# The Philosophical Review/Volume 1/Review: Schwarz - Das Wahrnehmungsproblem vom Standpuncte des Physikers, des Physiologen und des Philosophen

The problem of perception offers three remarkable features from the point of view of the physicist, physiologist, and psychologist respectively. The first finds that the sequences of the non- material world of ​tones and colors can be derived with great precision from the laws of mechanical processes, like the vibrations of material particles of air and ether. The second finds that whatever stimulus is applied to a sensory nerve, the nerve always reacts with the same sort of sensation, and conversely, that if the same stimulus affects different nerves, the sensations will belong to different senses. The psychologist, lastly, finds that all the data of sense are instinctively and invariably referred to external existences, and never to the observer's internal condition. Not one of these facts could have been anticipated. The reduction of the brilliancy and variety of tones and colors to the mechanical processes of atoms is surprising. But after agreeing to it, it is no less surprising to discover the specific physiological functions of the sensory nerves, and to find that this does not invalidate the physicist's calculations. Lastly, it remains a mystery how consciousness obtains a knowledge of any existence external to itself. Moreover, the simplest explanations of these several facts are in conflict. We cannot call sense impressions effects of general mechanical processes, if they are at the same time effects of the special constitution of the organs; we cannot call them the latter if they are objective existences alien to consciousness. Hence the difficulty which Dr. Schwarz proposes to solve, and hence also the threefold division of his subject.
He starts from natural ("naïve") realism as the basis of all the scientific theories. In it he distinguishes a metaphysical assertion and a methodological procedure, which are really independent of each other. The procedure asserts three dogmas. (1) It regards touch as the primary sense, and its data as informing us of the real nature of things, and interprets the deliverances of the other senses with reference to touch. This privileged position of the data of touch is due to their relative permanence, while those of the other senses are secondary, because variable. (2) Of these variable data, those which are presented under the customary conditions of observation are regarded as informing us of the properties of things, continuing to exist unperceived, while unwonted and abnormal impressions are treated as transitory appearances. (3) Permanent alterations in the “properties” of things are explained by causation — as effects of the action of other things without the recognition of any interaction. Such is the method whereby natural realism supports its metaphysical assertion of external things independent of our conclusions.
The physicist transforms the world as constituted by natural realism by a method of his own. (1) Remaining under the influence of the realistic dogma as to the supremacy of the tangible, he reduces the “properties” of things to mechanical processes and regards them as the signs of the latter.
​This method is independent of his metaphysic, which is substantially that of Locke, and distinguishes between the properties of matter which are primary and given by the objects of touch, and those which are secondary like sounds and colors, and subjective, i.e. effects of the motions of atoms, etc., on consciousness. This assertion leads to a conflict with the principle of the conservation of energy, since the physical forces are already equated in the motions of the atoms, and the soul, therefore, must create the subjective colors, tones, etc., out of nothing.
But this subordination of the data of the other senses to those of touch is a practically convenient method of treating them, rather than a valid derivation, and makes the generation of the qualitative differences of the senses from the quantitative differences of atomic vibrations, etc., incomprehensible. This difficulty is created by ignoring the psychological co-ordination of the various senses. In the order of knowledge, moreover, tones and colors are prior to atomic and ethereal vibrations. Lastly, it is on evolutionist grounds improbable, that if vibrations devoid of color, light, and temperature had been the original fact, they would have been so variously transformed by the senses.
Hence, as a matter of metaphysics, the physicist has either to become an idealist and admit the subjectivity of the data of touch also, or to assert the objectivity also of sounds and colors. The latter view is more natural, and harmonizes with the method of physics, if a parallelism between, e.g. vibrations and colors is substituted for the causation of the second by the first.
The second realistic dogma, that reality belongs only to the normal appearances of things, leads the physicist to assert the dependence of some sounds, colors, etc., on the physiological condition of the organs of sight, hearing, etc., in order to account for abnormal appearances like after-images, fused tones, etc. Science cannot ignore them simply because they are practically unimportant, and so physiology is appealed to. Thus the physiological treatment of perception is throughout based on the physical explanation which it supplements, and so admits neither of a special physiological method nor of a metaphysic. These points are treated in a very detailed and complicated discussion, which shows that physical explanations will go much further in physiology than has generally been admitted, and that the assertion of peculiar and specific physiological activities of the sense organs is untenable. Nevertheless, the physical theory fails to explain, e.g. the dimness of indirectly seen objects (for which a psychological explanation must be adduced) and can provide no satisfactory theory of color. In the last resort this failure is due to the defects of the mechanical theory itself.
The inference from all this is that the metaphysic, though not the method, of physical science has broken down. But on the other hand ​the metaphysic, if not the methodology, of natural realism may be maintained. Psychologically, realism is tenable; for (1) pure sensations, as yet unassociated and unrelated, must underlie all psychic combination; (2) externality is an original datum in sensation. Philosophically, an abandonment of realism is not necessitated by the objections of idealism. These objections Dr. Schwarz discusses upon the old lines of the thing-in-itself, which he will not permit his opponents to disclaim (pp. 385 ff.), but hardly so as to convince one that he has fully appreciated their strength. The book concludes with a declaration (p. 406) that it is best and simplest to regard perception as an ultimate process which does not admit of further analysis, and leads to a trustworthy, though not complete, cognition of an existence independent of consciousness.
From the philosophic point of view the chief merit of Dr. Schwarz's learned book seems to lie in the fulness of the illustration it affords of the scientific inadequacy of the obsolete metaphysic which still serves as the working theory on which scientific procedure is based. And considering the practical purpose and mutual isolation, which have so long prevailed in the physical sciences, their inconsistencies and inadequacies will seem pardonable. Still Dr. Schwarz has done good service by pointing out these difficulties specifically and in detail. We may thank him also for his admission that a possible solution of the difficulty lies in the direction of a comprehensive idealistic metaphysic, all the more if his own proposal of a reversion to primitive realism should prove unacceptable. His delusion on this subject seems to be largely due to the fact that he has substituted for the actual opinions of the "plain man" with all their grotesque crudity, an expurgated version thereof, which philosophers have constructed for purposes of convenience in academic discussion, and entitled "Natural Realism," much as they have constructed the two varieties of "subjective idealism" which Dr. Schwarz ascribes to Berkeley and Fichte. The truth is, that the plain man's view is very different from Dr. Schwarz's realism, and ten times more inconsistent and incoherent than the physicist's view which is developed from it. And though our author's view is enabled to maintain some degree of coherence, until it is brought face to face with all the facts, and asked, e.g. to explain what is the reality perceived in dreams or in the hallucinations and illusions of delirium (what can the doctrine of the non-deceptiveness of the senses make of such facts?) a final collapse seems inevitable as soon as criticism is directed upon it in its turn. It would hardly be necessary even to ask what is meant by "independent of, or external to" consciousness. The truth seems rather to be, that the effort to understand the universe starts much further back than Dr. Schwarz's pseudo-natural realism, in a chaos where fact, illusion, and fancy are not yet distinguished, and where there is as yet no pretence at coherence. This amorphous mass of primitive ​perplexity is overlaid with successive strata of metaphysical interpretation, and these deposits will go on with growing precision and refinement until a completely congruous account of all the facts is reached. But though it is well to be reminded of the foundations on which we must build, and of the primary data our solutions must satisfy, the truth surely lies ahead of us and not behind us.
F. C. S. Schiller.
This work is in the public domain in the United States because it was published before January 1, 1929.
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