The Domain of Natural Science is the subject I have chosen for the course of Gifford Lectures which the Senatus Academicus have done me the honour of inviting me to deliver. Any attempt to define and delimit the domain of Natural Science must concern itself with the questions what Natural Science is and what it is not; what its precise functions within the general domain of Thought may be; what the nature of its relations is with other parts of that wider domain; in what manner it has grown up and what we may reasonably expect from it in the future; and to what kind of essential limitations it is subject.
Our general mental outlook upon the world contains a great mass of ideas and knowledge of which the origin is so remote in the development of our race that they may perhaps least inadequately be described as instinctive notions and knowledge. We possess also a heterogeneous mass of unsystematized ideas in large part traditional in the society in which we have grown up. Besides these we possess a stock of ideas and knowledge of a more or less systematized character drawn from the religious philosophical and scientific thought of the past and the present. My choice of subject has been made in the hope of doing a little to promote clarity of view as regards the relation which that special kind of thought which in accordance with established usage we denote by the name Natural Science has with that greater complex of ideas to which I have alluded and which conditions our general mental attitude towards the psychical and physical world.
The denotation of the term Science is not fixed by usage with absolute precision. In the wider sense of the term a critical and systematic study of any clearly marked out region of thought is described as a Science provided that study attains or at least aims at a reasonable standard of rigour in relation to classification and subsumption under general laws in dealing with its special subject matter. Thus for example Philology Ethics Psychology Economics Anthropology Textual Criticism and even Heraldry are spoken of as Sciences. On the other hand Metaphysics is not usually spoken of as a Science probably because however systematic it may aim to be its subject matter is too universal embracing in fact the whole of experience and existence. The term Natural Science with which I am here specially concerned is generally restricted to denote the group of those special Sciences which concern themselves with the study of what we call physical phenomena including the cases in which the phenomena are connected with living organisms. In the somewhat narrow sense in which I shall employ the term Natural Science excludes any direct consideration of the mental or psychical facts in living organisms from its purview”; although this restriction is not universally accepted in connection with the group of Biological Sciences. It may be objected against this avowedly narrow use of the term Natural Science that it implies an undue restriction of the term Nature involving the relegation of the mental side of life to a place outside Nature. This objection has undeniable weight. My employment of the term Natural Science in the meaning that it denotes the Science of the physical world is a matter of convenience only and is not intended to indicate the acceptance of the theory that there exists any ultimate barrier between physical Nature and the mental life of man.
The object I have indicated of describing and delimiting the domain of Natural Science can only be attained by undertaking an examination from the inside of the methods of procedure the assumptions and the course of development of various special parts of Natural Science. Anything like a complete examination of the history of the development and an analysis of the methods of each one of the group of the Natural Sciences would be a gigantic task far beyond the powers of any single individual. To do this would require the co-operation of an army of specialists intimately acquainted with the details of the present and past states of the very numerous departments of Natural Science. Happily it does not seem altogether impossible to attain at least some measure of success in an attempt to define in general terms the nature of the contributions which the Natural Sciences are fitted to make to a general view of the world by adopting the comparatively modest procedure of examining the methods and principles of some typical branches of Science and especially of those branches which may be regarded from a methodological point of view as in a more advanced stage of development than the others. It might perhaps be regarded as the more logical method to commence at once this process of examination and analysis and upon its completion to deduce the more general conclusions which could be extracted from the results obtained. But it is more practicable if less logical first to state with as much precision as possible the general conclusions which it is hoped to establish and then later to support and illustrate these conclusions by means of an analysis of the history and general features of special branches of Science. Accordingly in the first few lectures a general account will be given of what may be regarded as the foundations of the method adopted in the various departments of Natural Science and conclusions will be stated as to the nature of the knowledge of the physical world which organized Science affords. Moreover some indications will be given of the relation of Science with other elements of thought and especially with Philosophical thought and speculation. In particular an attempt will be made to trace the character of the limitations to which Scientific knowledge is subject. After these earlier lectures the examination in some detail of various typical portions of Science and of many scientific theories will be undertaken. If in this the main part of the course I devote what may seem a disproportionately large amount of time to scientific theories which have at the present time been abandoned modified or subsumed under wider theories the explanation must be taken to be that my object is not to attempt to perform the impossible task of giving an accurate account of the present state of Natural Science even in a few of its branches but rather by means of an historical retrospect to disclose the essential characteristics of all the theories and laws which go to make up Natural Science. It is probably less difficult to discern the principles which underlie the essential methods of Science and thus to obtain a grasp of their true character and of the limitations to which they are subject by examining and dissecting theories which have attained a crystallized form than by attempting a complete analysis of the tentative and rapidly changing theories which actually direct at the present time the gigantic efforts that are being made to advance our knowledge of natural phenomena.
