiar ground. The constituents of man’s
+physical environment have been classified by the physicist, the chemist
+and the bacteriologist. Their effects upon the physical characteristics
+of an organism form the subject matter of physiology. It is possible to
+speak of the action of sunlight and humidity, oxygen pressure and diet,
+infectious and contagious germs, iodine and calcium salts with some
+measure of confidence. All these things are features of man’s physical
+environment or of the physical environment of any other animal. The
+methods for investigating their influence are well tried. The concept
+of a uniform physical environment is tangible. It can be explained to a
+pragmatist or a presbyterian, a behaviourist or a bimetallist.
+
+It is another thing to speak about a uniform social environment.
+The factors which determine man’s social behaviour are obscure and
+elusive. Even to-day any dogmatism on the relative importance of
+heredity and environment assumes an almost frivolous aspect when the
+attitude of the experimental biologist is brought to bear on the
+evidence. Analogies from the animal kingdom have been pressed into
+the service of those who emphasize the rôle of either the one or
+the other. Kropotkin’s _Mutual Aid_ was the _reductio ad absurdum_
+of that attitude to social problems. Kropotkin was neither more nor
+less scientific than the exponents of nature red in tooth and claw.
+Both were irrelevant. The same irrelevance has been evident whenever
+biologists have attempted to rationalize their political sentiments.
+The anti-feminist appeals to the fighting and protective male. The
+feminist can retort by invoking the worm Bonellia of which the male
+lives as a parasite in the generative passages of the female. The
+eugenist pictures the human poultry farm nicely mapped out in pens,
+each surrounded by its own partition of wire-netting with a few holes
+here and there. Maybe the Rhode Island Reds have scratched their way
+into the proper preserve of the Partridge Cochins. Sooner or later the
+cosmic poultryman, aided by wise statesmen, will put them back where
+they belong. His opponents can reply that class differences exist in
+insect communities. The difference between a white ant queen and a
+termite worker is more striking than the difference between royalty and
+factory girls; and it is a difference determined by diet. Encouraging
+illustrations in support of any social doctrine can be brought forward
+by those who prefer analogy to analysis.
+
+It might be hoped that the study of human history would assist, but the
+record of history is ambiguous. A striking instance of this ambiguity
+is to be found in Professor Carr Saunders’ book on the Population
+Problem. In the course of a temperate and on the whole well-balanced
+discussion of the racial factor in history, Carr Saunders remarks that
+the
+
+  “Nordic peoples are mostly Protestant and the Mediterranean peoples
+  mostly Catholic and Greek. The fact,” he continues, “that during
+  the Reformation a choice was set before most European nations as to
+  what religion should be adopted--the issue hanging in the balance
+  for some time in many places--seems to indicate that the conditions
+  were more or less equalized and the adoption of the Protestant
+  religion by the Nordic type was influenced by certain innate
+  characters attaching to that type.”
+
+Even if we make a very generous allowance for the genetic homogeneity
+of the Nordic and Mediterranean populations in mediæval times, an
+entirely different interpretation of the same facts is equally
+plausible. At the time when Christianity received official recognition
+the countries to which Carr Saunders refers as predominantly Nordic lay
+on the fringe of Roman Imperial domination or completely outside it.
+The process of christianizing the Nordic geographical region was still
+in its infancy when the Holy Roman Empire embarked on its ephemeral and
+inglorious career. It was hardly complete, when controversy within the
+Western Church began to assume sinister proportions. With the exception
+of the Saxons the conversion of the Germanic peoples, including the
+Frisians, took place in the early part of the eighth century. The
+official conversion of Saxony occurred about A.D. 800. Christianity
+was accepted by the ruling powers of Denmark towards the end of the
+tenth century and by those of Norway and Sweden at the beginning of
+the eleventh century. The conversion of East Prussia, Latvia and
+Pomerania occurred during the twelfth century, and the conversion of
+Lithuania did not occur until the middle of the fourteenth century. In
+those countries which Christianity penetrated last of all the conflict
+between the ruling houses and the temporal claims of the Papacy was
+generally most acute. Where reformers could seek protection in the
+clemency of monarchs at loggerheads with the Pope, they spread their
+doctrines successfully. Where there only existed a religious movement,
+it was speedily extinguished. The Reformed doctrines spread in those
+countries where Christianity had been more recently introduced, and
+where the political sovereignty of the Pope and the economic power
+of the Church as a landowner were least firmly entrenched and least
+agreeable to the secular authorities. Catholicism had taken root in
+the ancient civilization of the Mediterranean region, when the Nordic
+peoples were outside the pale. If it is true that the Nordic peoples
+gravitated to Protestantism, it is equally true that they happened
+to inhabit the geographical region most remote from Rome. There is
+no reason to suppose that their choice of locality was determined by
+any characters peculiar to their type or relevant to the progress of
+theological discovery.
+
+In seeking to make allowance for the significant factors of man’s
+social environment there is no body of accredited information to which
+the geneticist can turn. There are as many schools of psychology
+as there are schools of philosophy. The introspective psychologist
+approaches social behaviour from a purely teleological standpoint,
+interpreting the means in relation to the end it fulfils. The
+behaviourist adopts a mechanistic attitude, seeking to interpret the
+end as predestined by the means. One speaks of a directing intelligence
+and instinctive action. The other speaks of intelligent behaviour and
+unconditioned response. Between the two schools there is a great gulf
+fixed. It is that which separates the philosophy of Plato from the
+teaching of Democritus. It is not merely a difference of perspective
+or of minor issues. Such differences exist in an exact science. The
+psychologists disagree about the very nature of inquiry into the basis
+of social behaviour; and there is no immediate prospect that they will
+come to terms. Meanwhile the eugenist finds himself impaled on the
+horns of a dilemma. The methods of animal genetics are mechanistic;
+but the behaviourist is suspicious of the genetical standpoint; while
+the introspective psychologist fails to define the characteristics of
+social behaviour in a form suitable for genetic analysis.
+
+When Binet and Terman published their psychological tests, it seemed
+that there was a brighter prospect for the objective study of mental
+inheritance. Of late the psychologists themselves have begun to adopt a
+less confident attitude. Recently the Stanford school of workers have
+conceded a conservative allowance of 20 per cent. for the influence of
+home environment on the intelligence quotient. We have no grounds for
+believing that the ingenious system of home ratings adopted by Miss
+Burks (1927) in this investigation include all the significant factors.
+Consequently this figure represents a minimum. The Chicago school
+have investigated the intelligence quotients of foster children, and
+adopt an even more sceptical attitude to the value of the I.Q. as a
+measure of genetic endowment. Tallman has investigated the intelligence
+quotients of sixty pairs of identical twins. It was found that the mean
+difference between pairs of brothers and sisters of different ages on
+the one hand and pairs of non-identical twins on the other was larger
+than the difference between pairs of non-identical twins and pairs of
+identical twins. Accepting the most conservative allowance, it may
+be stated with some confidence that the contribution of environment
+to the intelligence quotient is at least as large as the recorded
+differences between racial and occupational groups subject to different
+environmental influences.
+
+For two generations eugenists have been writing about mental
+inheritance. As far as I am aware Professor MacDougall alone has
+pointed out that the attempt to formulate a concept of mental
+inheritance raises a very formidable issue which challenges the
+foundations of current biological philosophy. He himself faces the
+difficulty by returning to the Lamarckian fold. Lamarck’s position
+was at least consistent. He conceived heredity in mental terms. His
+theory was teleological throughout. Galton was not consistent, and
+his disciples have been less so. Since Weismann’s time the study of
+heredity has become more and more explicitly materialistic. To the
+modern geneticist heredity is one aspect of the physical process
+involved in the production of a new unit of living matter. His
+hypotheses are conceived in physical units. The gene has space-time
+dimensions. Mental inheritance is a meaningless collocation of words,
+unless it is possible to bring the concept of mentality within the
+mechanistic framework. That is what the behaviourist school in
+psychology has undertaken to do. The future of social biology depends
+on the success which attends their efforts.
+
+Fifty years have passed since Francis Galton published _Hereditary
+Genius and An Enquiry into Human Faculty_. Since then there have been
+notable changes in the attitude which scientists have adopted both
+towards heredity and human faculty. The work of Mendel, Bateson and
+Morgan has enormously enriched our knowledge of hereditary transmission
+in animals. The work of Loeb, Sherrington and Pavlov has opened up new
+horizons in the study of animal behaviour. The biological analysis
+of social behaviour presupposes that both methods can be brought
+to bear upon it. It may be premature to adopt a confident attitude
+to the prospects, but it is legitimate to state that there is no
+likelihood of solving the problem which Galton propounded so long as
+eugenists continue to regard it as the exclusive prerogative of the
+evolutionist. The enthusiasms engendered first by the reception of
+Darwin’s hypothesis and subsequently by the spectacular advances which
+have resulted from Mendel’s discovery, encouraged the eugenist to adopt
+an extremist attitude. New and no less noteworthy developments in the
+physiology of the nervous system have encouraged the behaviourist to go
+as far as possible in the opposite direction.
+
+It is not difficult to understand how this has happened. In Galton’s
+time the analysis of animal conduct had not progressed beyond the
+recognition of those simple units of behaviour which Pavlov calls
+“unconditioned” reflexes. The scratch reflex evoked on stimulating
+the lumbosacral region in the spinal dog is an example of this type.
+Given the same external situation, it can be elicited in any member of
+the canine species. There are therefore two principal factors which
+determine the scratch reflex. One is the immediate stimulus. The other
+is the _inherited_ structure of the nervous system. Simple reflexes
+of this kind play very little part in man’s social behaviour; but
+modern physiology recognizes a more complex type, which Pavlov calls
+the “conditioned” reflex. The study of these promises to meet some of
+the requirements of a biological analysis of man’s social behaviour.
+The conditioned reflex is not characteristic of all the members of a
+species subjected to the same immediate situation. It depends upon
+the time relations of other stimuli which have previously acted upon
+the organism. Within certain limits it is possible both to predict
+the outcome, when the time relations of previous stimuli are defined,
+and to account for a totally different pattern of behaviour in two
+individuals who inherit the same neuromuscular organization. It was
+natural that Galton’s generation should harp on the hereditary basis of
+social conduct. They were beginning to understand a type of behaviour
+in which the genetic factor is the significant variable, and to apply
+their knowledge to the interpretation of “instinct” in animals. It is
+not surprising that the behaviourists should adopt the opposite point
+of view. They are beginning to understand a type of behaviour in which
+the genetic factor is less important, and to apply the new methods to
+the study of Man himself.
+
+Even if the behaviourist reaction goes too far in neglecting the
+genetic aspect of social behaviour, it will have performed one
+considerable service to social biology. Biology and sociology coincide
+in the attempt to distinguish what characteristics of human society
+are related to those characteristics which man shares with all other
+animals, and what characteristics of human society are related to
+characteristics which man shares with no other animals. The geneticist
+is only concerned with the former, since the material basis of
+inheritance in man and other animals is substantially the same. It is
+the physiologist who is brought into contact with the characteristics
+which distinguish man from other animals. Man inherits an immensely
+developed forebrain; and this circumstance frees him from many of
+the restrictions which heredity imposes upon the brute creation. The
+forebrain is the structural basis of conditioned behaviour; and what
+distinguishes man pre-eminently from all other animals is the extent
+to which his behaviour is conditioned by previous experience. A truly
+biological analysis of human society must build on the recognition that
+man is the most teachable of animals. This is a profound truth which
+the eugenist has neglected. The behaviourist has reopened the door
+which the eugenist closed. The selectionists succeeded in presenting
+evolution in a form acceptable to their contemporaries. Man was dragged
+down from his celestial eminence. His place among the brutes became an
+accepted commonplace of the naturalistic outlook. Sentence had been
+passed upon him. Henceforth he must live within the prison of his
+own genetic limitations. Before the portals of his primeval dungeon
+Heredity stood with a flaming sword. In his new surroundings Man could
+still demand a retrial, because selectionism was the product of his
+own forebrain. That trial is still in process. Science has not yet
+promulgated its final verdict. Galton conducts the prosecution. Watson
+cross-examines for the defence. Man is released on bail, pending the
+result of his appeal.
+
+In English law there is a wholesome provision which forbids the public
+discussion of evidence until the case is closed. In science there is
+no penalty for contempt of court. It is a pity that there is not. The
+discussion of the genetical foundations of racial and occupational
+classes in human society calls for discipline, for restraint and for
+detachment. Nothing could make the exercise of these virtues more
+difficult than to force the issue into the political arena in the
+present state of knowledge. This is precisely what the eugenist has
+done. The result is that social biology is encumbered with a vocabulary
+of terms which have no place in an ethically neutral science; and a
+growing literature of inquiries repeats all the shortcomings which
+animal genetics has outgrown. Of these shortcomings anecdotalism is
+the least. All biologists recognize the disastrous consequences of
+constructing evolutionary hypotheses on the testimony of the stock
+breeder and the pigeon fancier. Only an undue haste to establish
+conclusions which can be made the basis of legislation has arrested the
+development of social biology in its anecdotage.
+
+Quotations from well-known contributions by eugenic writers will
+exempt me from the charge of overstating the danger to which I
+allude, when I speak of the anecdotal method. Few would deny the
+desirability of shedding further light on the contribution of heredity
+to feeblemindedness. It is the concern of the social biologist to do
+so. Goddard’s familial studies on this problem have been extensively
+quoted by eugenic writers. In his investigation several hundred
+individuals in the Vineland training-school for mental defectives were
+classified by the Binet test as morons. Goddard conducted inquiries
+into the family histories of these individuals, and records them
+in his book. He concludes that a certain type of feeblemindedness
+is determined by a single Mendelian factor. This conclusion is
+logically untenable apart from the evidence, because his criterion
+of feeblemindedness was a segment arbitrarily cut off from a normal
+distribution curve; but the method which he employs rather than the
+conclusions he infers is the issue to which I would direct attention.
+Mendel initiated a new epoch in genetics by clearly defining the nature
+of the character which he studied. That practice is the keystone of
+the science which has developed from his pioneer labours. The Binet
+test may be legitimately employed as a means of providing an objective
+definition of feeblemindedness; but since the Binet test is a recent
+innovation, it is obvious that Goddard could not employ it to identify
+feeblemindedness in the parents and grandparents of his cases at the
+time of writing. The method he adopted is stated in the following
+passage (_Feeblemindedness_, p. 20):
+
+  “The ease with which it is sometimes possible to get satisfactory
+  evidence on the fifth generation is illustrated in the Kallikak
+  family. The field worker accosts an old farmer--‘Do you remember
+  an old man Martin Kallikak (Jr.) who lived on the mountain edge
+  yonder?’ ‘Do I? Well I guess. Nobody’d forget him. Simple, not
+  quite right here (tapping his head), but inoffensive and kind. All
+  the family was that. Old Moll, simple as she was, would do anything
+  for a neighbour. She finally died, burned to death in a chimney
+  corner. She had come in drunk and sat down there. Whether she fell
+  over in a fit or her clothes caught fire nobody knows. She was
+  burned to a crisp when they found her. That was the worst of them,
+  they would drink. Poverty was their best friend in this respect,
+  or they would have been drunk all the time. Old Martin could never
+  stop as long as he had a drop. Many’s the time he’d rolled off of
+  Billy Parson’s porch. Billy always had a barrel of cider handy.
+  He’d just chuckle to see Martin drink and drink until finally he’d
+  lose his balance and over he’d go.’”
+
+At the conclusion of this recital Goddard asks, “Is there any doubt
+that Martin was feebleminded?”
+
+It may at least be said for Goddard’s work that it contains some
+presumptive indications that genetic factors play a significant part
+in determining certain kinds of feeblemindedness. It is doubtful
+whether any plausible conclusions can be drawn from the dreary history
+of the Jukes. In his monograph on the Jukes in 1915, Estabrook only
+ventures to proffer one definite statement concerning hereditary
+transmission in the Jukes family. It is that “there is an hereditary
+factor in licentiousness.” I have searched through his memoir for a
+single indication of the way in which he defines licentiousness and its
+allelomorphic opposite chastity. Out of a large number of monotonously
+similar family case histories I shall quote the only one which contains
+any suggestion of the meaning he attaches to the latter. This (Case G)
+is as follows:
+
+  “A cousin mating of chaste individuals was followed in the first
+  generation by no licentiousness. In the second generation from the
+  cousin mating no licentiousness appears, although the father of
+  one of the children of this generation had cohabited previous to
+  marriage. Their one daughter was chaste, but she has one daughter
+  brought up in a good home free from bad influences, who was very
+  erotic but is at present chaste. The third child of this cousin
+  mating of chaste people, Addie, married a man who had acquired
+  syphilus and had one son an inefficient syphilitic who died of
+  tuberculosis. Addie died of syphilis at 20. The fourth child Alta
+  V 78 who was always chaste, married but had no children. Horace
+  the only other child of Alfred who reached maturity was reputed
+  chaste but was intemperate: he married a chaste woman and had nine
+  children, all of whom are chaste.”
+
+Before we take the risk of wrecking the machinery of social biology
+by exceeding the speed limit of rational inquiry, it is desirable
+to ascertain the reasons for such haste. Dr. Estabrook has recorded
+his own reasons in quantitative terms. “Dugdale estimated a loss to
+society of $1,250,000 by the Jukes family from 1800 to 1875. The loss
+to society caused by mental deficiency, crime, prostitution, syphilis
+and pauperism of these 2,800 people is now estimated at $2,093,685. If
+the drink bill is added, this total becomes $2,516,685.” The reason
+for this addition will be more apparent to a prohibitionist than to a
+brewer. Mr. Chesterton might retort by asking whether there are no idle
+young clubmen in New York whose annual upkeep is equivalent to the loss
+entailed by the Jukes during the last century and a half. Deplorable
+as the history of the Jukes may be, its consequences to civilization
+may be less disastrous than half an hour’s conversation between a
+manufacturer of armaments and a newspaper proprietor. In such matters
+private values influence our opinions more than those issues which can
+be discussed in the public forum of science. Estabrook’s arithmetic
+does not convince me that we should exchange the experimental and
+sceptical temper of scientific inquiry for the facile slogans of the
+parliamentary candidate.
+
+The eugenic movement was founded to encourage “the study of agencies
+under social control that may improve or impair the racial qualities
+of future generations either physically or mentally.” That aim might
+be taken as a statement of the scope of social biology, when due
+allowance is made for the full requirements of a scientific inquiry
+into the nature of “mental inheritance.” There are a few prominent
+eugenists who have adhered to this praiseworthy and modest programme.
+Professor Carr Saunders who has been prominently associated with
+the eugenic movement in England has consistently expressed himself
+with discrimination and restraint on the complex issues which the
+genetic structure of human society involves. If I am disinclined
+to follow him in the alarmist attitude which he adopts towards the
+differential fertility which has accompanied the recent decline of the
+European birth-rate, I entirely agree with him in recognizing that the
+differential fertility of occupational groups is a matter for careful
+and comprehensive investigation. To make any satisfactory predictions
+about the outcome of the present decline it is necessary to ascertain
+what factors have contributed to the reduction of the birth-rate, what
+genetic differences distinguish different occupational groups, and how
+such differences are transmitted. The impressive array of evidence
+which Beveridge, Stevenson and Carr Saunders have presented strongly
+suggests that the spread of contraceptive practice has been the main
+factor in the decline of the birth-rate. The German and Swedish data of
+Grotjahn and Edin point to the conclusion that contraceptive practice
+is spreading to all sections of society. If this is so the problem
+of differential fertility is solving itself. Of genetic differences
+which distinguish occupational groups we have no definite information.
+Even if we had, it would be necessary to know how such differences
+are transmitted before prophesying disaster. Haldane’s mathematical
+analysis of the effect of selection shows that a selective process
+must be continued for a very long period in order to produce an
+appreciable effect on the distribution of a character which depends on
+the co-operation of several recessive genes. An attitude of calvinistic
+gloom towards the future of human society is not a necessary
+consequence of the biological study of human society.
+
+In discussing the influence of eugenic propaganda in this essay I
+have been primarily concerned with the dangers of speculating upon
+questions whose philosophical importance is less apparent than their
+practical interest. I trust that I have made it abundantly clear that
+I am in no sense hostile to eugenics as defined above. Were I to
+indulge in the luxury of stating a purely personal opinion about the
+genetics of human society, it would be somewhat as follows. It is
+probable that extremes of intellectual accomplishment or defect are
+significantly determined by genetic variation. It is highly unlikely
+that extreme types of defective are reproducing disproportionately. It
+is also doubtful whether genius has ever been biologically fertile.
