ND   Jacques Maritain Center : Psychology / by Michael Maher, S.J.



Dualism and Monism. -- Psychological theories concerning the nature of man and the relations of body and mind are classed as Dualistic and Monistic. Dualism teaches that Mind and Body are two really distinct principles; whilst Monism maintains that both mental and corporeal phenomena are merely different manifestations of what is really one and the same Reality. According to the character of the opposition and mutual independence ascribed to the two principles by different thinkers of the former school, we have Ultra-Dualism and Moderate Dualism. To the previous class belong Plato and Descartes; to the latter Aristotle and the leading Scholastics. As both forms of dualism agree in teaching the spirituality of the soul, we shall defer further comparison of them for the present.

Monism. -- Of Monistic theories there are three chief types: Monistic Spiritualism or Idealism; Materialism; and a third doctrine which has been variously described as the Double-aspect Theory, the Identity-Hypothesis, the New Spinozism, and also simply Monism. There is rooted in the intellectual nature of man a craving for the unification of knowledge, for the reduction of facts and truths to the fewest and most general principles. And we ourselves maintain that the only truly satisfactory account of the Universe as a whole is Monistic -- that philosophical system which derives the multiplicity of the world from a single indivisible spiritual principle, God. But the present question is not the origin of the Universe, but the inner constitution of the individual human being; and the attempts to ignore the essentially disparate character of mind and matter, and to reduce either to the other, or to identify them both in some inconceivable tertium quid seem to us among the most lamentable perversions of a rational instinct which the history of philosophy has to show.

Spiritualist Monism or Idealism. -- This theory overcomes all difficulties as to the relations between body and mind or the possibility of inter-action between them by boldly denying the reality of any material substance existing in itself without the mind. It holds that our consciousness of mental states is immediate and primary, whilst our assurance as to the reality of matter is at best mediate and secondary. It insists on the fact that our notions of substance, cause, energy, and the like, are all in the first place derived from the consciousness of our own mental activities, and that in the final analysis we can never know anything about the nature of matter except what is given in our psychical states. It assumes that matter could not act upon mind; and finally concludes that the most philosophical course is to deny all extra-mental reality to matter, and to look upon the seemingly independent material world as an illusory creation or emanation of mind itself. But the Monist does not stop here. In his desire for unity he does not merely deny real being to matter, he asserts that all minds are in reality one -- all individual conscious existences being but wavelets surging on the one ocean of Universal Consciousness.

Criticism. -- As opposed to the Materialist the Idealist seems to us impregnable. Our reasons for the rejection of Idealism, which are not available by the Materialist, we have already stated (pp. 100, 113-117); so we can merely refer the reader back to them here. Against the Monistic aspect of the theory, which denies the real plurality of minds, we would urge in addition: (1) The complete absence of proof -- nay, of the possibility of proof. (2) Its direct conflict with our immediate internal experience. My own individuality, my real oneness, the complete insulation, the thorough exclusiveness of my personality are the best attested and the most fundamental convictions of my life. If I admit the existence of other men in any form, I must accept their testimony to the same experience in their own case. To reject this clear evidence of universal experience for the sake of some obscure a priori postulate of unity is irrational. (3) It is inconsistent with freedom and responsibility. If all finite minds are but phases or moments of the Absolute Spirit, possessing no substantial reality of their own, it seems impossible that such finite spirits can be guilty or the Infinite Spirit innocent of sin. Some idealistic monists -- Lotze, for instance, if we do not misunderstand him -- believe they can adopt Monism yet evade these consequences. Such a course seems to us impossible. It is only by changing the meaning of words and inconsistently allowing real plurality of beings that they can reconcile their systems with the ethical convictions of mankind.

Materialism. -- Conveniently assuming that experience establishes the existence of the brain as a permanent extended substance, but affords no evidence respecting the abiding reality of the mind, the materialist seeks to show that the cerebral substance is the sole and ultimate cause or ground of all our conscious states. Consciousness, he teaches, is a property of matter, or the resultant of sundry properties of material elements combined in a complex manner. The progress of physiological science proves, he alleges, more and more clearly every day the dependence of intellectual processes on neural functions. Moreover, it is impossible to imagine how conscious states can act upon matter or cause bodily movements; whilst the doctrine of the conservation of energy and the law of inertia are incompatible with the view that the mind is an immaterial being exerting a real agency in the material universe. Such is the general argument of materialism; but it will conduce to clearness, if we examine its chief tenets in detail.

Thought is not a Secretion of the Brain. -- In expositions of the coarser forms of materialism such assertions as the following have been boldly put forth: "La pensée est une secretion du cerveau." (Cabanis.) "There subsists the same relation between thought and the brain, as between bile and the liver." (Vogt.) Moleschott describes thought as "a motion in matter," and also as a "phosphorescence" of the brain.{1} Other philosophers of like metaphysical acumen have been found to proclaim the existence of the soul to be disproved, because anatomy has not revealed it -- the "dissecting knife" having never yet laid it bare.

Writers of this calibre scarcely deserve serious refutation. To speak of thought as a "secretion" or "movement" of cerebral matter is to talk deliberate nonsense. Thought is essentially unextended. The idea of virtue, the judgment that two and two must equal four, the emotion of admiration, are by their nature devoid of all spatial relations. The various secretive organs effect movements and material products. Their operations occupy space; and the resulting substance is possessed of resistance, weight, and other material properties. The process and the product can be apprehended by the external senses; and they continue to exist when unperceived. Conscious states are the exact reverse in all these features. The microscope has never detected them. They cannot be weighed, measured, or bottled. When not perceived they are non-existent; their only esse is percipi. Even Herbert Spencer is forced to admit, "That a feeling has nothing in common with a unit of motion becomes more than ever manifest when we bring them into juxtaposition."{2} Tyndall acknowledged the same truth in a paragraph often cited: "The passage from the physics of the brain to the corresponding facts of consciousness is unthinkable. Granted that a definite thought and a definite molecular action in the brain occur simultaneously, we do not possess the intellectual organ, nor apparently any rudiments of the organ, which would enable us to pass by a process of reasoning from one to the other. They appear together, but we do not know why. Were our minds and senses so expanded as to enable us to see and feel the very molecules of the brain, were we capable of following all their motions, all their groupings and electric discharges, if such there be, and were we intimately acquainted with the corresponding states of thought and feeling, we should be as far as ever from the solution of the problem -- 'How are these physical processes connected with the facts of consciousness?' The chasm between the two classes remains still intellectually impassable."{3}