The state of various branches of Science in our day is such as to lead to a vivid appreciation of the unwisdom of considering any scientific theory as having attained finality. Recent experience has shown that a well-established and successful theory may be liable to fundamental change owing to the discovery by observation or experiment of new facts incapable of reconciliation with the theory in the form in which it has for long been accepted. At the end of the course an attempt will be made to draw some general conclusions of a kind which may be regarded as having a bearing upon the great central problem the unbiased treatment of which was indicated by Lord Gifford in his Will as the object for which the Gifford Lectureships were to be founded. The difficulty of the task I have undertaken is such that adequately to cope with it would strain the resources of anyone who had spent his life in the consideration of the Philosophy of Science. It can be undertaken only with much diffidence by one whose consideration of the weighty matters involved therein has been limited by the scant leisure available in a life in which attention has been concentrated in the main upon the absorbing technique of a single branch of Science.
During the last century and a half the life and work of multitudes of human beings have in our own country and in the civilized world in general undergone a revolutionary change due to the application of Science in all branches of Industry. Vast populations now exist which at a former period could neither have been fed nor provided with work. The use of the motive power of steam introduced in the eighteenth century its application to locomotion on land and sea in the nineteenth century the invention of the oil engine with its application to aviation in the twentieth century; the electric telegraph the telephone wireless telegraphy and telephony and other applications of Electromagnetism are all traceable to the discoveries of Pure Science. The development of the Biological Sciences has led to applications of the most far-reaching importance in Agriculture Hygiene and in the healing Art. These applications of Science give indications of future extensions in which the present limits maybe indefinitely transcended. Other results of the application of Science are embodied in the great chemical industries of which one of the most ominous results is apparent in the discovery of explosives of vast destructive power. These results of Natural Science and many others too numerous for mention in its persistent efforts to dominate physical nature have furnished us with the mechanical means of securing an indefinite improvement in the welfare of mankind if a wise use is made of the power with which they endow us. They have also provided our civilization with the material means of committing suicide if the increased mechanical powers which they afford are not accompanied by a corresponding rise in the ethical standards which actuate nations in their dealings with one another. In conjunction with the revolutionary industrial and economic consequences which have arisen from modern applications of Science vast changes have been produced in the mental outlook of multitudes of men and these changes have given rise to social problems of the most far-reaching character of which the solutions are not in sight. These problems are such that even in the view of optimists it may need centuries of unrest and strife before relative social stability is restored. These matters must however here be left on one side. I have referred to them because some of the effects of Science upon the thought of the world are of an indirect character and are not simply logical consequences of the development of purely scientific thought but are rather due to the stimulating effect on the imagination produced by the great increase in the mechanical appliances at our disposal and to the enlargement of the mental horizon consequent upon the increased means of communication we possess having abolished the comparative isolation in which considerable aggregations of human beings formerly lived. However our attention must be confined to the more direct relations between scientific thought and mental life in general.