+Between the two extremes there is probably a neutral zone in which
+somatic variability plays a larger part than genetic differences in
+determining social behaviour. At present it is impossible to assess
+with precision the mean genotypic endowment of different social
+groups, whether occupational or racial. Even if it were, the precise
+significance of the mean would be problematical. I think it highly
+unlikely that such mean differences as may exist provide any basis for
+establishing new social barriers or reinforcing old ones, still less
+for curtailing opportunities of education and the exercise of political
+responsibility. On the other hand it is not unlikely that there does
+exist a section of genetic types on the borderline of extreme defect
+not segregated from the rest of the community and more fertile than
+others of the same social grade. With Mr. Chesterton I am inclined to
+doubt whether they represent a larger proportion in one social class
+than in any other. Unlike Mr. Chesterton I see no reason why society
+should not deal with this issue as a genetic problem, when it is
+clearly proved to be a genetic problem. Indeed I think it arguable that
+it would be wiser not to take any risk of encouraging the feebleminded
+to breed. At present I see no way of stopping them.
+
+There can be no disagreement concerning the desirability of exploring
+every avenue in human genetics. This cannot be done without enlarging
+the scope of the official census with the support of a sympathetic
+government. Hitherto Eugenic propaganda has been dominated by an
+explicit social bias which, in England, can only serve to render the
+Eugenic standpoint unpalatable to a section of the community which for
+good or ill seems to be assuming the rôle of a governing class. The
+greatest obstacle to the spread of a sane eugenic point of view is the
+eugenists themselves. By recklessly antagonizing the leaders of thought
+among the working classes the protagonists of eugenics have done their
+best to make eugenics a matter of party politics, with results which
+can only delay the acceptance of a national minimum of parenthood.
+These last remarks I repeat are a statement of purely personal opinion.
+Biologists share the human frailty which prompts all of us to entertain
+beliefs fortified by insufficient evidence; but there is no reason why
+the biologist should fail to make it clear, when he is speaking as a
+professional biologist and when he is speaking as a private citizen.
+From a purely scientific standpoint the problem of human inheritance
+can only be regarded as a virgin field in which the prospects of an
+early and abundant harvest are by no means bright. I believe that the
+eugenists have performed a useful task in emphasizing the need for a
+biological analysis of human society. The furtherance of that task will
+not be promoted by propaganda which overstates the achievements of
+the present, while underestimating the difficulties which lie ahead.
+Evolutionary inquiry was brought to an end in ancient Greece, when
+philosophy became the handmaiden of politics. Further progress was
+checked when philosophy became the bondservant of theology. Eugenics
+like Greek philosophy derived its first impulse from natural science.
+It soon entered into alliance with the politician. It is fast finding
+its most stalwart supporters among the clergy. It can only realize
+the aims of its founder by bringing the science of genetics into
+closer relationship with other methods of studying human biology and
+annulling the marriage of biological inquiry with political propaganda.
+As a private citizen the biologist is entitled to his own opinions
+concerning the merits of sterilizing the unfit, just as he is entitled
+to his own opinions on the Single tax or the advantages of capital
+punishment. Such opinions usually belong to his private world. In
+his public capacity, as a biologist, he is primarily concerned with
+sterilizing the instruments of research before undertaking surgical
+operations upon the body politic.
+
+
+
+
+PART III
+
+HOLISM AND THE PUBLICIST STANDPOINT IN PHILOSOPHY
+
+SUMMARY
+
+
+When the conclusions of physicists are supplemented by the enquiries
+of the biologist we are led to a schematization of experience which
+permits us to discuss the nature of matter and life on a neutral
+ground. This neutral ground is the _public world_ of science. It
+represents what is significant for the purpose of discourse. Idealistic
+philosophers have assumed the nature of reality as the goal of
+philosophy; but the concept of reality is essentially equivocal. For
+the purpose of discourse we have to assume that the neutral ground
+is the real thing. In private we are at liberty to reject this view.
+Temperament decides which of these alternatives we adopt. There is
+therefore no hope of arriving at universal agreement in discussing the
+nature of reality. To the introvert reality resides in the domain of
+mystic experience. To the extrovert the public world is the nearest
+approach to a complete representation of reality which our limited
+range of receptor organs permits us to construct. The belief that
+philosophy can settle the nature of reality, and that it is possible to
+arrive at universal conclusions independently of the methods of science
+and mathematics arose in the period of decadence of Greek philosophy.
+It developed in modern Europe under the influence of ecclesiasticism.
+Freed from the bondage of clerical control, philosophy must undertake
+the more modest task of discussing what characteristics of belief
+determine their communicability or _publicity_, and indicating how the
+problems of existence can be resolved into their public and private
+components. From this standpoint educational theory must be based on
+a recognition of the respective spheres of _publicity_ and _privacy_.
+Organized religious belief and ritual is based on a confusion between
+the two. The same confusion exists in the pragmatist philosophy.
+
+
+
+
+IX. BIOLOGY AND HUMANISM
+
+  “But the mortallest enemy unto knowledge, and that which hath
+  done the greatest execution upon truth, hath been a peremptory
+  adhesion unto authority; and more especially, the establishing of
+  our belief upon the dictates of antiquity. For (as every capacity
+  may observe) most men, of ages present, so superstitiously do look
+  upon ages past, that the authorities of the one exceed the reasons
+  of the other. Whose persons indeed far removed from our times,
+  their works, which seldom with us pass uncontrolled, either by
+  contemporaries, or immediate successors, are now become out of the
+  distance of envies; and, the farther removed from present times,
+  are conceived to approach the nearer unto truth itself. Now hereby
+  methinks we manifestly delude ourselves, and widely walk out of the
+  track of truth.”--Sir Thomas Browne, _Pseudodoxia Epidemica_
+
+
+§1
+
+Evolution does not enable us to make any spectacular predictions
+which can be verified here and now. Its importance lies in satisfying
+our curiosity about human origins in a manner consistent with the
+present state of scientific knowledge. It provides a philosophical
+framework for biological enquiry on the one hand and for our attitude
+to the problem of human destiny on the other. From a purely technical
+standpoint Darwin’s specific contribution to the evolutionary doctrine
+was the hypothesis of natural selection. The hypothesis of natural
+selection, in the form in which Darwin stated it, has been modified out
+of all recognition to accommodate later enquiries into the nature of
+heredity and variation. Such enquiries did not receive their impetus
+from the _Origin of Species_. They followed the course prescribed by
+Mendel’s experiments upon the kitchen pea. How then has it come to
+pass that Darwin has earned a position of pre-eminence only comparable
+with that of Newton in modern times? Is not the answer that Darwin is
+the only great natural philosopher who has emerged, since the time of
+Aristotle, from the ranks of the biologists? When the fullest allowance
+is made for the inadequacy of contemporary knowledge to meet all the
+demands of the evolutionary problem, what still distinguishes Darwin’s
+contribution from that of his numerous predecessors in the same field
+is the consistency and thoroughness with which he set out to explore
+the implications of evolution in every department of biological
+information available at that time. By so doing he laid the foundations
+of a new humanism akin to science, and created a philosophical issue
+whose magnitude has only become apparent since the rise of the
+behaviourist school in psychology. Evolution took the discussion of
+human affairs out of the hands of the humanistic philosophers, and
+brought it within the legitimate domain of scientific method.
+
+From the dawn of philosophical controversy two opposing tendencies
+have competed for mastery. One is based upon confidence in the
+testimony of our receptor organs. The other mistrusts the evidence of
+the senses. One relies on patient observation. The other appeals to
+axioms which require no proof. One has its impulse in curiosity about
+Nature. The other is preoccupied with human obligations. Between the
+two extremes there have been many makeshifts. As one has fallen into
+discredit, another has taken its place. The only permanent feature
+of philosophical discussion is the impossibility of effecting a
+permanent reconciliation between those who have called themselves, at
+different periods of history, materialists and idealists, nominalists
+and realists, empiricists and transcendentalists, mechanists
+and vitalists, to emphasize some new aspect of a fundamental
+incompatibility. In the distinction between publicity and privacy it
+has been suggested that this antinomy does not necessarily reside
+in the system of nature. It arises because our curiosity exceeds
+our information. Up to a certain point we succeed in pooling our
+experiences by the method of science. In so doing we construct the
+public world. The method of science has achieved its most conspicuous
+success in dealing with inanimate objects and with the brute creation.
+To the few who are genuinely interested in these things the extent of
+our knowledge has always seemed of more importance than the magnitude
+of our ignorance. Hence there have always been philosophers of a type
+which, for want of a better term, may be called _materialistic_. The
+majority of people are not interested in natural objects except in
+so far as the knowledge which science confers contributes to their
+personal comfort. Man is pre-eminently interested in himself. So long
+as science cannot satisfy that curiosity his private and personal
+values assume a greater importance than the academic hypotheses of
+science. Philosophers who teach us to distrust the guidance of our
+sense data flatter our egotism, and soothe our vanity. Science cannot.
+On the other hand science can supply us with aviation, broadcasting
+and twilight sleep. Transcendental philosophy can only offer us the
+good life. The politician distrusts the mechanist, because Science
+provides no concept of divine right to fortify social privilege. He
+cannot go all the way with Parmenides and identify the way of the
+senses with the way of error, because scientists are too useful.
+The only philosophy for the plain man who wants a plain answer to
+a plain question is some sort of compromise between the standpoint
+of transcendental metaphysics and mechanistic science. Since the
+sixteenth century humanistic philosophy has been dogged by the problem
+of accommodating man’s interest in the world around him with his
+interest in his own person. Worldly interests compel civilized man to
+recognize the claims of science up to a certain point. Egotism prompts
+him to demand some supernatural sanction for the vagaries of his own
+social conduct. For three centuries traditional philosophy has been
+haunted by the possibility that science might in the end succeed in
+satisfying man’s curiosity about his own nature. Darwin made that
+possibility the explicit concern of scientific enquiry. From mediæval
+times all attempts to effect a reconciliation between the empirical
+standpoint and transcendental values have been concerned with defining
+separate spheres of influence in which science and metaphysics can
+operate without mutual interference. On that basis philosophy is still
+taught in our universities to-day. Darwin’s _Descent of Man_ challenged
+the complacent dualism which had permitted humanistic philosophy
+and utilitarian science to pursue an independent course from the
+Renaissance to the middle of the nineteenth century.
+
+At every stage in the advance of scientific knowledge a new
+system has arisen to conserve some fragments from the wreckage of
+supernatural beliefs. There have been three outstanding attempts
+to effect a compromise between observation and inspiration. The
+systems of Aristotle, of Descartes and of Kant each exhibit features
+characteristic of the state of contemporary scientific knowledge. Each
+has a peculiarly interesting significance in the history of biological
+science. The system of Aristotle was the last will and testament
+of Greek biology. The system of Descartes was finally overthrown
+by the evolutionary theory. The system of Kant is predestined to a
+similar doom, when professional philosophers are prepared to face the
+disquieting consequences of modern research on the “labyrinthine organ”
+and Sherrington’s work on the “muscular sense.” If it is too early to
+predict the fate of holism, it is instructive to reflect on that of its
+predecessors.
+
+
+§2
+
+Aristotle undertook the task of finding a place for science in a
+civilization in which scientific enquiry was approaching its decline.
+His problem was simplified by the circumstance that the conflict
+between teleology and mechanism had arisen as a conflict of interest
+rather than interpretation. Burnet insists that the idea of purpose
+only emerged at a comparatively late date in the history of Hellenic
+science, and the more recent researches of Cyril Bailey emphasize the
+same aspect of the incompatibility of natural and moral philosophy
+in ancient Greece. Greek philosophy had inherited from the Hesiodic
+cosmogony the belief that Chaos was the beginning of all things, gods
+and men alike. It was unfettered by the Chaldean Fall and the doctrine
+of creative providence. Aristotle’s system was therefore an attempt to
+harmonize two tendencies which had come into being independently of
+one another. One begins with Thales. It bore fruit in the brilliant
+speculations of Leucippus and Democritus. It survived after Aristotle’s
+death in the mechanical discoveries of the Alexandrian school. In
+the poem of Lucretius it made a final gesture of august rhetoric. To
+modern civilization it bequeathed the indestructibility of matter, and
+the atomic concept which was revived by Gassendi in the seventeenth
+century. Its rival was anti-scientific and mystical. It diverted
+enquiry from the observation of nature to the duty of man. It was
+preoccupied with the good life, with the soul and with the hereafter.
+It began with the Eleatics and the Pythagoreans. It gave birth to the
+school of Plato; and its influence survived long after the extinction
+of Hellenic civilization. Through Philo Platonism transmitted the Logos
+to the Nazarenes, and at a later date the neoplatonists equipped the
+Church with the apparatus of the Trinitarian controversy. It completed
+its contribution to Western culture in the Council of Trent, when the
+mystery of human life, death and duty were placed for all time on a
+firm foundation of deductive reasoning.
+
+The success of Platonism was assured by the powerlessness of Greek
+materialism to satisfy the requirements of Greek politics. The plain
+man wanted to know whether the wise man will obey the laws, if he
+knows that he will not be found out? With transparent honesty Epicurus
+could only reply that a simple answer is difficult to find. The benign
+and tolerant humanism which Epicurus grafted on the soil prepared by
+the atomists was ill suited to flourish in the stern climate of the
+military state. Like holism, Aristotle’s system was a shrewd blending
+of science and statesmanship. It enabled its author to combine a
+personal predilection for natural history with a political partiality
+for slavery.
+
+Aristotle borrowed from Plato the doctrine which identifies the φυσις,
+or real nature with the best or most normal condition of a thing. He
+rejected the respect for mathematics which Plato borrowed from the
+Pythagoreans, and incorporated Plato’s teleology in his theory of the
+physical world. One disastrous effect of this may perhaps be seen
+in the neglect and preservation of more ancient work. Empedocles is
+known to have made observations on respiration and the movement of the
+blood. It would seem that he had recourse to experiment of a crude
+kind. One fragment of his writings contains a hint that he came very
+near to anticipating Torricelli and Harvey. The details have been lost.
+Empedocles also put forward a theory of vision. He held that the eye
+contains fire. Sight is produced when the fire within the eye goes
+forth to meet the object. A hypothesis so well adapted to the view
+which interprets life by “correlating the initiation of the activity
+with its end” was, as might be expected, immortalized by Plato to the
+calamity of physical and physiological enquiry. Science had a long road
+to traverse before men learned the truth of Nietzsche’s statement that
+“the most valuable knowledge is always discovered last, but the most
+valuable knowledge consists of methods.”
+
+The fundamental incompatibility of the naturalistic and Platonic
+attitude to the Nature of Life is illustrated by the following passage
+from the writings of a contemporary philosopher, Professor Wildon Carr:
+
+  “It is wholly inadequate to classify natural objects into the inert
+  and the living, into objects which are not responsive and objects
+  which are responsive to external impressions, and then to seek to
+  specify the property or character which differentiates the one
+  class from the other. Life is a perfectly definite and distinctive
+  phenomenon. It is not a thing, neither is it the character of
+  a thing. It is a purposive activity exercised within clearly
+  ascertainable limits and having a definite range. I use the term
+  purposive without any implication of awareness. Living activity
+  is purposive in the meaning that it can only be understood by
+  correlating the initiation of the activity with the end. The nature
+  of the activity is plainly recognizable, however difficult it may
+  be to conceive the agent, agents or agency which the activity
+  implies.... Life is individual: it exists only in living beings,
+  and _each living being is indivisible, a whole not constituted of
+  parts_.”
+
+The concluding remarks of this passage are somewhat reminiscent of the
+Athanasian creed, the germs of which were actually derived from the
+neoplatonists. It displays the sterilizing influence of the Platonic
+teaching in a peculiarly explicit form. If the words quoted in italics
+were actually true, experiments carried out daily by medical students
+in physiological and pharmacological laboratories would be impossible.
+The physiologist takes the living machine to pieces and studies the
+properties of its several parts. The experimental embryologist can
+put it together again. Ross Harrison grafts the head end of a tadpole
+of one species on to the tail end of a tadpole of another species.
+The progress of modern biology has been made possible by the implicit
+rejection of the attitude which Professor Wildon Carr advocates; and
+this is not merely true of the growth of experimental physiology as
+a quantitative science. In our generation Bergson has rehabilitated
+the evolutionary doctrine in teleological language. Its history very
+clearly shows that the rise of the evolutionary hypothesis in its
+modern form is traceable to the liberation of biological enquiry from
+Aristotelean teleology. Two centuries of research, fertilized by
+the experimental temper which Vesalius reintroduced into the study
+of medicine, paved the way for a new school of naturalists in the
+eighteenth century. Ray and Linnæus took up the comparative study of
+animal life where Aristotle had left it. At a later date Cuvier, Milne
+Edwardes and Owen founded a school of comparative anatomy which--unlike
+post-Darwinian morphology--made the issue of experiment the final
+court of appeal. It was thus that Darwin and Wallace brought to the
+discussion of Man’s place in Nature a mass of new data, accumulated in
+the process of displacing the teleological bias under whose influence
+Greek biology steadily declined. It is futile to blame Aristotle for
+the influence which his particular form of compromise exerted on the
+history of biology. In Aristotle’s time it was impossible to say: “Here
+is a property of living matter, the teleological attitude leads us
+to make such and such predictions; quantitative analysis leads us to
+contrary conclusions: let us submit the merits of the two methods to
+the issue of experiment.” Aristotelian biology was not an experimental
+science.
+
+When Aristotle infused into Greek biology the teleology of Platonism,
+natural science had already progressed as far as it was destined to
+advance without coming into conflict with teleological presumptions;
+but the inevitability of the conflict was not yet apparent, and
+does not emerge as a clearly defined issue in Greek philosophy.
+Greek materialism, like modern science, was the offspring of secular
+curiosity. For this reason it is easy to trace the germs of modern
+hypotheses in the speculations of the ancients. It is more difficult
+to determine how far such analogies are merely verbal. The extent to
+which the Greeks had recourse to experiment has given rise to lively
+controversy. We are more familiar with their beliefs about nature than
+with the evidence on which they relied. To reconstruct the scientific
+knowledge of Anaximander and Empedocles from the fragments of their
+writings which remain is a task no less formidable than that of a
+future historian who has nothing but the torn pages of a Harmsworth
+encyclopædia to provide evidence of contemporary science. The fact
+remain that the scientific knowledge of the ancients lacks two
+features which are highly characteristic of modern enquiry. Greek
+science was static. Having no means of measuring short intervals
+of time, the Greek could make little use of dynamical notions. The
+mathematical technique for dealing conveniently with dynamical
+calculations was not evolved until Greek geometry was supplemented
+by the universal arithmetic of the Arabs. Galileo’s dynamics was the
+death-blow to Aristotelian teleology. To the Greeks time relations were
+philosophical enigmas. They had not as yet become objects of scientific
+enquiry. Modern mechanistic biology lays emphasis on _process_. Greek
+biology was still dominated by _structure_. This preoccupation gave
+rise to the distinction between form and substance which assumes a
+prominent place in the Aristotle of the schoolmen, and persisted
+in modern science, until the dynamical concept of electromagnetic
+mass was put forward. A second characteristic which distinguishes
+contemporary science from the natural philosophy of the Greeks has
+been emphasized less by historians of science. This may be because
+astronomy and mechanics were developed by the school of Alexandria in
+close association with mathematics. That brilliant but short-lived
+phase in the science of antiquity was post-Aristotelian. Astronomy was
+the only branch of natural science which had attained the precision of
+measurement in Aristotle’s time.
+
+The distinction between Aristotelian vitalism and the modern biological
+standpoint is most apparent in the attitude which Aristotle adopted to
+quantitative investigation. “Mathematical accuracy of language,” he
+declares, “is not to be required in all things, but in those things
+that do not involve any connexion with matter. Wherefore such is not
+the natural (alternatively _physical_) mode of discovering truth, for
+perhaps the whole of Nature involves matter. Therefore first must we
+investigate what Nature is. For in this way also will it be evident
+about what only natural science is conversant, and whether it is the
+province of one science or many to speculate into causes and first
+principles.” This passage occurs in the first book of the Metaphysics.
+There are other passages in which the same point of view is expressed.
+They show conclusively that Aristotle was not content with ignoring the
+connexion between mathematics and science. He definitely asserted that
+the quantitative study of natural phenomena is not the correct one.
+In this he went further than Plato. While Plato despised the study of
+physics and biology, he recognized the vital dependence of astronomy
+on mathematics and valued its pursuit. The standpoint which Aristotle
+adopted is comprehensible. His interest in nature was mainly that of
+the naturalist. He did not study living creatures in the belief that by
+so doing he would be able to predict their behaviour. That possibility
+only emerged into prominence when Lavoisier and Laplace brought the
+thermometer and the balance to the study of respiration. By then the
+spectacular progress of physics had necessitated a new adjustment of
+the claims of moral and natural philosophy. The philosophy of Descartes
+liberated biology from developing within the limitations prescribed by
+the Aristotelian system.