Thought is a not a Function of the Brain. -- In a scarcely less crude way consciousness is sometimes described as a function of the brain: "There is every reason to believe that consciousness is a function of nervous matter, when that matter has attained a certain degree of organization, just as we know the other actions to which the nervous system ministers, such as reflex action, and the like, to be."{4} "Thought is as much a function of matter as motion is."{5} The use of the term "function," however, does not better the materialist's position with any reader not contented with payment in obscure words. What is a "function of matter"? The only "functions" of matter of which physical science is cognizant consist of movements or changes in matter. Now, thought, as we have just pointed out, is nothing of this sort. If we employ this word at all, we must speak of intellectual activity as a function of something utterly opposed in natnre to all known subjects of material force. When mental processes are at work, movements indeed take place in the nervous substance of the cerebrum, and it is accordingly true that the brain "functions" and expends energy whilst we think. But neither this functioning nor the energy expended constitutes thought. As Tyndall says, the "chasm" between the two classes of facts still remains "intellectually impassable."

Thought is not a Resultant of material forces. -- Büchner, by comparing the organism with the steam-engine, seeks to prove that mental life is merely the result of the complexity and variety of the material forces and properties at work in the former. "Thought, spirit, soul, are not material, not a substance, but the effect of the conjoined action of many materials endowed with forces or qualities. . . . In the same manner as the steam-engine produces motion, so does the organic complication of force-endowed materials produce in the animal body effects so interwoven as to become a unit, which is then by us called spirit, soul, thought. The sum of these effects is nothing material; it can be perceived by our senses as little as any other simple force, such as magnetism, electricity, etc., merely by its manifestations."{6}

This is a fair example of the random methods of reasoning employed by materialists. What is the resultant of the aggregate of forces accumulated in the steam-engine? It is nothing more nor less than movements of portions of matter, all perceptible by the external senses. If the engine drags a train, we may speak of the motion of the latter as being a single effect, but the occurrence has only a moral or metaphorical unity. It is really a series of events, a vast assemblage of parts of matter moving other parts. When we turn to the living organism, we find, indeed, a similar set of movements and displacements of matter, but we find also in addition to these physical occurrences, and differing from them, as Mr. Spencer says, "by a difference transcending all other differences," the very phenomenon to be explained, "spirit, soul, thought." Granting, then, for the sake of argument, similarity between the material forces collected in the steam-engine and in the human body, at most the legitimate inference would be that the various movements and organic changes observable in the body were the outcome of its material energy; but there is not a shadow of a reason for attributing the distinctly new phenomenon of consciousness to that energy. In the final sentence another piece of confused and inconsistent thinking is introduced. Thought is there likened to the "simple forces, magnetism and electricity." But the only known manifestations of electricity and magnetism consist in the production of movement. Consciousness, however, is revealed in a different way. Of the nature of electricity or magnetism as a simple force we know nothing. The word is merely an abstract term to denote the unknown cause of a certain species of movements coming under external observation. On the other hand, of mental states we have immediate internal experience; and that experience discloses conscious life as centred in one single being, in a peculiar indivisible unity utterly repugnant to the composite nature of a material subject.{7}

Unknown Properties of Matter. -- Against the spirituality of the principle of thought, it was objected by Locke that matter has a great variety of wonderful and unlike properties, that our knowledge of these is still very limited, and, consequently, that we are not justified in asserting that matter could not be the subject of intellectual activity: He also says this statement is derogatory to the Divine power, implying that God Himself could not endow matter with the faculty of thought. We most readily admit our knowledge of matter to be still very inadequate; and we allow that matter possesses many unlike qualities. But it is not from mere dissimilarity in character subsisting between mental and material phenomena -- although this dissimilarity "transcends all other differences" -- that we infer a distinct principle. It is from the absolute contrariety in nature which sets them in opposition. In spite of the imperfect condition of our acquaintance with matter, we can affirm with absolute certainty that some new properties, e.g., self-motion, can never be discovered in it. It is, too, no reflexion on the power of God to say that He cannot effect a metaphysical impossibility, such as the endowment of an extended substance with the indivisible spiritual activity of self-consciousness would be.

Dependence of Mind on Body. -- The spirituality of the soul, it is said, is disproved by the absolute dependence of mental life on bodily conditions -- a dependence more effectively established by Physiology and Pathology each succeeding year. We find, it is asserted, that intellectual ability varies in proportion to the size of the brain, its weight, the complexity of its convolutions, and the intensity of its phosphorescent activity. Mental powers develop concomitantly with he growth of the brain, and similarly deteriorate with its decay or disease: "The doctrine of two substances, a material united with an immaterial, . . . which has prevailed from the time of Thomas Aquinas to the present day, is now in course of being modified at the instance of modern Physiology. The dependence of purely intellectual operations such as memory upon material processes has been reluctantly admitted by the partisans of an immaterial principle, an admission incompatible with the isolation of the intellect in Aristotle and Aquinas. . . Of the mind apart from the body we have no direct experience and absolutely no knowledge. . . . In the second place, we have every reason to believe that there is in company with all our mental processes an unbroken material succession.{8} This argument in behalf of Materialism gains much of its weight with many minds from the belief that those who formerly defended the spirituality of the soul conceived it as an independent entity standing out of all relations to the body. The allusion to St. Thomas in the passage just quoted is an expression of this belief. Recent advances in physiological knowledge, it is imagined, have disproved this supposed mutual isolation of the two substances, consequently the inference is that modern science has rendered untenable the spirituality of the soul.

Criticism. -- Now, in the first place, this historical theory is utterly false. It is mainly since the rebellion against Scholasticism, inaugurated by Descartes, that this exaggerated antagonism between soul and body has been advocated by anti-materialist thinkers. The central idea of the Peripatetic Psychology, as expounded by every leading writer, from Albert the Great to Suarez, is the conception of the soul as substantial form of the body -- a view which implies the most intimate union and interdependence between these two coefficient principles of man.