Prolonged investigation of the ideas and beliefs of existing races in a primitive state of development together with indications obtained from historical and archaeological sources of conditions in the earlier ages of mankind have made it possible to reconstruct in broad outline the concurrent factors which made up the complex of ideas about natural phenomena among primitive peoples. The earliest conceptions of this kind may be roughly subsumed under three heads. First there existed at all times a body of knowledge of the uniformities of Nature some of which had an origin reaching back in the experience of the race to the simian or to the still earlier ancestry of man. Much of this knowledge involved no reflection and it may perhaps not unfittingly be described as instinctive knowledge. A considerable part was obtained as the result of the experience of the individual or was communicated to him by his fellows. Such knowledge whether of the kind I have called instinctive of racial origin or of the kind dependent on individual experience was due to the necessity for action of men or their ancestors in their physical environment for self-preservation the obtaining of food and shelter and generally for the maintenance of the life of the individual and the tribe. Such knowledge of an unsystematic character largely unconscious and involving little or no reflection we may describe as common knowledge. Its origin was empirical and this common knowledge acquired empirically was the true parent of Science.
The second class of ideas of primitive peoples may be brought under the head of Animism. To primitive man the distinctions between himself and his environment and between the psychical and the physical were blurred and indistinct. His own thoughts feelings appetites and passions he ejected outwards into the objects by which he found himself surrounded. Thus he peopled the world of objects with spirits and demons of like nature with himself under the influence of the same motives of action the same passions and appetites. For him all Nature was alive; all objects were the residences of spiritual beings whose actions might be influenced by supplications persuasion sacrifices and threats. But the spirits which animated Nature were like men themselves highly capricious and their actions often unintelligible. To their agency were attributed many of the calamities such as diseases and storms which fall upon men. It is to Animism and animistic conceptions that we may trace back many of the Philosophical and Religious problems which have perplexed mankind in later ages.
The third class of ideas which are found in primitive man may be brought under the head of Magic. Instead of supplications and sacrifices being employed to persuade external Nature to action of a kind favourable to the wishes and interests of man a similar end was attained by a form of compulsion embodied in Magical ritual. The essence of Magic has been described by Carveth Read as follows1:
Magic supposes constant connexions of events due to the agency force influence or virtue of charms rites and spells; which connexions however are found only to be tendencies of some events to excite others inasmuch as they may be frustrated by counteracting charms rites or spells. Magic is entirely constituted by notions of force sometimes violent as in the discharge of an enchanted spear; sometimes subtle like the efficacy of an opal; intangible invisible and operating at a distance through space and time like a witch's spells that eclipse the sun or moon. These forces have only a one-sided relation to the workaday world; they meet with no resistance from what we take to be the “properties of matter” such as weight and impenetrability; but are themselves entirely exempt from natural law; what we call the “real world” has no hold upon them; they live in a world of their own. They are absolutely immeasurable; and hence the causation which is certainly implied in the notion of their operation is indefinite and becomes vaguer and vaguer as the magical system develops; and all this is the opposite of what happens in the history of Science. In spite of having a necessary ground in the human mind Magic and Science are contrasted from the first in their development grow wider and wider apart in their methods and ideas more and more opposed. If either can be said to precede the other it is Science (at least in its earliest and crudest form) that precedes Magic.