+
+Two events contributed significantly to the situation which Descartes
+faced at the beginning of the seventeenth century. The period which
+intervened between Aristotle and Descartes witnessed the rise of
+Christianity and the origin of a new cultural synthesis within the
+world of Islam. At Alexandria natural science and mathematics still
+flourished, when Christianity became the official faith of the
+Roman Empire. Five centuries after the death of Aristotle Diophantus
+made what seems to have been the first definite contribution to the
+development of algebraical analysis. Alexandrian science came to an end
+when “on a fatal day in the holy season of Lent,” Hypatia the expositor
+of Diophantus “was torn from her chariot, stripped naked, dragged to
+the church, and inhumanly butchered by the hands of Peter the reader
+and a troop of savage and merciless fanatics.” Two centuries later what
+was spared by the religion of Cyril was consigned to the flames by the
+victorious armies of Islam.
+
+While Christianity and Mohammedanism were competing to appease the
+deeper needs of mankind, the genius of a dark-skinned people was
+preparing the stage for a rebirth of European culture. Before the
+destruction of a second library of Alexandria the Greek learning had
+filtered into the middle East through the hospitality which the Persian
+court extended in turn to the banished Platonists, the Jews and the
+heretic Nestorians. In India Brahmagupta and his successors had applied
+themselves to the same problems which Diophantus had assailed. Half
+a century before the foundation of the University of Baghdad Hindu
+astronomical tables and the rhetorical algebra of the far East had been
+introduced into Persia. By the beginning of the ninth century the works
+of Ptolemy, Euclid, Hippocrates and Aristotle had been translated into
+Arabic. At the end of the tenth century the Moorish culture was firmly
+established in Europe. In the universities of Cordova, Seville and
+Toledo, the study of medicine and mathematics flourished side by side.
+The medical schools of Italy and France were outposts of the Moorish
+culture in the twelfth and thirteenth centuries. The Moors extended
+the Alexandrian pharmacopeias; and advanced the study of anatomy.
+Jewish missionaries of the Moorish culture brought the tradition of
+dissection into Italy. From Arabic manuscripts Italy first made contact
+with the resources of Greek science. Arabic learning transmitted the
+texts from which ecclesiasticism imbibed its taste for metaphysics,
+and at the same time contributed two influences subversive to the
+Aristotelian system. It gave birth to chemistry as an experimental
+science, and it developed the beginnings of syncopated algebra. The
+invention of algebra made possible the efflorescence of physics when
+Greek geometry had long since completed its task as the midwife of
+mathematical astronomy.
+
+From the fact-loving temper of Aristotle the naturalist Arabic
+curiosity had absorbed all that could be used as a basis for scientific
+enquiry. In the Sorbonne the Platonic ingredients of his system brought
+fresh grist to the mill of theological controversy. By seeking for
+“causes and first principles,” Aristotle in his own words had made
+philosophy the “divine science.” As the divine science it was pressed
+into the service of orthodox theology and the Protestant revolt against
+ecclesiastical authority. During the fourteenth and the fifteenth
+centuries the resources of the Eastern Empire were ransacked for the
+rhetoricians and sophists neglected by the empirical disposition of
+Arabic scholarship. The political speculations of the ancients became
+the rationale of Protestant democracy. As the influence of Platonism
+on science succumbed to the success of the new experimental and
+quantitative methods which were gaining ground in physics, classical
+humanism completed the divorce of moral and natural philosophy by
+elevating the authority of Plato in politics: but before classical
+humanism had gained ascendancy in the mediæval universities, an
+ascendancy which became a monopoly in the grammar schools, Arab science
+had implanted in the oldest seats of European learning a seed destined
+in the fullness of time to challenge not merely the authority of
+church councils but the authority of print, to place the authority of
+experience above the authority of the written word, as Protestantism
+had placed the authority of the written word above the authority of
+church councils.
+
+Plato would have had little use for physicists in his Utopia. To outlaw
+science was the last thing which Protestant rulers were prepared to do.
+The great navigations had made science a necessity to the mercantile
+interests. So long as they refrained from making themselves a nuisance,
+like Servetus whose inability to envisage the Trinity in its correct
+numerical proportions earned for him a harsher fate than that of
+Galileo, scientists must be left alone. The world had outgrown the
+Aristotelian compromise. The time had come to replace it by some new
+device.
+
+The Cartesian philosophy met the new situation by defining separate
+spheres of autonomy for the scientist and the metaphysician. It did
+not attempt to mix metaphysics and science in a uniform system of
+nature. With his propositions and demonstrations “which establish the
+existence of God and the distinction between the mind and body of man
+disposed in geometrical order” Descartes stumbled upon the felicitous
+notion that God ordained the investigation of nature according to
+strictly mechanistic principles. “Now that I know him,” he discloses
+in Meditation V, “I possess the means of acquiring a perfect knowledge
+respecting innumerable matters, as well relative to God Himself and
+other intellectual objects as to corporeal nature, in so far as it is
+the object of pure mathematics.”
+
+So piety prescribes that the scientist, contrary to the admonition
+of Aristotle, must apply mathematics to the investigation of nature.
+By the same process of reasoning or inspiration Descartes arrives at
+the conclusion that teleological hypotheses in natural science are an
+impious abrogation of the prerogatives of Deity. “Likewise finally,” he
+asserts in the _Principles of Philosophy_, “we will not seek reasons
+of natural things from the end which God or nature proposed to himself
+in their creation (i.e. final causes), for we ought not to presume so
+far as to think that we are sharers in the counsels of Deity, but,
+considering him as the efficient cause of all things, let us endeavour
+to discover by the natural light which he has planted in us, applied
+to those of his attributes of which he has been willing we should have
+some knowledge, what must be concluded regarding those effects we
+perceive by our senses; bearing in mind however what has been already
+said, that we must only confide in this natural light so long as
+nothing contrary to its dictates is revealed by God himself.”
+
+As Descartes was prepared to concede to mechanistic science the entire
+brute creation, the Cartesian framework provided plenty of latitude
+for biological investigation. Descartes stimulated experimental
+physiology by his own ingenious speculations; and his influence on
+physiology survived after it had been superseded by later philosophical
+systems. In biology the Cartesian tradition has fallen into discredit
+through the rise of evolutionary ideas. The evolutionists persisted in
+following “the natural light;” and their theological contemporaries
+maintained that it led them to conclusions contrary to what had been
+“revealed by God Himself.” Since then biologists have been faced with
+the alternative of pressing forward to a more radically mechanistic
+conception of life, or abandoning it altogether. I have called the
+extension of the mechanistic conception the _publicist standpoint_ in
+contradistinction to _holism_, the most recent compromise.
+
+In _Science and the Modern World_ Dr. Whitehead calls the period
+immediately before the Renaissance the Age of Reason. That which
+followed is the Age of Faith. The Age of Argument and the Age of
+Confidence might perhaps describe the difference in more significant
+terms. Confidence in the method of science has grown gradually with
+the expansion of civilization. What is called modern science has
+arisen, because innumerable, at first independent, lines of enquiry
+have coalesced. It has not come into being because the men who have
+pursued these separate but converging paths have had any general
+theory about nature as a whole, purposeful or otherwise. Curiosity has
+always induced some men to speculate without investigating, others to
+investigate without speculating beyond their terms of reference, and
+a good many to do both. Aristotle was neither the first nor the last
+scientist to write a natural history and a volume of Gifford lectures.
+Newton divided his time between gravitation and the prophecies of
+Daniel. Faraday elaborated a theory of the ether and advocated
+the tenets of Sandemanism. Aristotle’s natural history, Newton’s
+gravitation and Faraday’s ether were not the philosophical complements
+of their respective ethical, political or devotional beliefs. Aristotle
+dissected animals, Newton gazed at the stars, Faraday experimented
+with his electrical machine, because they were interested in living
+creatures and the heavenly bodies and electrical phenomena.
+
+The pursuit of science has its personal impulse in curiosity and its
+social impulse in the power which science confers. The Greeks accepted
+or rejected as illusory the evidence of their senses. In Aristotle’s
+system science does not beg for a philosophical sanction. It was
+reserved for the piety of Descartes to introduce the singular idea
+that the scientist requires a licence to practice signed and stamped
+by the metaphysician. The idea that science requires a metaphysical
+justification has been revived by Dr. Whitehead who adopts a novel, and
+I think incorrect, view of Hume’s contribution to philosophy. When the
+scientist enters the field of contemporary philosophical controversy,
+he is confronted with a jargon whose existence has very little
+historical or logical connexion with the assumptions on which he works.
+It is not surprising that he remains, in the words of Dr. Whitehead,
+“blandly indifferent” to the arguments with which Hume refuted those
+notions of causality and inference which traditional philosophers have
+chosen to regard as the justification of science. The important fact
+about Hume’s argument is that he refuted the pretensions of moral
+philosophy by the same arguments which demolished the irrelevant dogmas
+which natural philosophy inherited from the age of scholasticism.
+
+Starting from a purely introspective basis Descartes attempts to find a
+justification for the growing confidence of mankind in the testimony of
+the senses. The subjective empiricism of Locke is still groping after
+the same solution. Hume pursues this method to its bitter conclusion;
+and shows that it led to complete scepticism. He proves to his own
+satisfaction that the method of introspection cannot be made the basis
+of socially communicable knowledge. The theory of a public world builds
+upon that foundation, by examining the characteristics of questions
+to which a socially communicable answer is possible. The strength of
+Hume’s position is more apparent in our own generation than it was at
+the time, when he wrote. Our expectation of living has increased as
+we have learned to worry less about the good life and more about the
+good drain. That the questions with which science deals are legitimate
+objects of enquiry and that the method which science adopts is the most
+satisfactory way of answering them is tacitly accepted by everybody who
+avails himself of the amenities of a railway time table, the bioscope,
+the telegraph office, the diphtheria vaccine, the ocean liner and the
+air mail. If we do not attempt to answer the questions which perplexed
+Socrates, it is because we have at our disposal a vastly greater body
+of material to guide us in determining what characteristics of a
+question make it suitable for being asked. We cannot say whether the
+wise man will obey the laws, if he thinks that he will not be found
+out; but we are less interested in knowing the answer, because we know
+that it is highly probable that his finger prints will be traced.
+Detective fiction has familiarized us with other devices which have
+replaced the deathbed confession of the repentant atheist.
+
+Hume applies the Cartesian method, demonstrates its sterility, and
+arrives at this attitude which he states with no uncertain sound in a
+passage which occurs at the conclusion of the essay on “The Sceptical
+or Academical Philosophy.” “When we run over libraries persuaded of
+their principles, what havoc must we make? If we take in our hand any
+volume of divinity or school metaphysics for instance, let us ask, Does
+it contain any abstract reasoning concerning quantity or number? No.
+Does it contain any experimental reasoning concerning matter of fact
+and existence? No. Commit it then to the flames. For it can contain
+nothing but sophistry and illusion.”
+
+In Hume’s scepticism natural science is no longer the man with the
+muck rake, and metaphysics is no longer the divine science. Kant’s
+critique now appears to salvage supernaturalism by a compromise in
+which the Cartesian method is reversed, and a greater confidence in
+scientific method is evident. He invokes science to save the soul
+of man. Newton’s system had made space and time the basic concepts
+of science. The physiology of Kant’s generation had not extended
+its enquiries beyond the range of the five senses with which the
+Greek empiricists were familiar. Kant seized upon this limitation of
+eighteenth-century biology to substantiate the contention that science
+draws upon information which is independent of sensual experience. In
+Kant’s idealism space and time, the basic concepts of science, appear
+as purely mental constructions. This was not a new point of view; but
+the prominence it assumed was new, and resulted from the character of
+contemporary science and the conclusions which Hume had advanced.
+
+Volumes of speculation on the relation of time and space to sensual
+experience have been written both by physicists and metaphysicians on
+the assumption that the human frame possesses no means of recording
+its own rhythms and its orientation to the earth’s gravitational
+field. Mach is the only natural philosopher who has hinted at the
+possibility that the Kantian argument might be re-examined from the
+modern biological standpoint. Modern physiology is not circumscribed
+like the physiology of Kant by the five senses. It recognizes ten or
+eleven distinct types of receptor elements in the human body. Two
+of these are immensely significant to the attitude which we adopt
+to Kant’s criticism of Hume’s position. In 1828 the experiments of
+Flourens first demonstrated that animals are receptive to the influence
+of gravity. The receptive area in our own bodies is located in that
+part of the internal ear, sometimes called the labyrinthine organ. Just
+as removal of the eye prevents a fish from responding to its background
+by colour change, destruction of the labyrinthine organs abolishes its
+characteristic orientation in space, when swimming. We do not say that
+a cat falls on all fours, because it has a priori knowledge of space
+relations. It falls on all fours, because the orientation of its body
+as a whole is recorded by its labyrinthine organ, and the appropriate
+muscles are brought into play by reflex action. The possibility that
+orientation of individual members with reference to one another might
+be regulated by a self-recording arrangement is a comparatively recent
+discovery. Sherrington has shown that the tendons and muscles possess
+special structures which he calls proprioceptors. They respond to the
+stretching of the muscles. By virtue of those muscular rhythms which
+Galileo employed as his standard of reference in devising the first
+clock, the human body is itself a self-recording timepiece. Pavlov does
+not appeal to a priori knowledge of time to interpret the interval
+which elapses between the ringing of a bell and the secretion of saliva
+in a dog.
+
+The belated discovery of the labyrinthine organ and the proprioceptors
+is easy to understand. We live in a world in which day and night follow
+one another. We can close our eyes and darken our vision. The eyes are
+exposed to view. Their connexion with light calls for no elaborate
+demonstration. The labyrinthine organ and the proprioceptors are only
+accessible to dissection or to the microscope. We can never get away
+from the influence of gravity or the rhythms of our own bodies. What we
+never miss, we fail to notice. This peculiarity of our corporeal nature
+gives a peculiar and fallacious plausibility to Kant’s contention
+that we can take away from a body its colour, weight or smell, all of
+which can be “referred to mere sensuous experience,” while “the space
+which it occupied still remains and this is utterly impossible to
+annihilate in thought.” To annihilate space is not an impossible feat
+of imagination for the modern biologist. In Rupert Brooke’s poem the
+heaven of fishes harbours the worm that never dies. If the metaphor
+had been pushed a little further, it would have transpired that the
+philosophy of fishes might well contain many axioms that are omitted
+in the Kantian critique. Fishes in general have no eyelids. They can
+be kept in a uniformly illuminated aquarium without the experience of
+darkness. The sharks and their allies possess a small duct by which
+the internal ear communicates with the exterior. It would not be an
+impossible operation to remove and replace the contents of their
+labyrinthine organs, and render them temporarily indifferent to the
+earth’s gravitational field. A philosophical fish confined from birth
+to a uniformly illuminated aquarium and subjected from time to time to
+this simple operation, might conceivably invert the Kantian argument.
+He would be shocked by the gross materialism of an undulatory theory of
+light; but he would be willing to be convinced about any quaint views
+upon space which the piscine physicists propounded.
+
+
+§3
+
+Kant’s doctrine that space and time are concepts necessarily
+independent of one another and of sensory experience has only come into
+conflict with the fruits of scientific enquiry in our own generation.
+In spite of this the influence of Hume has steadily increased and
+the influence of Kant has declined during the intervening period.
+Psychology, brought into existence by Kant’s appeal for a science which
+would define the characteristics of a priori knowledge, has betrayed
+its parent. In every department of human enquiry investigators are
+asking, does it contain any abstract reasoning concerning quantity or
+number, does it contain any experimental reasoning concerning matter
+of fact or experience? Mr. Bertrand Russell, an impenitent advocate
+of a priori knowledge in his capacity as a mathematician and an
+uncompromising empiricist in his capacity as an educationist, tells
+us that “logic must no more admit a unicorn than can zoology, for
+logic is concerned with the real world just as truly as zoology.” Dr.
+MacDougall, the most vigorous contemporary critic of the behaviourist
+standpoint, is devoting his energies to the breeding of genetically
+pure stocks of Wistar Institute white rats. A professor of political
+science in London University so far departs from the traditions of
+his discipline as to collect statistics on the number of hours which
+members of Parliament actually devote to their democratic activities.
+It was said by an old Scots balladmonger, “I care not who makes the
+nation’s laws, while I sing her songs.” When the modern descendant of
+Democritus is assured that materialism is on the decline, he may well
+reply in a similar vein. We all behave as if we were behaviourists
+nowadays.
+
+Between Hume and Darwin, Adam Smith, Malthus, Quételet and Marx sowed
+the seeds of the behaviourist standpoint in the soil of the humanities.
+Darwin’s _Descent of Man_ precipitated a new phase in the revolution
+which was replacing classical humanism by a humanism which draws its
+inspiration from the success of natural science and looks to the
+scientist to supply it with the first principles of method. It was no
+longer possible to challenge the claim of science to the study of the
+brute creation. The recognition of man as a by-product of the same
+secular agencies undermined the last defence of the metaphysician.
+Hegelian philosophy was a forlorn and belated attempt to lock the
+stable doors after the horses had long since escaped. The piety of
+Descartes had conceded that animals are automata. The brutal candour
+of Darwin emphasized in a new light the fact that man is an animal. It
+was fitting that William James should arise in the fullness of time to
+proclaim the new gospel that philosophers are also men. If the full
+force of this devastating sequence was not apparent to the pragmatic
+apologists of the Pelagian heresy, it has acquired a new, and, I
+believe, epochal significance through the breakdown of the Cartesian
+distinction between reflex and voluntary activity in modern physiology.
+
+To-day the influence of Hume’s empiricism and Darwin’s doctrine of
+descent can be seen in every branch of social enquiry. In history
+the materialistic bias is evident in the writings of those who would
+be least willing to commit themselves to economic determinism as a
+general hypothesis of social development. Economics has completely
+severed its moorings to moral philosophy, and proudly boasts that
+it is an ethically neutral science. The genetic aspect of human
+behaviour is recognized in new endowments to encourage the pursuit of
+social biology. If social psychology has hitherto remained immune
+to the influence of modern research on animal behaviour, it borrowed
+its equipment of instincts from the discredited speculations of the
+selectionists. The humanities have passed out of the hands of the
+grammarians in the higher seats of learning. Before another generation
+has passed the accomplished fact will be officially sanctioned in the
+earlier stages of education.
+
+In its long apprenticeship to theological dogma classical humanism
+has created a type of philosophy which is inimical to the temper
+of scientific enquiry. This tradition has been perpetuated in our
+educational system by associating the study of history and human
+affairs in general with an exclusively linguistic rather than with a
+scientific training in early life. The belief that philosophy lies
+outside the province of science and that logic is more fundamental than
+science has been so thoroughly inculcated by the classical tradition
+that most men of science accept it with servile complacency. It is not
+surprising that many of them view with alarm the magnitude of the new
+territories which scientific method has incorporated within its domain.
+In every period the birth of a new tradition has made the forces of
+reaction more stubborn. This fact must be accepted. It is unwise to
+expect results of far-reaching importance in social science in the
+immediate future. If astronomy is the most exact of the observational
+sciences, it is also the oldest. It began in Babylon and Egypt about
+six thousand years ago. Economists and eugenists who hope to outgrow
+their phlogiston theories in one generation take an unduly hopeful view
+of the rapidity of scientific progress. New forms of compromise will
+come to the rescue of custom thought and power thought, before social
+science is able to replace the wrong way of asking a question by the
+right way.
+
+It is highly probable that the next century will witness a
+consolidation of supernaturalistic tendencies in western Europe. It
+is legitimate to entertain the possibility that the rival attitude,
+reinvigorated by fresh triumphs of scientific method in the treatment
+of human affairs, will revive with greater vitality, if not in our
+own civilization, in that which takes its place. I am in complete
+agreement with Dr. Haldane, General Smuts, Professor Eddington and
+Dr. Whitehead, when they assure us that the materialistic tendency
+in philosophy, which was gaining ground under Darwin’s influence, is
+less popular to-day. I venture to interpret the reaction in a way
+with which they would not agree, and to believe that it has retreated
+_pour mieux sauter_. The mid-nineteenth century in Great Britain was
+a period of prosperity and expansion. In Huxley’s generation unbelief
+was the luxury of a privileged class which was not afraid of the man
+in the street. The period in which we live is one of ferment and
+disintegration. In its impetuosity to settle the problems of human
+conduct, it will not be content to await the slow advance of science.
+Mechanistic philosophy cannot offer to the privileged a supernatural
+sanction for the things they value most. It cannot proffer to the
+unprivileged the shadowy compensation of a world into which the
+thought of science is unable to penetrate. A mechanistic philosophy
+might conceivably be popular in a society in which gross inequalities
+of possession did not exist. To-day it can only flourish among those
+who have leisure to study, when their privileges are not compromised
+by social unrest. He who has the temerity to defend the mechanistic
+position need not expect any laurels from his own generation. He
+cannot seek sanctuary in the fearless candour of a contemporary Huxley
+or a contemporary Tyndall. He must extract what comfort he can glean
+by reflecting that the system of Aristotle triumphed over that of
+Epicurus, and the thought of the nineteenth century was nearer to
+Epicurus than to Aristotle. Scanning the new blossoms which have lately
+been added to the nosegay of philosophic compromise, he will say with
+Swinburne,
+
+  “But for me their new device is barren, the times are bare,
+  Things long past over suffice, and men forgotten that were.”
