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Lecture 7. The Problem of Body and Mind.

§ 1. The Approach to the Problem. § 2. What Must Be Recognised from the Biological Side. § 3. What Must Be Recognised from the Humanist Side. § 4. Various Theories of the Relation of ‘Mind’ and ‘Body’. § 5. Monistic Speculation along the Line of the Double-Aspect or Correlation Theory.

§ 1. The Approach to the Problem.

IT is with a heightened sense of responsibility that we turn to the ancient problem of the relation of body and mind. But it is a question in regard to which the biologist has something to say, and it cannot be evaded in a study of Animate Nature nor in prolegomena to a philosophy of Animate Nature. By the latter we mean a consistent thinking together of what we know and feel about Animate Nature along with what we know and feel about other orders of facts.

As the view to which a biologist is most naturally led may seem, at first sight, disappointing, and may even be misunderstood as a capitulation of the citadel of personality, we would plead that after we get past what seems to most thinkers the quite untenable position of crude materialism, with its Gothamite metaphysic, and what seems to most scientific workers the quite untenable position of subjective idealism, and the theory of epiphenomenalism, which is materialism in modern garb, the conclusion we come to does not imply any practical depreciation of the reality of the bodily system and activity on the one hand, or of spiritual values and the thought-life on the other. If we avoid the three fatal errors of false simplicity just mentioned, it is not perhaps of great moment what theory—monist or dualist, parallelist or animist—we are led to adopt. We must choose the interpretation which is most consistent with the rest of our thinking and experience.

What is familiar ground to the expert philosopher is full of pitfalls alike to the biologist and to the man in the street, and we probably do well to remind ourselves that the way we put the question of the relation between mind and body may be misleading. It is often asked: Is the body the real thing and the mind a derivative illusion? Or is the mind alone real and the body in some way dependent? These questions are badly put, for both bodily activity and the thought-life are real. A conviction of the actuality of the body as an agent to be reckoned with need not imply that the mind is in any way illusory. Nor need a conviction of the reality of the mind, readily reached by any one who has ever made up his mind, imply that the body is not substantial and effective. The practical truth is, that what we call the mind counts, and that what we call the body counts; or perhaps that what counts is body-mind or mind-body. So far there is general agreement. But are there two distinct and disparate real activities—a player and an instrument, so to speak, or is there one order including both bodily and mental processes, metabolism and awareness of meaning? Is there interaction of two orders of being, or correlation within one order? (See Lloyd Morgan, 1915, p. 6.)

We know ourselves by our senses as organisms; we know ourselves also as thinking, feeling, purposing, endeavouring beings. For immediate experience there is unity. For scientific purposes, however, it seems almost necessary to separate off the two aspects, or processes, or systems, and the problem arises how we are to think of them in relation to one another. But the fact is that ‘body’ and ‘mind’ are alike abstractions. Prof. A. E. Taylor has said: “The severance of the original unity of experience into a physical and a psychical aspect is entirely a product of our own abstraction-making intellect. ‘Body’ and ‘Soul’ are not given actualities of experience, but artificial mental constructions of our own” (1903, p. 314).

Yet here again, while many of us are impressed in our experience with the inter-dependence rather than independence of these “two aspects”—bodily and mental—we must admit that we do not find it an easy task to explain what we mean by the phrase “two aspects” in this particular connection. The words do not seem to grip.

In stating the problem Prof. Lloyd Morgan takes the case of the processes involved in seeing a candle. The rays of light affect the receptors of the retina, a physical relatedness (a), but as the stimulus passes by optic neurones to the visual centre in the occipital lobe of the cerebrum, there is a superadded physiological factor (b), so that the entire process may be called ab. But if we definitely take note of the candle and adjust ourselves deliberately to it there seems to be a third kind of relatedness, a psychical process, so that the whole process may be called abc. We have thus (1) the receptors in physical relation to the physical object; (2) the visual centre in physiological and physical relation to the receptors and through them to the object; and (3) something in psychical relation in some way to the visual centre, and through it to the receptors, and ultimately and essentially to the candle as representing the external world. This something we call the mind. (1915, p. 4)… “The mind is somehow a mid-term receiving messages from the object in the external world and issuing messages to the organs concerned in behaving appropriately to that object. Whenever the mind is thus effective in guidance we have what we called abc-process. The distinguishing feature in such guidance is a context of meaning within a sphere of interest.” Using the term mind in this sense, we have to consider its relation to the processes that go on in the cortex of the brain, and, anticipating our subsequent discussion, we may say that there are two main views. “According to the first there are two radically distinct and wholly disparate orders of being—the mental order and the physical order,” which interact. “According to the second there is only one order within which there are distinguishable types of relatedness and of process, e.g., physical, physiological, and psychical. Any given term may be coincidentally related to other terms in these severally distinguishable ways. This is the abc-interpretation already suggested.” On the second view the c process is always correlated with ab processes; on the first view the c process is independent of any physiological correlate.

§ 2. What Must Be Recognised from the Biological Side.