In the main the beginnings of scientific knowledge arose out of that element which we have called common knowledge but throughout its development Science has not completely disentangled itself from notions drawn from the domains of Animism and Magic. Traces of Animism and Magic in their cruder forms are still to be found in the most civilized communities and they are to be observed in undiminished strength in some of the lower races of mankind. Magic and Science have in common with one another the recognition of certain uniformities in the sequence of events and in this point both of them are sharply distinguished from Animism; but this similarity is of small importance compared with the deep seated differences in their outlook and methods; and the history of the development of Science exhibits at all times the tension and conflict between the fundamentally divergent attitudes of mind which they represent. To a considerable extent this tension between Science and Magic and Animism was in earlier times held in check by the fact that what elements of genuine scientific knowledge existed were largely in the hands of the same persons who were adepts in Magic. The Wizard or Medicine Man or the Priest had very frequently some knowledge of the course of natural events greater than that possessed by the ordinary members of the tribe or community. This real knowledge assisted him in bolstering up his power and in increasing his reputation for possessing special means of influencing the course of natural phenomena. In conjunction with what we now regard as the fantastic cures for ailments that the Medicine Man prescribed he also employed some modicum of empirical knowledge which can be regarded as rudimentary Science. The magical power possessed by the rainmaker of influencing the weather was often eked out by some knowledge obtained from observation of the course of the seasons. At all times moreover there probably existed here and there individual members of the community whose exceptional mentality or occupation impelled them to obtain some increased empirical knowledge of the properties of material objects and of the course of natural events and to leave aside or subordinate the methods of Magic. The comparatively slow progress of Natural Science in early times may with much plausibility be attributed to the fact that Magic combined with the prevailing hypostatization of mental and physical qualities gave almost unrestricted rein to the imagination and led to a luxuriant growth which left far behind that steady progress of knowledge which could only be made by the exercise of the sober qualities requisite for the patient investigation and comparison of facts.
No doubt Animism and Magic had some indirect effect in stimulating the acquisition of knowledge by their encouragement of the practical arts as adjuncts of their ceremonies but in the main the attitude of mind which they encouraged was hostile to those habits of mind which favour the growth of scientific knowledge. But the principal driving force in the beginnings of Science was of the practical order; the urgent necessity for some kind of measurement for the determination of position in navigation by means of observation of the stars and for knowledge of the properties of materials used in building and in the arts. Slowly the beginnings of genuine scientific curiosity arose in some individuals and under favourable conditions in particular places. Some account of Greek Science and of the sharp contrarieties within it due to the contest between genuine scientific method and ideas of animistic and magical origin will be given in later lectures. From the time of Leucippus and Democritus onwards there was in Greece a real rival to Animism; the physico-mechanical theory of the world. In medieval times the progress due to Greek thinkers was submerged by Scholasticism with its belief in occult qualities; genuine Science was only kept alive by the Arabs whose knowledge was partly drawn from Indian sources. After the renaissance involving as it did the rediscovery of Greek thought Science recommenced its path of progress which has continued with unabated vigour from the sixteenth century until our own time.
Both Animism and Magic like the common knowledge of phenomena out of which Natural Science has grown have their modern descendants. If the validity of the theories be admitted which trace back many of the features of the more highly developed mental life of the modern world to ancient animistic and magical ideas we have no warrant for treating these features with indiscriminate disdain on account of what appears to us the fantastic crudity of their ancestry. It would indeed appear that Animism Magic and common knowledge in their earliest forms and in their later development through the ages are all three natural growths representing persistent and normal forms of activity of the human mind under the influence of ineradicable impulses. The cruder forms of animistic conceptions still exist among uncivilized races to-day and they have never completely disappeared even in the higher races. In the sixteenth and seventeenth centuries in the age in which the foundations of modern Science were being laid by such men as Kepler Galileo and Newton animistic notions took terrible shape in the employment of the stake and the gibbet for the purpose of combating the works of ubiquitous demons as exhibited in witchcraft.
As the functions of the thinking part of the community became gradually more differentiated the tension between Science and the other elements of thought attained increased sharpness. This tension took at various times the form of violent conflict; especially when scientific ideas arose which seemed to threaten the traditional ideas and the higher or lower interests of the great religious corporations. An ancient religious system carries with it through the centuries in its written or oral traditions a great deal of material which either explicitly or in its descriptive language incorporates the views of natural phenomena which were current at the time when the traditions first took a relatively fixed form. These views about the natural world usually come to be regarded by most people as forming an essential part of the system which cannot be changed or eradicated without entailing serious injury or even destruction upon the whole religious system. This attitude of mind is shared by the official representatives of the system in question who are frequently disposed to use the influence of their corporation to combat any attempt to replace in the popular mind the older scientific or quasi-scientific conceptions by more modern ones due to the progress of scientific knowledge in later times. After a longer or shorter period of strife the newer scientific view receives acceptance or is at least acquiesced in; and it is ultimately discovered that the older elements of a scientific complexion which were embodied in tradition were not really an essential part of the system; and this even in cases in which the change to the newer scientific view involved some modification in the more strictly religious tradition.