Consequently, so far from ignoring or admitting "with reluctance" the influence of bodily conditions on mental operations, the greatest emphasis is laid upon the fact, as any one possessed of an elementary acquaintance with the writings of St. Thomas or any other scholastic, on the appetites, imagination, sense-perception, memory, and the passions, must know. Mediaeval philosophers were just as well aware as our wise men of to-day that age, bodily fatigue, the processes of digestion, disease, stimulants, and the like, affect our mental operations; and in taking these into account they had to meet by anticipation every difficulty that has or can be raised from the physiological quarter. Physiology has brought to light no facts of essentially novel significance in their bearing on this problem. It has, indeed, given us a better knowledge of the material structure of the brain and nervous system, and of the occurrence of special processes there in conjunction with mental states; but the general principle of interdependence between mind and body, illustrated in such facts, was forced on the human intellect in its very earliest attempts at psychological speculation. Moreover, it ill becomes Cerebral Physiology, which is still in a very backward state, to dogmatize in this fashion.{9}

In the next place, assuming for the moment that all the assertions regarding the intimate relations between neural conditions and mental life were accurately true, and in no way exaggerated, how would this prove more than an extrinsic dependence of the soul on the body which it enlivens? "For, suppose for an instant that human thought was of such a nature that it could not exist without sensations, without images and signs (I do not mean to say that no kind of thought other than this is possible); suppose, I repeat, that such were the conditions of human thought, is it not evident that a nervous system would be then required to render sensation possible, and a nervous centre to render possible the concentration of sensations, the formation of signs and of images? According to that hypothesis, the brain would be the organ of imagination and of language, without which there would be no thought for the human mind."{10} In such a case -- and this is precisely the theory of St. Thomas -- whatever affects the organ or instrument of the mind will naturally modify mental operations. Now we have shown (c. xiv) bow intellect requires as an essential condition the operations of sense and imagination, and is therefore extrinsically dependent for its materials on these organic faculties. But, on the other hand, study of the character of its activity (c. xii.) has also proved to us that the spiritual power transcends the material order, and that this power is in its nature essentially and intrinsically independent of matter. The continuity of the organic process, if proved, would be accounted for by the exercise of the imaginative faculty, which the intellect requires as a condition of its operation. That neither imagination nor organic memory are, as Bain implies, intellectual activities, must have been evident from the earlier part of this work.

In answer to the sage observation that we never find mind apart from the body, it is sufficient to reply that concomitance does not prove identity, and that at all events we often find body without mind. Whenever we meet with a new group of properties or effects incapable of being accounted for by previously known causes, we are bound, according to the universally recognized canons of physical science, to assume a new cause for these phenomena. As regards the part of the difficulty which lays stress on the relations between the character of the brain as a whole and intellectual ability, whilst we readily admit that the vastly superior mental faculties of man would lead us to anticipate in his case a more perfect instrument than is to be found in the brute kingdom, it is worthy of notice that science has as yet completely failed to assign any distinct property of man's brain by which his intellectual superiority is marked.{11}

Man not a Conscious Automaton. -- All Materialists necessarily teach that conscious states can never condition or determine bodily movements, but Dr. Shadworth Hodgson was, we believe, the first frankly to admit the still more incredible consequence that states of consciousness never condition, determine, or modify each other. "There is real action and reaction between organs and parts of organs in a nervous system, as well as between nerve and other parts of the organism and between nerve and external stimuli; but there is no real reaction of consciousness upon nerve, and no real action and reaction of states of consciousness upon each other."{12} Again, "Process-contents of consciousness do not stand in any relation of real conditioning to one another. It is not pleasure or pain, for instance, which conditions desire or aversion; nor is it desire which conditions volition or reasoning; but the neural or cerebral actions which condition the antecedents condition in their continuation the consequents also."{13} To make his meaning quite clear, Mr. Hodgson takes the example of a man turning aside to avoid a wheelbarrow. The old-fashioned view is "that the state of consciousness is a really operative link in the chain of events." This is a delusion. The true positive explanation is that the physical impression on the retina determines the nervous processes which result in the appropriate movement. The mental state is a mere epiphenomenon. "Throughout the process consciousness is initiated by and depends on nerve-motion and not vice versa. . . . (The opposite view) would involve the assumption that at some point or other of the process, either consciousness began to act as a real condition (having previously been a conditionate only), or an immaterial agent, which had previously been dormant, was roused to activity. But neither alternative is positively conceivable; neither of them has any observed facts in its favour. On the other hand, we can render all the phenomena positively intelligible on the hypothesis of neural action above set forth."{14}

Dr. Hodgson is the ablest and most consistent exponent of psychological materialism at the present day; but his candid acceptance of the consequences of that theory seems to us to provide as perfect a reductio ad absurdum as we need desire. Were the avoiding of present visible obstacles the only operations to be accounted for, the comparatively simple psychical and physical processes involved might, perhaps, as in the case of reflex action, be thus mechanically explained. But a little reflexion suggests problems which it will require considerable courage to solve in this fashion. Thus: When the novelist is thinking out his plot, or the detective is striving to piece together the fragmentary clues of a hidden crime, does no idea, feeling, or desire which wakes up within him exert any influence on his subsequent mental states? Do his thoughts never "stand in any relation of real conditioning to one another?" When we say that the consciousness of having received a deliberate insult has excited anger and hatred which generated au implacable desire of revenge, and that this motive instigated the plotting and committing of a cunningly contrived murder, is our language throughout purely mythological? Is it possible to believe that the feeling of the insult has itself contributed nothing towards arousing the hatred, nor this passion towards planning of the revenge? Does the apprehension of the premisses of a syllogism play no real part in eliciting the inference? If materialism be true, Dr. Hodgson's conclusion is inevitable; the neural antecedents and they alone condition the neural consequents, the incidental phenomena of a conscious state which happened to accompany the former have no influence upon the incidental phenomena accompanying the latter. Unless we accept this conclusion, we are told we must admit that consciousness is really active or that "an immaterial agent which had previously been dormant was roused to activity." We are glad to see the inevitable alternative so clearly and so candidly stated. The doctrine of an immaterial soul is surrounded with obscurities and difficulties which it would be foolish to ignore or to seek to conceal. We certainly cannot picture a soul by the imagination; still less can we imagine how it acts on the body, or how mental acts and nervous processes influence each other. But it is indifferent logic to deny the reality of an event because we cannot imagine the mode of its occurrence; and the inability of our imagination to conceive the nature of immaterial agency is a frail reason, indeed, upon which to reject the doctrine of a spiritual soul and embrace a system of materialism that makes such astounding demands upon our powers of faith.