+
+
+
+
+X. PUBLICITY, REALITY, AND RELIGION
+
+  “Conscientiousness in small things, the self-control of the
+  religious man, was a preparatory school for the scientific
+  character, as was also, in a very pre-eminent sense, the attitude
+  of mind which makes a man take problems seriously, irrespective of
+  what personal advantage he may derive from them.”--Nietzsche, _The
+  Will to Power_.
+
+
+§1
+
+Whatever may be said against pragmatism, it served a useful purpose
+in calling attention to the connexion between people’s temperaments
+and their philosophies. William James classified philosophers in
+two genera, the tender-minded and the tough-minded. I believe that
+there exists a more fundamental distinction between two types which
+correspond to the introvert and the extrovert of the psychiatrist.
+Our attitude to the scope of philosophy is determined by whether
+we take an individualistic or a social view of what constitutes
+truth. In the one case our canons of logic will be inferred from an
+examination of the properties of propositions which carry conviction
+to ourselves individually, in the other by an examination of the
+properties of propositions which are best equipped to obtain general
+assent. For this reason I am not convinced that Bertrand Russell
+is right in thinking that modern logic brings the most devastating
+criticism to bear on traditional philosophy. Modern logic has not
+been devised with the aim of achieving the same results as those
+which constitute the goal of traditional philosophers. It is not
+surprising that traditional philosophers, finding its conclusions
+unpalatable, remain unconverted. Modern logic is the offspring of
+mathematics, and mathematics has developed in intimate association
+with science. For the last seven hundred years traditional logic and
+introspective philosophy have been no less intimately associated with
+theology. Hence has arisen the arrogant assumption that on account of
+its subject matter introspective philosophy is more fundamental than
+science. There is no reason why we should regard it in this light.
+If philosophy is knowledge, it is presumably something transmissible
+by discourse. Otherwise it is difficult to formulate any distinction
+between knowledge and mere opinion or superstition. We cannot therefore
+discuss knowledge without taking into account the people who share
+it. The most important characteristic of scientific beliefs is
+their communicability. Those who take the social as opposed to the
+individualistic attitude to truth will embark on their adventures by
+examining the characteristics of scientific judgment. To any one who
+is not an incorrigible individualist the results of scientific enquiry
+must establish the anatomy of philosophy. Whether I am by temperament
+an individualist or otherwise I am forced to submit to the discipline
+of discourse in practice. Let us suppose that two individuals N and
+M are engaged in public discourse concerning the Nature of Life. N
+states the proposition “I (N) am a conscious being.” M states “I (M)
+am a conscious being.” The only neutral ground for the discussion of
+the two statements is the more general statement “N and M are conscious
+beings.” In the nomenclature suggested elsewhere in these essays this
+neutral ground is the resultant of the public components of the two
+original statements which N and M make. Personal statements may be
+looked upon as complex variables. Philosophy is the technique of
+operating with the real (public) part of such statements and separating
+them from the imaginary (i.e. private) part. This distinction is not
+abolished by the fact that the temperaments of some philosophers lead
+them to apply the term _real_ to the private and _imaginary_ to the
+public component. The fact remains that in public discourse we have
+to operate with the public component. The public statement “N and M
+are conscious beings” implies our ability to define characteristics of
+behaviour which are denoted by the adjective _conscious_. This task
+which now lies within the scope of biological investigation refines
+the publicity in the concept of consciousness. For the performance of
+public discussion the term “_I_” is a member of the class denoted by
+“_Man_.” Anything implied in public discussion by the statement “I am
+conscious, etc.,” is included in the statement “Man is a conscious
+animal.” The significance of anything which cannot be subjected to this
+limitation is a purely _private_ matter. From this it follows that a
+discussion of the Nature of Life is complete, when we have taken into
+account the characteristics of conscious behaviour. On the contrary
+view the propositions of philosophy are not necessarily communicable.
+
+The theory of a _public world_ suggested in a previous essay on the
+Nature of Life corresponds very closely with the attitude adopted by
+Poincaré in the following passage which occurs in his _Foundations of
+Science_:
+
+  “Sensations are therefore intransmissible or rather all that is
+  pure quality in them is intransmissible and forever impenetrable.
+  But it is not the same with relations between these sensations.
+  From this point of view all that is objective is devoid of all
+  quality and is pure relation.... Nothing therefore will have
+  objective value except what is transmissible by discourse...”
+
+So far as it goes there is nothing essentially new in this statement.
+It represents an attitude common among thoughtful people with a
+scientific training. Professor Eddington is in agreement with it when
+he writes:
+
+  “For reasons which are generally admitted, though I should not
+  like to have to prove that they are conclusive, I grant your
+  consciousness equal status with my own; and I use this second-hand
+  part of my consciousness to ‘put myself in your place.’ Accordingly
+  my subject of study becomes differentiated into the contents of
+  many consciousnesses, each constituting a _view-point_. There then
+  arises the problem of combining the view-points, and it is through
+  this that the external world of physics arises. Much that is in any
+  one consciousness is individual, much is apparently alterable by
+  volition; but there is a stable element which is common to other
+  consciousness. That common element we desire to study to describe
+  as fully and accurately as possible, and to discover the laws by
+  which it combines now with one view point, now with another. This
+  common element cannot be placed in one man’s consciousness rather
+  than in another’s; it must be in neutral ground--an external
+  world... The external world of physics is thus a symposium of the
+  worlds presented to different view-points...” (p. 283, _The Nature
+  of the Physical World_).
+
+How then does it come about that “a universal Mind or Logos would
+be, I think, a fairly plausible inference from the present state
+of scientific theory”? (p. 338). Or again, how are we to draw the
+conclusion “from those arguments from modern science that religion
+first became possible for a reasonable scientific man about the year
+1927”? I think that we may possibly find an answer to these questions
+by bearing in mind that Professor Eddington’s external world is the
+external world of physics rather than the public world of physics plus
+biology. Throughout his exposition he assumes that biologists are still
+committed to the dualistic standpoint of the Cartesian tradition. Thus
+he states: “a mental decision to turn right or turn left starts one
+of two alternative sets of impulses along the nerves to the feet. At
+some brain centre the cause of behaviour of certain atoms or elements
+of the physical world is directly determined for them by the mental
+decision...” (p. 312). It is not clear why there is in what Professor
+Eddington calls the “mystical experiences” of different people
+sufficient “neutral ground” to provide the basis of a symposium with
+as universal a sanction as that of the external world of physics. That
+after all is implicit in our notion of religion. It is not difficult
+to see why he finds no objection to placing his external world under
+the direction of a universal mind, since he assumes that the teleology,
+which has been abandoned in dealing with non-living matter, is quite
+indispensable in dealing with living matter.
+
+It must be admitted that Professor Eddington could claim the support
+of at least one eminent biologist who holds that the method of the
+biologist is different from the method of the physicist, and the
+method of the physicist can never be applied to the analysis of
+“conscious behaviour.” However stoutly Dr. Haldane may advocate the
+first proposition his many distinguished contributions to biological
+science are little calculated to illustrate its truth. He has made
+important additions to our knowledge of the physical chemistry of the
+blood by adopting the method of the physicist. When, if ever, he has
+departed from that method he has done so without the assent of his
+fellow physiologists. The practice of even the most exemplary persons
+not infrequently falls short of the loftiness of their professions,
+and it is perhaps unfair to criticize Dr. Haldane on this account.
+The weakness of Dr. Haldane’s philosophical position resides in the
+fact that he gives no consideration to the new issues raised by the
+physiology of the conditioned reflex. Pavlov’s work has shown us that
+even when he is dealing with “conscious behaviour,” the biologist
+can still approach the subject matter of his enquiries with the same
+attitude which the physicist adopts.
+
+On the whole people are more interested in conscious behaviour than in
+anything else. Before science could attempt to tell us something about
+conscious behaviour, Poincaré’s outlook could never have a far-reaching
+appeal. The history of human thought again and again proves that people
+will always fall back on the language of magic, when the language of
+science provides them with no vocabulary in which to discuss the things
+that interest them most. Magical views of the world have declined not
+because science disproves them, but because science provides better
+ways of discussing the same issues. If we can usefully treat the
+characteristics of conscious behaviour without invoking a holistic
+or animistic concept of consciousness, the scope of introspective
+philosophy must in time dwindle to a vanishing point. Philosophy will
+then confine itself to examining the logical structure of scientific
+theories. It may seem more natural, more in keeping with common sense,
+to think of a wholeness defined by the term consciousness than to face
+the tremendous intellectual effort of envisaging the behaviour of an
+organism from an atomistic standpoint. If the latter contains within
+it the capacity of growth and of yielding verifiable conclusions which
+cannot be derived from the traditional point of view, consciousness
+must go as gravitation and action at a distance must go, however much
+Kant and common sense may urge the _a priori_ necessity of a Euclidean
+space and a measure of time that is independent of it. As scientific
+investigation invades the domain of conscious behaviour the way will be
+open for developing a new outlook in philosophy, one that is neither
+intrinsically monistic nor intrinsically pluralistic, since it makes no
+such claims to finality as the academic philosophies of the past have
+usually done.
+
+
+§2
+
+Professor Eddington, like Professor Whitehead, entertains the hope
+that science may eventually lead us to conclusions about the universe
+involving something more than practical utility on the one hand and
+mere intellectual satisfaction on the other. The reasons which they
+give are not sufficiently definite to criticize, as they would perhaps
+themselves admit. It is more easy to understand the point of view of
+Mr. Sullivan, an impenitent individualist, who is frankly resentful
+towards science, because science cannot serve the needs of theology or
+provide sanctions for his æsthetic predilections.
+
+  “The greater importance that men attach to art and religion,” he
+  maintains, “is not due simply to their ignorance of science. Art
+  and Religion satisfy deeper needs; the problems they deal with
+  are intrinsically more important.... Our æsthetic and religious
+  experiences need not lose the significance they appear to have
+  merely because they are not taken into account in the scientific
+  scheme....”[8]
+
+The real significance of these remarks would be much clearer, if Mr.
+Sullivan had substituted the word _personally_ for _intrinsically_.
+Mr. Sullivan is by temperament an individualist philosopher. For him
+what is _true_ has a specially personal value. Scientific beliefs are
+only _convenient_. Thus in discussing the system of Copernicus he
+makes the comment, “it was convenient; the question of whether it was
+true or untrue was not explicitly discussed.”[9] Consistently with the
+individualistic standpoint in philosophy Mr. Sullivan does not divulge
+the inward revelation which empowers him to distinguish with such
+nicety between propositions that are “true” and propositions that are
+merely “convenient.”
+
+It sounds very impressive to state that science leaves out of account
+man’s religious and artistic experiences, that religion and art satisfy
+deeper cravings and so forth; but religion and art are two words which
+are rarely used by any two people in the same sense or by any one
+person in the same sense on two successive occasions. Which religion
+does Mr. Sullivan mean? Is he a Buddhist, a Seventh Day Adventist,
+a Shintoist, or a Bahai? Is his religion an ethic or a cosmogony,
+or both? Until he has defined his position more explicitly, it is
+difficult to be quite sure what he is talking about. The terms art and
+religion are used in very different senses. That being so, to say that
+everybody has religious or æsthetic experiences does not necessarily
+imply the existence of any common plane of thoughtful intercourse
+other than the conceptual world of science. An expert social hostess
+recognizes this when she wisely refrains from asking Mr. A who is
+interested in Art to meet Mr. B who is interested in Art.
+
+In seeking to transcendentalize his private world, Mr. Sullivan
+has not been altogether felicitous in coupling together Art and
+Religion. Although many people become very irritable in the course of
+a discussion on the merits of vorticism or free verse, most educated
+persons admit on reflection that such discussions owe their interest to
+the light they shed on differences of temperament in the disputants.
+It is true that professors of literature in Universities and rather
+youthful reviewers sometimes take a more pontifical view of their
+own powers of divination, but even our schools have got beyond the
+stage, when it was thought proper that children should be whipped into
+believing that Wordsworth’s _Idiot Boy_ is a _great_ poem. Whether Mr.
+Sullivan chooses to say that Van der Waal’s equation is true or merely
+convenient, it may be suggested that he would embark on a discussion of
+its truth or convenience with some hope of final agreement. I believe
+that Mr. Sullivan would embark upon an argument about a question of
+æsthetics with much less hope of changing his opponent’s attitude than
+if he were discussing Van der Waal’s equation. Mr. Sullivan has no
+need to appeal for a transcendental sanction for æsthetic experience.
+Æsthetics are questions about which sophisticated people agree to
+differ.
+
+With religion it is different. Whereas a person can have very genuine
+artistic interests without claiming a universal, transcendental or
+_public_ sanction for his own preferences, religion ceases to be
+religion and becomes æsthetics or ethics, when it does not put forward
+such claims. A consideration of the following illustration will make
+this clear. A derives satisfaction from reciting Mr. Yeats’ poem, “The
+faeries dance in a place apart...” etc. B derives satisfaction from
+singing the evangelical hymn that contains the lines “Bright crowns
+there are, bright crowns laid up on high...” Inasmuch as the first form
+of satisfaction involves neither belief nor unbelief, it is properly
+described as artistic or _æsthetic_. Inasmuch as the second implies
+in addition the conviction that a certain ponderable object exists at
+a certain height from the earth’s surface, as in the cruder forms
+of evangelism it does, the satisfaction derived from singing it is
+_religious_.
+
+The word religious is used in so many different senses that it is
+dangerous to employ it at all without examining it more closely.
+Cynical paradox-mongers not infrequently complain that materialists
+are “religious.” When so used, the term merely implies a sense of the
+importance of belief. In an unscientific age persons of this type
+would probably gravitate towards some form of religious organization.
+Looking at religious organizations as a whole one sees two sharply
+contrasted components in the majority: views about human conduct or
+the ethical aspect of religion and views about the nature of the
+universe or cosmogony. To-day, most educated people regard the latter
+as the proper sphere of science. We are told by modernists that the
+earlier chapters of the Book of Genesis are to be cherished for the
+sublime ethical teaching they impart. What sublime ethical teaching
+is implied in the prohibition to eat of the fruit of the tree of
+Knowledge or in the story that woman was manufactured from a man’s rib
+as an afterthought of creation need not detain us. It is only partly
+true to say that liberal theologians have surrendered the sphere of
+cosmogony to science. They have surrendered the details, but they have
+not surrendered the prerogative of imposing upon whatever cosmogony
+the scientists supply a teleology of their own. This teleology is, it
+is true, so attenuated as to embarrass the advance of science far less
+than those more crude revivals of animism sometimes inappropriately
+classified under the generic heading New Thought. Its justification
+becomes less and less calculated to carry conviction, as the domain of
+scientific method is officially sanctioned by the Churches. The advance
+of scientific knowledge reinforces the suspicion that an attitude to
+experience which leads to misleading or sterile conclusions about the
+details of our cosmogony can hardly be expected to prove essential to
+the finished picture.
+
+Just as the cosmological aspect of religion has become resolved into a
+_public_ component which has passed over into the province of science
+and a personal component for which the mystic seeks to formulate
+some ulterior transcendental sanction, the ethical side of religion
+consists of values which must be taken or left and prohibitions or
+admonitions which can be rationally discussed as instruments for
+promoting the acceptance of these values, if the latter are taken for
+granted. Here again the claims of liberal theologians become more
+modest with the advance of more complex methods of social organization.
+Sunday observance, fasting, prohibitions against dancing, smoking and
+theatricals become less and less fashionable. Even in the domain of
+sex, where animistic views of human conduct are more obtrusive, we
+find that Anglican deans are making the entertaining discovery that
+birth control is fully compatible with the teachings of Christianity.
+Most Christians will agree that war is contrary to the “spirit of
+Christ’s teachings.” When a war happens to be in progress, they give no
+objective evidence that this conviction differentiates their conduct in
+any way from that of people who are not in the least interested in the
+spirit of Christ’s teaching. An exception might here be made in favour
+of the Quakers. The Society of Friends, the only religious body which
+engaged the respect of Voltaire, have shown so little disposition to
+proselytize that they are hardly to be looked on as a religious body.
+They might with equal propriety be called an organization of persons
+interested in the art of living. Significantly enough they do not call
+themselves a Church.
+
+In practice the hard and fast ethical claims of religious leaders
+tend with the advancement of civilization to become less pretentious.
+The details of regulating human conduct have been conceded to the
+politician and the educationist, just as cosmogony has been surrendered
+to the scientist. Religious organizations cling tenaciously to some
+obscure transcendental sanction for the fundamental assumptions on
+which the politician or educationist is expected to work, assumptions
+which, as earlier remarked, seem in actual practice curiously
+irrelevant to the behaviour of their devotees. The increasing vagueness
+which surrounds the nature of “revelation” in the teachings of Liberal
+Churchmen renders the task of making this sanction communicable one
+of overwhelming difficulty. In relation to human conduct there is
+obviously a large domain of questions on which rational discourse is
+possible, in so far as the fundamental assumptions are agreed upon
+by all parties. In this sense ethics belongs to the public world and
+ethics and politics are the same thing. There still remain private
+differences with regard to the premises. The Roundheads realized that
+transcendental ethics cannot be made the subject of argument. They
+acted intelligibly on the assumption that the only answer to the Divine
+Right of Kings was to make a spectacle of the head of Charles Stuart to
+Gods and men.
+
+When Professor Eddington employs the term mystical experience
+indifferently for æsthetic and religious sentiments, he is perfectly
+justified in so far as the ultimate constituents of religion, those
+residues of religious belief which have survived the secularization
+of social life and the advancement of scientific knowledge, belong
+to the private worlds. From a purely individualistic standpoint the
+“religious” satisfaction that the Liberal theologian derives from the
+crude teleology of the Chaldæan mythos is difficult to distinguish from
+the artistic satisfaction sought by others in the vague teleology of
+Wordsworth’s _Tintern Abbey_. Regarded from a social angle there is a
+profound difference between the religious and the artistic experience.
+Because of that difference Professor Eddington’s conclusion that there
+is nothing in the outcome of scientific enquiry to prevent a reasonable
+man from entertaining religious beliefs is a profoundly misleading one.
+When Professor Eddington speaks of religious experience he clearly
+means something which belongs to himself privately. When the vast
+majority of people speak of religion, they mean a body of beliefs which
+can be transmitted through the medium of discourse like scientific
+beliefs. Far from being regarded like artistic preferences as a private
+affair of the individual, such beliefs are promoted by exceedingly
+powerful organizations which still exercise an immense effect on social
+behaviour. This influence takes the form of interference on the part of
+the Churches in every attempt to encourage birth control, to promote
+true information about sex among the young or to humanize the divorce
+laws. The scientific philosopher is entitled to his own private mythos
+with which no sensible people would wish to interfere, provided that
+he does not pester his fellows with it. It is still permissible to ask
+whether he is justified in employing language in such an equivocal
+manner that his words will be used, when he must know they will be
+used, to give all the weight of a distinguished reputation to those
+forces of social organization which in the past have exercised a
+constant restraint on the freedom of scientific enquiry and do at
+present exert a tremendous influence upon the shaping of human conduct.
+
+That the distinction we have drawn above between the religious and
+the æsthetic is the significant one for the purpose of ordinary
+usage is easily seen by considering the dislike that some people
+entertain for pork. In a Gentile this is an æsthetic attitude. In the
+Jew it is a religious one. The thesis that artistic values, or more
+generally what Professor Eddington calls the mystical experience,
+belong to the private world requires an important qualification. It
+does not imply that Art cannot be made the subject of discussion. A
+mechanistic philosophical outlook is often stigmatized on account of
+its supposed dullness, and shunned because it seems to leave no place
+for after-dinner conversation. This is not so. The mechanistic outlook
+does not imply the end of æsthetic criticism. It merely insists that
+such criticism shall conform to the standards of the public world.
+There is abundance of fascinating problems dealing with the orientation
+of human interest to particular objects which come within the scope
+of æsthetic criticism. The theory of a public world which has been
+developed elsewhere leaves open the possibility that we may one day
+have genuinely scientific knowledge about these things. If that day
+comes, we shall be able to argue about art and ethics without losing
+our tempers. As the behaviouristic standpoint encroaches on the field
+of art criticism, it is probable that the nice distinction between
+those matters of taste which we call æsthetic values and those which we
+call ethical sanctions will seem more arbitrary than the advocates of
+Art for Art’s sake postulate.