I will here refer to three striking instances in which a violent shock has been given consequent upon the rise of new scientific theories to all those who had a traditional attachment to conceptions of the physical world which were in opposition to consequences of the new theories. The first and perhaps the most striking case to which I will refer was in the domain of Astronomy and involved the substitution of what is known as the Copernican system for the older Ptolemaic scheme. The method of representing the motions of the bodies of the solar system which Ptolemy worked out in detail and parts of which were due to Hipparchus and Apollonius depended upon the idea that the earth is at rest and the sun and planets in motion. Thus the Ptolemaic system of Astronomy was essentially geocentric. The earth being taken to be at rest each of the planets was supposed to describe an epicycle by a uniform revolution in a circle the centre of which moved uniformly in a circle round the earth which did not however occupy the centre of that circle. By proper adjustment of the radii of the circles and of the velocities of the planet and of the centre of the epicycle Ptolemy was able to give a fairly accurate representation of the apparent motion of the planet. In this manner he gave a systematic representation of the apparent motions of the sun and the planets; in particular the stationary points and the retrograde motions were represented. He was also able to represent the principal inequalities in the moon's motion. That the earth is a planet revolving round the sun as centre had been taught by Pythagoras to his disciples but the definite overthrow of the Ptolemaic system was initiated by Copernicus who represented the motion of the earth and planets as consisting of the uniform description of circular orbits with the sun at rest within each orbit but not at its centre. It was only later owing to the labours of Kepler that the elliptic form of the orbits with the sun in a focus was established. So far the whole change from the Ptolemaic to the Copernican system consisted as we should now describe it in the recognition of the fact that the relative motions of the sun and planets are much simplified by describing them as they would appear to an observer in the sun rather than to a terrestrial observer; that is by the adoption of a heliocentric description. It will be observed that so far the only change consisted in setting up a simpler description of one and the same set of facts. It was owing to the great work of Newton that the full importance of the change of descriptive scheme was made manifest; when the heliocentric description of the motions of the bodies of the solar system was seen to be consistent with a dynamical scheme of great formal simplicity; and one to which the geocentric description did not lend itself. Only after a prolonged period of bitter strife did the substitution of the Copernican system including the motion of the earth round the sun and its diurnal rotation round its axis for the Ptolemaic meet with general acceptance. The invention of the telescope contributed much to the consolidation of the new view. The violent opposition to this change arose from the fact that the substitution of the sun for the earth as the body of reference in the solar system appeared to involve a fundamental change in the importance of the earth its inhabitants and their affairs relatively to the rest of the Universe. Our world was degraded physically to the position of a single satellite of a single star amongst the vast numbers of bodies in the stellar Universe; and this appeared to involve a corresponding moral and spiritual degradation which it was thought would seriously react upon the current theological conceptions making it more difficult to maintain the importance assigned by those conceptions to man in his spiritual relations. The notion of the plurality of worlds which arose in this connection was one of the chief stumbling blocks; the teaching of Giordano Bruno on this matter formed one of the chief charges on which he was condemned to death.
The second instance to which I will refer of a shock to traditional conceptions was occasioned by the geological discoveries which assigned enormously greater antiquity to the earth than was admitted by the traditional biblical chronology in accordance with which the age of the earth was estimated at not more than about six thousand years. After a shorter and less violent conflict than in the case of the Copernican system the strength of the cumulative evidence adduced in favour of the great antiquity of the earth led to its general acceptance by educated persons.
