Popular Science Monthly/Volume 15/October 1879/The Results of Abstraction in Science

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THE old scholastic controversy as to the reality of universals has its analogue in modern times. Formerly the strife had its religious implications, and it was from the arsenal of theology that the defenders of realism procured their weapons. Theological realism has now been virtually abandoned, and it is to metaphysics that the realists appeal to defend their abstractions from the searching analysis to which scientific modes of thought would most assuredly subject them.

Realism was the doctrine that universals have a real existence, entirely independent of the concretes from which they were generalized. It was held, for instance, by the older realists, that there is in the universe a perfect circle, freed from the imperfections of those we are able to construct; that this is not an idea generalized from the circles we see; that it is not the result of abstracting the imperfections that are inseparable from any circle we can draw and confining our attention alone to its perfections; but that there really exists an archetype of which circles as we know them are merely imperfect reproductions. This doctrine, even among the scholastics, found its strong opponents, and in its cruder forms was obliged to succumb. In metaphysics, however, realism, in a more refined form, found a soil fitted to its luxuriant growth, and the belief in entities and quiddities, and the other metaphysical essences associated with these, spread to such an extent that the successive influences of men as powerful as Locke and Hume sufficed to check rather than to exterminate it. The scientific tendency of thought, in which these men were pioneers, is now making havoc among the heirlooms of a past civilization. This tendency, which accepts nothing on mere assertion, and which forces every belief to produce its credentials, is now bringing its methods to bear upon the entities of metaphysics, and proving conclusively that they are of no nobler descent than the phenomena in which they originated.

The decadence of realism affords so striking an example of the general change in the conception of nature that has taken place within the past three centuries as, to a certain extent, to justify Comte's generalization as to the natural development of thought. There could, historically, hardly be a better example of this change than in the consideration of the decline of the theological and metaphysical conceptions of nature and the abstractions that grow out of them.

All the recent advances in ethnology teach us that man, as far back as we can trace his beliefs, explained the universe by the only power that he knew—that which he was himself conscious of possessing. To him every manifestation of power was the act of some god or demon who inhabited the sun, the moon, the forests, or the waters, and whose vengeance (for the primitive man's faith in diabolical agencies might well shame the believers in the more sublimated theories in regard to that cheerful dogma at the present day) it was necessary to placate by offerings, by sacrifices, by penances, and by supplications. No adequate test of reality then existed, and the spirit of a dream was as truly materialized as anything that could not be subjected to those most "realizing" of all senses—touch and muscular power.

The whole history of fetiches, idolatry, and polytheistic religions generally shows how strong was the belief in the immanence of powers beyond the human. An increase of culture served to remove the home of the gods to more distant fields, and, as man learned to philosophize, metaphysics gradually encroached on theology. The ideas of Plato, which to him were as real as the fetiches to the savages, were, as abstractions, the metaphysical substitutes for the demons that had preceded them.

The contest of nominalism with realism, which, during the middle ages, waxed so hard, paved the way for the scientific—or, in the Comtean terminology, the positive—conception of nature. Discerning in a great class of phenomena the evident progress of thought, Comte was led to suggest his famous law. As certainly as it has been disproved as a general law that thought passes from the theological, through the metaphysical, to the positive stage, so certainly has this theory a sort of broad suggestiveness, which often leads to otherwise undiscovered truths. The odium naturally and justly attaching to Comte's later social theories has had the tendency to obscure the value of his philosophical speculations. It is a fault (if it be a fault) of all founders of systems to over-estimate the application of their theories. Impressed by the discovery of a new truth, what wonder if they group all things under their rubric, and leave to their followers the task of clearly defining its application? Although in his constructive theories Comte erred most fatally, yet the fertility of his suggestions gave a great impetus to a more scientific philosophy, and extended its bounds over hitherto untrodden fields. Many owe to him much more than they willingly admit—more than they themselves are conscious of; and his uncompromising nominalism has had the tendency more precisely to define the meaning of abstract terms, and clear philosophy, and through it science, of much metaphysical verbiage.

While thus scientific nominalism is clearly in the ascendancy, there is a certain phase of realism which enters so completely into many scientific discussions, and has such a broad bearing upon their decision, that it may well claim our attention.