+
+The conflict between religion and science tends to be obscured by the
+circumstance that the official apologists of the former, if they are
+well-educated persons, state their case in such a way as to convey
+the impression that they only claim that their view of human destiny
+is a permissible one. This does not alter the fact that religious
+leaders both of the right and left wing _behave_ on the assumption
+that their views have a universal sanction. In very few parts of the
+English-speaking world is it possible for a child to go to school
+without being taught the tenets of some religious body. One does not
+notice that Liberal theologians who state their case on the frankly
+private basis of mystical experience are much more sympathetic than
+Fundamentalists to the legitimate claims of the agnostic parent who
+wishes his child to have a secular education. The term religion cannot
+be detached in its objective, or in the terminology of these essays its
+_public_, aspect from _organization_. Professor Eddington has justified
+his right to a “mystical experience.” He has not proved his claim to
+have a _religion_ as the average parent understands that term. If the
+scientist uses the term _religion_ for something different, knowing
+that his words will be used by religious leaders to reinforce their
+claims to a universal sanction for their own “mystical experiences,”
+the secularist parent may legitimately feel that the scientist is not
+giving him a square deal as a fellow citizen.
+
+
+§3
+
+We must attribute to its long association with theology the idea that
+philosophy deals with something mysteriously called _Reality_, lying
+outside the secular province of science. The term Reality has acquired
+the value of magical gesture in academic philosophy. Its everyday
+use as a measure of the intensity of one’s conviction throws a good
+deal of light on what is meant when it is used to define the goal
+of philosophy. To the introvert the private world is most _real_. To
+those who have a more socialized attitude to experience the public
+world of science is most _real_. The fundamental difference that
+exists between the introvert and the extrovert type of philosophy
+is not abolished by introducing the word reality into the language.
+It is partly because the term “external world” has been used with
+more emphasis on its “reality” than on its communicability that I
+have preferred to speak of a _public world_. The classification of
+different experiences as external or internal is less important than
+the recognition that some are communicable and others less so. In
+this nomenclature scientific beliefs are distinguished especially by
+their _publicity_. The fundamental distinction between the domain of
+intellectual public enterprise and intellectual private enterprise
+is just as valid, whether we approach the question from the frankly
+solipsistic standpoint adopted by Professor Eddington on p. 268 of his
+Gifford Lectures or the equally explicit objective idealism of p. 272
+of the same work.
+
+In my undergraduate days there was a legend of an eminent philosopher
+and a Fellow of Trinity. Returning to his room in the early hours
+of the morning after a liberal potation of audit ale, he lay down
+upon the hearth-rug, covering himself with one of the large shallow
+footbaths which were still used by all classes of academic society.
+When his bedmaker arrived a little later, he explained that he was an
+oyster, and raised objections to any one tampering with his shell.
+I do not know whether the story is true, or whether the philosopher
+was a solipsist. I presume that in the course of the same day, he
+realized that his experience of the footbath had a more extended
+significance than his experience of the oyster shell. If he were a
+solipsist and decided to remain such after the incident in question,
+he was presumably forced to recognize from Audit eve onwards, that
+certain ingredients of his consciousness had a more permanent
+status than others. If human beings exist only in my own individual
+“consciousness,” they constitute necessary points of reference in
+classifying other types of experience. The distinction between
+_the_ public world and _my_ private world does not uniquely owe its
+usefulness or significance to any assumption concerning the existence
+of a reality external to my own consciousness. The important feature
+about the world construction of science is not its externality but its
+communicability. Communicability remains a perfectly definite basis
+for the classification of beliefs, even if I choose to deny that other
+human beings have an independent existence.
+
+In secret the individualist is entitled to cherish the belief that his
+own private world is more “real” than the public world of science. One
+suspects that Mr. Sullivan does so. Professor Eddington is evidently
+worried because he finds himself doing so. Under the influence of
+love or alcohol we have all been solipsists at some time or other. As
+Professor Eddington has lucidly stated in a passage quoted earlier in
+this essay, so soon as we engage in public discourse we are compelled
+to seek for a neutral ground. We agree to leave our private world
+behind. To make discourse possible we accept the neutral ground as
+the real thing. This neutral ground is the public world of science.
+The idea that philosophy is more fundamental than science has arisen
+through the absent-mindedness of philosophers. This permits them
+to overlook the fact that there cannot be philosophy unless there
+are philosophers. As soon as more than one individual begins to
+philosophize the search for a neutral ground becomes a necessity of
+social intercourse. From a social point of view the neutral ground is
+the only thing which can be spoken of as real. Although philosophers
+often try to give the impression that human beings exist in virtue
+of the fact that there is such a thing as philosophy, it is more
+sensible to hold that philosophy exists in virtue of the fact that
+there are human beings. Because philosophers are themselves members
+of human society, the proper goal of philosophy must be the search
+for propositions that have the property of _publicity_ or socialized
+reality.
+
+The recognition of this restores to philosophy an intelligible
+objective. From the point of view of the average person the philosopher
+is “a blind man in a dark room chasing a black cat that isn’t there.”
+The contempt of the plain man is partly justifiable, not because
+the plain man is entitled to a plain answer to every question he
+propounds, not because philosophers are blind, but because it is
+waste of time to chase the cat, if there is really no cat to chase.
+Traditional philosophy wedded to dogmatic theology has always assumed
+that the cat is there to chase. Of late years the cat of traditional
+philosophy, like the cat of _Alice in Wonderland_, has been gradually
+disappearing. For the purpose of apologetics there is little left
+of it but its smile. There have been philosophers who have been
+content to admit their blindness and refrain from putting forward
+any project to bell the cat. Of such was David Hume. It is now a
+hundred and fifty years since Hume was buried. This may be why he is
+recognized as an authentic philosopher. Those whose studies lead them
+to entertain views somewhat similar to those of Hume are more usually
+called anthropologists, physicists, physiologists, economists or
+generically experts, while they remain alive. The grudging benediction
+accorded to Hume’s remains by traditional philosophers is not wholly
+due to a conventional respect for those who have departed. Hume
+divested natural philosophy of some of the pretensions which it had
+imbibed from its association with scholasticism. Philosophers with
+an anti-scientific bias have chosen to regard this as an affront to
+science. The scientist looking back over a century and a half of
+unparalleled progress has no need to regard it as such. On the other
+hand the scope of “moral” philosophy has dwindled since Hume’s time.
+Psychology, until our own generation a branch of moral philosophy, is
+clamouring to be recognized as a science. Anthropology has undertaken
+the task of elucidating by painstaking observation those aspects of
+human behaviour which are _publicly_ connected with what Professor
+Eddington _privately_ speaks of as the “mystical experiences.” It may
+be true that scientists in our generation are less outspoken than
+Huxley and Tyndall in their criticism of traditional philosophy. It
+may be true that those scientists who enter the field of philosophical
+discussion often do so with the aim of reinforcing the beleaguered
+battalions of the apologists of dogma. It is doubtful whether there was
+ever a time in the history of western Europe when a secular outlook was
+more widespread, and when the hope of finding a rational basis for a
+universal religion was less forlorn.
+
+When philosophers speak of a rational basis for scientific belief, they
+seem to imply that the word rational can only signify that which is
+evident independently of experience. It is profoundly doubtful whether
+we can form any judgment about such a question. If it is possible to
+arrive at a decision of this kind, I suspect that the solution will
+come from those who study the behaviour of infants and the history of
+science. There seems to be little hope of obtaining a solution from
+introspective philosophers. In the meantime science will continue to
+progress, whether the belief that relations between experience can be
+ascertained is a rational one or is itself an outcome of experience,
+whether the public world is the actual world or a shadow world,
+whether the conclusions of science appeal to common sense or seem more
+incredible than fairy tales. In a machine-made civilization however
+unpalatable to common sense the conclusions of science may prove, the
+future of science is assured.
+
+In the philosophy of Hume we find the pragmatic justification of
+science first stated explicitly. “To philosophize,” according to Hume,
+“is nothing essentially different from reasoning on common life.”
+Kant’s anxiety to give scientific enquiry a “rational” sanction was
+based on the frank recognition that Hume’s scepticism threatened the
+future of moral philosophy more than the future of science. Yet Kant
+himself could not escape from the pragmatic criterion of publicity,
+in asserting the superiority of his own system to that of Plato, who
+“abandoning the world of sense, because of the narrow limits it sets to
+the understanding... did not reflect that he made no real progress by
+all his efforts, for he met with no resistance which might serve him
+for a support, as it were, whereon to rest, and on which he might apply
+his powers.”
+
+In accepting Hume’s critique of traditional rationalism and attempting
+to reinstate moral philosophy on the same footing of social convenience
+as natural science, the modern pragmatists have proved more than they
+intended. By insisting on the temperamental basis of philosophical
+belief, pragmatism has robbed moral philosophy of all claim to
+universality; and implicitly relegated it to the status of an art.
+James believed that the doctrine of immortality is a physiological
+necessity for some people. For others it is evidently not. Some people
+anticipate with gratification an eternity of hymn singing. Others
+shudder at the fate of the Struldbrugs. Both those who do find it
+necessary to believe in immortality, and those who do not, live to-day
+as citizens of a society whose amenities are the fruit of scientific
+knowledge. In a machine-made civilization the amenities provided by
+science are a necessity to every one. It is necessary to live in order
+to philosophize. When the philosopher has finished all that he has to
+say about the Nature of Life, it is the biologist who is called in by
+his relatives to certify that he is legally dead. The universality
+of science transcends in a very practical sense those differences of
+temperament which determine the predilections of moral philosophers.
+Scientific hypothesis makes social activity possible.
+
+
+
+
+XI. PRIVACY, PUBLICITY, AND EDUCATION
+
+  “Nothing does more harm in unnerving men for their duties in the
+  present, than the attention devoted to the points of excellence
+  in the past as compared with the average failure of the present
+  day.”--Whitehead, _Science and the Modern World_
+
+
+§1
+
+Two conclusions, it seems to me, can now be drawn from the progress of
+science. One is that, since we can never know everything we should like
+to know, every individual has a right to his own private world. The
+other is that there is no excuse for the sophisticated person refusing
+to recognize where his private world ends and the domain of social
+knowledge or the public world begins. From the first it follows that
+there is no necessary antagonism between the claims of science and art
+in a modern theory of education. From the second it follows that true
+education is necessarily secular. It is generally agreed that education
+includes something more than vocational training. Modern industry
+offers to the majority of people the prospect of more opportunities for
+cultivated leisure. It is arguable on the other hand that as time goes
+on work may become more rather than less monotonous for most people.
+Training of the individual to use his leisure in ways which will
+not bring him into conflict with his neighbours provides a possible
+basis for the public discussion of cultural education in what may be
+called its æsthetic aspect. The Theory of the Public World does not
+necessarily imply that such discussion is valueless. It does not lead
+to the conclusion that the æsthetic side of education is unimportant.
+It does necessitate a reconsideration of the attitude which the teacher
+should be encouraged to adopt. A modern theory of education should
+begin by defining the respective spheres of _privacy_ and _publicity_.
+
+I shall illustrate what I mean by privacy with special reference to
+the teaching of poetry in the school. I can see no good reason why
+a child should be expected to like Keats’ _Ode to a Nightingale_. I
+can see excellent reasons why he should know that it was written, and
+where to find it. One of the characters in a play by Eugene O’Neill
+is made to say: “I love dynamos. I love to hear them sing. They’re
+singing all the time about everything in the world.” Mrs. Fife was an
+American. She had almost certainly never heard a nightingale sing. In
+England, where the nightingale is an indigenous species, its overrated
+vocal performances are hardly less familiar to the average child. To
+the majority of people brought up from childhood in urban surroundings
+dynamos are closer to Nature. They are things that they can see and
+hear. Churchyard owls and beds of asphodel belong to books rather than
+to life. For the average citizen it may be valuable to know that the
+word Hippocrene does not mean the same thing as hippopotamus. From
+every point of view enlarging the vocabulary is an important part of
+education. Enlarging the vocabulary and developing an interest in
+literature as a means to cultivated leisure in adult life are entirely
+separate issues.
+
+I once asked a friend who is a biologist whether he was interested
+in modern poetry. He hesitated and replied that he quite liked
+_Evangeline_. I am almost certain that he had not opened Longfellow’s
+works since he was a schoolboy, unless he had received from an aunt
+one of those editions which are bound in mauve suède and sold for
+Christmas and birthday gifts. He was no less truthful than most of us.
+He displayed a motor reaction which can be evoked from many people who
+have been educated on the assumption that the teacher’s business is
+to cultivate “good taste.” If one of our leading dailies were to make
+favourite English poets the subject of a prize competition, it is safe
+to predict that Wordsworth would receive many more votes than William
+Blake. It would be interesting to ascertain the number of hours devoted
+after school age to the perusal of the works of Wordsworth and Blake
+by those who would vote for one or the other. I know of no one who has
+undertaken this task as a thesis for the Ph.D. degree; but I would
+hazard the surmise that the aggregate would favour Blake rather than
+Wordsworth. The modern teacher has abandoned the exegetical method in
+favour of the “play way.” But the advocate of the play way is no less
+certain that if he likes Shakespeare, his pupils ought also to like
+Shakespeare. If he is really interested in Shakespeare, and has an
+engaging personality, he may succeed so long as they remain under his
+influence. It does not follow that the pupil will carry into adult life
+the means of enjoying his leisure in a way that will not be a nuisance
+to his neighbours.
+
+In discussing the æsthetic aspect of education, it is difficult to
+exclude the intrusion of one’s private values. I am aware of this
+difficulty. Anything which I proffer to the discussion is of a very
+tentative nature. The cultivation of taste involves two separate
+issues. Conventionally it signifies the existence of some fixed
+standard of correct enjoyment. The cultivation of good taste in
+this sense is only justifiable if we have satisfied ourselves that
+philosophy can provide a rational sanction for the affirmations
+of æsthetic experience. If we have reached the conviction that the
+affirmations of æsthetic experience have no status in the Public World,
+we have no justification for interfering with another person who
+reads John Oxenham’s _Bees in Amber_ in preference to Conrad Aiken’s
+_Punch the Immortal Liar_, or the works of Miss Ella Wheeler Willcocks
+in preference to the sonnets of Edna St. Vincent Millay. I think
+experience would sustain the statement that people who habitually read
+Coventry Patmore or Francis Thompson are temperamentally different from
+people who prefer to read Osbert Sitwell or Carl Sandburg. I suspect
+too that such temperamental differences exist even in early childhood.
+They are therefore outside the realm of argument or education. On the
+other hand, experience convinces me that many would read poetry in
+adult life, if they had not been repelled in childhood by the sickly
+romanticism or pedantic archaicism of those writers who are usually
+exhibited as models of good taste. Possibly a number of people who read
+Mr. Kipling would not do so if they had access to more sophisticated
+forms of entertainment. Many others do not read poetry and rather
+despise those who do, because they have never realized that the subject
+matter of poetry is not necessarily circumscribed by a holistic view
+of sex or confined to the domestic affairs of the minor Greek deities.
+There is a legitimate sense in which taste can be cultivated. We may
+go through life impoverished, because we have never been introduced to
+sources of satisfaction which might enrich our experience. It is the
+proper function of the educationist to acquaint us in early life with a
+great variety of opportunities of socially agreeable behaviour. Having
+done this, he or she must leave us to select what is most appropriate
+to our temperamental peculiarities.
+
+The technique of education in its æsthetic aspect has received
+less thoughtful attention than its more practical problems. After
+a succession of ludicrous experiments, educationists now realize
+that the attendance of art galleries is not increased by forcing
+children to draw one white cone, a pyramid and two cubes piled up on
+a drawing-board. It is also recognized that a weekly period devoted
+to the tonic sol-fa notation does not make a nation musical. I would
+suggest that the disappointing results of æsthetic education are
+pre-eminently due to the fact that educationists have never recognized
+that æsthetic values do not belong to the public world. I would go
+further and suggest that more positive results might be achieved, if
+our educational practice were founded on a recognition that æsthetic
+preferences come within the proper domain of what I have called
+_privacy_. Education has too long been dominated by the æsthete
+who regards his own values as having some final and transcendental
+sanction. Because temperaments differ, æsthetic education can never
+leave a permanent impress on the majority of people, so long as it
+is dominated by a school of private opinion, whether that school is
+Shakespearian or Shavian, Realist or Vorticist. The rising influence
+of science, if it checks the influence of pontifical æstheticism is
+calculated to reinforce rather than curtail the æsthetic aspect of
+modern education.
+
+In _Science and the Modern World_, Dr. Whitehead has maintained the
+contrary view. He affirms that “in regard to the æsthetic needs
+of civilized society the reactions of science have so far been
+unfortunate.” I do not think that there is any historical justification
+for this assertion. During the Renaissance there was a very intimate
+connexion between the progress of biological science and the
+development of painting and engraving. Human beings and horses had
+been represented with some measure of biological fidelity in Greek
+plastic art. But realistic treatment of animals and plants in general
+was a late development of the Art of the Renaissance. Most of the
+descriptive biology of Aristotle, of Theophrastus, and of the Arabs was
+a dead letter when it filtered into modern Europe. The descriptions in
+the Greek and Arabic herbals were too indefinite to be adequate for
+purposes of identifying species without the aid of good illustrations.
+Anyone who will take the trouble to refer to the originals of Conrad
+Gesner’s _Natural History_ or Gerrard’s _Herbal_ will appreciate the
+statement that Dürer initiated a new epoch in biology by depicting a
+recognizable rabbit. It was no fortuitous circumstance that Leonardo da
+Vinci was both a distinguished anatomist and a distinguished painter.
+The naturalist of the Renaissance had to be an artist. There were no
+cameras. The tradition of Realism in Art developed side by side with
+the progress of medicine to meet a need which no longer exists.
+
+To-day we have cameras, and Realism in Art is declining. I venture
+to suggest that the invention of cinematography, though still in
+its infancy, is unfolding new artistic horizons. It is still common
+to find that educated people disregard its latent possibilities as
+Puritan England despised the stage. It is unwise to assume that
+Victorian ideas of Art have more finality than future generations will
+in all probability ascribe to them. Silas Marner, who had never seen
+a skyscraper or a dynamo, could not be expected to like the _Cabinet
+of Dr. Caligari_ or Capek’s _R.U.R._ For the same reason we should
+not expect Whitechapel school-children to enjoy Landseer and the
+Lake poets. To the Victorian æsthete a machine and a factory were
+necessarily ugly. The Immortal Stagyrite had settled the criteria of
+beauty two thousand years before. It is worthy of note that American
+industrialism rarely impresses the visitor with that drab monotony
+which is so characteristic of the English town. This may be partly
+because American education has been less dominated by the æsthetic
+predilections of a pre-scientific era in human history. The increasing
+importance of science in education need not react unfavourably on its
+artistic function. If it has done so, it is not because science has at
+any time dominated our conception of a cultural education. The cultural
+value of science has hardly been recognized as yet.
+
+
+§2
+
+However defined, education includes fitting the individual for some
+kind of productive activity. On this account the place of science
+as a part of vocational training is now securely entrenched in our
+educational system. The hard logic of economic necessity has forced us
+to make more and more concessions to natural science. It is doubtful if
+more than a handful of educationists see clearly that those changes in
+the structure of civilization which have necessitated such concessions
+have made scientific study of paramount importance in cultural
+education. The terms cultural and vocational are, by many people,
+still used coextensively with literary and scientific. It is true that
+science is not directly concerned with the æsthetic side of education.
+If in addition our definition of culture includes an intelligent
+orientation to human society, ignorance of science is incompatible
+with a cultured outlook in the present age. The special features of
+modern civilization depend on the extent to which scientific knowledge
+has been applied to the conquest of Nature by mankind. The picture of
+the physical universe which science offers for our contemplation is
+therefore the nucleus of what is socially most vital in our time.
+
+The task of giving science a place in our conception of cultural
+education presupposes a good deal more than the addition of obligatory
+science subjects to the curriculum. Chemistry is usually taught in
+universities so as to ensure that the student will be able to discharge
+with competence the work of an analyst in the public service. It
+is also possible to teach the same subject in such a way that the
+student gets some glimpse of the adventure of scientific knowledge,
+some insight into the method of science as a way of dealing with
+human experience, some apprehension of the challenge which throughout
+the ages science has issued to comfortable beliefs and established
+traditions. This attitude to the study of science is still rare among
+those who have been educated on exclusively scientific lines. The
+classically educated person can at least be said to have something
+which was once a culture. He has a more or less consistent attitude to
+the world around him. In spite of all that is said about the menace
+of scientific materialism, a consistent mental attitude is very rare
+in scientific men. They usually have two attitudes, one for the
+laboratory, one for Sundays and the domestic circle. This is partly
+because scientific education has been almost entirely vocational in its
+emphasis.