Lastly I will refer to the controversies excited by the publication in 1859 of Darwin's Origin of Species and in 1871 of his Descent of Man. Although the idea of evolution of species and even the suggestion that man was descended from a race of lower animals were by no means novel the special form which Darwin gave to these ideas the weight of the evidence he produced and the cogency of his reasoning were such as to call the attention of the world to these views in so striking a manner as to produce a violent though short storm of opposition from those who feared the effect upon the traditional ideas of the spiritual nature of man and his dignified position in the scale of living beings. The passionate repulsion which Darwin's theory called forth in some quarters is illustrated by the celebrated debate on the subject between Huxley and Bishop Wilberforce at the Oxford meeting of the British Association in 1860.
Belief in the descent of man from races of lower animals was in direct opposition to the current views about the Fall of man from a state of perfection or at least of innocence; in fact it appeared to amount to a reversal of this idea by substituting the conception of a slow ascent of man from indefinitely lower conditions of body and spirit. Here again the outcome has been much as in the first two cases I have referred to. The doctrine of evolution has been generally accepted by educated people at least as regards the physical side of man though not in all cases in accordance with the detailed views of Darwin himself. By the world at large it has been silently acquiesced in; at all events the world has survived the shock and the time of violent and public opposition to the main conception of the evolution of man and other species belongs to the past.
The conflict of conceptions of which I have spoken has lasted with varying degrees of intensity into our own time. One of the maxima of this conflict occurred about the middle of the nineteenth century at a time when the striking discoveries in various branches of Science especially in Astronomy Chemistry and Biology together with the far-reaching character of such generalizations as the law of the Conservation of Energy and Biological evolution had filled men of Science with a feeling of confidence which sometimes took an aggressive form. At the present time owing both to a more critical examination of scientific theories and to the flood of newly ascertained facts which have led to modifications of theories which were formerly supposed to have attained final forms and to the recognition of distinct limitations in their scope the attitude of men of Science towards their theories has become much more cautious than it was in the nineteenth century. This change of attitude of men of Science together with greater openness of mind on the part of the representatives of religious thought has led to a marked diminution of the acrimony which has at times characterized the relations between those whose interests are in the main scientific and those for whom religious considerations are paramount. The tension of which I have spoken is essentially due to deep lying divergences of mental attitude towards the world dependent not only on differences due to varying types of education tradition and occupation but also to fundamental temperamental divergences. This tension is often to be found within the complex mental make-up of one and the same individual impelling him either to adopt some form of compromise between the contending conceptions and impulses in his mind or else to set up a state of equilibrium in which the diverging sets of ideas are retained so to speak in separate compartments of his mind and lie side by side without coming into direct conflict with one another. But this kind of mental dissociation is not possible for all persons; and thus in many minds a state of mental unrest of uncertainty of alternations of scepticism and belief has been produced which is not conducive to that contentment of mind which is requisite for the highest efficiency of active agents in the work of the world. Even in our own time there are a considerable number of persons some of them highly cultivated and intelligent whose feeling towards the Natural Sciences is one of suspicion or repulsion sometimes conscious but perhaps more often unconscious or instinctive. This feeling of hostility or repulsion is partly temperamental due to a distaste for the schematizing habits of mind of scientific thinkers which are alien to those more intuitional modes of apprehension that are congenial to many minds. But this feeling is also largely and perhaps in a preponderating degree due to a fear that the Scientific view of the world leaves no room for the domain of freedom spontaneity and values for teleological conceptions or generally for the spiritual order of things.
