35. Philosophy, as we know, leads to a complete reversal of this primitive conclusion, and shows that the contemplated is a synthesis of contemplations, the Physis being also the Æsthesis. Psychological investigation shows that the objects supposed to have forms, colors, and positions within an external hemisphere, have these only in virtue of the very feelings from which they are supposed to be separated. The visible universe exists only as seen: the objects are Reals conditioned by the laws of Sensibility. The space in which we see them, their geometrical relations, the light and shadows which reveal them, the forms they affect, the lines of their changing directions, the qualities which distinguish them,—all these are but the externally projected signs of feelings. They are signs which we interpret according to organized laws of experience; each sign being itself a feeling connected with other feelings. We project them outside according to the “law of eccentric projection”—which is only the expression of the fact that one feeling is a sign of some other, and is thereby ideally detached from it. According to this law I say, “my Body”; just as I say, “my House”; or, “my Property.” Misled by this, Dualism holds that in the very fact of detaching my Body from my Self, calling it mine, is the revelation of a distinct entity within the body. But that this is illusory, appears in the application of this same law of eccentric projection to sensations and thoughts, which are called mine, as my legs and arms are mine. If it is undeniable that I say my Body—and thus ideally detach the Body from the Soul—it is equally undeniable that I say my Soul; and from what is the Soul detached? In presence of this difficulty, the metaphysician may argue that neither Body nor Soul can be coextensive with its manifestations, but demands a noumenal Real for each—a substratum for the bodily manifestations, and a substratum for the mental manifestations. This, however, is an evasion, not a solution of the difficulty. If we postulate an unknown and unknowable noumenon, we gain no insight: first, because Philosophy deals only with the known functions of unknown quantities, and therefore leaves the x out of the calculation; secondly, because, granting the existence of these noumena, we can have no rational grounds for asserting that they are not of one and the same nature; for we have no grounds for any assertion whatever about them. And if it be urged against this, that Consciousness testifies to a distinction, I answer that on a closer scrutiny it will be found to testify to nothing more than a diversity of manifestation. All therefore that comes within the range of knowledge is, How does this diversity arise?
36. There are two ways, and there are only two, in which differences arise. These are, 1°, the modes of production of a product, and, 2°, our modes of apprehension of the product. Things may be very different, and yet to our apprehension indistinguishable, so that we regard them as identical; and they may be identical, yet appear utterly unlike. A mechanical bird may seem so like a living bird, and their actions so indistinguishable to the spectator, that he will not suspect a difference, or suspecting it, will not be able to specify it. Of both objects, so long as his modes of apprehending them are circumscribed, he can only say what these imply: he sees familiar forms, colors, and movements, which he interprets according to the previous experiences of which these are the signs. But by varying the modes of apprehension, and gaining thus a fuller knowledge, he finds that the two products have very different modes of production; hence he concludes the products to be different: the mechanism of the one is not the organism of the other; the actions of the mechanical bird are not the actions of the living bird. The fuller knowledge has been gained by viewing the objects under different relations, and contemplating them in their modes of production, not as merely visible products. He sees the mechanism performing by steel springs, wheels, and wires, the work which the organism performs by bones, muscles, and nerves; and the farther his analysis of the modes of production is carried, the greater are the differences which he apprehends.
37. Now consider the other side. One and the same object will necessarily present very different aspects under different subjective conditions, since it is these which determine the aspect. The object cannot be to Sight what it is to Hearing, to Touch what it is to Smell. The vibrations of a tuning-fork are seen as movements, heard as sounds. In current language the vibrations are said to cause the sounds. Misled by this, philosophers puzzle themselves as to how a material process (vibration) can be transformed into a mental process (sensation), how such a cause can have so utterly different an effect. But I have formerly[209] argued at some length that there is no transformation or causation of the kind supposed. The tuning-fork—or that Real which in relation to Sense is the particular object thus named—will, by one of its modes of acting on my Sensibility through my optical apparatus, determine the response known as vibrations; but it is not this response of the optical organ which is transformed into, or causes the response of the auditory organ, known as sound. The auditory organ knows nothing of vibrations, the optical nothing of sounds. The responses are both modes of Feeling determined by organic conditions, and represent the two different relations in which the Real is apprehended. The Real is alternately the one and the other. And if the one mode of Feeling has a physical significance, while the other has a mental significance, so that we regard the vibrations as objective facts, belonging to the external world, and the sounds as subjective facts, exclusively belonging to the internal world, this is due to certain psychological influences presently to be expounded. Meanwhile let us fix clearly in our minds that both vibrations and sounds are modes of Feeling. My consciousness plainly assures me that it is I who see the one, and hear the other; not that there are two distinct subjects for the two distinct feelings. Add to which, manifold uncontradicted experiences assure me that the occasional cause—the objective factor—of the one feeling, is also the cause of the other, and not that the two feelings have two different occasional causes. From both of these undeniable facts we must conclude that the difference felt is simply a difference of aspect, determined by some difference in the modes of apprehension.
38. Assuming then that a mental process is only another aspect of a physical process—and this we shall find the more probable hypothesis—we have to explain by what influences these diametrically opposite aspects are determined. From all that has just been said we must seek these in the modes of apprehension. There can be no doubt that we express the fact in very different terms; the question is, What do these terms signify? Why do we express one aspect in terms of Matter and Motion, assigning the process to the objective world; and the other aspect in terms of Feeling, assigning the process to the subjective world?