+
+That it is still necessary to emphasize the place of science in
+cultural education is a heritage of the humanistic revival. Until
+comparatively recent times the leading educationists of western Europe
+were agreed that the cultural side of education is satisfactorily
+accommodated by a study of two dead languages. The founders of the
+Grammar Schools were men who after a life-long devotion to Latin and
+Greek had found in the classical authors a link with the living past
+and a real source of æsthetic delight. Their pupils rarely progressed
+sufficiently far with the rules of accidence and syntax to acquire
+any genuine knowledge of classical literature or ancient history. The
+number of modern Englishmen who enjoy Scandinavian drama or Russian
+fiction through the medium of translated works is certainly greater
+than the number who deliberately read the classical tragedians in the
+original. Leaving out of account professional historians, the number
+of people who have been inspired to learn more about ancient history
+through dipping into Mr. Wells’ _Outline_ is probably greater than the
+number of those who as schoolboys acquired a taste for history from
+construing Xenophon, Thucydides, Cæsar and Quintus Curtius Rufus. The
+grammarians, in the words of Mr. Wells, were fumbling with the keys of
+the past to open the doors of a ransacked treasure chamber. It is now
+widely recognized that the results of classical education have been
+disappointing. In relation to the æsthetic side of education, it cannot
+be said to have promoted the growth of what Dr. Whitehead calls “a
+living art which moves on and yet leaves its permanent mark.” Socially
+it started at the wrong end. An intelligent orientation towards
+society presupposes a knowledge of the history of human society. It
+also presupposes on the part of the individual a vital appreciation
+of his own surroundings. Unfortunately, the obsolescence of classical
+education is not the result of a reasoned conviction of its cultural
+inadequacy. The influence of the grammarians declined because they
+could not meet the practical requirements of our age.
+
+Science came to occupy its present status in the school curriculum
+as part of a comprehensive change in educational outlook associated
+with the rise of the manufacturing class to political power. The
+aristocratic tradition in education, with its humanistic bias towards
+formal logic, Latin and Greek, sufficed so long as the Church and
+Law were the principal professions which attracted the sons of the
+well-to-do. The coming of the machine age opened up new horizons of
+professional activity necessitating prolonged and highly specialized
+training. With the development of new international communications
+came a greater demand for acquaintance with the living languages of
+a nation’s customers abroad. Initially the demand for science in
+education was justified on purely vocational grounds, a fact which has
+given scientific education on every step of the educational ladder a
+fundamentally utilitarian tendency. In our own time the demand for
+biological instruction as a school subject has been very largely
+motivated by a utilitarian objective. The public is told how important
+it is that our future citizens should realize that by studying the
+domestic habits of the mosquito biologists have made it possible for
+engineers to construct the Panama Canal. It is further argued that
+if our future citizens were brought up to entertain a more lively
+respect for them, in short, to give them a greater measure of financial
+support, biologists would very shortly eradicate house-flies, idiot
+children, bean-weevils and bed-bugs; make it possible for anxious
+parents to have a family of twelve girls at will and keep the working
+classes alive exclusively on tinned food.
+
+The tremendous development of scientific knowledge which followed
+the coming of the machine was a phenomenon whose social consequences
+could hardly be envisaged by those who put forward the plea for
+scientific instruction in the earlier part of the nineteenth century.
+To-day we can look back over the last century and a half on the growth
+of a form of civilization which owes its special characteristics to
+the power over nature which scientific knowledge has conferred. It
+is now possible to realize that an appreciation, not merely of the
+conclusions of science, but of the experimental temper of scientific
+reasoning, has become essential to the intelligent orientation of the
+individual to an environment more and more determined by the creative
+thought of science. The classical ideal which is compatible with the
+view that a man may rightly be considered educated and remain ignorant
+of man’s place in the physical universe, as depicted by science for
+our imaginative reflection, is an arrogant and impertinent pretension
+which thinking people will soon cease to countenance. Those who have
+pressed the claims of scientific education have concerned themselves
+very little with providing a substitute for what the advocates of
+classical humanism honestly attempted to achieve. The influence of the
+Utilitarian School of educationists has superseded what might be called
+the School of Grammatical Paleontology. One result is that education
+has been made accessible to a much greater proportion of people. There
+has grown up a generation of educationists who recognize that heaven
+does not necessarily lie about us in our infancy. On all sides we see
+the determination that children shall enjoy school. We now have in
+our midst the Aimiably Maternal School. There is a danger that the
+Aimiably Maternal educationists will encourage children to regard
+childhood as an end in itself; but it is to them that we must look for
+the development of the æsthetic side of education. They are replacing
+the cultivation of “good taste” by the aim of self-realization. They
+are giving _privacy_ its proper place in the theory of education. The
+domain of publicity--the task of emphasizing the cultural importance
+of science--still lies with the future. There are, it seems to me,
+two outstanding pre-requisites for the execution of this task, a
+recognition of the importance of biological instruction in the school
+and a closer relation between the teaching of science and of history in
+the university.
+
+
+§3
+
+A broader conception of the human significance of science will never
+be achieved until biology occupies a position of greater importance in
+the school curriculum. Biology contains within its province a point of
+contact with human life on the one hand, and the methods of an exact
+and experimental science on the other. Fortunately the educational
+value of biology is beginning to be recognized. The fact that biology
+has so recently been added to the school curriculum and that, by no
+means universally as yet, offers a singular opportunity for educational
+experiment. It is an opportunity which physics and chemistry,
+hampered by a heavy load of conservative tradition operating through
+cut-and-dried syllabuses and stereotyped textbooks, cannot provide.
+It is an opportunity which carries with it both responsibilities
+and dangers. The teaching of biology is in one way, and here lies
+the special opportunity, most fitted to initiate the pupil into the
+implications of the scientific outlook in human life. Biology handles
+the kind of matter, living matter, of which human beings are to us the
+most fascinating, entertaining and familiar varieties. On the other
+hand, and in this lies the chief source of danger, biology being a
+young science with a far greater diversity and complexity of subject
+matter, is less fitted to demonstrate the essentials of scientific
+reasoning than a more firmly grounded, older and more exact branch
+such as physics. We must face our task with a clear recognition of the
+danger that biological teaching will be made an excuse for supplanting
+the mental discipline of physics and chemistry by a miscellany of
+easily memorizable facts which illustrate no conclusions that can
+properly be dignified by the name of scientific principles. This is
+certainly what will occur if the Utilitarian school, with its emphasis
+on where house-flies go in winter, is given full scope in constructing
+our school syllabuses.
+
+In the early stages of the development of any branch of knowledge there
+is a period when it is necessary to amass facts indiscriminately,
+because the significance of particular classes of facts is not as yet
+apparent. For the study of living organisms in particular an enormous
+amount of detailed observation was essential before it was possible
+to formulate the mechanical problems which living matter presents for
+solution. In such an early stage it is a frequent and fruitful source
+of misunderstanding to dignify by the name of laws and theories,
+generalizations which are not scientific principles, but merely
+mnemonics. Biological textbooks are to this day full of architectural
+mnemonics. A pertinent instance is the germ layer theory. These have
+no relation to the generalizations of an exact science such as the
+Kinetic theory of gases or what is even more modestly called Avogadro’s
+Hypothesis. Biology in our generation has ceased to be merely an
+encyclopædia of descriptive information. It has to-day attained the
+status of an exact and experimental science. As such it is a child
+of the machine age. The realization of its new status is by no means
+universal even among biologists. This fact renders the danger to which
+I have alluded especially formidable.
+
+The birth of the doctrine of organic evolution, before the growth of
+the modern quantitative study of inheritance and variation, provided it
+with an experimental basis as a scientific theory, set biologists to
+the task of tracing hypothetical pedigrees. The amassing of an enormous
+volume of purely descriptive information acquired the reflected
+glory of those profound cosmological consequences which the concept
+of evolution implied. In the latter half of the nineteenth century
+the study of structure and activity became completely divorced. As a
+separate subject, focused to a large extent on clinical aspects of
+its subject matter, physiology branched off independently. Zoology
+ceased to be the scientific study of living animals, and became the
+architectural study of corpses and corpses malodorously mutilated in
+formalin. This development was not without consequences of some purely
+practical value. Increased knowledge of the life histories of many
+pests and parasites demonstrated the economic value of biological study
+to a parsimonious public. Without doubt such studies should continue
+to receive the financial support that their immense economic utility
+merits. They should be encouraged as technical developments of biology
+in the university. Their value is culturally irrelevant to our attitude
+towards the scope of biological teaching in the school. In the school
+the scope of biological teaching should be based upon the candid
+recognition that biology is primarily concerned with the Nature of Life.
+
+This will affect our practice in several ways, which can only be
+indicated here in very general terms. Elementary textbooks of zoology
+are written in such a way as to conceal the fact that anatomy was
+originally an experimental science. Galen had to ligate the ureters to
+convince the disciples of Erasistratus that the kidneys are the source
+of the urine. In textbooks of animal biology for beginners it is usual
+to describe the path of nervous impulse from the skin to the spinal
+cord and thence to the muscles, as if the reflex arc were something
+which is evident to inspection. A century and a half of continuous
+experimental enquiry elapsed between the work of Whyte, who first
+located the spinal cord as the meeting-place of “sensory” and motor
+impulses, and that of Waller, who completed the accepted schematization
+of reflex activity. It is of no educational value to be familiar with a
+textbook diagram of the reflex arc, unless the experimental evidence on
+which it is based is clearly understood. The teaching of biology can be
+as helpful as the teaching of chemistry to illustrate the methods of an
+experimental science. This implies that the teaching of animal biology
+must be emancipated from the shackles of the Darwinian tradition of
+pure morphology. Practical work must include dissection and microscopic
+observation; but dissection and microscopic observation must be
+supplemented by ample demonstrations of an experimental kind.
+
+To a very large extent the construction of our syllabuses will
+determine the method of presentation. The cultural value of all science
+teaching is at present hampered by a failure to emphasize the logical
+development of its subject matter. In the teaching of biology the
+facts of animal structure should only be presented in so far as they
+illustrate, and are strictly relevant to, an understanding of the
+characteristic properties of living matter. It is still customary
+in universities to begin the study of the anatomy of the frog by
+describing its external features. This is a purely architectural
+attitude to adopt towards an animal. If we must start with the
+external features of the frog, let us first study some characteristic
+manifestations of its ever-changing reactivity, such as colour response
+or mucus secretion, and having defined the experimental conditions
+which determine these reactions, proceed to examine their structural
+basis in as much detail as is relevant to our purpose. It is essential
+that continuity of theme should be developed in relation to a
+consideration of the organism as a dynamic system.
+
+The teaching of biology for its cultural value also implies the need
+for the fullest co-ordination with the teaching of chemistry and
+physics. As every educationist will agree, this is desirable not only
+from the cultural standpoint, but to get the best practical results.
+Here there should be no difficulty for the scientifically trained
+teacher. Such simple demonstrations as the experiments of Lavoisier
+and Priestley on respiration, or of the action of a digestive ferment,
+will reinforce the teaching of chemistry and may even quicken an
+interest in chemistry and physics, where it had not existed before.
+If an elementary introduction to Mendel’s laws illustrated on a
+comparatively inexpensive scale with poultry be included in the later
+stages of a school course, the teacher could take the opportunity of
+experimentally demonstrating the elementary laws of probability. This
+would provide a helpful introduction to a branch of algebra which in my
+opinion is relegated to an unnecessarily and regrettably late stage in
+mathematical education. Being the youngest born, biology in the schools
+is the Cinderella of the sciences. Some of our headmasters appear
+to think that anyone is good enough to teach it. It is obvious that
+desirable results will not be accomplished, if biology is taught by
+teachers with an exclusive training in descriptive biology unfortified
+by the study of physics and chemistry.
+
+The æsthetic satisfaction derived from contemplating Man’s place in
+Nature will itself endow the study of biology with cultural value for
+a few people. But as a school subject biology can make a more general
+appeal to consideration as the basis of a new humanism. Few things in
+human life, if any, are the source of more universal inconvenience
+than sex. The difficulty of satisfying our appetite for food does not
+present any special difficulty so long as society provides us with
+the opportunity for work with adequate remuneration. In the domain of
+sex the difficulty of accommodating physiological necessity to social
+convenience extends to all ranks of society. In the nursery rhymes
+of childhood, in the fiction on which our adolescence is fed we are
+accustomed to romantic expectations which permanently unfit us for the
+realities of sexual experience. In adult life religious teaching and
+the legal code reinforce the magical view of sexual behaviour. Even
+among educated people few possess a secular vocabulary with which to
+discuss sex intelligently. It would be better for a child never to have
+heard of Plato than to reach puberty without a scientific knowledge of
+the nature of sex. If the introduction of biological instruction into
+the school sweeps away the holistic idea of romantic love, and helps us
+to envisage the difficult problem of congenial mating as a complex of
+diverse and separable issues, it will achieve the greatest reform which
+has hitherto been made in the educational process.
+
+
+§4
+
+Science will not occupy its proper place in cultural education so
+long as the scientific man himself is a man of narrow intellectual
+interests. In the university the task of educating a scientifically
+trained student with a broader outlook than we are accustomed to expect
+must begin in the way we teach science. To a minor extent this will be
+encouraged by breaking up our existing -ologies into smaller units. A
+biologist should not be prevented from studying physical chemistry to
+an advanced stage because he has neither time nor inclination to devote
+to a tedious routine of analysis devised for those who are going to
+take positions in dye-works. A physicist should be permitted to know
+something about the nature of biological enquiry without wasting half
+a year cutting hand-razor sections of stems and learning the names
+of pressed flowers, fish-bones and beetles. But the real romance of
+science, the realization of scientific understanding as a great mental
+adventure, will only be achieved when our teaching of science is
+brought into much closer relation with the study of history.
+
+There are several good reasons why the historical background of a
+scientific problem should always be brought into sharp relief in
+university and for that matter in school teaching. The student of
+mathematics who in the course of a single introductory lecture on
+the calculus completes the differentiation of the function _x^n_
+might be encouraged by the knowledge that he has covered in an hour a
+problem which took the generation of Barrow, Newton and Leibniz about
+forty years to solve. I venture to think that the introduction of a
+little history would make the first steps to algebraic symbolism more
+interesting at the school stage. At present it is usual to teach one
+subject algebra, in which certain conventions are laid down like the
+rules of bridge, and another subject geometry, in which the pupil
+learns at a comparatively advanced stage that the proposition
+_a(b + c) = ab + ac_ physically corresponds to a statement about the
+addition of areas of rectangular figures. The child is rarely, if
+ever, told how, from the discussions of such geometrical problems, the
+Hindu rhetorical algebraists of the first six centuries A.D. were led
+to deduce certain rules governing the properties of numbers, and how
+subsequently the Arabs simplified these rules by the development of a
+symbolic shorthand. Most elementary textbooks of physics contain _ad
+hoc_ proofs of certain verifiable consequences of the inverse square
+law in electrostatics and magnetism. Why anyone should ever have
+attempted to investigate the applicability of the inverse square law
+to electrostatic and magnetic attractions is rarely divulged. A little
+information about Newton’s interpretation of Kepler’s laws and the
+development of the theory of gravitational attractions subsequent to
+Newton’s work would suffice to show how natural it was that Cavendish,
+Coulomb and Gauss should test out the inverse square law in electricity
+and magnetism before exploring other possibilities.
+
+Sometimes for an entirely different reason a knowledge of scientific
+history will assist the teacher to a clearer exposition. The
+logical technique initially employed in elaborating new scientific
+generalizations is often capable of a much greater measure of
+simplification. The teacher who understands the history of his own
+branch of science will be more likely to realize this. It is generally
+held that electricity is a suitable branch of science to teach at
+the school stage. Electricity is much more directly related to the
+interests of the average boy than any other branch of physical
+science. In everyday life it is the phenomena of current electricity
+which we encounter chiefly. Historically, current electricity was
+not subjected to exact treatment till the phenomena of electrostatic
+attraction and of magnetism had been considerably elaborated with the
+aid of mathematical conventions drawn at first from the theory of
+gravitational attraction and later from the study of hydrodynamics.
+It thus happened that Ampere defined the unit of current in terms
+of magnetic potential. For this reason textbooks of physics usually
+introduce current electricity after a preliminary treatment of
+frictional electricity and magnetism. To-day the international unit
+of current is based on electrolysis. The chemical definition of
+current involves nothing more than the use of simple proportion.
+Given a generator and a chemical unit of current the definition of
+resistance follows empirically from studying changes in the dimensions
+and materials of the circuit. The idea of electromotive force can be
+deduced by studying the effect of changing the generator or tapping
+off current from different parts of a fixed circuit. Ohm’s law then
+emerges self-evidently in the course of the enquiry. At no point is
+it necessary to introduce difficult ideas imported from magnetism and
+beyond the range of the pupil’s mathematical knowledge. In testing
+out Ohm’s law, in measuring electromotive force or resistance,
+the galvanometer is only used as a null-point instrument. For an
+intelligent grasp of the meaning of current, potential and resistance
+it is therefore only requisite to know that magnets exist and that
+a suspended magnet is deflected in the neighbourhood of a current.
+Examination syllabuses are customarily constructed on the assumption
+that it is impossible to teach current electricity without first
+teaching frictional electricity and magnetism. There is no good reason
+why frictional electricity and magnetism should be introduced at an
+early stage. The only reason why the fundamental ideas of current
+electricity are made to appear so formidable is to be found in the
+history of the subject. The teacher who knows the history of his
+subject thoroughly will be more likely to realize this.
+
+The teaching of current electricity illustrates the possibility of
+co-ordination in science teaching in the school. Faraday’s laws of
+electrolysis are generally demonstrated at a fairly early stage in the
+teaching of chemistry. At this point the definition of the electric
+current and its measurement is most appropriately introduced. In a
+school where biology is taught a physical model will prove valuable
+to demonstrate the effect of fluid friction on the flow of liquids in
+explaining why blood spurts from an artery and trickles from a vein. By
+what Dr. Wrinch calls the principle of true analogy the same mode may
+be used to illustrate the ideas of potential, current and resistance.
+
+But the fundamental importance of the historical method in science
+teaching lies in the fact that no perspective of the relative
+significance of different types of scientific hypothesis, and no
+realization of the intellectual potentialities inherent in a scientific
+generalization, can be obtained without a knowledge of the kind of
+intellectual difficulties that new scientific ideas met with when they
+were first formulated. Half-hearted attempts are made to introduce
+historical information into scientific textbooks. They usually lay more
+emphasis on the outstanding contributions of individual men of genius
+than upon the development of ideas. If historical information is only
+used as a means of promoting ancestor worship, it does more harm than
+good. Histories of science are not invariably written by men who have
+a clear perspective of the general intellectual, and it might be added
+economic, tendencies of the periods with which they are dealing. For
+that reason they fail to inspire a critical and enquiring attitude
+in the reader. Scientific enquiry is essentially progressive. Yet
+scientific study does not invariably produce a progressive intellectual
+outlook. It is, I believe, because so few who study science attempt
+to envisage the generalizations of their subject in their historical
+perspective, that the product of a scientific type of education is
+often a more conservative type than the historian or even the classical
+humanist.
+
+A knowledge of the historical background of science is a necessary
+prerequisite to an apprehension of science as an intellectual adventure
+and a challenge to traditional ideas. To possess such an historical
+background necessitates a knowledge of human history as well as a
+knowledge of science. The creation of a new humanism based on the
+claims of natural science is a task which will require a reorientation
+of historical and scientific studies throughout the educational system.
+In the school this task is being simplified by the revolt against a
+tradition which laid too much emphasis on purely national issues.
+Teachers of history are ceasing to believe that children should be
+taught to draw maps of the battles of Oudenarde and Malplaquet. The
+history of ideas is beginning to assume more prominence than the
+technicalities of military strategy.
+
+In a few universities departments have been founded with the aim of
+studying the history of science. There are at present all too few
+scientists who like Dr. Singer are capable of promoting a deeper
+knowledge of the progress of science. The history of science is
+not a history of pure deduction. It is not a meaningless incident
+that Leeuwenhoek, a Hollander, used pepper suspensions to make the
+first cultures of micro-organisms. It is not a mere coincidence that
+Leeuwenhoek and Hartsoeker simultaneously discovered the spermatozoon.
+The first microscope was the signal of a new era in biological science.
+The invention of the microscope followed shortly after Descartes
+formulated the laws of refraction of light. It is a task for the
+historian of science to place this sequence in its proper relation to
+the interests stimulated by the great navigations, and the struggle
+for sea-power. A great measure of encouragement to the study of the
+history of science in the university would, I believe, infuse new ideas
+into the study of both history and science. It would also re-establish
+a vital relation between philosophy and science. Instruction in the
+history of scientific thought could be a nucleus for the synthesis
+of each fragment of the mosaic of natural knowledge into a coherent
+picture of the public world as we know it through the medium of
+scientific enquiry. The philosopher of the future may well be the
+historian of science.
+
+
+
+
+XII. THE PUBLICIST STANDPOINT AND HOLISM
+
+  “I am no coward who would seek in fear
+  A folk-lore solace or sweet Indian tales:
+  I know dead men are dead and cannot hear
+  The singing of a thousand nightingales...”
+                         James Elroy Flecker
+
+
+§1
+
+The history of philosophy has witnessed a succession of makeshifts to
+accommodate the utilitarian claims of science and the rival demands
+of what Robert Briffault appropriately calls custom thought and power
+thought. At every stage in the advance of scientific knowledge new
+territories have been wrested from the domain of custom thought and
+incorporated within the legitimate province of scientific method.