The undeniable success of Natural Science of the palpable order exhibited in the mechanical inventions which have transformed modern life while investing Natural Science with a certain glamour has sometimes intensified this fear. That this fear is not prima facie groundless or due to the merely conservative habits of timid minds appears with clearness when the bold attempts are taken into account which were made by various representative men of Science during the last century to erect an all-embracing World-Philosophy on the basis of a Mechanical theory of Nature. It is instructive to consider in this connection some specimens of the pronouncements of prominent men of Science. Perhaps the most famous utterance of this kind is that of Laplace in his essay on probability (1812) which exhibits in the most striking way the feeling of confidence produced by the triumphant success of Astronomers in applying the law of gravitation to the calculation of the motions of the bodies of the solar system. Laplace writes:
We ought then to regard the present state of the universe as the effect of its antecedent state and as the cause of the state that is to follow. An intelligence who for a given instant should be acquainted with all the forces by which nature is animated and with the several positions of the beings composing it if further his intellect were vast enough to submit those data to analysis would include in one and the same formula the movements of the largest bodies in the universe and those of the lightest atom. Nothing would be uncertain for him; the future as well as the past would be present to his eyes. The human mind in the perfection it has been able to give to astronomy affords a feeble outline of such an intelligence. Its discoveries in mechanics and in geometry Joined to that of universal gravitation have brought it within reach of comprehending in the same analytical expressions the past and future states of the system of the world. All its efforts in the search for truth tend to approximate it without limit to the intelligence we have just imagined.
As a remarkable example of confident scientific dogmatism the following quotation from the preface to Büchner's well-known work Kraft und Stoff published in 1855 is of much interest:
If these pages may venture to claim any merit or characteristic it is that of representing a determination not to shrink with dismal horror from the simple if unavoidable consequences of an unprejudiced contemplation of nature from the standpoint of empirical philosophy but to admit the truth regardless of what may follow. We cannot make things different from what they are and nothing seems to us more preposterous than the attempts of some distinguished naturalists at introducing orthodoxy into natural science. We do not pretend to bring forward anything absolutely new or anything that had never been heard of before. Similar views and views cognate to ours have been taught in all ages and some of them were laid down by the oldest Greek and Indian Philosophers but their groundwork which is necessarily empirical could only be supplied by the progress of natural science in the present century. It is therefore obvious that these views in their present clearness and consistency are essentially a trophy of modern times and closely related with the new and gigantic achievements of empirical science. Indeed scholastic philosophy ever riding the high though from day to day more and more emaciated horse lays the flattering unction to its soul that these views have long been disposed of and would fain consign them to the limbo of oblivion with which object it has labelled them “Materialism” “Sensationalism” “Determinism”and so on; nay the gentlemen of that school go so far in their assumed supercilious superiority as to talk of having given them “he historical quietus.” But they themselves are going down day by day in the public estimation and losing ground in their speculative hollowness before the rapid rise of the empirical sciences which are making it daily more evident that both the macrocosmic and microcosmic worlds obey at every stage of their genesis existence and subsidence the mechanical laws which lie in the very nature of things. Starting from the recognition of the indissoluble relation that exists between force and matter as an indestructible basis the view of nature resting upon empirical philosophy must result in relegating every form of super-naturalism or idealism from what may be called the hermeneutics of natural facts and in looking upon these facts as wholly independent of the influence of any external power dissociated from matter. There seems to us to be no doubt about the ultimate victory of this realistic philosophy over its antagonists. The strength of its proofs lies in facts and not in unintelligible and meaningless phrases. But in the long run there is no contending against facts it is useless to kick against the pricks.
Again in his chapter on Thought Büchner writes:
That thinking is and must be a mode of motion is not merely a postulate of logic but a proposition which has of late been demonstrated experimentally.
Consciousness like thought is a performance or action or phenomenal activity of certain parts or tissues of the brain and in that capacity it is subject to all the changes which take place in the condition nutrition and growth of the brain.... How and in what way the atoms the nerve cells or to speak generally matter began to produce and bring forth sensation and consciousness is quite unimportant for the purpose of our investigation it is sufficient to know that such is the case... The simple solution of the problem lies in the fact that not only physical but also psychical energies inhere in matter and that the latter always becomes manifest wherever the necessary conditions are found or that wherever matter is arranged in a certain manner and moved in a certain way in the brain or the nervous system the phenomena of sensation and thought are produced in similar fashion as those of attraction and repulsion are under other conditions... The development of mind from matter is indeed one of the latest most difficult and most complicated triumphs of physical forces and is the product of a protracted toil rising from step to step through countless centuries till reaching the height of humanity. Nor can we say what shall be brought forth of similar fruit by the coming ages: we must confess that perhaps as yet we see only the incomplete the imperfect and that perchance we have no conception of what matter may yet be able to accomplish in its further evolution in mental phenomena and faculties by further complications and yet more highly developed forms of motion.