Monism. -- The most serious assault, however, which at present is being directed against the doctrine of a spiritual soul and future life is that of Monism proper. In its best known forms this metaphysical hypothesis, for it is essentially a metaphysical conception, has been styled the Double-Aspect Theory and the Identity-hypothesis, because of its maintaining that mental states and the concomitant nerve-changes are simply different "aspects" of one and the same being. It has been called the New Spinozism from its affinity to the metaphysical theory of the father of Modern Pantheism; and it has also been termed the doctrine of Psychophysical parallelism from its denial of all interaction between the psychical and the physical processes which take place in the living being. This doctrine of parallelism might, of course, be united with a metaphysical theory of Dualism, as in the systems of Descartes and Leibnitz; indeed, it is to Dualism it naturally points, but now-a-days it is generally employed in the interests of Monism for the purpose of describing the supposed relations of bodily and mental states. Marked by important differences in the hands of its various exponents, Monism, in all its forms, adheres to the cardinal tenet that Mind and Body are not two distinct realities but merely two "aspects," "sides," or "phases" of one being, and that there is no real interaction between mental and bodily states. W. K. Clifford, A. Bain, Herbert Spencer, Huxley, and among recent psychologists, Professor Höffding, are among the best known advocates of this theory; so we shall sketch and briefly examine their views.

The term Mind-stuff was invented by Clifford to denote the material out of which he asserts that human minds are formed. According to him there is attached to every particle of matter in the universe a bit of rudimentary feeling or intelligence. When the molecules of matter come together in certain forms and proportions, the attached atoms of mental life fuse into a complete self-conscious mind.{15} Neither the molecules of matter, however, nor the appended morsels of mind can have any influence on the other. At least, this is Clifford's doctrine at times: "The physical facts go along by themselves, and the mental facts go along by themselves. There is a parallelism between them, but there is no interference of one with the other."{16}

The only arguments suggested in defence of these doctrines are the assertions: (1) that Physiology has established an absolute and complete parallelism between psychical and physical facts; (2) that physics has proved the impossibility of any mutual interaction between them; and (3) lastly, the fact that Clifford's view is essential to the theory, that all of us, both mind and body, have been developed out of inferior organic forms and ultimately out of inorganic matter. Thus in his own words: "The only thing that we can come to, if we accept the doctrine of Evolution at all, is that, even in the very lowest organisms, even in the amoeba which swims in our own blood, there is something or other inconceivably simple to us, which is of the same nature with our consciousness, although not of the same complexity, that is to say (for we cannot stop at organic matter, knowing as we do that it must have arisen by continuous physical processes out of inorganic matter), we are obliged to assume, in order to save continuity in our belief, that along with every motion of matter, whether organic or inorganic, there is some fact which corresponds to the mental fact in ourselves." (Op. cit. p. 266.)

Defenders of a spiritual philosophy are not necessarily opposed to Evolution, when that hypothesis is properly limited and defined: but Clifford's statement that we know all living beings "must have arisen by continuous physical processes out of inorganic matter," is almost amusing for its audacity. It is, of course, simply the reverse of the truth. An overwhelming weight of scientific evidence and authority establishes the fact that life is never evolved from inorganic matter. Even scientists as unlikely to be prejudiced against the doctrine of abiogenesis as Huxley and Tyndall are forced to confess that evidence of a single case of spontaneous generation has never yet been adduced. As regards the other arguments, we may for the present merely call attention to the truth that even were complete parallelism, in the sense of reciprocal correspondence between every form of mental state and definite neural processes, fully demonstrated -- hopeless though the prospect of this result be -- nothing would have yet been effected towards the reduction of mental activity to a mere appendage of such nervous changes. As for the statement, that science has proved the non-interference of the two sets of phenomena, it is both false in itself and in conflict with Clifford's own teaching on other occasions, and with that of the school to which he belongs. The majority of that school teach that bodily processes, at all events, determine changes in our mental states.

Dr. Bain does not appear to go quite so far as Clifford. Mental life in man he considers to be a "subjective aspect" of bodily changes; but that there are "subjective aspects" attached to all movements of every kind of matter he has not the courage to assert. This position, of course, leaves on his hands the awkward difficulty -- why should this very curious "subjective aspect," of which there is no trace in the rest of the material world, suddenly manifest itself in the case of those portions of the universe which we call living beings? To atone, however, for the deficiency just mentioned, he is vigorous enough in insisting that mental life is but an "aspect" or "side" or "face" or "phase" of neural changes, and that therefore it has no reality independent of such changes, and no power of affecting their course. He strongly objects to the phrase, "Mind and body act upon each other." There is merely a continuous series of physical events with inactive subjective "aspects." "We have," he assures us, "every reason for believing that there is in company with all our mental processes, an unbroken material succession. From the ingress of a sensation, to the out-going responses in action the mental succession is not for an instant dissevered from a physical succession."{17} The neural changes are determined solely by neural antecedents: the material sequence carries with it the mental sequence, but cannot in the slightest degree be modified by the latter. Nevertheless: "The only tenable supposition is, that mental and physical proceed together as undivided twins. When therefore we speak of a mental cause, a mental agency, we have always a two-sided cause; the effect produced is not the effect of mind alone, but of mind in company with body. That mind should have operated on the body is as much as to say, that a two-sided phenomenon, one side being bodily, can influence the body; it is after all body acting upon body.

The line of mental sequence is thus, not mind causing body, and body causing mind, but mind-body giving birth to mind-body: a much more intelligible position."{18}

Herbert Spencer seems to hold approximately the same view as Dr. Bain, though his general system of Evolution would appear to lead on to Clifford's doctrine of mind-stuff. Mental states, he allows, cannot be identified with nervous processes. The two sets of facts are separated by "a difference which transcends all other differences." All forms of consciousness are, he teaches, resolvable into elementary units of feeling akin to electric-shocks. These correspond to pulses of molecular motion transmitted through the sentient nerves. But the sensation of shock made known through our inner consciousness can never be analyzed into the physical movements observable, if at all, by our external senses. These are his words: "When the two modes of Being which we distinguish as subject and object have been severally reduced to their lowest terms, any further comprehension must be an assimilation of these lowest terms to one another: and, as we have already seen, this is negatived by the very distinction of subject and object, which is itself the consciousness of a difference transcending all other differences. So far from helping us to think of them as of one kind, analysis serves but to render more manifest the impossibility of finding for them a common concept -- a thought under which they can be united. Let it be granted that all existence distinguished as objective may be resolved into the existence of units of one kind (material), . . . and let it be further granted, that all existence distinguished as subjective is resolvable into units of consciousness, similar in nature to those which we know as nervous shocks, . . . can we think of the subjective and objective activities as the same? Can the oscillation of a molecule be represented in consciousness side by side with a nervous shock and the two be recognized as one? No effort enables us to assimilate them. That a unit of feeling has nothing in common with a unit of motion becomes more than ever manifest when we bring the two into juxtaposition."{19} In spite, however, of the incompatible character of physical and mental processes, Spencer finally concludes that both are but "faces" or "aspects" of one and the same substratum: " Mind (i.e., conscious-states) and nervous action are subjective and objective faces of the same thing."{20} The ground for this unification of mental and physical phenomena is the same as that urged by Clifford and Dr. Bain -- the intimate correspondence between the two series. As to the nature of this one ultimate reality, of which mental and bodily activities are but diverse aspects, Spencer assures us that it is unknowable.