It is possible, as we have seen, to apply to a living body many of the methods of chemistry and physics, and to give chemical and physical descriptions of isolated observèd processes. The more that is done, the more will the distinctively vital stand out in relief. If it can be shown that the balsam's jerking out of its seeds admits of complete mechanical description in terms of tensions, elasticity, and the like the more obvious will be the distinctively vital factor in the sundew's fly-catching successes. But no adequate chemico-physical description has yet been given of any distinctively vital process. A new aspect of reality wells up within organisms, which are material systems none the less, and we require new concepts for its description. Even in their simplest forms organisms are integrated systems, capable of unified regulatory action and of registering experiences.

But just as the mechanical description has its limitations, so is it with the biological. In our study of Animal Behaviour we have seen evidence of the gradual disclosure of another aspect of reality which transcends the biological. Mentality wells up from the spring. It appears at first in traces only, so that we are not quite sure whether it is there or not, just as it is not very easy to be sure whether a calcareous Alga, or a dormant chrysalis, or a hibernating snail is living or not. But by and by there is a copious flow, and we have no hesitation in saying that the rook or the parrot, the dog or the elephant, has a mind of its own. The student of science is organically more interested in establishing the fact that the study of living things requires concepts which are not needed in the study of the heavenly bodies, than in a discussion of what, in principle, is meant by Life. Similarly he is more interested in establishing the fact that the study of animal behaviour—and not in its higher reaches only—requires concepts which are not needed in the study of the everyday functions of the body, than in a discussion of what we mean by Mind. But we cannot be satisfied without at least facing the old problem of the relation between body and mind. It is in reality a metaphysical question, but the metaphysical interpretation must be consistent with what we know of the facts, and we shall begin by stating what must be recognised from the biological side.

Our theory of the relation of mind and body (if it be a relation) must be consistent with what we know of individual development. The intelligent mammal begins its individual life as a pinhead-like cell, and for a long time it must be admitted that psychological methods or formulæ are quite inapplicable. The developing ovum of a rabbit (fide Brachet) can go on developing for some time outside of the maternal body,—it is a self-contained implicit organism. We do not understand how it is managed, but it has born with it the potentiality of the big brain and the intricate behaviour. There is a gradual emergence of reflexes, of tropisms, of spontaneous exertions, of experiments, of learning, of putting two and two together, of clever behaviour and, in man, of occasional wisdom. In our own case we are sure that as the minute structure of the cerebral cortex increases in complexity, the child becomes more intelligent; as the child becomes more intelligent, the cerebral cortex increases in complexity. Not a single nerve-cell is added after birth, but the inter-relations between the cells increase in number, and the brain becomes a labyrinth. There are no new nerve-cells, but there is normally no lack of new ideas in the growing boy.

(b) Our answer to the body and mind problem must be consistent with what we know of the historical facts. In the course of evolution the nervous system has become gradually more complex and behaviour gradually more masterly, wider in range, more fertile in resource. We do not wish to make too much of the nervous system, for the method of trial and error, for instance, is practised by animals with no nervous system at all, and a very definite capacity for learning may be exhibited by an animal, like a starfish, without a single ganglion in its body. But when we have made this admission we must advance to the other fact that evolution of brains and evolution of behaviour have proceeded hand in hand, in intimate correlation.

(c) The theory we frame as to the mind and body relation must be consistent with the fact of their functional inter-dependence. We express one side of this inter-dependence when we say, “the spirit is willing, but the flesh is weak”, which suggests the picture of a worn-out instrument unequal to the player's demands. We express another side of the inter-dependence when we say of our friend that “he died in his prime, of a broken heart, having lost interest in life”, which suggests the picture of a strong organisation or society crumbling away because of the resignation of one who was its heart and soul.

A large and a complex brain among Vertebrates is correlated with a dominance of intelligent behaviour. The more convolutions the greater the fulness and freedom of life. An intricate brain among Arthropods is correlated with subtlety of instinctive behaviour. Thus an important part of the ant's brain is big in the worker, smaller in the queen, and almost absent in the drone. Retardation or warping of the development of the nervous system is associated with enfeeblement or disharmony of mental life. Fatigue, or poisoning, or degeneration of the nervous system has its mental correlate. Injury to particular areas of the brain may bring about specific changes in behaviour, e.g., disorders of speech. It seems, for instance, that an area at the base of the third convolution on the left side of the brain is the seat of the impressions and processes associated with remembrance of the movements of articulation; that an area affecting the first and second left temporal convolutions is similarly associated with memory of the sound of words; that an area at the posterior part of the second parietal convolution on the left side is similarly associated with visual images of words and letters (see Bergson's Creative Evolution).

