1. Modern Philosophy has moved along two increasingly divergent lines. One, traversed by Galileo, Descartes, Newton, and Laplace, had for its goal the absolute disengagement of the physical from the mental, i.e. the objective from the subjective aspect of phenomena, so that the physical universe, thus freed from all the complexities of Feeling, might be interpreted in mechanical terms. As a preliminary simplification of the problem this was indispensable; only by it could the First Notion of primitive speculation be replaced by the Theoretic Conception of scientific speculation.204 The early thinker inevitably invested all external objects with properties and qualities similar to those he assigned to human beings, and their actions he assigned to human motives. Sun, moon, and stars seemed living beings; flames, streams, and winds were supposed to be moved by feelings such as those known to move animals and men. Nor was any other conception then possible: men could only interpret the unknown by the known, and their standard of all action was necessarily drawn from their own actions. Not having analyzed Volition and Emotion, above all not having localized these in a neuro-muscular system, men could not suspect that the movements of planets and plants, and of streams and stones, had motors of a different kind from the movements of animals. The scientific conception of inert insensible Matter was only attained through a long education in abstraction; and is assuredly never attained by animals, or by savages. But no sooner were vital conditions recognized, than the difference between vital and mechanical movements emerged. When men learned that many of their own actions were unaccompanied either by Love or Hate, by Pleasure or Pain, and that many were unprompted by conscious intention, while others were unaccompanied by conscious sensation, they easily concluded that wherever the special conditions of Feeling were absent, the actions must have some other motors. Intelligence, Emotion, Volition, and Sensation being one by one stripped away from all but a particular class of bodies, nothing remained for the other bodies but insensible Matter and Motion. This was the Theoretic Conception which science substituted for the First Notion. It was aided by the observation of the misleading tendency of interpreting physical phenomena by the human standard, substituting our fancies in the place of facts, manipulating the order of the universe according to our imagination of what it might be, or ought to be. Hence the vigilance of the new school in suppressing everything pertaining to the subjective aspect of phenomena, and the insistance on a purely objective classification, so that by this means we might attain to a knowledge of things as they are. By thus withdrawing Life and Mind from Nature, and regarding the universe solely in the light of Motion and the laws of Motion, two great scientific ends were furthered, namely, a classification of conceptions, and a precision of terms. Objective phenomena made a class apart, and the great aim of research was to find a mathematical expression for all varieties under this class. Masses were conceived as aggregates of Atoms, and these were reduced to mathematical points. Forces were only different modes of Motion. All the numberless differences which perception recognized as qualities in things, were reduced to mere variations in quantity. Thus all that was particular and concrete became resolved by analysis into what was general and abstract. The Cosmos then only presented a problem of Mechanics.

2. During this evolution, the old Dualism (which conceived a material universe sharply demarcated from the mental universe) kept its ground, and attained even greater precision. The logical distinction between Matter and Mind was accepted as an essential distinction, i.e. representing distinct reals. There was on the one side a group of phenomena, Matter and Force; on the other side an unallied group, Feeling and Thought: between them an impassable gulf. How the two were brought into relation, each acting and reacting on the other, was dismissed as an “insoluble mystery”—or relegated to Metaphysics for such minds as chose to puzzle over questions not amenable to experiment. Physics, confident in the possession of mathematical and experimental methods which yielded definite answers to properly restricted questions, peremptorily refused to listen to any suggestion of the kind. And the career of Physics was so triumphant that success seemed to justify its indifference.

3. In our own day this analytical school has begun to extend its methods even to the mental group. Having reduced all the objective group to mathematical treatment, it now tries to bring the subjective group also within its range. Not only has there been more than one attempt at a mathematical Psychology; but also attempts to reduce Sensibility, in its subjective no less than in its objective aspect, to molecular movement. Here also the facts of Quality are translated into facts of Quantity; and all diversities of Feeling are interpreted as simply quantitative differences.