+Each new annexation has called forth some new compromise to meet the
+requirements of power thought. Scientific hypothesis is ethically
+neutral. The politician insists that his theories of human conduct
+must present an aspect of academic plausibility. Darwin’s doctrine
+undermined the complacent dualism which had kept philosophy and
+natural science in water-tight compartments for centuries. It produced
+a vigorous revolt against supernatural beliefs. In our generation
+unbelief has spread to all sections of the community with results that
+are disquieting to those who pursue the study of philosophy in the
+hope of rationalizing their social prejudices. It is high time for
+make-believe to stem the tide of unbelief. Inevitably a new compromise
+emerges to meet the new situation. Beneath its downy wing holism
+takes all that mechanistic science can offer to industry and all that
+statesmanship can cull from metaphysics.
+
+“The time has now come,” writes Dr. Haldane, “for giving decent
+burial to the mechanistic theory of life in the same grave with
+the vitalistic theory.” I agree with Dr. Haldane in so far as many
+questions which were contested thirty years ago by those who called
+themselves mechanists and vitalists have ceased to be regarded as being
+so fundamental as the contestants imagined or even as being amenable
+to a final decision. Although the publicist standpoint is admittedly
+a rehabilitation of the mechanistic theory in the light of those
+biological developments which have brought into being the behaviourist
+standpoint in psychology, I have myself preferred to use the term
+_publicist_ for my own point of view. It is rather tiresome to be
+forced to answer for every misdemeanour of somebody else who happens to
+call himself a mechanist or a behaviourist. I can therefore sympathize
+with Dr. Haldane’s disinclination to accept the vitalistic label for
+his own beliefs. I differ from Dr. Haldane in thinking that we are any
+nearer to a final reconciliation between a difference of philosophical
+outlook that arises from the fact that philosophers have different
+temperaments. If we have outgrown the differences of statement which
+underlie the controversy between the older vitalistic and mechanistic
+standpoints, we have not outgrown the differences of temperament which
+underlie the existence of the two theories.
+
+I have no disposition to state dogmatically the possibility
+of explaining all the properties of living matter in whatever
+physico-chemical terms will be employed two thousand years hence. Still
+less am I willing to be responsible for the billiard ball theory of
+matter which both Dr. Haldane and General Smuts have identified with
+the mechanistic conception of life. I am content to foresee enormous
+possibilities for the extension of physical interpretations of the
+properties of living matter. I fail to see how human knowledge will
+progress on any logical assumption but that implied by the principle
+of mechanism in its most general terms. I am not able to accept Dr.
+Haldane’s belief that the traditional methods of physiology are
+useless in discovering the properties of conscious behaviour, though I
+should hesitate to predict, except in a very tentative way, how far we
+shall progress in this direction. If I have seemed to exaggerate the
+possibilities inherent in the future of biological enquiry, my excuse
+must be that my aim is to stimulate interest in a new philosophical
+outlook. If there is such a person as the dogmatic mechanist, his views
+are not what I imply by the publicist standpoint.
+
+When all this has been said, there still exists a very radical
+difference between the publicist standpoint and the holistic to
+which Dr. Haldane subscribes. That difference lies in the fact that
+the holist denies the possibility that a certain type of logical
+procedure is capable of establishing relations between certain realms
+of experience. Nobody denies that such relations remain at present
+unascertained. Any dogmatism that comes into the discussion is implicit
+in the holistic theory. Dr. Haldane’s position is not merely a
+rejection of dogmatic materialism. “I am whole-heartedly in agreement,”
+he writes, “with General Smuts in believing that anything which can
+properly be called scientific physiology is impossible apart from the
+assumption of what he has called holism.”
+
+Of holism as a philosophy of biology enough has been said elsewhere.
+It contains within it no promise of future progress. Dr. Haldane has
+endeavoured to persuade us that this is not so. I am not able to
+follow his argument. We have wasted time, he assures us, in trying to
+understand the _mechanism_ of kidney secretion, when we should really
+have been striving to find out how the kidneys... “engage in their
+function of keeping normal the diffusion pressures of water and various
+other non-colloid constituents of the blood.” A mechanist, even if we
+grant that he is misguided and presumptuous in hoping to elucidate the
+mechanism of secretion, is equally concerned with solving the problem
+which interests Dr. Haldane. The physiologist who sets out to tackle
+it will proceed in the same way as a mechanist, whether he calls
+himself one or not. He will not first postulate a wholeness of the
+non-colloidal constituents of the blood inexplicable in terms of the
+individual constituents themselves.
+
+The physiologist studies the properties of the muscle-nerve preparation
+because he believes, rightly or wrongly, that by so doing he will be
+guided to interpret how muscles and nerves play their respective parts
+in the behaviour of a whole animal. Dr. Haldane himself has devoted
+years of research to elucidating the properties of hæmoglobin. I
+presume, he has done so in the hope of throwing light on the way in
+which the supply of oxygen to the tissues is regulated. Most of his
+brother physiologists would agree that Dr. Haldane’s distinguished
+researches on the physico-chemical properties of a respiratory pigment,
+which is a very small part of the economy of an animal, do tell us a
+good deal about what to expect in the behaviour of the organism as a
+whole. Whatever Dr. Haldane may say on the platform he is as good a
+mechanist as anyone else in the laboratory. Throughout a distinguished
+career of research he has consistently concentrated his attention upon
+certain limited parts of organisms. His statement that physiology is
+impossible without holism must be taken as a _jeu d’esprit_. So long
+as biology was dominated by the Aristotelian concept of individuality
+it remained descriptive. Physiology began when biologists undertook
+the task of interpreting the behaviour of the organism as a whole by
+studying methodically the behaviour of its constituent parts. If it be
+suggested that there is any other physiology, there is no trace of its
+existence.
+
+Perhaps the appeal of holism is partly due to the curious circumstance
+that physiologists are notoriously mechanistic about the aspects of
+physiology they study themselves, and hardly less often vitalistic
+about aspects of physiology with which they are unfamiliar. The divorce
+of morphology from experimental biology after the rise of the natural
+selection theory tended to produce the zoologist who is exclusively
+preoccupied with the anatomy of dead animals, and the physiologist
+who is exclusively preoccupied with the casualties of the hospital.
+In another place I have attempted to show that Dr. Haldane could
+find in modern genetics the clearest evidence that the biologist
+only progresses when he interprets his data in the same way as the
+physicist or chemist interprets his. In another branch of physiology,
+which like genetics lies outside the domain of the clinician on the
+one hand and the physical chemist on the other, Dr. Haldane will not
+find that the work of Sherrington and Pavlov provides abundant evidence
+that the holistic attitude is less impotent to suggest new lines of
+experimentation on reflex action or is more useful in promoting an
+understanding of the process of learning.
+
+Laying aside the purely biological aspect of the holistic attitude,
+there are some more general issues which remain to be discussed. It
+is never easy for a hostile party to do justice to the standpoint
+of another school of opinion. I hope therefore that I shall not be
+accused of drawing a caricature of the holistic theory. To avoid
+doing so I shall quote freely from the writings of those who support
+it. Holism, as I understand it, differs from the primitive animism
+which sees a personal reality behind or within physical objects. It
+differs from vitalism which sees an essential gulf between the living
+and the non-living. It differs from the common-sense dualism which
+invokes Mind as a separate and irreducible concept in dealing with the
+characteristics of “conscious behaviour.” The difference lies in this,
+that entirely new properties emerge at _various_ levels of existence.
+_Between_ these levels we can operate successfully with the atomistic
+logic of science, interpreting the properties of a complex system from
+a study of the properties of its several constituents. _At_ these
+levels we encounter new properties “which,” in the words of General
+Smuts, “could never have been predicted from a knowledge merely of the
+parts.” General Smuts mentions under the terms Matter, Life and Mind
+three principal oases within this desert of uncertainty. Even these
+do not constitute regions within which the continuous extension of
+scientific method may be applied successfully. Within the territory
+of matter “the molecules of water and carbon dioxide are real wholes
+with new emergent properties.” Thus physics, chemistry, biology and
+psychology are in Dr. Haldane’s terminology “independent sciences.”
+
+As far as I am able to see, there is no room for disagreement about how
+the scientist proceeds within these prescribed territories. Scientific
+generalizations are attempts to show how the characteristics of complex
+systems can be inferred from the properties of their constituent
+parts. This means, more specifically, when the problem can be reduced
+to mathematical symbolism, that an equation which defines the four
+dimensional relations of any system will contain no terms that are
+not present in some or other of the equations which determine the
+space-time relations of the constituents of the system. This procedure,
+admitted Forsyth (1929) in a recent paper delivered to the British
+Association, “is very largely justified in principle and by results.”
+He continued to remark, in conformity with the standpoint developed
+in these essays, that “the question is not that of a division of
+spheres or levels of existence, some of which are capable of complete
+explanation on mechanistic principles, while others are incapable...
+for there is no sphere which is not in any degree susceptible of the
+application to it of the terms and categories of mechanism.”
+
+  “Nevertheless,” he contends, “it is gradually coming to be
+  recognized that this procedure gives only a partial explanation
+  of _any_ natural process. There is, in any complex process, a
+  principle of synthesis involved, such that, instead of the whole
+  being the mere sum of the parts and being explicable by the mere
+  composition or combination of the parts, it is rather the case that
+  the parts can only be explained by reference to the whole, since
+  they are modified by their relation to it. If so, mechanism must
+  be supplanted, or at least supplemented, by a mode of explanation
+  that gives due regard to this. This principle of wholeness or unity
+  is exemplified in many different spheres of fact, e.g. in atomic
+  structure, in chemical synthesis, in the life of an organism and
+  even in the character of the single life-cell, in the processes
+  of perception and volition, and also in so-called reflex action,
+  in the development of personality and the attainment of social
+  control. Holism, then, signifies that everything in the universe is
+  in some form or another, and in greater or less degree, potentially
+  or actually, an organic whole; that as anything develops to a
+  fuller realization of its potentialities or a fuller perfection
+  of its nature, it becomes more truly such a differentiated and
+  yet unified whole; and that, by implication, the universe itself
+  is an infinite organic whole.... This involves that nothing in
+  nature can be explained merely as the result of preceding processes
+  or anterior stages of development. The lower or simpler is the
+  condition without which the appearance of the higher or more
+  complex would be impossible; but the development to higher levels
+  is possible at all only through the impulse to organic unity or
+  synthesis under the controlling influence of the infinite whole.”
+
+There exists no difference of opinion concerning the statement that
+there emerge at different levels of complexity in natural phenomena
+specific properties which cannot as yet be deduced from a knowledge
+of simpler systems. Holism seems to imply the further qualification
+that such properties will never be interpreted in this way. If I am
+right in my understanding of the holistic standpoint, I am at liberty
+to leave the onus of proving so dogmatic a conclusion on the shoulders
+of those who assert it. I am prepared to go further and point out
+certain difficulties in the way of proving it, difficulties which,
+in the existing state of knowledge, appear to me to be insuperable.
+The first is that of explaining why, if physics, chemistry, biology,
+etc., are intrinsically independent types of enquiry, it happens that
+there exist such extraordinary similarities in their procedure. The
+use of the phrase “scientific method” implies that such similarities
+do in fact exist. Dr. Haldane’s many distinguished contributions to
+the advance of physiology might be cited to show how much biology has
+in common with physics and chemistry. A second difficulty which arises
+is of a different kind, and illustrates the fundamental similarity
+of temperament which unites the vitalistic and holistic theories.
+Scientific investigation is constantly shifting the levels at which
+new irreducible concepts must be invoked. This permits us to entertain
+the suspicion that _emergent_ properties are only properties about
+which we are ignorant. We are under no necessity to regard the present
+classification of the sciences as anything more than a convenience
+for arranging time-tables in educational institutions. Before the
+enunciation of the first law of thermodynamics by Mayer and Joule,
+heat was a branch of physics quite as separate from mechanics as is
+chemistry from physics to-day. Organic chemistry to Henry was not, as
+it is to our generation, the chemistry of the carbon compounds. It was
+a field in which emerged something “peculiar to animated bodies and
+superior to and different from the cause which has been called chemical
+affinity.” In the same year as that in which Henry expressed this view
+Wöhler succeeded in synthesizing urea. Why should we be so certain that
+our present classification of “independent” sciences will, like the
+poor and the Roman Church, be always with us? To this question I can
+see no appropriate reply from the holistic point of view. Unless holism
+can provide us with a clue that will enable us to distinguish whether
+an impasse in scientific enquiry is due to the imperfection of our
+knowledge or to the emergence of new properties as “creative” entities,
+its acceptance could only have the sinister effect of holding back
+scientific investigation.
+
+On its negative side the holist goes much further from what might
+be called a centre programme than does the dogmatic mechanist. The
+principle of mechanism or experimental determinism is compatible with
+the recognition of different levels of complexity or wholes; for what
+is analysable is complex, and what is complex consists of interrelated
+parts which together constitute a whole. Holism on the other hand
+provides us with no explanation of why the principle of mechanism is so
+astonishingly successful. The logic of science is inadequate according
+to General Smuts. Dr. Haldane asserts that the method of the biologist
+is different from that of the physicist. We are not told how we can
+proceed to invent a new and equally successful logic. We are not told
+in what precise respect the method of the biologist does differ from
+that of the physicist. On its positive side holism leaves us waiting
+for a new revelation. Holism is sometimes referred to by its advocates
+as a category, sometimes as a principle. What the _principle_ of holism
+can do for us remains to be seen. Its popular appeal resides in its
+promise to restore to ethical values a rational basis. I suspect that
+this promise is a general election promise.
+
+Though holism does not assume, like the cruder forms of vitalism, a
+specific élan vital or entelechy, it differs from the less explicit
+vitalistic theories in detail rather than essentials. In a similar
+way, the alternative view which I have called publicism is a modern
+development of the mechanistic conception of life. What I define as
+the publicist standpoint in philosophy is distinguished from the
+traditional mechanistic attitude in physiology by extending the limits
+of verifiable knowledge. To a large extent traditional mechanistic
+physiology investigated the behaviour of an organism in so far as
+its behaviour can be predicted, when all synchronous conditions
+are rigidly controlled. It adopted a frankly agnostic attitude to
+those characteristics of behaviour in which the antecedent situation
+is pre-eminently significant to the co-ordination of stimulus and
+response. The Vitalist school recognized the existence of a definite
+problem in claiming that a complete solution of the Nature of Life
+must take into account the problem of consciousness. They failed to
+indicate the precise requirements of the problem, and they therefore
+failed to suggest the requisites for its solution. Their assault upon
+the mechanistic position collapsed, because they did not state what
+precise characteristics of the behaviour of living systems are defined
+by the term consciousness. If the concept of consciousness is to be
+made clear, it is first necessary to state what properties of the class
+_living systems_ are denoted by its use. This necessitates a definition
+of the characteristics of conscious behaviour, and an investigation of
+the way in which it is possible to investigate them. Only when this
+task is accomplished, can we claim to have undertaken a philosophical
+exposition of the Nature of Life. Vitalism failed to define the concept
+of consciousness, because it did not make the necessary distinction
+between its public and private components. The characteristic of all
+essentially private statements is the supposition that the means is
+referable to the end. The characteristic of all essentially public
+propositions is that the end is considered in connexion with the
+means. Traditional mechanism disregarded the problem of consciousness.
+Traditional vitalism assumed that it is impossible to discuss the
+characteristics of conscious behaviour without introducing teleological
+implications. The supreme philosophical importance of the work of
+Pavlov’s school lies in the fact that it has inverted the traditional
+way of looking at the problem of consciousness.
+
+In stating the essential features of the publicist standpoint, I
+shall indicate first its significance in current biological thought
+and second its attitude to the scope of philosophy. In its purely
+biological aspect the publicist standpoint recognizes the folly of
+stating dogmatically the possibility of reducing all the properties
+of living matter to physico-chemical terms. On the other hand it
+recognizes that biology increasingly makes use of physico-chemical
+concepts. It also recognizes that we can at present foresee no limit to
+the successful application of physico-chemical concepts to its subject
+matter. It recognizes the fact that there is no immediate prospect
+of reducing the analysis of some of the properties of living matter
+to the level of pure physics and chemistry. It also recognizes that
+biology has advanced conspicuously in those regions where the biologist
+adopts to the subject matter of his enquiry an attitude similar to
+that of the physicist in approaching the realm of inanimate nature.
+In particular it sees no necessity for the introduction of teleology
+into the study of the evolution or behaviour of living beings. It goes
+further than the older mechanistic outlook in explicitly renouncing
+the traditional dualism of mind and matter, since it envisages the
+possibility of indefinitely extending the study of behaviour in
+terms of reflex action. The publicist standpoint does not assert the
+possibility of disproving the validity of animistic concepts which have
+dominated biology in the past, and still persist in a more or less
+attenuated form. It relies on the increasing measure of success which
+accompanies the application of quantitative and experimental methods of
+investigating evolution and behaviour to supersede them. In biology as
+in physics magical views fall into desuetude, because more profitable
+ways of dealing with phenomena take their place.
+
+Since philosophy itself is part of the behaviour of a particular
+organism, the scope of philosophy must, from the publicist standpoint,
+bear examination in the light of modern biological concepts. In the
+external world of modern physics the distinction between _substance_
+and _form_ has been superseded. In the public world of science, i.e.
+the external world of physics enlarged to take in the subject matter
+of biology, the distinction between mind and matter does not remain
+fundamental. What is fundamental is behaviour. This public world is the
+domain of socialized belief. Whatever cannot be incorporated in its
+ever-widening territory must remain impenetrable through the medium
+of discourse. Only propositions that deal with behaviour in its more
+extended sense have the property of _publicity_ or social reality.
+Reality as a goal of philosophical enquiry is equivocal, since inborn
+temperament, digestive activity, erotic preoccupations and various
+other factors decide whether to a given individual the constituents
+of the public world or of his own private world are more real.
+Propositions that have publicity are ethically neutral. The hope that
+philosophy can find a sanction for values is therefore illusory.
+
+
+§2
+
+From the publicist standpoint the business of philosophy is to resolve
+the problems of human thought into their public and private components.
+The public component of the problem of consciousness is the analysis
+of the characteristics of “conscious behaviour.” The private component
+offers no profitable basis for discussion. Because traditional
+physiology has failed to recognize that the concept of consciousness
+has a public component, it has been natural to assume that a
+mechanistic explanation of consciousness is pure nonsense. Biological
+progress has annexed the study of conscious behaviour from the province
+of the private worlds. To the private worlds belong values. Though
+differences in values are exaggerated by differences in distribution
+of wealth and opportunities of education, there is no prospect that we
+shall reach any general agreement by attempting to rationalize them.
+In this sense the publicist standpoint is pluralistic. On the other
+hand the domain of the public world is always encroaching upon the many
+private worlds. In that sense the publicist standpoint tends towards
+monism as a limiting case. It offers no short cut to finality. It
+recognizes the slow accumulation of scientific knowledge as the only
+road to the gradual socialization of beliefs.
+
+In providing no hope for a rationalization of ethical values, the
+publicist standpoint comes within the category of the somewhat diverse
+schools of opinion to which Bertrand Russell refers as the New
+Realism. If it were possible to prove that a particular set of values
+is the correct one, a great service could be rendered. People would
+then be able to argue about human conduct and artistic productions
+without losing their tempers. I fail to see that holism contains any
+promise of achieving a consummation so devoutly to be wished. Ethical
+systems, as Mr. Russell observes, are usually found to contain a _non
+sequitur_. Ethical values represent the private component of social
+behaviour. Whether the public component will ever come within the scope
+of physiology remains to be seen. Many thoughtful people have been
+antagonized towards the mechanistic conception of life, because they
+associate it with rash and superficial views about human relationships.
+This is an intelligible but not necessarily a logically justifiable
+reaction to the naïve self-confidence with which some eugenists, the
+“histriometers” and other schools of “intelligence” testers have drawn
+pretentious conclusions from the resources of immature biological
+theories and inadequately developed biometrical methods. With such
+grotesque simplicity did Descartes apply to the physiology of Man
+the embryo mechanics of his own time. In reality nothing inherent in
+the most dogmatic assertion of the mechanistic conception of life is
+logically inconsistent with recognizing the possibility that biology
+has many new truths to unfold before sociology can securely build its
+foundations on biological theory, the likelihood that sociology must
+for long pursue its independent investigation of the natural history
+of the human species before it is ready to draw extensively on the
+resources of biology. Only during the first half of the nineteenth
+century did the concept of Conservation of Energy initiate the era
+of modern physiology. Only during the latter half of the nineteenth
+century did physical chemistry begin to elucidate those phenomena of
+osmosis, colloidal solution and membrane potential now regarded as
+fundamental for a mechanistic analysis of the living cell. We have
+therefore no reason to suppose that biologists have elucidated in
+their own field all those principles which will assist the historian
+and the anthropologist to advance further in their studies. Arrogant
+and premature generalizations of individual biologists (not always,
+or even, I suspect, generally, of the mechanistic persuasion) are
+regrettable. They do not justify an attitude of distaste for the
+mechanistic conception of life. I have usually observed that the
+disposition to interpret the whole field of sociology in narrowly
+conceived biological terms is associated with a strong antipathy to the
+physico-chemical interpretation of vital phenomena.