The senescence of the worker hive-bees after their all too strenuous short life is correlated with observable fatigue-changes in their brains, and the influence on the human nervous system of degeneracy of the thyroid gland is correlated with the semi-idiocy of cretinism. There is no question-begging in giving these illustrations of the way in which our mind's activity and development are bound up with the health and development of the body, for it is quite open to any one to hold that the brain, for instance, is the instrument in and through which the mind realises its desires and ideals. “It may be held also,” an expert psychologist writes, “that the gradual failure of powers with old age or the temporary failure with illness or fatigue—failure which, though primarily physical, seems to reach to the very core of the mind's being—is defect not of the player, but of the instrument on which he plays, and through which alone his genius can find fitting expression” (J. L. McIntyre; Hastings' Cyclopœdia, vol. x, p. 778). Our present point is simply that, whatever be our theoretical interpretation, it must do justice to the facts of correlation. For whatever theory we adopt, these facts remain.

§ 3. What Must Be Recognised from the Humanist Side.

In pondering over the body and mind problem we must never lose sight of the supreme reality of ‘mind’. We need not dwell on the fact that we do not know anything of Nature save in the selective mirror of our minds; it is more important to insist on the positive reality of the thought-life, the most real fact in the world. There must surely be some bungling with words when the distinguished physiologist Prof. Jacques Loeb speaks of our existence being “based on the play of blind forces and only a matter of chance”, and of ourselves as “only chemical mechanisms”. Ideas are not impalpable will-o'-the-wisps, they have hands and feet. “My mind to me a Kingdom is,” not a dispensable emanation suspended tremulously over the physical, like the heat-haze over the cornfields. The starry firmament on high is scarce more awe-inspiring than the spiritual edifice—scientific and ethical, artistic and religious—which man has built outside himself. Neither in peace nor in war can we ignore the larger values of the true, the beautiful, and the good without imperilling body as well as soul. Whatever theory we adopt about body and mind—monist or dualist, correlationist or interactionist, organicist or animist—these facts remain.

One of Darwin's services was to show man's solidarity with the rest of creation, his affiliation to a mammalian stock. That this was a very important contribution to human thought is recognised almost unanimously, and no one any longer dreams that the dignity or value of a result is affected by the historical conditions of its becoming or evolution. Yet it seems fair to point out the risk, that focussing attention on the rock whence Man was hewn and the pit whence he was digged, may lead to an under-estimate of the apartness and uniqueness of Man as compared with the rest of creation. He is separated off by reason or the power of conceptual inference, by morality or the habit of controlling his conduct in reference to ideals, by the possession of true language or Logos. Man was the greatest of mutations—a new synthesis; and it is certain that in him organismal individuality finds a new and finer expression which we call Personality.

§ 4. Various Theories of the Relation of ‘Mind’ and ‘Body’.

To the question how we are to think of our thought-life and our brain-life in relation to one another at least seven answers have been given, but we need not give all of them the same amount of attention. Two of them fall if we conclude, as we have done, that mechanistic formulation does not give an adequate account of the world of organisms. These two are (I) thoroughgoing materialism, and its modern representative, (II) epiphenomenalism. (I) According to thoroughgoing materialism, mind is fictitious and the only realities are matter and motion. Sensation, according to Hobbes, is nothing but motion; and the brain, according to Cabanis, secretes thought as the liver secretes bile. To this it may suffice to answer that the mechanical theory of organisms breaks down; that we cannot satisfactorily explain our thinking in terms of laws of matter and motion which are the results of our thinking; and that we cannot think clearly to ourselves the proposition that mind is a function of the brain, or that the motion of particles produces the emotion of joy.

(II) According to Huxley's epiphenomenalism, the stream of consciousness is like the chain of foam-bells on the river, called into existence by the real physico-chemical processes in the brain, and ceasing as these cease. The real causal sequence is to be found in the neuroses which are assumed to admit of mechanical formulation; the sequence of psychoses is due to that of the neuroses, for the elements of consciousness have no influence either on one another or on the activities of the creature. The psychoses are the shadows cast by the vanes of the cerebral windmill, or the creakings of the machinery, or at the best the electrical sparks which accompany the friction. There may seem to be two watches, but only one is going (the brain); when the going watch ticks there is an echoing tick in the other; nay more, by induction the going watch may cause movements of the hands of the watch which only seems to go. Perhaps the most generous image is, that the elements of consciousness are the short-lived foam-bells on the wonderful current of cerebral processes.

We cannot accept this view because it is wrapped up with the mechanistic hypothesis, because it hands over the reins of life to matter and motion, because it denudes the thought-life of all reality. When biologists become preoccupied with the psychical concomitants of blots in the brain, or with the localisation of particular mental functions in particular areas in the cerebral cortex, they are apt to lean towards epiphenomenalism, but this has to be corrected by trying to see life whole.

