27. The second question proposed was, In what sense can Feeling be correctly spoken of as an Agent in organic processes? This brings us face to face with a much-debated topic, the relation of Body and Mind; and demands a theoretic interpretation of that First Notion which expresses universal experience, namely, that what I know as Myself is a Body, in one aspect, and a Soul, in the other. What I call my Body is a persistent aggregate of objective phenomena; and my Soul is a persistent aggregate of subjective phenomena: the one is an individualized group of experiences expressible in terms of Matter and Motion, and therefore designated physical; the other an individualized group of experiences expressible in terms of Feeling, and therefore designated psychical. But, however contrasted, they are both simply embodiments of Experience, that is to say, are Modes of Feeling. All Existence—as known to us—is the Felt. The laws of our organism compel us, indeed, to postulate an Existent which is extra mentem—a Real not Ourselves—but the same laws debar us from any knowledge whatever of what this is, or is like. We know Things absolutely in so far as they exist in relation to us; and that is the only knowledge which can have any possible significance for us. 28. It is impossible for me to doubt that I am a Body, though I may doubt whether what is thus called is anything377 more than a group of feelings. It is impossible for me to doubt that I am a Soul; though I may doubt whether what is thus called is more than a group of bodily functions. In separating what is unquestionable from what is questionable, we separate the fundamental facts of consciousness from the theoretic interpretations of those facts: no theoretic interpretation can efface or alter the facts. Whatever Philosophy may discover, it cannot displace the fact that I know I am a Soul, in every sense in which that phrase represents Experience: I know the Soul in knowing its concretes (feelings), and in knowing it as an abstraction which condenses those concretes in a symbol. The secondary question is, Whether this abstraction represents one Existent, and the abstraction Body another and wholly different Existent, or the two abstractions represent only two different Aspects? this may be debated, and must be answered according to theoretic probabilities.
29. What are the probabilities? We are all agreed that Consciousness is the final arbiter. Its primary deliverance is simply that of a radical distinction. It is silent on the nature of the distinction—says nothing as to whether the distinction is one of agents or of aspects. It says, “I am a Soul.” With equal clearness it says, “I am a Body.” It does not say, “I am two things.” Nor does the fact of a radical distinction imply more than a contrast of aspects, such as that of convex and concave. The curve has at every point this contrast of convex and concave, and yet is the identical line throughout. A mental process is at every point contrasted with the physical process assumed to be its correlate; and this contrast demands equivalent expression in the terms of each. The identity underlying the two aspects of the curve is evident to Sense. The identity underlying the mental and physical process is not evident to Sense,378 but may be made eminently probable to Speculation, especially when we have explained the grounds of the difference, namely, that they are apprehended through different modes. But although I admit that the conclusion is only one of probability, it is one which greatly transcends the probability of any counter-hypothesis. Let us see how this can be made out.208
30. We start from the position that a broad line of demarcation must be drawn between the mental and the physical aspect of a process, supposing them to be identical in reality. Nothing can be more unlike a logical proposition than the physical process which is its correlate; so that Philosophy has hitherto been forced to forego every attempt at an explanation of how the two can be causally connected: referring the connection to a mystery, or invoking two different agents, spiritual and material, moving on parallel lines, like two clocks regulated to work simultaneously. But having recognized this difference, can we not also discern fundamental resemblances? First and foremost, we note that there is common to both the basis in Feeling: they are both modes of Consciousness. The Mind thinking the logical proposition is not, indeed, in the same state as the Mind picturing the physical process which is the correlate of that logical proposition—no more than I, who see you move on being struck, have the same feelings as you who are struck. But the Mind which pictures the logical proposition as a process, and pictures the physical process as a bodily change, is contemplating one and the same event under its subjective and objective aspects; just as when I379 picture to myself the feelings you experience on being struck I separate the subjective aspect of the blow from its objective aspect. Secondly, between the logical proposition and the physical process there is a community of causal dependence, i. e. the mode of grouping of the constituent elements, whereby this proposition, and not another, is the result of this grouping, and not another. In fact, what in subjective terms is called Logic, in objective terms is Grouping.