+
+In its inability to rationalize values many people will see a serious
+limitation of the publicist standpoint. From the days of the
+Schoolmen, philosophy has been the “divine science.” It has become
+so customary to regard philosophy as the handmaid of theology and
+politics, that Henry Sidgwick and others have refused the use of
+the term philosophical for a point of view which does not meet this
+requirement. We justify this by assuming that the fabric of society
+would dissolve, if we believed that our ethical notions contained no
+element of finality. It follows that the materialist is to be regarded
+as a bad man, and scepticism is coupled with immorality, though there
+is nothing in the root meaning of the word morality to suggest why
+this should be so. In _Science and the Modern World_ Dr. Whitehead
+censures the materialist philosophy of the nineteenth century,
+because, he declares, it “emphasized the given quantity of material,
+and thence derivatively the given nature of the environment. It thus
+operated most unfortunately upon the social conscience of mankind.
+For it directed almost exclusive attention to the aspect of struggle
+for existence.”[10] I am unable to understand why the political and
+ethical shortcomings of the nineteenth century should be attributed to
+the influence of materialistic philosophy. The number of materialistic
+philosophers was far less than the number of persons who responded
+to the appeal of the Tractarian Movement. The Lancashire mill-owners
+who were getting rich quickly were the type of men who attended their
+Nonconformist conventicles with regularity and subscribed to the London
+Missionary Society. Against the view that society must necessarily be
+based on a struggle for the means of subsistence continental Socialism
+appeared, rightly or wrongly, as a vigorous reaction; and continental
+Socialism was the only political movement which can rightly be said to
+have been explicitly dominated by a materialist philosophy. I cannot
+discern that there has been a very close historical connexion between
+people’s religious, philosophical and political views on the one hand
+and their social conduct on the other. It is not easy to explain why
+the French revolutionaries were anti-clerical and deistic, while the
+first chartists and pioneers of trade unionism in England were in close
+touch with the Evangelical Revival. Christianity, with its oriental
+insistence on the enmity between flesh and spirit and the vanity of
+worldly riches, would seem little fitted to provide a satisfactory
+rationalization of the sentiment of western civilization. Yet for long
+it has done so.
+
+Educational and political institutions grow in response to the
+exigencies of human demands which are not necessarily influenced by
+any ethical considerations. This may be seen by considering the case
+of Mr. X, who lives in Balham and has a passion for pineapples. Mr.
+X, not being bothered about metaphysics, is no more disposed than
+the majority of his fellow-citizens in Balham to assert any final or
+transcendental sanction for his passion for pineapples. He accepts it
+as part of his modest unassuming existence. This does not prevent his
+writing a letter to _The Daily Mail_, when an import tax on pineapples
+makes it impossible for him to indulge his predilection for the fruit
+without forgoing other cultural amenities. Meanwhile Mr. Y, who lives
+in Tooting and nevertheless cherishes an earnest desire for more and
+better pineapples, has written to _The Daily Herald_. Mr. X and Mr.
+Y are now joined by Mr. Z of Whitby, whose letter appears in _The
+Yorkshire Post_. By this time the Press cannot resist the social
+pressure that is brought to bear on the pineapple policy of the party
+in power. The evening papers announce in headlines “Nation-wide
+movement against Pineapple Protection.” Mrs. J of Houndsditch is
+pestering Carmelite House with correspondence on the potato shortage,
+and Miss C of Cheltenham is writing to the Chancellor of the Exchequer
+about the rising price of prunes. In official circles the determination
+to do something which will distract attention from prunes, pineapples
+and potatoes takes shape. If the pressure is firm enough the tax
+on pineapples and prunes goes, and a promise to give the fullest
+consideration to the potato shortage is extracted. Alternatively a
+popular film-star is knighted, and the Press, equipped with better
+copy, announces that this correspondence must cease forthwith.
+
+There is a difference between a predilection for pineapples and the
+pursuit of those amenities which are referred to by more abstract terms
+such as _justice_. Pineapples are less frequently a matter of life and
+death to those who eat them. Men and women rarely go to the stake or
+march to battle for the sake of more and better pineapples. They will
+fight for bread, and a roof over their heads and an eight-hour day.
+Concerning those forms of social activity which bring us most into
+conflict with our fellow-beings we are prone to demand some final or
+transcendental sanction for action. Social co-operation is perfectly
+realizable without recourse to any such extravagant claims. It is
+permissible for a professional philosopher to doubt whether there would
+really be more misery in the world if the ethical convictions of human
+beings were more lax.
+
+In stating this possibility, I am not endeavouring to give the
+impression that I wish to be regarded as a “rational” person. If I
+aspire to a more rational outlook than that of some of the writers
+whose standpoint I have criticized, it is not because I have no
+private world of my own, but because I hope that I am more successful
+in separating my public beliefs from my private sentiments. I do not
+pretend that I have no ethical prejudices. My ethical prejudices are
+as strong as those of most vitalistic philosophers with whom I am
+acquainted. Often it happens that my prejudices about conduct are not
+the same as theirs. Where we differ I see absolutely no prospect of
+arriving at agreement through the medium of argument. I doubt whether
+I could ever agree with Dr. Haldane about a just remuneration for
+the miner. I accept without hesitation Dr. Haldane’s authoritative
+views on miner’s silicosis. There is a world of private values which
+I do not and can never share with Dr. Haldane. I have no awareness
+of anything in the universe which is anything like the Deity of Dr.
+Haldane’s Gifford Lectures. His arguments leave me as unconvinced as I
+was before I read them. Dr. Haldane’s Deity is part of Dr. Haldane’s
+private world. In general I agree with Dr. Haldane’s interpretation of
+the Dissociation Curve of hæmoglobin. If in any points I do not follow
+his reasoning, I should probably agree with him on closer examination
+of his evidence and inferences. Alternatively I might be able to point
+out objections to some of his conclusions. I believe that he would then
+examine my objections sympathetically, and, if he could not dispose of
+them, modify his views. Dr. Haldane’s Dissociation Curve for hæmoglobin
+is not, like Dr. Haldane’s Deity, part of Dr. Haldane’s private world.
+It has become part of the public world.
+
+In my own private world the pursuit of intellectual honesty is a matter
+to which I attach a good deal of importance. I cannot reconcile with
+my notion of intellectual honesty a confusion between the ethically
+neutral constituents of the public world and my private convictions
+about conduct. When I contend that a rational philosophy must be
+ethically neutral, I do not pretend that I have no private world of
+my own. I leave open the possibility that the way in which people
+come to adopt different philosophical views may one day be made the
+subject of public discussion as a problem of human behaviour. In my own
+private world a sense of responsibility to other human beings impels
+me to refuse to let people think that I am speaking in my capacity as
+an expert, when I am really giving vent to my sentiments as a private
+citizen. I do not regard my own private world as unimportant to myself.
+I choose my immediate friends mainly on the basis of preferences which
+belong to it. I am unable to understand the disposition to confuse the
+two issues. It is quite possible to separate them in practice. Sir
+Charles Sherrington has written an authoritative work on the central
+nervous system, the importance of which is a public issue. He has also
+published a volume of verse. In my private capacity I happen to like
+it very much. I will go further and express the opinion that highly
+creative work in science, such as Sherrington’s, is not unusually
+associated with an intense system of private values. I admire Professor
+Sherrington because of the versatility that makes him both a scientist
+and a poet. But I admire him still more because he has not enclosed the
+_Integrative Action of the Central Nervous System_ and the _Assaying
+of Brabantius_ in one cover as a volume of Gifford Lectures. In
+publishing them separately, he seems to me to set an example of honesty
+and modesty which some of his contemporaries might well be persuaded
+to emulate. William Bateson was a great scientist with very strong
+political prejudices with which I have no private sympathy. Bateson’s
+intellectual honesty was of so fine a calibre that he consistently and
+publicly refused to associate with Eugenic Reform, lest, he explained,
+his eminence as a geneticist should appear to give sanction to views
+in forming which his personal sympathies were likely to override his
+judgment.
+
+More than a century ago David Hume concluded his essay on _The
+Academical or Sceptical Philosophy_ by contending that “morals and
+criticism are not so properly objects of the understanding as of taste
+and sentiment.” If philosophy has advanced at all since the time of
+Hume, I am inclined to think that there is less immediate prospect of
+making politics a science and more definite information to warrant
+the hope that the study of morals may one day become part of an
+experimental analysis of how human beings behave. I can see no reason
+to suppose that in any other sense will it ever be possible to bring
+the affirmations of æsthetic and ethical experience into line with
+scientific beliefs. “If we reason concerning beauty,” as Hume observed,
+“we regard a new fact, to wit the general taste of mankind or some
+such fact which may be the object of reasoning and enquiry.” The rise
+of anthropology suggests that there are matters of fact which Hume did
+not actually specify. The substance of his argument remains valid.
+Science has advanced only when observation has emancipated itself from
+the affirmations of æsthetic and ethical experience. To set before us
+the goal which Dr. Whitehead proposes may result in hampering science
+without fertilizing philosophy. Ethics and æsthetics, like politics and
+religion, are, in Trotter’s words, “still too important for knowledge
+and remain subjects for certitude, that is to say, in them we still
+prefer the comfort of instinctive belief, because we have not learnt
+adequately to value the capacity to foretell.” If it was evident to
+David Hume, it is still more evident to-day that a “rational and
+modest” philosophy will aim less at providing a formula for complete
+agreement than at reaching a sensible understanding about matters on
+which we should be content to differ.
+
+In undertaking to refute Hume’s arguments Kant assumed the validity
+of his conclusions in the method which he adopted. He employed _a
+priori_ principles to establish the existence of a “faculty of pure
+_a priori_ cognition.” There were at that time no available materials
+for a _public_ discussion of the problem which he propounded. In
+our generation a new epoch has been initiated by the physiology of
+the conditioned reflex. We can now see the correct form in which
+Kant’s problem must be stated, if we are to emerge from the dilemma
+which arises from the fact that by temperament some philosophers
+are extroverts and others introverts. It is no longer a question of
+deciding how we come to know, but how we _learn_. If we are too eager
+to await the solution of this problem on a purely physiological basis,
+we have no need to turn, like Kant, to introspective philosophy for an
+answer. The educational practice of Madame Montessori can throw more
+light on the origin of the concept of _number_ than Kant’s discussion
+of the proposition that seven and five make twelve.
+
+The influence of Christianity in the western world has tended to make
+the impersonal detachment of science repugnant to most people. We
+are taught that knowledge puffeth up, but charity edifieth. This, of
+course, in its own language, expresses the ecclesiastical conviction
+that human nature is fundamentally sinful. Whatever we choose to
+regard as good or bad, from the biological standpoint human nature
+is neither the one nor the other. Man is a very teachable animal. For
+that reason it is through intelligent understanding of the springs of
+human action that the elimination of social discord is most likely
+to proceed. Those who advocate the religious appeal as the basis of
+social education have to provide us with an explanation of why the
+practical implications of revealed dogma rarely receive any recognition
+before the exigencies of economic necessity compel people to act in
+conformity to them. No one would deny that religious leaders took a
+prominent part in the movement for the abolition of chattel slavery. It
+is also a singular fact that the Protestant Churches entered no protest
+against the slave-trading activities of Frobisher, Drake and their
+fellow-heroes of sea warfare. Nor did they disturb themselves with the
+problem until the rise of the factory system had created conditions
+which promoted the growth of a different form of labour contract. If
+war as a means of settling international disputes is abolished in
+our generation, it is not unlikely that religious apologists will be
+telling our grandchildren about the prominent part which churchmen
+took in founding Peace Societies. They will probably be right. War as
+an institution is becoming so menacing a scourge to civilization that
+even religious bodies are making themselves active in denouncing it.
+But if war is to be denounced on the basis of some revealed and final
+view of human conduct, how are we to explain the fact that a negligible
+minority of esoteric sects have discovered so significant a conclusion
+during the past two thousand years of church history? Should we not
+rather say that the urgency of the modern problem has created a new
+rationalization? Must we believe that war exists because by nature
+human beings are sinful and delight in slaughtering one another? Can
+we believe that men are so constructed that they can be induced by
+religious conviction to love their neighbours as themselves? Is it not
+rather a fact that men are on the whole stupid and indifferent, and
+that thoughtful people regard war as an intolerable nuisance, but are
+not as yet clear about how it can be avoided? Is it not to patient
+study of the ways and means of organizing international government
+rather than to ethical dogma or religious fervour that we must look for
+the creation of permanent peace?
+
+From a social point of view I do not think it is a demerit of any
+philosophy of Life that it provides no pleasant rationalizations as a
+guide to polite conduct. One would be more interested in discovering
+some way of ensuring how people can be induced to act consistently
+with their professions. No religious organization in recent times
+has succeeded in achieving this result on a large scale. Theology is
+not entitled to criticize a philosophy because it supplies no basis
+for ethical values. Theology has failed to show how human beings can
+be induced to behave in conformity with the ethical values which it
+imposes on them. For the present I shall eat pineapples in preference
+to prunes, whether philosophy provides me with a good reason for
+doing so or not. Men will not be prevented from demanding a living
+wage because philosophy fails to evolve an ethical theory of the
+state. A man may be a gourmand without first becoming an Epicurean
+or a masochist without embracing asceticism as a moral creed. Ethics
+only lie within the scope of the publicist standpoint in so far as
+philosophy may indicate the lines along which it is profitable to
+investigate how people come to articulate certain combinations of
+speech symbols, and how what they say about their actions is related
+to other manifestations of motor activity which they display.
+
+
+§3
+
+I am not unaware of a criticism of the newer mechanistic outlook which
+has already been made by an anonymous contributor to _Nature_ in
+discussing a symposium at the 1929 meeting of the British Association:
+
+  “The extreme behaviourists or biomechanists, perhaps represented at
+  the conference to judge from reports by Professor Hogben, will of
+  course refuse to take account of any process which does not admit
+  of physico-chemical analysis or description--a position that does
+  not work out well in our daily life and conversation where we have
+  to allow at every turn for intelligent or even rational purpose.”
+
+The objection implied in these words is closely akin to a fallacy which
+is reiterated in most theories of the vitalistic or holistic type. The
+publicist standpoint does not imply that we do know everything about
+human behaviour. On the contrary it urges that we know in part and we
+prophesy in part. I suppose that even the most pessimistic exponent
+of the vitalistic school would admit the possibility that science
+will in the course of time modify our habits of conversation in many
+directions. Everyday conversation always lags behind the advance of
+scientific knowledge. It would not be difficult to illustrate how
+frequently our habits of conversation in moments of intellectual laxity
+are saturated with pre-Copernican and pre-Darwinian views about the
+universe. It is in no way remarkable that our habits of conversation
+have as yet failed to accommodate themselves to the advances in
+biological knowledge that are opening up new fields of investigation
+into the characteristics of “conscious behaviour.” I am prepared to be
+told that I have repeatedly implied traditional views about thought,
+memory, consciousness and the like in writing these essays. As I bring
+them to a close I will frankly admit the truth of the charge. The
+common language which I was brought up to use does not contain the
+words which would be suitable to a thoroughly consistent development of
+my present views. I give expression to them, knowing that much which I
+have written will appear very foolish to those who enjoy the advantage
+of living two thousand years after I am dead. Had I the ingenuity and
+astuteness to invent a completely consistent symbolism for the views I
+have advocated, I could entertain no likelihood that anyone now living
+would read what I have to say. My own inconsistencies and imperfections
+do not lead me to infer that human beings will always be forced in
+their everyday conversation to discuss the problems of human existence
+with all the limitations to which I am subject.
+
+We are told by Professor Eddington and Dr. Haldane that the
+abstractions of physical science have taken us further and further away
+from Man, the starting-point of our enquiries. Experimental biology in
+probing into the traditional distinction between reflex and voluntary
+activity permits us to recognize that science is in process of taking
+within the scope of its method fields of intimate human interest.
+Mechanists of a past generation could not conceive them as capable
+of annexation. In bringing us back to our starting-point biology has
+strictly adhered to the method of enquiry which has proved successful
+in constructing the fruitful abstractions of physics and chemistry.
+We can thus look forward to a time when the method of science will
+claim for its field everything which comes within the scope of what
+people will agree to call knowledge. Because social activity lies
+within the realm of what Dr. Haldane calls “conscious behaviour” the
+older mechanistic outlook failed to provide the foundations of a
+comprehensive interpretation of the Nature of Life. It left Man as the
+peculiar province of that diffuse type of discussion which draws its
+sustenance from the abstract noun and comes to fruition as magical
+gesture. It should occasion no surprise that the new horizon revealed
+by the growth of biological enquiry now seems contrary to common
+sense and inconsistent with the language we are accustomed to use in
+everyday life. Man has existed on this planet for perhaps a matter
+of five hundred thousand years. During that period little more than
+five thousand years have been occupied by the building of civilized
+society. Of that fraction the main development of the essentially
+social language of science has been compressed to a very large extent
+within the last five hundred years. We are still the creatures of a
+tradition of fear, of superstition and of misunderstanding, of childish
+self-assertion and savage self-submissiveness to magical prohibitions
+handed down to us from what Professor Levy has aptly called the
+unsavoury past.
+
+The majority of men are impatient towards the discipline which science
+imposes upon us. That impatience is a bulwark of magical beliefs. It
+has been well said by Trotter: “In matters that really interest him,
+man cannot support the suspense of judgment which science so often has
+to enjoin. He is too anxious to feel certain to have time to know.
+So that we see of the sciences, mathematics appearing first, then
+astronomy, then physics, then chemistry, then biology.” Because science
+does not flatter our self-importance, because science makes stringent
+demands on our willingness to face uncomfortable views about the
+universe, because patience with the slow advance of science requires
+the effort of intellectual self-renunciation, human nature, deeply
+rooted in its unsavoury past, is on the side of vitalistic theories.
+Social privilege is repelled by the mechanistic outlook because of its
+ethical impartiality. Age brings its impressive authority to reinforce
+both human nature and social privilege. When the spirit of intellectual
+adventure dies and with it the courage to face the austere neutrality
+of a universe which mocks the self-importance of our individual lives,
+when the ruthlessness of death and decay threatens to rob us of the
+few circumstances propitious to personal comfort, when the limitations
+of our greatest achievements are no longer assuaged by the prospect
+of renewed opportunities, it becomes all too easy to find the formula
+which provides a compromise for the conflicting claims of magic and
+science. Perhaps the time will come when our knowledge of the Nature of
+Life will provide an explanation of this circumstance.
+
+
+
+
+FOOTNOTES
+
+
+[1] An examination of the precise significance of this adjective is
+undertaken in the essay on the Nature of Life, p. 80 et seq.
+
+[2] That a volley of afferent nerve impulses passes along the vagus
+nerve to the brain at each heart beat is a fact which can be physically
+demonstrated with the Einthoven galvanometer.
+
+[3] British Association 1929, Section D.
+
+[4] Professor Wildon Carr, in defending the vitalistic standpoint,
+explicitly states this, as quoted in a later essay.
+
+[5] I refer to the Uniformitarian doctrine.
+
+[6] This objection does not apply to the use of the word mutation in
+its strictly etymological connotation as a process in contradistinction
+to a type.
+
+[7] Two quotations from his writings may be added to justify the
+foregoing criticism of Weismann. Concerning the essentially creative
+rôle of Natural Selection he wrote, “The transformation of a species
+as well as the preservation of its constancy are based upon natural
+selection, and this is incessantly at work, never ceasing for a
+moment.” (_Germ Plasm_, p. 414.)
+
+Elsewhere he states that heredity and variation are coextensive. “We
+have seen that this transmission affects the whole organism, and
+extends to the most trifling details, and we also know that it is never
+complete, and that the offspring and parent are never identical, but
+that the former always differs more or less from the latter. These
+differences give rise to the phenomenon of _variation, which thus
+forms an integral part of heredity, for the latter always includes the
+former_.” (_The Germ Plasm_, p. 410.)
+
+[8] _The Bases of Modern Science_, pp. 234-5.
+
+[9] _The Bases of Modern Science_, pp. 234-5.
+
+[10] _Science and the Modern World_, pp. 255-6.
+
+
+Transcriber’s Note: “{sic}” in the text is the transcriber’s. Simple
+cases of typographical error have been silently corrected. Some sections
+numbered “§1” were not present at chapter beginnings in the original,
+and have been added in order to standardize the hierarchy of headings.
+The book cover image that accompanies some ebook formats is original
+and placed in the public domain.
+
+*** END OF THE PROJECT GUTENBERG EBOOK 78368 ***