Criticism of Monism. -- Each form in which the Double-Aspect theory has been advocated, stands exposed to numberless special difficulties, but here we have room to touch only on a few of the most general objections, which tell universally against every representation of the doctrine.

1. Dilemma. -- The advocate of the new system must accept either of two alternatives. He must, with Clifford, look upon this "double-aspectedness" as a universal property of matter; or he must, with Dr. Bain, limit it to living beings. In the first case he has to make an absolutely incredible assumption without a scrap of evidence in its favour. In order to do away with the souls of a few living beings, who do not constitute the one-hundred-millionth part of the mass of the physical world, he has to assign a mental life to every grain of sand and drop of water on the earth. He has to ascribe to every molecule of matter in the universe something the nature of which cannot be imagined, and of the existence of which neither the experiments of science nor the observation of mankind has ever discovered the slightest trace. Such is the modest demand on our powers of faith made by scientists -- who can, when it suits them, be so exacting in their demands for proof. Even Tyndall, sympathetic though he be with such views, is forced to declare: "It is no explanation to say that objective and subjective are two sides of one and the same phenomenon. Why should the phenomenon have two sides? There are plenty of molecular motions which do not exhibit this two-sidedness. Does water think or feel when it rises into frost ferns upon a window-pane? If not, why should the molecular motions of the brain be yoked to this mysterious companion consciousness?"{21}

Should he adopt the second alternative, the defender of this double-faced theory has to explain the unaccountable appearance of the subjective aspect where it presents itself in conscious beings. It is a new phenomenon, differing from all previously existing phenomena by "a difference that transcends all other differences." Whence does it come? Physicists will not admit creations out of nothing, and neither will they allow that consciousness is merely a new form of the material energy of the universe, even were such a transformation conceivable. If material force is transmuted into mental states, then, unless the law of the conservation of energy be abandoned, the reverse operation must also hold, and mental states must be capable of issuing forth in the form of physical action. Conscious mental states would thus be capable of acting upon matter: but this is precisely what advocates of Monism declare to be impossible. That mental acts cannot affect material processes is the most fundamental article of their creed. Accordingly, whichever of the two necessary alternatives he accepts, the anti-spiritualist finds himself in an equally unsatisfactory position.{22}

2. Mental States not Composite. -- If we inquire more closely into the nature of this hypothetical "stuff," out of which intelligence, emotion, and volition are alleged to be manufactured, the absurdity of the doctrine is brought still more closely home to us. What is this material? Is it conscious? Most supporters of the theory, we believe, would answer, No. How then is it like our mental life? Does a multiplicity of unconscious acts constitute an act of conscious intelligence? If, on the other hand, we ascribe real but incipient consciousness to the molecules of matter, and if mental life is the outcome of their combination, it would seem that a mental existence ought to belong to all material objects with which experience presents us. Have plants, or their leaves, or the various parts of the human body minds of their own? Is a new steam-tug a thing of joy to itself? What are the emotions of a deserted coal-mine? Or is it only very small lumps of coal that have minds? Is the soul of carbon different in kind from that of nitrogen or oxygen?

But even were it granted that such allotments of subjective-aspect were attached to all molecules of matter, they would not solve the problem. We have already demonstrated the spirituality of man's intellect and will, and we have shown the peculiar, indivisible character of supra-sensuous acts, such as conception, judgment, reasoning, and self-consciousness; but in doing so we have disproved the double-aspect theory. The unity of consciousness cannot be an amalgam of morsels of subjective-aspect essentially dependent on extended molecules. Simple abstract ideas, judicial acts and free volitions, cannot be a mere compound of electric shocks or of unconscious units. They are indivisible acts, and they must pertain to an indivisible agent other than matter. As Lotze argues, analogical inferences from the combinations of physical forces to the fusion of mental states mislead, not only from the dissimilarity of the two classes of events, but from inaccuracy in describing the operations of the former. In nature two abstract 'forces' or 'motions' never coalesce to form a resultant. What really happens is that two bodies, moving or at rest, produce a motion of a body or bodies. Now movements or forces existing in this concrete way are not simple, but divisible into parts seated in the various molecules of the body. But in thought, especially in the unity of consciousness involved in judgment and self-knowledge, we have a real concrete, indivisible activity, which accordingly must pertain, not to an assemblage of separate molecules, but to a single simple agent.{23} Somewhat similarly James writes:

"The theory of mental units 'compounding with them. selves,' or 'integrating' is logically unintelligible. It leaves out the essential feature of all the 'combinations' we actually know. All the combinations which we actually know are EFFECTS wrought by the units said to be combined upon SOME ENTITY other than themselves. Without this feature of a medium or vehicle, the notion of combination has no sense. In other words, no possible number of entities (call them as you like, whether forces, material particles, or mental elements) can sum themselves together. Each remains in the sum what it was; and the sum itself exists only for a bystander who happens to overlook the units and to apprehend the sum as such; or else it exists in the shape of some other effect on an entity external to the sum itself. . . . 'A statue is an aggregation of particles of marble; but as such it has no unity. For the spectator it is one; in itself it is an aggregate; just as to the consciousness of an ant crawling over it, it may again appear a mere aggregate.' (Royce.) . . . Musical sounds do not combine per se into concords or discords. Concord and discord are names for their combined effects on that external medium the ear. Where the elemental units are supposed to be feelings the case is in no wise altered. Take a hundred of them, shuffle and pack them as close together as you can (whatever that may mean), still each remains the same feeling it always was, shut in its own skin, windowless, ignorant of what the other feelings are and mean. There would be a hundred-and-first feeling there, if when a group or series of such feelings were set up a consciousness belonging to the group as such should emerge. And this hundred-and-first feeling would be a totally new fact; the hundred original feelings might, by a curious physical law, be a signal for its creation, when they came together; but they would have no substantial identity with it, nor it with them, and one could never deduce the one from the others, or (in any intelligible sense) say that they evolved it. Take a sentence of a dozen words, and take twelve men and tell to each one word. Then stand the men in a row or jam them in a bunch, and let each think of his word as intently as he will; nowhere will there be a consciousness of the whole sentence. We talk of the 'spirit of the age' and the 'sentiment of the people,' and hypostatize public 'opinion.' But we know this to be symbolic speech, and never dream that the 'spirit,' 'sentiment,' etc., constitute a consciousness other than and additional to that of the several individuals whom the words 'age,' or 'people,' or 'public' denote. The private minds do not agglomerate into a higher compound mind. This has always been the invincible contention of the spiritualists against the associationists in Psychology."{24}