The epiphenomenalist theory (which regards mentality as a negligible phosphorescence of life) is to be rejected on common-sense grounds because we are sure that in human life consciousness and awareness of meaning count for much. It is rejected by most biologists because they cannot evade the conviction, we can hardly say conclusion, that mentality is pervasive throughout all creatures that exhibit genuine behaviour, associative memory, and profiting by experience; and because they find it difficult to believe in the elaboration and persistence of what is, on the epiphenomenalist theory, a useless by-play, counting for nought. And if it be asserted that the persistence and evolutionary elaboration may be accounted for because consciousness is the inevitable by-product of the all-important inter-relations of nerve-cells, then we have slipped back again into the slough of materialism. And it does not seem unfair to put to those who say that thinking is only the phosphorescence of an exuberant cerebral metabolism, the question, “What, then, must the theory of epiphenomenalism be held to be? A will-o'-the-wisp looking at itself?”

Against the theory that the mind does not count let us note the opinion of Professor Sherrington, one of the most distinguished investigators of the nervous system. In his important book The Integrative Action of the Nervous System, he says: “The concomitance between certain nervous reactions and psychosis seems an alliance that strengthens the restless striving of the individual animal which is the passport of its species to continuance of existence” (p. 333).…“Certain it is that if we study the process by which in ourselves this control over reflex action is acquired by an individual, psychical factors loom large, and more is known of them than of the purely physiological modus operandi involved in the attainment of the control” (p. 390).

Only in the analytic laboratory or systematic museum can we rest satisfied with a view of Animate Nature which maintains that mind does not count. By sympathy if not by science we are sure that to leave mind out is a travesty of the facts. Especially in its higher reaches, life is suffused with feeling and meaning.

In his Birds and Man Mr. Hudson tells of what his brother once saw on a lonely sheep-farm on the southern frontier of Buenos Ayres. “Immense numbers of upland geese in great flocks used to spend the cold months on the plains where he had his lonely hut; and one morning in August in the early spring of that southern country, some days after all the flocks had taken their departure to the south, he was out riding, and saw at a distance before him on the plain, a pair of geese. They were male and female—a white and a brown bird. Their movements attracted his attention and he rode to them. The female was walking steadily on in a southerly direction, while the male, greatly excited, and calling loudly from time to time, walked at a distance ahead, and constantly turned back to see and call to his mate, and at intervals of a few minutes he would rise up and fly, screaming, to a distance of some hundreds of yards; then finding that he had not been followed he would return and alight at a distance of forty or fifty yards in advance of the other bird, and begin walking on as before. The female had one wing broken, and, unable to fly, had set out on her long journey to the Magellanic Islands on her feet; and her mate, though called to by that mysterious imperative voice in his breast, yet would not forsake her; but flying a little distance to show her the way, and returning again and again, and calling to her with his wildest and most piercing cries, urged her still to spread her wings and fly with him to their distant home.

“And on that sad, anxious way they would journey on to the inevitable end, when a pair or family of carrion eagles would spy them from a great distance—the two travellers left far behind by their fellows, one flying, the other walking; and the first would be left to continue the journey alone” (Birds and Man. 2nd Ed., 1915, p. 214). The realm of animal life is crowded with this sort of thing.

(III) Also to be rejected is subjective idealism, which is the extreme antithesis of epiphenomenalism, and finds nothing real but the routine of personal conscious experience. This amounts to a denial of the existence of the physical world and of the possibility of science; it is the non-pos-sumus of solipsism.

(IV) A fourth view—common as a working-hypothesis at least—goes by the name of psycho-physical parallelism. It admits the reality of both mental and cerebral processes, but regards them as concomitants merely, without interaction, two parallel causal chains, each complete in itself. We may think of two watches tied together, keeping perfect time, but constructed on different principles and using different notations. This view was subjected to what seems to us destructive criticism in Professor Ward's first course of Gifford Lectures on “Naturalism and Agnosticism”; but it is still held by some psychologists of distinction, either simply as a convenient way of formulating the facts, or with a metaphysical theory behind it—namely, an idealistic view of material phenomena.

Besides psycho-physical parallelism there are in the field three possible theories. One is much favoured by philosophers—(V) the theory of psychical monism. Another view, (VI) the soul-theory or animism, does not seem to be favoured by many philosophers or by many scientific investigators, but may be true for all that. The remaining theory, much favoured by biologists, is (VII) the two-aspect or identity hypothesis. It seems to us that each of these theories has its particular advantages and its particular difficulties, and that a decision must at present be left with the individual according to his personal experience. In our judgment the biological facts mostly favour the two-aspect theory, but we have no assurance that it is the most valid.

(V) Psychical Monism. According to the doctrine of psychical monism, conscious process is the only reality, and though what we call physical objects and physical processes are also real, they owe their reality to being conscious processes or activities in disguise. We can formulate physical processes as if they consisted of the movements of bodies, but our formulation is purely symbolic. There are no things that move, nor things that have potential energy, there are no individualities outside the conscious stream. Things vanish away; things in themselves are regarded as mental in their nature. Needless to say, students of science are rarely attracted to this view. But it is to be suspected that the provocation to antipathy is in part due to confusing metaphysical and scientific language.