4. Thus far the one school. But while this Theoretic Conception stripped Nature of consciousness, motive, and passion, rendering it a mere aggregate of mathematical relations, a critical process was going on, which, analyzing the nature of Perception, was rapidly moving towards another goal. Locke, Berkeley, Hume, and Kant, directing their analysis exclusively to the subjective aspect of phenomena, soon broke down the barriers between the physical and mental, and gradually merged the former in the latter. Matter and its qualities, hitherto accepted as independent realities, existing where no Mind perceived them, were now viewed as the creations of Mind—their existence was limited to a state of the percipient. The old Dualism was replaced by Idealism. The Cosmos, instead of presenting a problem of Mechanics, now presented a problem of Psychology. Beginning with what are called the secondary qualities of Matter, the psychological analysis resolved these into modes of Feeling. “The heat which the vulgar imagine to be in the fire and the color they imagine in the rose are not there at all, but are in us—mere states of our organism.” Having gained this standing-place, there was no difficulty in extending the view from the secondary to the primary qualities. These also were perceptions, and only existed in the percipient. Nothing then remained of Matter save the hypothetical unknown x—the postulate of speculation. Kant seemed forever to have closed the door against the real Cosmos when he transformed it into a group of mental forms—Time, Space, Causality, Quantity, etc. He propounded what may be called a theory of mental Dioptrics whereby a pictured universe became possible, as Experience by its own a priori laws moulded itself into a consistent group of appearances, which produced the illusion of being a group of realities. He admitted, indeed, that by the operation of Causality we are compelled to believe in a Real underlying the appearances; but the very fact that this Causality is a subjective law, is proof, he said, of its not being an objective truth. Thus the aim of the mechanical conception was to free research from the misleading complexities of subjective adulterations, and view things as they are apart from their appearances; but this aim seemed illusory when Psychology showed that Time, Space, Matter, and Motion were themselves not objective reals except in so far as they represented subjective necessities; and that, in short, things are just what they appear, since it is only in the relation of external reals to internal feelings that objects exist for us.

5. Idealism has been the outcome of the psychological method. It has been of immense service in rectifying the dualistic conception, and in correcting the mechanical conception. It has restored the subjective factor, which the mechanical conception had eliminated. It has brought into incomparable clearness the fundamental fact that all our knowledge springs from, and is limited by, Feeling. It has shown that the universe represented in that knowledge, can only be a picture of the system of things as these exist in relation to our Sensibility. But equally with the mechanical conception it has erred by incomplete analysis. For a complete theory of the universe, or of any one phenomenon, those elementary conditions which analysis has provisionally set aside must finally be restored. When Quality is replaced by Quantity, this is an artifice of method, which does not really correspond with fact. The quality is the fact given in feeling, which we analytically refer to quantitative differences, but which can never be wholly resolved into them, since it must be presupposed throughout. One color, for example, may be distinguished from another as having more or fewer undulations; and so we may by abstraction, letting drop all qualitative characters, make a scale of undulations to represent the scale of colors. But this is an ideal figment. It is the representation of one series of feelings by another series of different feelings. No variation of undulations will really correspond with variation in color, unless we reintroduce the suppressed quality which runs through all color. Attempt to make one born blind feel, or even understand, Color by describing to him the kind of wave-movement which it is said to be, and the vanity of the effort will be manifest. Movement he knows, and varieties of movement as given in tactile and muscular sensations; but no combination and manipulation of such experiences can give him the specific sensation of Color. That is a purely subjective state, which he is incapable of experiencing, simply because one of the essential factors is absent. One set of objective conditions is present, but the other set (his sense-organ) is defective. Without the “greeting of the spirit” undulations cannot become colors (nor even undulations, for these also are forms of feeling). Besides the sense-organ there is needed the feeling of Difference, which is itself the product of past and present feelings. The reproduction of other colors, or other shades of color, is necessary to this perception of difference; and this involves the element of Likeness and Unlikeness between what is produced and reproduced. So that a certain mental co-operation is requisite even for the simplest perception of quality. In fact, psychological analysis shows that even Motion and Quantity, the two objective terms to which subjective Quality is reduced, are themselves Fundamental Signatures of Feeling;205 so that here, as elsewhere, it is only by analytical artifice that the objective can be divorced from the subjective. Matter is for us the Felt; its Qualities are differences of Feeling.