Absurd consequences. -- Advocates of psychophysical parallelism as well as of all forms of materialism agree at least in this, that mental states cannot act on the body. The main object in describing conscious activity as parallel to, or as an aspect, or phase of a nervous process, is to emphasize its incapacity for the production of any physical change. If it be once admitted that mental agency is really operative ad extra, that conscious states do really originate bodily movements, then the one great excellence claimed for The monistic theories with which we are here engaged is abandoned.{25} The existence of an efficient energy distinct from material force is admitted, and the chief tenet of the spiritualist philosopher is granted. It is to guard against such a contingency that Bain and Höffding insist "that there is no rupture of nervous continuity;" and Clifford that "the physical facts go along by themselves," and "the mental facts go along by themselves." The admission of a second real agent capable of interfering with or modifying in the most infinitesimal degree the course of material events is absolutely fatal to all monistic anti-spiritualist systems. But we venture to doubt whether the astonishing consequences in regard to most of our beliefs -- scientific as well as vulgar -- which inevitably proceed from the denial of mental efficiency have been adequately realized by these writers.

Mind's efficacy in Evolution. -- The theory of Evolution, for instance, will have to wear a somewhat altered appearance as a rational explanation of facts, if it be true that conscious states never influence bodily movement. The doctrine of natural selection in the animal kingdom is built on the assumption of serviceableness of pleasure and pain in the struggle for life. Herbert Spencer never wearies of expatiating on the utility of both the agreeable and the disagreeable qualities of action in the contest for existence. Pleasure and pain are according to him not merely the foundations of morality, but the prime agents in the development and perfecting of all sentient life.{26} Darwin is still more copious in showing how accidental actions, qualities, and experiences which afford satisfaction, in consequence of that satisfaction, emerge triumphant from among innumerable variations, and thus secure their own preservation. The beautiful colours and songs of several species of birds, for example, are held to be the result of long gradual evolution under the constant action of sexual selection -- individuals inheriting richer attractions more easily securing mates. But what "utility" or "serviceableness" can fine colours or pleasant or painful feelings possess in the struggle for life if they never determine or modify bodily activity? If conscious states and cerebral processes are merely parallel series of events which never act on each other, how can the preference for agreeable feelings favour the production of the movements to which the feelings are attached? How can pleasure or pain exert a selective influence in favour of certain kinds of physical action?

Other Minds non-existent ? -- Again, if thought never really influences action, what proof have we that other minds than our own exist? We at present infer other minds because we look on certain actions and expressions of our fellow-men as effects of certain feelings and volitions akin to our own, and deem them incapable of happening except in consequence of such mental states. But according to the new theory these actions are nothing of the sort. They are merely the effects of previous neural groupings; and might have taken place just the same whether the mental states accompanied them or not. The latter are merely appended inactive "phases," or "epiphenomena," which can occasion "no rupture of nervous continuity." We may still, perhaps, infer the existence of other brains, but logically the gestures, words, and actions of our neighbours might have been precisely the same if consciousness had no existence.{27}

But reflexion discovers consequences still more surprising. The whole past history of the world, the building of cities, the invention of machinery, the commerce of nations, the emigrations of peoples, the rise and fall of civilizations, all that has been done on this planet by human beings, might have happened in precisely the same way if there had never awoke to consciousness a single human mind! All the pain and sorrow, all the joy and gladness, all the love and anger that we suppose to have governed the world's history might never have been, and that history might have run exactly the same course! The neural groupings, the cerebral movements, which were the true, ultimate, and only causes of the various actions of human beings, have never once been interrupted, modified, or interfered with by those "aspects" or "phases" which constitute the "parallel" series of conscious states, since the first man appeared on the earth. Given the original collocation of the material atoms from which the present cosmos has been evolved, and every event, down to the least incident of our daily life, was therein rigidly and sufficiently determined, even though no single act of intelligence or volition had ever wakened into life!{28}

4. Meaningless Terms -- Finally, the entire vocabulary used in the exposition of the theory, is a veritable museum of nonsensical and sophistical terms. Hyphens, ambiguous epithets, and cloudy metaphorical language are profusely employed in pretended explanations of facts of which no real account is given. What idea is really conveyed to the mind by such words as "double-aspect," "mind-stuff," "two-sided cause," "subjective and objective sides of the same fact," "undivided twins," "double-faced unity"? We know what is meant by "stuff" when we talk of the materials out of which a table or a suit of clothes is made, but the word becomes absolutely unmeaning when spoken of an intellectual idea, like that of Being, or of the simple cognitive act of self-consciousness. "Double-aspect" signifies, or ought to signify, two views or points of viewing what is known to be one and the same thing; but here we have two sets of facts or things "differing by a difference that transcends all other differences." Surely , then, to speak of the unextended mind and the material brain as "aspects" of the same fact, is merely a childish attempt to deceive ourselves with half-understood words.

Similarly, the terms, "objective side of a feeling" and "subjective side of a nervous current," when intended to be taken as a philosophical explanation, and not as mere metaphorical phrases expressive of ignorance, are a perversion of language. "The expression, 'a two-sided cause,' is one of those figures of speech which are the crutches of Metaphysics, and enable halting theories to make progress. We find the same difficulty in realizing in our mind the conception of a two-sided cause as we have in realizing a blue-sound or a three-sided motion."{29} A Cause is defined in Dr. Bain's own Logic. as "the entire aggregate of conditions or circumstances requisite to the production of the effect." But if mental states form part of the aggregate of conditions required to effect a given movement, then mind is no longer a mere aspect" of physical processes: it is a really efficient agent which occasionally "ruptures the nervous continuity," and Mr. Bain's doctrine, in company with all other forms of materialistic monism, at once falls to the ground. If mental states do not co-operate in the production of physical changes, then they must not be described as past-causes, or the "side" of a cause, without self-contradiction.