(VI) Animism. Of all the theories of the psycho-physical relation the oldest and perhaps the most attractive is animism, the soul-theory. In its clearest form it maintains the actuality of the soul as an embodied psychical being, which realises itself in interaction with the bodily organism. The soul is, apart from the bodily organisation, the ground of the unity of consciousness; it makes sensation, meaning, endeavour, and guidance possible. Its relation with the body is reciprocal, for while it controls the body, the bodily processes supply to it the content of consciousness. Interacting with the body, it develops into the centre of personality. It may conceivably attain to an existence independent of the life of its partner.

On Bergson's view, the brain is the medium between consciousness and the external conditions of life; it is “the organ of attention to life”, keeping the mind in contact with reality. But thought, he maintains, is in great part independent of the brain, and “there is infinitely more in a human consciousness than in the corresponding brain”. If the mental life thus transcends the cerebral life, if the brain serves simply to translate a small part of what goes on in mind, then personality is not permanently tethered to protoplasm.

The animist need not occupy the extreme position that the body is but an instrument on which the mind plays. Wiser and truer is the view that through the body the mind is educated, disciplined, and enriched. As Aliotta puts it, “The body is not something with which the mind can dispense, it is not the forbidding prison which the Platonists depicted in such gloomy colours, it is no torture-chamber in which mind is doomed to expiate some mysterious crime, but rather the fertile soil in which alone the plant of spirituality can develop and blossom.”

Among the advantages of animism we recognise (1) its emphasis on the supremacy and efficiency of what we call mind or spirit; (2) that it nevertheless faces the fundamental and all-pervading fact of body; (3) that its idea of interaction or reciprocal influence, though perhaps inconceivable, is a good working hypothesis, fitting many familiar facts; and (4) that it is congruent with that attractive and optimistic view of the world which assures us of the conservation of values. A spirited and scholarly defence of Animism has been furnished by Dr. W. MacDougall in his book on Body and Mind.

Difficulties in the Way of Animism. All the statements that have been proposed of the body and mind puzzle have their particular difficulties, and they are not awanting in the case of animism.

(a) The whole trend of science is to emphasise the influence of the bodily life on the thought-life, and although we are told that this only means that the soul cannot realise itself except in co-operating with its partner the body, we are haunted by the knowledge that particular defects in the instrument are terribly perturbing to the player.

(b) The experiences of mathematicians and other thinkers at a high level lead us to attach considerable importance to unconscious cerebration, to actual achievements on the part of the personality when the partner whose task is with thinking appears to be in abeyance.

(c) The characteristic feature of the animalistic theory is the idea of interaction, and this raises several serious difficulties. For how can the mind act on metabolism or metabolism on the mind? How can there be interaction between two disparate series? As Professor Stout (Manual of Psychology, Chap. III.) puts it, “When we come to the direct connection between a nervous process, and a correlated conscious process, we find a complete solution of continuity. The two processes have no common factor. Their connection lies entirely outside of our total knowledge of physical nature on the one hand, and of conscious process on the other.” It has been answered that the force of this difficulty is in the assumption that the two series are absolutely disparate, an assumption which the undeniable correspondence between the two series disproves. To positive vitalists there is no particular difficulty, for the non-material psychoid or entelechy which directs brain-processes will be readily susceptible to the influence of the mind; but this is a purely verbal relief, since it leaves us in face of the difficulty of the psychoid's or entelechy's capacity of acting on metabolism. We have admitted the difficulty of explaining what is meant by the “two-aspect theory” or “the double-faced unity”, but we are not sure that the idea of interaction is any more intelligible. We suggest, however, to those who uphold the idea, that the difficulty will appear less if it be recognised that the vital activities of the organism, considered apart from its psychical activities, are not susceptible of satisfactory mechanical description. When we have abandoned a mechanistic view of the organism, we have made a step of importance towards understanding what Professor Ward calls the internal or inter-subjective relation that the subject bears to its organism.

It is often said that animism involves a breach with the principle of the conservation of energy. If mind really counts, it is argued, work is done which the antecedent energy-conditions do not fully account for. If the mind acts on the brain in a way that tells, then some energy disappears from the books, for the mind is outside the sphere of energy-transformations. But to suppose that the mind acts on the material system without expending energy is, the critics of animism continue, to forsake scientific procedure, for the law of the conservation of energy cannot be broken.

Now we are not concerned in the defence of animism, but this criticism is not one that commends itself to us. The doctrine of the conservation of energy includes two propositions. In the first place, it suggests that the total amount of energy in the universe is a constant, but this is rather a pious opinion than an established fact. The less we say regarding the universality of the conservation of energy the better, for we do not know. But in the second place it is a regulative principle, based on experimental evidence, which states that in any closed physical system at work the energy expended in one way must be gained in another. The organism and its environment are comparable to the change-office outside an exhibition; there are ceaseless transformations, but the amount of cash is not only the same in the evening as in the morning, it is the same all through the day. The question is whether, with this regulative principle in view, we can think of mind acting on body or of body acting on mind?

Various answers have been given, and we shall take the worst first.