6. Not that this result is to be interpreted as freeing our Theoretic Conception from its objective side, and landing us in Idealism, which suppresses the real universe. The denial of all reality apart from our minds, is a twofold mistake: it confounds the conception of general relations with particular relations, declaring that because the External in its relation to the sentient organism can only be what it is felt to be, therefore it can have no other relations to other individual reals. This is the first mistake. The second is the disregard of the constant presence of the objective real in every fact of Feeling: the Not-Self is emphatically present in every consciousness of Self.

The legitimate conclusion is neither that of Dualism nor of Idealism, but what I have named Reasoned Realism (Problems, Vol. I. p. 201), which reconciles Common Sense with Speculative Logic, by showing that although the truth of things (their Wahrheit) is just what we perceive in them (our Wahrnehmung), yet their reality is this, and much more than this. Things are what they are felt to be; and what they are thought to be, when thoughts are symbols of the perceptions. Idealism declares that they are nothing but this. It is against this nothing but that Common Sense protests; and the protest is justified by Reasoned Realism, which, taking a comprehensive survey of the facts, thus answers the idealist: “Your synthesis is imperfect, since it does not include all the data—notably it excludes the fact of an objective or Not-Self element in every feeling. You may, conceivably, regard the whole universe as nothing but a series of changes in your consciousness; but you cannot hope to convince me that I myself am simply a change in yourself, or that my body is only a fleeting image in your mind. Hence although I conclude that the Not-Self is to you, as to me, undivorceable from Self, inalienable from Feeling, in so far as it is felt, yet there must nevertheless be for both of us an existence not wholly coextensive with our own. My world may be my picture of it; your world may be your picture of it; but there is something common to both which is more than either—an existent which has different relations to each. You are not me, nor is the pictured Cosmos me, although I picture it. Looking at you and it, I see a vast whole of which you are a small part; and such a part I conclude myself to be. It is at once a picture and the pictured; at once subjective and objective. To me all your modes of existence are objective aspects, which, drawing from my own experience, I believe to have corresponding subjective aspects; so that your emotions, which to me are purely physical facts, are to you purely mental facts. And psychological analysis assures me that all physical facts are mental facts expressed in objective terms, and mental facts are physical facts expressed in subjective terms.”

7. But while Philosophy thus replaces the conceptions of Dualism and Idealism by the conception of the Two-fold Aspect, the special sciences in their analytical career have disregarded the problem altogether. The mechanical theory of the universe not only simplified research by confining itself solely to the objective aspect of phenomena, but by a further simplification set aside all vital and chemical relations, to deal exclusively with mechanical relations. In ascertaining the mathematical relations of the planetary system, no elucidation could possibly be gained from biological or chemical conceptions; the planets therefore were provisionally stripped of everything not mechanical. In systematizing the laws of motion, it was necessary to disengage the abstract relations from everything in any way resembling spontaneity, or extra-mechanical agency: Matter was therefore, by a bold fiction, declared to be inert, and its Motion regarded as something superadded from without.