Abstraction is necessary to all knowledge. As soon as we advance at all beyond the knowledge of concretes—as soon even as we begin to compare one thing with another, and note their resemblances and differences—so soon we commence the process of abstraction and generalization. This mental act is not only the foundation of all conscious classification, but it is itself the infancy of consciousness. The earliest perception of resemblance in two objects which, next to the perception of difference, is the lowest term to which consciousness can be reduced, and which probably appeared contemporaneously with organized matter, was the result of incipient abstraction. The likeness of two things not identical, but resembling each other in many respects, would be perceived by any being possessed of the least consciousness. As the differences increase and the resemblances decrease in number, it is only by a thinking away from (abstracting) the differences and confining: the attention to the resemblances, that classification commences.

One of the greatest difficulties in dealing with the early growth of consciousness is the lack of terms applicable to it. Man commences to philosophize only when he is far advanced in culture, and the terms he then uses are ill fitted to express the mental acts of men far below him in intelligence, and in a still greater degree of those lowest orders of animals in whom consciousness first appears. However ill they may express our meaning, we are confined to the words we have, and they must be accepted as indicating but in a slight degree the mental process going on in the early organisms. When we speak of the abstraction necessary to the perception of resemblance, it is of course to be understood that the process is but slightly analogous to the classification of the scientist; still, fundamentally it is the same. For long ages before man appeared upon the earth this unthinking classification was going on. A brain was gradually being developed which had impressed upon it the experiences of its myriad ancestors, and which furnished to the primitive man an instrument of thought enabling him to adapt himself to surrounding conditions with far more success than his less favored compeers. The æons during which man struggled with the forces of nature, all the while gaining slight increments of experience and knowledge of nature's laws which he transmitted to his descendants, were necessary to the production of the Greek philosopher who, from his highly specialized mind, could evolve a theory of the universe. Ignorant of the vast ancestry of human experience, it is no wonder that men should have been ready to accept any but the true explanation of our belief in the laws of nature, and should have been unable to discern any relationship between those laws which to them appeared necessary and immutable and those newly discovered laws or sequences which they believed might be easily set aside.

Viewed in the light of evolution, a law of nature is merely the most generalized expression for a particular occurrence of phenomena. Take, for instance, the law of the conservation of energy: observation, long continued, shows that with whatsoever objects we deal, and-however we may apparently destroy the energy contained in them, yet closer observation, with more accurate instruments, will discern that the energy previously visible has only disappeared to reappear in another form. Finding the same result in every case to which we are able to apply our tests, and discovering no exception to the rule, we abstract the particular objects we have been considering, and, confining our attention to the persistence of energy which each displays, group this class of phenomena into one category and express the likeness by the law that energy endures.

Each deduction from a law is a separate verification of its truth, and as these verifications increase in number the probability of finding an exception decreases. Hence, the law soon assumes a form of necessity as different as possible from its original character. Add to this that many of the laws of nature have only to be expressed to be admitted—laws whose concretes were objects of observation to our earliest ancestors away back in the youth of life upon our globe, and are, to us at least, intuitive—and we see how natural the attribution of necessity to them appears. Besides this, the word law conveys a meaning entirely outside its scientific acceptation. As popularly used it expresses the command of a ruler; and this civil or theological meaning, as applied to the laws of nature, is continually being brought to scientific discussions, much to the detriment of their clearness. Mathematics alone among the sciences has been able to keep clear of these dangerous alliances, and we there still see the word used in its properly scientific application as an order of sequence merely. Although mathematical. law is not coextensive with physical law, it is this meaning which we should endeavor to preserve. The word is an unfortunate one at best, and some philosophers and scientists have advocated its disuse and the substitution of some more accurate term; but it is too deeply rooted in scientific language for that, and we can only enter a protest against its use in scientific discussions in other than a scientific sense. We have only to consider the scientific genesis of the term to obtain a rule for its application. Considered merely as the generalized expression of the result of observation, we clearly perceive that, however long these observations may have continued, they carry with them no necessity except in so far as relates to our own organism. It is just here that the idea of necessity asserts its power. Take the most fundamental law of mechanics, or even (for the supposed necessity in each case arises in the same way) one of the primary axioms of mathematics, and, by an analysis of the genesis of these conceptions, we shall, with the aid of the light that the theory of evolution sheds into those obscure recesses of the mind where consciousness is coming into being, be enabled to perceive there the process of the growth of this mental necessity in direct correspondence with the evolution of the organism. Through untold ages have the ancestors of man beheld numberless objects break into parts, no one of which was ever as large as the original whole. Through vast geological ages have these facts been impressed upon an evolving mind which, as it never perceived the contrary, had not the data upon which even to imagine it. With this immense induction behind him no wonder, man, when he was able to speculate, asserted the necessary truth of the axiom that "the whole is greater than any of its parts." A necessity for a particular order in nature we know nothing of; that conception arises from the growth of the organism in correspondence with nature as it is.