(1) It has been suggested that some physical energy may rise into mental energy and some mental energy may sink into physical energy. But mental energy is a mere metaphor. On this theory it is supposed that, if the physical energy is locally augmented by the influence of mind, e.g., of a strong will, a corresponding amount of physical energy in another part of the system disappears, say in engendering a feeling of self-approbation. When the resources of the change-office till are augmented by a remarkable operation in receiving cash they are automatically reduced to a corresponding amount by a remarkable operation in disbursing the same. This seems more like art than science and the preservation of the balance savours of the miraculous.

(2) We have already referred to Professor Poynting's suggestion that the will may act as a guiding power changing the direction of motion of the atoms and molecules of the brain, and that the amount of energy will not be changed, since a deflecting force does no work. “But the interposition of the guiding power does affect the transformation of energy; instead of the clash which the physicist would foretell there would be a new configuration as the molecules glided past each other in their new directions.” This is an interesting position, but the difficulty of thinking of mind shunting material particles is surely hardly less than the difficulty of materialism that brain-motion causes consciousness. It is almost certain that this attempt to square animism and the doctrine of the conservation of energy is on quite the wrong line, for it pictures the mind acting mechanically on matter in motion. But if the mind can thus determine the direction of physical processes, say in the brain, the disparateness of mind and body is surely given up. Even Lotze spoke of “elements of mental life, intervening between the operation of the corporeal organs, and filling gaps between the single links of the chain of vital processes”, but can we think of mind producing an impact or causing motion? What we call mind bulks largely in Animate Nature, but surely whatever be its mode of operation it is not that of a shunter. W. K. Clifford compared the belief in this kind of psychical influence upon material things to the belief that the wagons of a railway train are held together by the friendly feeling of the engine-driver for the guard.

(3) The animist is probably on firmer ground when he simply refuses to be tyrannised over by the principle of the conservation of energy. That principle was established in reference to inorganic systems which can be adequately summed up in dynamical terms, belonging to a domain without spontaneity or alternatives or endeavour. We need not allow a law of our own making to dogmatise as to what is possible or impossible in systems run on different lines. No doubt the life of the organism conforms on the whole to the principle of the conservation of energy, as calorimeter experiments prove; perhaps it corresponds absolutely; but what we are concerned to maintain is, that there is no reason grounded in the constitution of nature why a living material system should entirely correspond as regards energetics to a non-living material system.

In this connection it should also be noticed that just as a spark may cause an explosion, and cutting a tape may launch a liner, an emotion may intervene to considerable purpose in bodily affairs without it being possible to prove by calorimetric methods whether its interaction is accompanied by expenditure of energy or not.

It need hardly be said that the view of the soul as something extended in space is not the genuine animism, no matter how subtle that ‘something’ may be. Mr. Norman Pearson (1916) works with a soul which “has no resemblance to the ponderable matter of our senses…is finer even than the imponderable ether of our inference…is, in fact, the nearest conceivable approach to spirit.” This may be a legitimate hypothesis, for one cannot dogmatically assert that the extended in space is exhausted by ordinary physical methods, but it is not pure animism.

(VII) The Two-Aspect Theory. There remains a view to which biological facts incline us, ‘the two-aspect theory’, or the ‘Identity Hypothesis’, or the ‘correlation theory’. We think of the organism as one, as, while it lives, an indissoluble psycho-physical being. The mind and the body are both abstractions, very convenient for purposes of discourse; there is but one reality, the life of the organism, which has a subjective aspect known as psychosis and an objective aspect known as neurosis. The living creature gives an account of itself in two ways. It can know itself as something extended and intricately built up, burning away, moving, throbbing; it can also know itself as the seat of sensations, perceptions, feelings, wishes, thoughts. But there is not one process, thinking, and another process, cerebral metabolism; there is a psycho-physical life—a reality which we know under two aspects. This view may be associated with the names of Aristotle, Spinoza, Fechner, Ebbinghaus, Lloyd Morgan. Cerebral control and mental activity are, on this view, different aspects of one natural occurrence. What we have to do with is the unified life of a psycho-physical being, a body-mind or mind-body.

The advantages of the two-aspect theory, if it is tenable, are (1) that it does justice to the extraordinarily intimate inter-dependence of what we call ‘mental processes’ and ‘brain-processes’. It regards them as two equally real aspects of the continuous life of the organism. There is not merely a material watch with a ticking which we call consciousness; there is not merely a thought-life with an illusion of associated things; there are not two watches which keep time without interacting, nor yet two watches which interact; there is one watch with two sides, which we call objective and subjective. The objective side is the body as a living whole; the subjective side in Man's case is the unity of mind. (2) The psycho-physical being is one, but its two aspects are not always equally clear to us. In thinking out a mathematical problem we may be quite unaware of anything hut our thought-experiments, yet the evidence points to the possibility of these being continued by us (by the organism) without any conscious endeavour. In the application of an anæsthetic, one level after another of the conscious life is obliterated in precise relation to the degree of chloroforming, till by and by complete unconsciousness may result. It looks as if the uninterrupted life of the instrument kept the player in being, it looks as if the life were one. (3) It is extremely difficult to think of the mind in the ante-natal period; it is less difficult to think of a psycho-physical being, in whose one-cell phase the psychical aspect is as non-explicit as it is in the adult life during deep anæsthesia. (4) It is easier to think of evolution on this double-aspect view, for what has come about has always been simultaneous progress in the expression of both aspects—more intricate bodies with their counterpart in subtler behaviour, a growing mentality and its counterpart in a more complex brain-life.