Let the example chosen be a logical process as the mental aspect, and a neural process as its physical correlate. The particular proposition may be viewed logically, as a grouping of experiences, or physiologically, as a grouping of neural tremors. Here we have the twofold aspect of one and the same reality; and these different aspects are expressed in different terms. We cannot be too rigorous in our separation of the terms; for every attentive student must have noted how frequently discussions are made turbid by the unconscious shifting of terms in the course of the argumentation. This is not only the mistake of opponents who are unaware of the shifting which has occurred in each other’s minds, so that practically the adversaries do not meet on common ground, but cross and recross each other; it is also the mistake of the solitary thinker losing himself in the maze of interlacing conceptions instead of keeping steadily to one path. Only by such shifting of terms can the notion of the physical process causing, or being transformed into, the mental process for a moment gain credit; and this also greatly sustains the hypothesis of Dualism, with its formidable objections: How can Matter think? How can Mind act on Matter causing Motion?
39. Those who recognized that the terms Matter and Mind were abstractions mutually exclusive, saw at once that these questions, instead of being formidable, were in truth irrational. To ask if Matter could think, or Mind move Matter, was a confusion of symbols equivalent to speaking of a yard of Hope, and a ton of Terror. Although Measure and Weight are symbols of Feeling, and in this respect are on a par with Hope and Terror, yet because they are objective symbols they cannot be applied to subjective states, without violation of the very significance they were invented to express. No one ever asks whether a sensation of Sound can be a sensation of Color; nor whether Color can move a machine, although Heat can, yet the one is no less a sensation than the other. On similar grounds no one should ask whether Matter can think, or Mind move Matter. The only rational question is one preserving the integrity of the terms, namely, whether the living, thinking organism presents itself to apprehension under the twofold aspect—now under the modes of Feeling classified as objective or physical; now under the modes classified as subjective or mental.
40. We are told that it is “impossible to imagine Matter thinking,” which is very true; only by a gross confusion of terms can Thought be called a property of cerebral tissue, or of Matter at all. We may, indeed, penetrate beneath the terms which relate to aspects, and recognize in the underlying reality not two existences, but one. Our conceptions of this reality, however, are expressed in symbols representing different classes of feelings, objective and subjective; and to employ the terms of one class to designate the conceptions of the other is to frustrate the very purposes of language. Matter and Mind, Object and Subject, are abstractions from sentient experiences. We know them as abstractions, and know the concrete experiences from which they are abstracted. Philosophers, indeed, repeatedly assure us that we neither know what Matter is nor what Mind is, we only know the phenomenal products of the action and reaction of these two unknown noumena. Were this so, all discussion would be idle; we could not say whether Matter was or was not capable of thinking, whether Mind was or was not the same as Matter, we could only abstain from saying anything whatever on the topic. What should we reply to one who asked us to name the product of two unknown quantities? So long as x and y are without values their product must be without value. If the value of x be known, and that of y unknown, then the product still remains unknown: x + y = x + 0 = x. Therefore, unless the Objective aspect were the equivalent of the Subjective aspect, it could never be subjectively present. Feeling is but another aspect of the Felt.
41. It is because we do know what Matter is, that we know it is not Mind: they are symbols of two different modes of Feeling. If we separate the conception of citizenship from the conception of fatherhood, although the same man is both citizen and father, how much more decisively must we separate the conception of Matter, which represents one group of feelings, from the conception of Mind, which represents another? One element in the former is common to the whole group, namely, the reference to a Not-Self, induced by the sensation of Resistance, which always ideally or sensibly accompanies the material class. The axiom, I feel, ergo I exist, has its correlative:—I act, ergo there are other existents on which I act; and these are not wholly Me, for they resist, oppose, exclude me; yet they are also one with Me, since they are felt by me. In my Feeling, that which is not Me is Matter, the objective aspect of the Felt, as Mind is the subjective aspect.
But since Hunger and Thirst, Joy and Grief, Pain and Terror, are also felt, yet are never classed under the head of Matter, the grounds of the classification of feelings have to be expressed. Professor Bain makes the distinction between Matter and Mind to rest solely on the presence or absence of Extension: this is the decisive mark: Matter he defines as the Extended. The definition is inadequate. When I see a dog and its image reflected in a pool, or see a dog and think of another, in the three cases dog, image, and idea have Extension; but I recognize the dog as a material fact, the idea as a mental fact; and although the image of the dog has material conditions by which I am optically affected, just as the idea has material cerebral conditions, I recognize a marked difference between them and the dog, due to the different modes of apprehension. The dog is known as a persistent reality, which, when Sight is supplemented by Touch, will yield sensations of Resistance, and thus disclose its materiality. The image vanishes if I attempt to touch it; I see its outlines waver and become confused with every disturbance of the surface of the pool; the idea vanishes when another idea arises; whence I conclude that neither has material reality, because neither has the Resistance which characterizes the Not-Self. The image and the idea may be referred to material conditions, but so may pains, terrors, volitions, yet these are all without Extension, simply because they are not visual feelings.
42. Matter does not represent all feelings, but only the objective sensibles; and these are not all characterized by Extension, but only those which directly or indirectly involve optico-tactical experiences accompanied by muscular experiences. Matter is primarily the Visible and Resistant; and secondarily, whatever can be imagined as such; so that ether, molecules, and atoms, although neither visible nor tangible, are ranged under the head of Matter. Color is a feeling as Sound and Scent are feelings, and although material conditions are equally presupposed in all three, yet Color alone has Extension, and because it can be imaged it has a more objective character than the others, which having no lines and surfaces, want the optical conditions for the formation of images, and are less definitely connected with tactical and muscular experiences. Nevertheless, since Sound and Scent are obviously associated with objects seen and touched, they have a degree of materiality never assigned to such feelings as Hunger and Thirst, Pleasure, Terror, and Hope.