7a. And this was indispensable for the construction of those ideal laws which are the objects of scientific research. Science, as we often say, is the systematization of Experience under the forms of ideal constructions. Experience implies Feeling, and certain fundamental Signatures, all reducible to the primary discernment of Likeness and Unlikeness. Hence Science is first a classification of qualities or discerned likenesses and differences; next a measurement of quantities of discerned likenesses and differences. Although measurement is itself a species of classification, it is distinguished by the adoption of a standard unit of comparison, which, being precise and unvarying, enables us to express the comparisons in precise and unvarying symbols. Whether the unit of length adopted be an inch, a foot, a yard, a mile, the distance of the earth from the sun, or the distances of the fixed stars, the quantities thus measured are symbols admitting of one invariable interpretation. The exactness of the mathematical sciences is just this precision and invariability of their symbols, and is not, as commonly supposed, the source of any superior certainty as to the facts. The classificatory sciences, which deal with qualities rather than with quantities, may be equally certain, and represent fuller knowledge, because involving more varied feelings, but they cannot pretend to exactness. Even on the quantitative side, certainty is not identical with exactness. I may be quite certain that one block of marble is larger than another—meaning that it affects me more voluminously—but I cannot know how much larger it is, without interpreting my feelings by the standard of quantity—the how-muchness as represented by that standard. The immense advantages of exact measurement need not be insisted on. The Biological Sciences, which are predominantly classificatory, can never rival the Cosmological Sciences in exactness; but they may reach a fuller knowledge; and their certainty will assume more and more the character of exactness as methods of measurement are applied to their classifications of qualities. The qualitative and quantitative aspects of phenomena are handled by the two great instruments, Logic and Mathematics, the second being only a special form of the first. These determine the general conceptions which are derived from our perceptions, and the whole constitute Experience.

8. What is the conclusion to which these considerations lead? It is that the separation of the quantitative from the qualitative aspect of phenomena—the objective mechanical from the subjective psychological—is a logical artifice indispensable to research; but it is only an artifice.206 In pursuance of this artifice, each special science must be regarded as the search after special analytical results; and meanwhile this method should be respected, and no confusion of the boundaries between one science and another should be suffered. Mechanical problems must not be confused by the introduction of biological relations. Biological problems must not be restricted to mechanical relations. I do not mean that the mechanical relations present in biological phenomena are not to be sought, and, when found, to be expressed in mechanical terms; I mean that such an inquiry must be strictly limited to mechanical relations. Subjective relations are not to be denied, because they are provisionally set aside, in an inquiry into objective relations; but we must carefully distinguish which of the two orders we are treating of, and express each in its appropriate terms. This is constantly neglected. For example, nothing is more common than to meet such a phrase as this: “A sensory impression is transmitted as a wave of motion to the brain, and there being transformed into a state of consciousness, is again reflected as a motor impulse.”

The several sciences having attained certain analytical results, it remains for Philosophy to co-ordinate these into a doctrine which will furnish general conceptions of the World, Man, and Society. On the analytical side a mechanical theory of the universe might be perfected, but it would still only be a theory of mechanical relations, leaving all other relations to be expressed in other terms. We cannot accept the statement of Descartes that Nature is a vast mechanism, and Science the universal application of mathematics. The equation of a sphere, however valuable from a geometrical point of view, is useless as an explanation of the nature and properties of the spherical body in other relations. And so a complete theory of the mechanical relations of the organism, however valuable in itself, would be worthless in the solution of a biological problem, unless supplemented by all that mechanical terms are incompetent to express.

9. The course of biological speculation has been similar to the cosmological. It also began with a First Notion, which compendiously expressed the facts of Experience. Nor can any Theoretic Conception be finally adopted which does away with these facts, known with positive certainty, and popularly expressed in the phrase: “I have a body, and a soul.” We may alter the phrase either into “I am a body, and I am a soul”; or into, “My body is only the manifestation of my soul”; or, “My soul is only a function of my body”; but the fundamental experiences which are thus expressed are of absolute authority, no matter how they may be interpreted. That I have a body, or am a body, is not to be speculatively argued away. That I move my arm to strike the man who has offended me, or stretch out my hand to seize the fruit which I see, is unquestionable; that these movements are determined by these feelings, and are never thus effected unless thus determined, is also unquestionable. Here are two sets of phenomena, having well-marked differences of aspect; and they are grouped respectively under two general heads, Life and Mind. Life is assigned to the physical organism, or Body—all its phenomena are objective. Mind is assigned to the psychical organism, or Soul—all its phenomena are subjective. Although what is called my Body is shown to be a group of qualities which are feelings—its color, form, solidity, position, motion—all its physical attributes being what is felt by us in consequence of the laws of our organization; yet inasmuch as these feelings have the characteristic marks of objectivity, and are thereby referred to some objective existence, we draw a broad line of demarcation between them and other feelings having the characteristic marks of subjectivity, and referring to ourselves as subjects. Psychological analysis shows us that this line of demarcation is artificial, only representing a diversity of aspect; but as such it is indispensable to science. We cannot really separate in a sensation what is objective from what is subjective, and say how much belongs to the Cosmos apart from Sensibility, and how much to the subject pure and simple; we can only view the sensation alternately in its objective and subjective aspects. What belongs to extra-mental existence in the phenomenon of Color, and what to the “greeting of the spirit,” is utterly beyond human knowledge: for the ethereal undulations which physicists presuppose as the cosmic condition are themselves subjected to this same greeting of the spirit: they too are ideal forms of sensible experiences.