Monism: Conservation of Energy and Law of Inertia. -- To many minds the most serious attack in recent years on the spirituality of the Soul is that based on the doctrine of the conservation of energy. Though sometimes specially directed against free-will, the objection, if valid at all, disproves the possibility of any influence of mind upon body. Physical energy, defined as capacity for doing work, may be either kinetic, e.g., that of the flying bullet, or potential, e.g., that of an elevated weight. Numerous experiments in chemistry and physics go to show that in the transmutations of energy from one form to another none is lost or gained; and the results have been formulated in the statement: The sum of the kinetic and potential energies of any isolated system of bodies remains constant. This conclusion has been still further generalized in the form of the Law: The sum total of energy in the universe always remains the same. From this generalization the positivist psychologist passes to a further inference, the doctrine of "psychophysical, parallelism " -- mental and bodily changes never affect each other; and then by one more logical leap to Monism -- mind and body are mere diverse phenomenal manifestations of one substratum.

It has also been maintained that this final conclusion is confirmed, if not independently proved by the principle of inertia, Newton's first law of motion: "Every body continues in its state of rest or uniform motion in a straight line except in so far as it may be compelled by impressed forces to change its state."

Harald Höffding is perhaps the ablest exponent of this argument, so we shall cite from his Outlines of Psychology. The italics are ours:

"Material phenomena appear in the form of space. . . . This characteristic distinguishes them from states of consciousness, yet does not contain anything by which the material is sharply defined and closed off as a world in itself For we might conceive these spatial movements as brought about by something non-spatial. The material world would in that case lie open to influences from without. But scientific research makes such a possibility always more inadmissible. It now applies in all departments the principle that every material movement must be explained by another material movement. The very first principle (the law of inertia) on which natural science is based, is that the state of a material point (rest or movement in a straight line) can be altered only through the influence of another material point.{30}. . . This principle cannot from its nature admit of rigid proof. It is the fundamental assumption with which natural science comes into existence. . . . The like holds true of a more special principle, namely, of the conservation of matter and energy. Modern chemistry is based on the assumption confirmed by numerous experiments that in all changes of matter the sum of the material atoms remains the same." (pp. 30, 31.) Living beings, Höffding assures us, are in no way an exception to this law. The old notion of a "vital force" governing the growth and reproduction of the living organism is illusory. "This doctrine is really only a mythological way of expressing the amazement which the unique character of organic phenomena excited." (p. 34.){31}

Still less does the mind act upon the body or vice-versa. "There is no justification for maintaining as a fact that a bodily process causes a mental process or the reverse. . . . The supposition that a causal relation may exist between the mental and the material is contrary to the doctrine of the conservation of energy, for at the point where the material nerve process should be converted (sic) into a mental activity a sum of physical energy would disappear without being made good by a corresponding sum of physical energy." (p. 55.) "It will be easily seen that it avails nothing to say that the mind may not be able to increase the sum of physical energy, but that it can alter the direction of the applied energy. A physical movement does not change its direction except under the influence of a physical force of a certain strength. So that this subterfuge also of necessity makes the energy of consciousness a physical energy." (p. 56.){32} As there is a perfect correspondence between mental and neural processes, whilst the law of the conservation of energy precludes real interaction between them, the only satisfactory scientific conception of their relations is that "Mind and body, consciousness and brain are evolved as different forms of expression of one and the same being."

" Both the parallelism and the proportionality between the activity of consciousness and cerebral activity point to an identity at bottom. . . . We have no right to take mind and body for two beings or substances in reciprocal interaction." (64.){33} In fine, "the Identity-hypothesis regards the mental and material worlds as two manifestations of one and the same being both given in experience." (66.) Still, lest the reader might begin to suspect that the scientific psychologist has after all lapsed into Metaphysics, he is reassured and comforted by the statement: "Concerning the inner relation between mind and matter, we teach nothing; we suppose only that one being works in both. But what kind of being is this? Why has it a double form of manifestation, why does not one suffice? These are questions which lie beyond the region of our knowledge." (Op. cit. p. 67.)

Criticism: Metaphysics inevitable. -- It may be justly urged that any positivistic attempt to disprove the interaction or the real duality of mind and body based on the Conservation of Energy, viewed as a generalization of physical science and prescinding from all metaphysics, is necessarily illegitimate and worthless. Every interpretation of this Law involves some metaphysical theory. The doctrine can certainly not be invoked as an established truth of positive science incompatible with real interaction between mind and body, whilst its own philosophical significance is altogether ignored. The notions of causality, action, energy, and the like, are derived, in the first instance, from the mind's own real activity and its immediate experience of exerting real influence over thoughts and bodily movements. (pp. 368, seq.) All our conceptions of energy, causality, interaction between material agents presuppose the experience of personal causality -- of the real influence of mind on body. If it be an illusion to think that the mind really influences the body, it must be equally erroneous to suppose that any one body really influences another. What then, is the precise meaning of the "first principle of exact science" that "the state of a material point can be altered only through the influence of another material point?" It will not avail the positivist to turn round now, and say that by "causal action" or "influence" of material agents on each other, he only means constant succession or concomitance. For such constant succession or concomitance cannot be denied to obtain with respect to the mental and bodily processes. The truth is, the positivist Psychologist, by professing to abjure all metaphysics, evades the obligation of defining those metaphysical conceptions with which all real science is saturated, and then employs them alternately in the sense ascribed to them by Hume or by Reid, by phenomenism or by common sense, as he finds convenient for his argument.{34}

2. Constancy of Energy not a Necessary Truth. -- The law is not a necessary a priori axiom, but a generalization from experience. Now many writers urge that the law is not demonstrated to hold accurately for any living organism; and that there is no possibility of its ever being rigidly proved respecting the universe as a whole. The experiments establishing the exactness of the law, from the nature of the case, have been fully satisfactory only in reference to portions of inanimate matter; whilst the very point in dispute is its applicability to living sentient beings. The animal structure is an extremely delicate machine, in which the action of a relatively small force may liberate or transform a very large quantity of latent energy, pretty much as the faintest pressure of a hair-trigger pistol may explode a powder-magazine.{35} In such a case the pouvoir décrochant -- the force which frees the stored-up energy -- is so infinitesimally small as to be quite inappreciable when incorporated in the total result. In this view the law is admitted to possess approximate but not absolute accuracy in regard to sentient or rational beings.{36} Consequently there always remains room for the interaction of mind and body, though the total quantity of energy in the universe should thereby undergo infinitesimal variations.