The old metaphysical conception of types has perhaps had as much influence on scientific controversy as any abstract term. Alike with species, useful when regarded purely as an abstraction from concretes and as an hypothetical form about which to group different individuals, when regarded as a reality it may prove, even in the hands of an able scientist, an ignis fatuus, luring him from the solid ground of scientific knowledge into the quagmires of metaphysical speculation. Like all abstractions, when sufficiently limited in their application, they may lead to useful results, and may suggest resemblances that might otherwise escape the observer. Thus to the conception of types was Goethe indebted for the valuable suggestion he gave to biology. Although these realistic conceptions of abstraction have sometimes brought forth valuable scientific hypotheses, yet their effect commonly has been the reverse. Like the doctrine of final causes, which is popularly supposed to have suggested to Harvey the circulation of the blood, by opening the question as to the use of the valves in the veins, so the doctrine of the existence of types has sometimes been productive of good results; but, as the doctrine of final causes, whatever may be its theological truth, is utterly extra-scientific, and has consequently been a steady opponent of any advance beyond present knowledge, so the theory of types has proved one of the strongest enemies to the acceptance of the theory of evolution. It was his metaphysical belief in this conception that was avowedly the basis of Agassiz's opposition to evolution. Types and species were to him real existences, to which phenomenal existence corresponded. There existed in the universe, for instance, an archetypal form on which vertebrates were modeled. Genera and species corresponded with these types in a greater or less degree, and the assumption that varieties were incipient species which, by successive modifications, could grow into "good species," was, in his view, the introduction of complications into biology sufficient to destroy all classification. Looked at from this standpoint, his vast biological knowledge only served to furnish him with stronger weapons in defense of his position. It may well be doubted whether any proof, however strong, would have been sufficient to have changed his opinion; for metaphysical conceptions, like spiritual substances, yield to no carnal weapons.

Herein consists the great danger in the introduction of abstractions into scientific discussions. Let them once be assumed to have an existence outside the concretes from which they are formed—and the tendency with many is to consider them in this light—and no argument, based upon the observation of phenomena, is sufficient to overthrow them. It can not be too strongly impressed upon the minds of all that science has nothing to do with such conceptions. As science consists in the observation of phenomena and the deduction of the laws of their orderly occurrence, and as scientific hypothesis consists in the prediction of the order of the future occurrence of phenomena and the linking together of diverse phenomena under an assumed order, we see that there is no place where these realistic conceptions can enter. Their sphere, if anywhere, is in metaphysics and theology. Scientists should exercise the utmost care not to misapprehend their own terms, and should then compel acquiescence in the meaning they give to them. Looseness in the use of words is one cause of the indefiniteness that pervades the controversy between the scientists and the theologians.

Force, cause, matter, and science itself are abstract terms, and when analyzed into their concretes will assume a meaning very different from that often given them. All that we scientifically know of force is, that it connotes the presence of motion (i. e., things moving) under different conditions. These we separate into actual and potential motion, and the cause of the motion into actual and potential force or energy. Here the necessity of the use of these abstract terms is at once apparent, as we can scarcely make an assertion without employing them. Cause, as in the above-mentioned case of law, is simply the preceding conditions of any phenomenon, and in the absence of which, as far as we know, it can not occur. Likewise matter, the most "real" of all abstractions, is, scientifically speaking, merely the symbol of a congeries of the phenomena of extension; and Professor Tyndall was speaking entirely within scientific bounds when he said he discerned in it the promise and potency of all forms of life. This did not in the least prejudice the materialistic-idealistic controversy as to its ultimate constitution. In his case he had repeatedly distinctly avowed his nonacceptance of metaphysical materialism, and in a few concise sentences had adduced a stronger argument against that belief than can easily be found in the literature of the subject. The same may be said about the use of the terra "vitality" by Professor Huxley and its relegation by him to the limbo of other defunct "itys." This, which has never ceased to be a red flag in the face of bellicose clergymen, was entirely within his province, and was merely a fine example of the exactness of definition of modern scientific nominalism. This misconception of the scientific use of abstraction appears in almost all the current criticisms of the utterances of scientific men from a religious standpoint. The fundamental difference between the scientific and religious conception of nature consists almost wholly in the manner of regarding abstract terms. Causes—efficient and final—mind, life, and the whole category of vast abstract entities, are to the religionist the most real of all existences; to the scientist they are merely generalized expressions, binding together a large class of phenomena.