10. This conclusion, however, was very slowly reached. The distinction of aspects was made the ground of a corresponding distinction in agencies. Each group was personified and isolated. The one group was personified in Spirit—an existent in every respect opposed to Matter, which was the existent represented in the other group. One was said to be simple, indestructible; the other compound, destructible. One was invisible, impalpable, beyond the grasp of Sense; the other was visible, tangible, sensible. One was of heaven, the other of earth. Thus a biological Dualism, analogous to the cosmological, replaced the First Notion. It was undermined by advances in two directions. Psychology began to disclose that our conception of Matter was, to say the least, saturated with Mind, its Atoms confessedly being ideal figments; and that all the terms by which we expressed material qualities were terms which expressed modes of Feeling; so that whatever remained over and above this was the unknown x, which speculation required as a postulate. Idealism, rejecting this postulate, declared that Matter was simply the projection of Mind, and that our Body was the objectivation of our Soul. Physiology began to disclose that all the mental processes were (mathematically speaking) functions of physical processes, i.e. varying with the variations of bodily states; and this was declared enough to banish forever the conception of a Soul, except as a term simply expressing certain functions.

11. Idealism and Materialism are equally destructive of Dualism. The defects of particular idealist and materialist theories we will not here touch upon; they mainly result from defects of Method. Not sufficiently recognizing the primary fact testified by Consciousness, namely, that Experience expresses both physical and mental aspects, and that a Not-Self is everywhere indissolubly interwoven with Self, an objective factor with a subjective factor, the idealist reduces Existence to a mere panorama of mental states, and the Body to a group in this panorama. He is thus incapable of giving a satisfactory explanation of all the objective phenomena which do not follow in the same order as his feelings, which manifest a succession unlike his expectation, and which he cannot class under the order of his mental states hitherto experienced. He conceives that it is the Mind which prescribes the order in Things; whereas experience assures us that the order is described, not prescribed by us: described in terms of Feeling, but determined by the laws of Things, i.e. the genesis of subjective phenomena is determined by the action of the Cosmos on our Sensibility, and the reaction of our Sensibility. He overlooks the evidence that the mental forms or laws of thought which determine the character of particular experiences, were themselves evolved through a continual action and reaction of the Cosmos and the Soul, precisely as the laws of organic action which determine the character of particular functions were evolved through a continual adaptation of the organism to the medium. These immanent laws are declared to be transcendental, antecedent to all such action and reaction.