Objections t? the Two-Aspect Theory.

(1) It has been objected that the phrase “two aspects of the same process” is unmeaning when forced upon the psycho-physical relation, where we have to deal with sequences of radically different orders, “apprehended in two radically different ways, the one by sense-perception, the other by reflective introspection”. Fechner spoke of the view of a sphere from the inside and from the outside being two aspects of the same thing, but in that case the one gives us the other, whereas we cannot in the least degree deduce the nature of the psychical from an observation of the physical, or contrariwise. But this objection states a false case, for the postulate of the identity hypotheses is that there never are two events, but always only one. We must not think of two disparate series, one teleological, implying a purposive selective unity, and the other mechanical, due to the refined and complicated organisation of the nervous system; we must think of one series fundamentally purposive and in its higher reaches consciously purposeful. As Bain put it, “The line of causal sequence is not mind causing body, and body causing mind, but mind-body giving birth to mind-body.” From a very different starting-point Samuel Butler said almost the same thing: “The idea of a soul, or of that unknown something for which the word ‘soul’ is our hieroglyphic, and the idea of living organism unite so spontaneously, and stick together so inseparably, that no matter how often we sunder them they will elude our vigilance and come together, like true lovers, in spite of us.”

(2) It is also objected to the identity hypothesis that there is lacking, except in the case of the introspecting psychologist, any observer occupying the inner-standpoint. But it is not in the least necessary to the theory that there should be any continuous observation of the subjective aspect. In ordinary daily life there is introspection only at intervals, when this miraculous power of self-awareness has a definite rôle to play. In animal life there is, of course, no demonstrable self-consciousness, but there is a mental life which cannot be interpreted in terms of the abstractions of the physiology of the nervous system. According to the identity hypothesis this mental life is one aspect, hypothetically imagined by us, of the very highest reach of the organism's activity.

(3) It is objected that the two-aspect theory simply invents and glorifies an X, an unknown and unknowable entity. To make clearer what we do in some measure know, it postulates an indefinable reality of which we can know nothing. “The one substance,” says Professor Stumpf, “which is supposed to manifest itself in the two attributes, the physical and the psychical, is nothing but a word which expresses the desire to escape from dualism, but which does not really bridge the gulf for our understanding.” But the charge “nothing but a word” is readily made and as readily recoils. The identity hypothesis does not pretend that we know anything like all about that fraction of reality which we call a living creature, nor that we can explain its having two aspects. It maintains, however, that we know this about organisms, that they are agents that do things, unique individualities that express themselves in endeavour, psycho-physical beings that burn away and yet remember, that ripen and rot and yet work towards ends which transcend themselves. What the ‘identity hypothesis’ or correlation theory postulates is not an unknown X, but an imperfectly known organism, whose pre-awareness of meaning is as real as its flesh-and-blood metabolism, yet inseparable from it.

Another objection to the ‘double-aspect’ interpretation is that we know ourselves as self-determining—for no one can get away from an immediate awareness of his personal agency—whereas the organism is determined from without, being part of the mechanical system of things. Can the same reality be determined from without and self-determining? But the objection must be disallowed, first because the organism has spontaneity, from the Amœba upwards, and is certainly not wholly determined from without; and, second, because when we examine ourselves carefully we find that our mental life is not wholly self-determined. It is an unnecessary difficulty to say that one aspect is teleological and the other mechanical; for we have given good reasons for believing that the organism is more than mechanical. ‘Body’ and ‘mind’ are both of the teleological or purposive type, for that is the nature of the creature from first to last.

§ 5. Monistic Speculation along the Line of the Double-Aspect or Correlation Theory.

On the Double-Aspect or Identity Hypothesis all animals are psycho-physical beings, and this is borne out by what is known of the behaviour of the very simplest, for we see Amœbæ going ahunting and Foraminifera working like selective artificers. But what of the plant world? Logically, we can make no halt, and there are curious phenomena which approach behaviour in carnivorous plants and climbing plants. In some cases, there is what looks like memory. But the continuity argument presses us further. Since it seems very likely that organisms arose upon this earth from not-living materials, in a manner at present obscure, are we to suppose that consciousness somehow entered ab extra into the early organisms when they were as yet only beginning; or that it was interpolated later when they attained to some degree of complexity; or that the analogue of consciousness, which some have called infra-consciousness, was present even in the domain of the inorganic? The desire for continuity impels us to the speculation that even the inorganic raw materials were psycho-physical. For in no case can we think of consciousness arising out of motion, any more than we can think of atoms uniting for love.