The term science does not, like the name of a religious sect, denote the belief in a set dogmatic formula, nor the acceptance of a certain class of ideas. There is no orthodoxy nor heterodoxy in science. On the contrary, the term science connotes the knowledge of the occurrence of certain phenomena in a certain definite order; and the term scientist denotes one who is versed in these facts, and who, from his knowledge of the past, is capable of making more or less probable guesses (hypotheses) as to the occurrence of these phenomena in the future, or in unexplored portions of the past. The attribution of more than this to the term science is not warranted. To say that true science teaches one thing and false science another is wrong. Science teaches nothing; it is itself knowledge rendered more exact. Vagueness of language and a looseness in the use of words lie at the root of many a difficulty. When we think of the numerous disputes that grow out of the misuse of words even on simple topics, and the difficulty there is in confining one's self to their pure signification, we can not wonder at this. It is a common defect in early education that pupils are not taught to attach sensible experiences to the words they repeat. Words are used with but an indefinite apprehension of the objects they are symbols of, and indistinct conception of the thought of others engenders indistinct thought in ourselves. It by no means suffices to establish the etymological meaning of words, for they are not, for the most part, scientifically constructed terms with precise significations, but are the result of the constant adaptation of old words to new uses, and are consequently often much distorted from their original meaning. Plato affords us an excellent model of the way to get at the meaning of terms. Take any of the Socratic dialogues and notice the trenchant manner in which the husks are severed from the true meaning of the words, and we see just what we must do with scientific terms if we would preserve their clearness. Should the logical teaching of our schools and colleges enforce this dialectical method as applied to scientific abstractions, we should see fewer attacks upon scientific men by those who utterly misapprehend their position.

It must be ever borne in mind that the scientist, as a scientist, has nothing to do with the metaphysical or theological implications of the words he uses. He employs them, as we have endeavored to point out, simply and purely to designate the occurrence of phenomena in a certain order which, could we sufficiently magnify our powers of observation, would be presented to our sensation in unequivocal terms. When the scientist transcends these limits, and then only, he is going beyond the bounds of science. The temptation to stroll about, regardless of limits, is often great, and the scientist, like most of his kindred, frequently indulges in these aberrations. When thus found, he is entitled to no consideration on account of any sovereignty he may claim to exercise in his usual habitat, and, if overthrown, may be drawn and quartered at the will of his victorious enemy without a remonstrance being uttered by his fellow scientists. He thus occupies a dual position: in one the knowledge he possesses gives to his assertions a certain authority and to his hypotheses a certain probability of which they are devoid in the other. The discussion and consideration of religious questions by scientific men is a common illustration of this; but the attempt to throw the weight of scientific authority on to one side or the other of any question regarding supra-sensible objects should be steadily frowned down. The acceptance of a thorough nominalism in science and as thorough a realism in religion is by no means incompatible. Faraday is reported to have replied, to an inquiry as to how he, with his well-known scientific rigor of thought, could hold certain religious opinions, that he did not subject those opinions to scientific tests, as he well knew they could not survive them. Nevertheless, he held them as firmly as though convinced of their scientific soundness. The knowledge of the disintegration of the body after death may coexist with a strong religious faith in its resurrection. A large proportion of scientific men hold religious beliefs for which they have, and care for, no scientific justification. The logical soundness of such a position we will not here discuss. All that we care to do now is to assert most strongly that in science abstractions have no "real" existence, and that, when the scientist says that the explanation of certain powers of animal life by the term "vitality" is no explanation, or that consciousness is dependent upon organization, or uses any of the thousand and one kindred abstractions in a scientific sense, it is sheer meddling to interfere. Were the duty of keeping metaphysics at home inculcated with half the ardor that is used in urging science not to stray, we should hear much less of the conflict between religion and science. As it is, the modern Quixotes see in every scientific definition an imaginary giant, which it is their duty and privilege to destroy. Would they observe a little more closely, they would discover the harmless mechanism of the structure, and would reserve their energies for attacks upon more vulnerable enemies.