The same idea of the primacy of matter over life and mind has been expressed by Tyndall:
Divorced from matter where is life to be found? Whatever our faith may say our knowledge shows them to be indissolubly joined. Every meal we eat and every cup we drink illustrates the mysterious control of Mind by Matter.
Huxley in spite of the fact that he professed to hold idealistic opinions expressed views somewhat similar to those of Büchner and Tyndall as to the relation of matter and consciousness. He writes1:
There is every reason to believe that consciousness is a function of nervous matter when that nervous matter has obtained a certain degree of organization just as we know the other actions to which the nervous system ministers such as reflex action and the like to be. As I have ventured to state my views of the matter elsewhere “our thoughts are the expression of molecular changes in that matter of life which is the source of our other vital phenomena.”... I really know nothing whatever and never hope to know anything of the steps by which the passage from molecular movement to states of consciousness is effected. All that I have to say is that in my belief consciousness and molecular action are capable of being expressed by one another just as heat and mechanical action are capable of being expressed in terms of one another.
Whatever we may think of the crude dogmatism of some of the pronouncements I have quoted we must not be blind to the enormous effect which such ideas have produced on the one hand in inducing large numbers of persons especially among the half-educated to believe that these and similar views expressed by prominent representatives of Science embodied completely demonstrated results of Science and on the other hand in producing a repulsion to Science often of an undiscriminating character among many who feared its disintegrating influence upon cherished conceptions and beliefs. It is for this reason that I have dwelt at some length upon the extreme claims of complete supremacy made by scientific thinkers in the last century. It will be observed that these claims were made on behalf of the special mechanical theory of matter in vogue in the nineteenth century so extended as to have become a complete theory of the physical and psychical domains. The effect of the later advances in Physics in the last thirty years especially in the domain of Electromagnetism has however been such as to produce a revolutionary change in many of the older conceptions of the properties of matter. The flood of new facts which have been discovered in connection with radiation and radioactivity has thrown the most serious doubts upon the range of applicability of the mechanical theories of the eighteenth and nineteenth centuries at least in the forms in which they were then held. The bold extension of those theories into a World-Philosophy has in consequence of our extended knowledge lost much of what plausibility it ever possessed. Not only the electromagnetic theory of the constitution of atoms and the quantum theory of energy but also the latest theory involving fundamental changes in our conceptions of the measurement of time and space and of gravitation have shaken to their foundations the notions upon which the older mechanistic theories were based. It must not however be assumed that however great are the modifications which physical theories of material phenomena may undergo in consequence of increased knowledge of facts the possibility has been for ever removed that some physical theory may again arise which may make claims of a far-reaching character similar to those which were made on behalf of the mechanical theory of matter in the nineteenth century. From the point of view of general thought the really fundamental question in this connection is whether or how far it is possible to represent the physical world as a closed and independent system of deterministic type uninfluenced by the psychical world. Whether such a closed scheme be what has been called mechanistic or not is from the point of view of those who are concerned primarily with the relations between scientific thought and the larger world of thought a matter of secondary importance.
As a result of modern criticism of the foundations of Science a view of the nature of scientific laws and theories has arisen principally from the ranks of men of Science which differs in some important respects from the opinions formerly held on such matters. This view which I propose to explain in the next three lectures has met with acceptance by many men of Science of eminence and by some Philosophers. But it would be going too far to say that the scientific world in general has attained that degree of emancipation from certain ideas which have held sway for ages which would be implied in the complete acceptance of the view of the domain of Natural Science to which I refer.
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