There has been great progress in the course of evolution, but on the identity hypothesis we think rather of potencies being raised to higher powers than of the interpolation of new faculties. Instead of insinuating a principle of life ab extra when a suitable mixture of proteins had been somehow synthesised, we suppose that a synthetic advance of materials, which were ever more than motions, made behaviour possible. Instead of insinuating mind ab extra when the organism became complex enough, we suppose that the progressive differentiation and integration of what was from the outset a psycho-physical being, by and by disclosed another aspect of its inherent reality, and experimenting with ideas became possible. And similarly with man's rational discourse and with the amazing phenomena of human society.

Biological monism has been characterised as a relapse to the old and crude metaphysics of hylozoism. Perhaps it is nearer the hylopsychism of some of the New Realists. “By hylopsychism I mean the theory that—The potentiality of the physical is the actuality of the psychical and the potentiality of the psychical is the actuality of the physical. Or, to put it in the form of a definition of consciousness: Consciousness is the potential or implicative presence of a thing at a space or time in which that thing is not actually present.”(W. P. Montague, p. 281). “By hylopsychism I wish to denote the theory that all matter is instinct with something of the cognitive function; that every objective event has that self-transcending implication of other events which when it occurs on the scale that it does in our brain processes we call consciousness” (p, 283).

Is there any difference between this and the monistic speculation of Prof. Lloyd Morgan? “Of simple awareness there can be no evidence by acquaintance, save in being aware. And since we cannot be an Amœba or an isolated neurone, an oak or an acorn, an attracting magnet or a shred of iron attracted thereto, we can never directly know whether in them some dim awareness is present or absent. None the less we may be permitted to suppose that awareness, as a specific mode of relation between terms, is ubiquitous throughout nature—basing this supposal on the principle of continuity. If here in us in high measure, then in the oak and the acorn, in the molecule and the atom, in their several measures and degrees” (1915, p. 10).

To demand of the biologist an explanation of the double aspect of the psycho-physical being is to demand the impossible. Organisms are unique facts; intelligent organisms are unique facts. But if the biologist is pressed hard and asked if there is no other unique fact beside which he can place his double-aspect organism, perhaps he may answer, “Why, there is only thought itself, which is subjective and objective at once,”

The ‘Body and Mind’ problem has served to stretch man' s brains for more than two thousand years, and there are many who would abandon it with the word ‘Ignorabimus’. But Man will never leave it alone, and the resolute endeavour after greater clearness is likely to bring its own reward even if the riddle remain unread. For the inquiry patiently prosecuted is likely to lead to a deeper appreciation of what we call ‘Body’ and of what we call ‘Mind’. And this deeper appreciation is the practically important result.


The approach to the difficult problem of the relation between ‘body’ and ‘mind’ has been cleared (a) by the argument that mechanical formulation is inadequate for the description of vital activities, and (b) by the recognition of the pervasive rôle of ‘mentality’ in Animate Nature.

In any consideration of the problem there must be borne in mind, from the biological side, how gradually mind develops in the individual, how gradually mind has evolved in the races of animals, and how intimately inter-dependent the psychical and neural processes are. Whatever theory is adopted, these facts remain.

In any consideration of the problem there must be borne in mind, from the humanist side, the reality of the thought-life, the reality of the external spiritual not-self which man has in the course of ages built up, and the potency of spiritual values in history and in everyday life. Whatever theory is adopted, these facts remain.

The question is how we are to think of our thought-life and of our brain-life in relation to one another, for we can at any rate talk of them as distinct actualities. At least seven answers have been given to this question. Two of these are only acceptable on the mechanistic hypothesis, namely (I) the throughgoing materialistic answer and (II) the theory of epiphenomenalism. The theory at the very opposite extreme—subjective idealism—(III) seems to deny the possibility of science. The theory of psycho-physical parallelism (IV) lands in apparently inextricable difficulties—so well exposed by Prof. James Ward. There remain in the field three possible theories:—(V) the theory of psychical monism, which few scientific investigators can entertain; (VI) the theory of animism or the soul-theory; and (VII) the identity hypothesis, or two-aspect theory, or correlation theory.

A case can be reasonably stated for the theory of psychical monism, for the soul-theory, and for the two-aspect theory, and a decision must be left with the individual according to his personal experience. Each theory has its own advantages and its own difficulties. When the biological facts are dominant in the mind the balance will swing towards the ‘two-aspect theory’ or ‘identity hypothesis,’ which regards the living creature as a psycho-physical unity, psychosis and neurosis being two aspects of one and the same continuous life.

Perhaps, as in the case of vitalism, the most consistent scientific position is to keep firmly to the fact that just as the everyday functions of the organism, not to speak of its development, heredity, and evolution, cannot be adequately described in terms of chemico-physical concepts, so it appears that many of the forms of behaviour cannot be adequately described in terms of the concepts of biology. A new aspect of reality is expressed requiring new categories—psychological categories. This is but a pedantic way of expressing what was said of old: “Surely the life is more than food.”