A similar exclusiveness vitiates the materialist doctrine. Overlooking the primary fact that Feeling is indissolubly interwoven with processes regarded as purely physical because they are considered solely in their objective aspect, the materialist fails to recognize the operation of psychological laws in the determination of physiological results; he hopes to reduce Biology to a problem of Mechanics. But Vitality and Sensibility are coefficients which must render the mechanical problem insoluble, if only on the ground that mechanical principles have reference to quantitative relations, whereas vital relations are qualitative. His error is the obverse of the vitalist’s error. The vitalist imagines that the speciality of organic phenomena proves the existence of a cause which has no community with the forces operating elsewhere; so, turning his back on all the evidence, he attempts to explain organic phenomena without any aid from Physics and Chemistry. The materialist, turning his back on all the evidence of quite special conditions only found at work in living organisms, tries to explain the problem solely by the aid of Physics and Chemistry. It is quite certain that physiological and psychological problems are not to be solved if we disregard the laws of Evolution through Epigenesis. The mental structure is evolved, as the physical structure is evolved. It is quite certain that no such evolution is visible in anorganisms, nor will any one suppose it to be possible in machines. From the biological point of view we must therefore reject both Idealism and Materialism. We applaud the one when it says, “Don’t confuse mental facts by the introduction of physical hypotheses”; and the other when it says, “Don’t darken physical facts with metaphysical mists.” We say to both, “By all means make clear to yourselves which aspect of the phenomena you are dealing with, and express each in its own terms. But in endeavoring to understand a phenomenon you must take into account all its ascertainable conditions. Now these conditions are sometimes only approachable from the objective side; at other times only from the subjective side.”

12. While it is necessary to keep the investigation of a process on its objective side, limited to objective conditions, and to express the result in objective terms, we must remember that this is an artifice; above all, we must remember that even within the objective limits our analyses are only provisional, and must be finally rectified by a restoration of all the elements we have provisionally set aside. Thus rectified, the objective interpretation of vital and mental phenomena has the incomparable advantage of simplifying research, keeping it fixed on physical processes, instead of being perturbed by suggestions of metaphysical processes. And as all physical investigation naturally tends to reduce itself to a mechanical investigation, because Mechanics is the science of motion, and all physical processes are motions, we may be asked, Why should not the mechanical point of view be the rational standing-point of the biologist? Our answer is, Because Mechanics concerns itself with abstract relations, and treats of products without reference to modes of production, i.e. with motions without reference to all the conditions on which they depend. Every physical change, if expressed in physical terms, is a change of position, and is determined by some preceding change of position. It is a movement having a certain velocity and direction, which velocity and direction are determined by the velocity and direction of a force (a pressure or a tension) compounded with the forces of resistance, i.e. counter-pressures. Clearly, the nature of the forces in operation must be taken into account; and it is this which the mechanical view disregards, the biological regards. The mechanical view is fixed on the ascertained adjustment of the parts, so that the working of the organism may be explained as if it were a machine, a movement here liberating a movement there. The biological view includes this adjustment of parts, but takes in also the conditions of molecular change in the parts on which the adjustment dynamically depends. Mechanical actions may be expressed as the enlargement or diminution of the angle of two levers; but chemical actions are not thus expressible; still less vital and mental actions.

13. The organism is on the physical side a mechanism, and so long as the mechanical interpretation of organic phenomena is confined to expressing the mechanical principles involved in the mechanical relations, it is eminently to be applauded. But the organism is something more than a mechanism, even on the physical side; or, since this statement may be misunderstood, let me say, what no one will dispute, that the organism is a mechanism of a very special kind, in many cardinal points unlike all machines. This difference of kind brings with it a difference of causal conditions. In so far as the actions of this mechanism are those of a dependent sequence of material positions, they are actions expressible in mechanical terms; but in so far as these actions are dependent on vital processes, they are not expressible in mechanical terms. Vital facts, especially facts of sensibility, have factors neither discernible in machines nor expressible in mechanical terms. We cannot ignore them, although for analytical purposes we may provisionally set them aside.

In the course of the development of the mechanical theory, the history of which has just been briefly sketched, biological problems have more and more come under its influence. There has always been a fierce resistance to the attempt to explain vital and sentient phenomena on mechanical, or even physical principles, but still the question has incessantly recurred, How far is the organism mechanically interpretable? And while the progress of Biology has shown more and more the machine-like adjustment of the several parts of which the organism is composed, it has also shown more and more the intervention of conditions not mechanically interpretable. We shall have to consider the question, therefore, under two forms. First, whether animals are machines, and if not, by what characters do we distinguish them from machines? Secondly, in what sense can we correctly speak of Feeling as an agent in organic processes?