31. Let us approach the question on a more accessible side. Sensation avowedly lies at the basis of mental manifestations. Now, rightly or wrongly, Sensation is viewed alternately as a purely subjective fact—a psychological process—and as a purely objective fact—the physiological reaction of a sense-organ. It is so conspicuously a physiological process that many writers exclude it from the domain of Mind, assign it to the material organism, and believe that it is explicable on purely mechanical principles. This seems to me eminently disputable; but the point is noticed in proof of the well-marked objective character which the phenomenon assumes. In this aspect a sensation is simply the reaction of a bodily organ. The physiologist describes how a stimulus excites the organ, and declares its reaction to be the sensation. Thus viewed, and expressed in terms of Matter and Motion, there is absolutely nothing of that subjective quality which characterizes sensation. Yet without this quality the objective process cannot be a sensation. Exclude Feeling, and the excitation of the auditory organ will no more yield the sensation of Sound by its reaction, than the strings and sounding-board of a piano when the keys are struck will yield music to a deaf spectator. Hence the natural inference has been that inside the organism there is a listener: the Soul is said to listen, transforming excitation into sensation. This inference380 only needs a more systematic interpretation and it will represent the biological theory, which demands something more than the reaction of the sensory organ—namely, the reaction of the whole organism through the sensory organ. I mean, that no organ isolated from the organism is capable of a physiological reaction—only of a physico-chemical reaction; and sensation depends on (is) the physiological reaction. When a sense-organ is stimulated, this stimulation is a vital process, and is raised out of the class of physico-chemical processes by virtue of its being the indissoluble part of a complex whole. Interfere with any one of the co-operant conditions—withdraw the circulation, check respiration, disturb secretion—and the sense-organ sinks from the physiological to the physical state; it may then be brought into contact with its normal stimuli, but no stimulation (in the vital sense) will take place, there will be no vital reaction.
Condensing all vital processes in the symbol Vitality, we may say Vitality is requisite for every physiological process. A parallelism may be noted on the subjective side: all the sentient processes may be condensed in the one symbol Sensibility (Feeling), and we must then say, No psychological process is possible as an isolated fact, but demands the co-operation of others—it is a resultant of all the contemporaneous conditions of Sensibility in the organism. In ordinary language this is what is meant by saying that no impression can become a sensation without the intervention of Consciousness—an ambiguous phrase, because of the ambiguity of the term Consciousness, but the phrase expresses the fact that in Sensation a process in the organism is necessary to the reaction of the organ.
32. Having recognized the distinction between the two processes objective and subjective, physical and mental,381 we have recognized the vanity of attempting to assign their limits, and to say where Motion ends and Feeling begins, or how Feeling again changes into Motion. The one does not begin where the other ends. According to the two-clock theory of Dualism, the two agents move on parallel lines. On the theory of Monism the two aspects are throughout opposed. Both theories explain the facts; which explanation is the most congruous with experience? Against the first we may object that the hypothesis of two Agents utterly unallied in nature wants the cardinal character of a fertile hypothesis in its unverifiableness: it may be true, we can never know that it is true. By the very terms of its definition, the Spirit—if that mean more than an abstract expression of sentient states—is beyond all sensible experience. This is indeed admitted by the dualists, for they postulate a Spirit merely because they cannot otherwise explain the phenomena of Consciousness. Herein they fail to see that even their postulate brings no explanation, it merely restates the old problem in other terms.
33. Up to the present time these same objections might have been urged with equal force against Monism. Indeed, although many philosophers have rejected the two-clock theory of Leibnitz, they have gained a very hesitating acceptance for their own hypothesis of identity. To most minds the difficulty of imagining how a physical process could also be a psychical process, a movement also be a feeling, seemed not less than that of imagining how two such distinct Agents as Matter and Mind could co-operate, and react on each other, or move simultaneously on parallel lines. Although for many years I have accepted the hypothesis of Monism, I have always recognized its want of an adequate reply to such objections. Unless I greatly deceive myself, I have now found a solution of the main difficulty; and found it in psychological382 conditions which are perfectly intelligible. But knowing how easily one may deceive one’s self in such matters, I will only ask the reader to meditate with open-mindedness the considerations now to be laid before him, and see if he can feel the same confidence in their validity.
34. One of the early stages in the development of Experience is the separation of Self from the Not-Self. I look out on “the vast extern of things,” and see a great variety of objects, included in a visible hemisphere. All these objects in various positions, having various forms and colors, I believe to be wholly detached from, and in every way unallied to, Myself. And what is that Self? It is my Body as a visible and tangible object, separated from all other visible and tangible objects by the constant presence of feelings connected with it and its movements, and not connected with the other objects. This constant presence of feelings is referred to a Soul, which I then separate from my Body, as an Inner Self; and from this time onwards I speak of the Body as mine, and learn to regard it in much the same light as other outer objects. In my na?ve judgment the external objects are supposed to exist as I see and touch them, whether I or any one else see and touch them or not: they in no sense belong to the series of feelings which constitute the Me. And since my Body resembles these objects in visible and tangible qualities, and also in being external to my feelings, it also takes its place in the objective world. Thus arises the hypothesis of Dualism which postulates a Physis, or object-world, and an ?sthesis, or subject-world: two independent existents, one contemplated, the other contemplating.
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 ?sthesis. Psychological investigation shows383 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 unknown384 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,385 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 formerly209 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 influences386 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 course387 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 t............