3. Mathematical Solutions. -- Distinguished mathematicians, however, have professed to reconcile the modification of bodily movement by the mind with the most rigid fulfilment of the law. One of the simplest solutions advanced is thus stated: "It is a principle of mechanics that a force acting at right angles to the direction in which a body is moving does no work, although it may continually alter the direction in which the body moves. No power, no energy, is required to deflect a bullet from its path, provided the deflecting force acts always at right angles to that path. . . . If Mind or Will simply deflect matter as it moves, it may produce all the consequences claimed by the Wilful School, and yet it will neither add energy nor matter to the universe."{37}

4. True Solution. -- The notion underlying most of the answers suggested -- that the Mind or Will merely directs, applies, or disposes of the energy stored in the organism -- contains, at least, part of the explanation; but their advocates seem to us frequently to err in representing the Mind as in a condition of excessive isolation from or independence of the body. Indeed, much of the strength of this difficulty is due to the erroneous conception of the mutual relations of soul and body prevalent among spiritualist writers since Descartes. In his theory (see above, p. 257), if the soul initiated or modified a series of bodily movements, it would do so after the manner of a foreign agent, and would therefore seem inevitably to alter the quantum of energy possessed by the alien material system with which it is supposed to interfere. But if, rejecting this ultra-dualism, we return to the Aristotelian conception according to which soul and body constitute one complete substantial living being of which the soul is the animating, actuating, or determining principle -- the formal cause, whilst the body is the determinable, material, quantitative principle, the difficulty at once loses more than half its force. The question is now no longer whether a spiritual agent can excite or modify the movements of a foreign material system without augmenting or diminishing the energy of that system, but whether the conscious states of a sentient being can determine the actualization and direction of the latent physical energy of that being without changing its amount. For, in this view, the material energy manifested in movement was previously stored in the living organic tissues; feelings and volitions merely determine the form it shall assume. Mental acts thus modify not the quantity, but the quality of the energy contained in the system. The distinction between quality and quantity in all forms of energy is the key to the solution of the difficulty.

This is admirably insisted upon by P. Couailhac in his recent able monograph on the problem.{38} Quantity and movement are the special object of the exact sciences; but they do not exhaust the content of the universe. In every transition from potential to actual energy, the qualitative element, he rightly urges, is as real and influential as the quantity. Direction, which is the qualitative element of movement, is as real and important as velocity and duration. In order that a material particle may move, it must take a definite path in space. But the quantity energy -- the velocity and the mass -- being given, an indefinite variety of such paths conceivably lie open to it. It does not dispose of quality to say that the direction of the moving body is due to the intensity of the forces playing on it. This merely pushes the question back. The effect of these forces is due as much to their quality as to their quantity, and so the qualitative element must ultimately be traced back to a directive principle distinct from quantity. Passing to the more complex movements of living organisms which start from a germ cell and develop into an animal of a particular species, the qualitative efficiency of the energy which determines the lines along which the embryo is to evolve becomes still more prominent. Whilst the quantity of the energy of the living organism at any time is the resultant of the material elements borrowed from external nature, the form of this energy is determined by the organizing force of the germinal principle; though the action of the latter is again conditioned by the nutriment absorbed. Finally, in the living conscious being this qualitative determining factor takes a still higher form, its range of activity is wider, its power of applying, directing, and disposing of the energy stored in the organism is more varied and more flexible, but it cannot alter the quantity of the capital funded in the self-moving machine. If, then, it be the quality of the forces distributed in the nervous system which the directive power of the soul immediately determines, the liberation and control of man's physical activity by his thoughts and volitions need not necessarily conflict with even the most rigid fulfilment of the Law of the constancy of the quantity of energy.{39} For a lengthy treatment of this subject, see "Energy," by the Author, in the American Catholic Encyclopedia.

The Law of Inertia, however, cannot be admitted to apply to conscious movements. Amongst the reasons for denying its validity, are these: (1) It is admittedly not self-evident. (2) It cannot be proved. (3) It at least seems to be directly contradicted by the internal experience of all men. (4) It would involve the incredible absurdities already dwelt upon. (pp. 513-516.) It is the unwarrantable application of this principle -- not that of the constancy of energy -- which is incompatible with dualism and the efficacy of mental action.

Agnosticism. -- The final outcome of Monism is Agnosticism. As in establishing our own doctrine, we have indirectly refuted this creed -- for since it professedly reposes not on reason but on faith, creed it is -- we cannot dwell on the subject further here. Indeed, since the Unknowable declines to recognize the laws of logic, rational criticism would be obviously futile. In its dark continent the identification of thought and matter may be peacefully accomplished without the disturbing interference of either the profane scientist or the impertinent philosopher. Screened off from the inconveniences of public discussion, rebellious facts and repugnant principles can there be silently suppressed. The freedom, responsibility, abiding identity and individuality to which conscious experience testifies can be rejected as irrelevant evidence -- because, of course, no evidence is accepted within the jurisdiction of the Unknowable. The difficulties of the theory which maintains that human thought has never influenced human civilization, are easily overcome -- the resources of the Unknowable being equal to all emergencies. Enjoying the hospitality of its ample territory, the most violent contradictions and implacable inconsistencies can rest in tranquil repose. Its frontiers once crossed, the Monist has reached a hallowed asylum, into which even the most relentless persecution of logic or common sense cannot follow him. There, at last, all objections are answered, all difficulties are solved, all doubts are assuaged by the one great axiom so well -- if not wisely -- expressed by Dr. Hodgson: "Whatever you are TOTALLY ignorant of, assert to be the explanation of everything else."

Additional Readings . -- Coconnier, ib. c. ii.; Farges, ib. pp. 136-106 Ladd, ib. cc. 9, 10.

{1} For an account of modern German Materialism, cf. Janet, Materialism of the Present Day, c. i.; also Margerie, Philosophic Contemporaine, pp. 191-226.

{2} Principles of Psychology, Vol. I. § 62,

{3} Address to the British Association at Norwich. Professor Huxley has, in one of his better moments, endorsed this doctrine. (Cf. "Mr. Darwin and his critics," Contemp. Rev. Nov. 1871.) But the passage tells equally against the "function" view of the next objection, advocated at times by Mr. Huxley himself.

{4} Prof. Huxley, Contemp. Rev. Nov. 1871.

{5} Huxley, Macmillan's Magazine, May, 1870.

{6} Kraft und Stoff (Trans.), pp. 135, 136.

{7} "Fifty million molecules, even when they are highly complex and unstable phosphorized compounds, gyrating in the most wonderful fashion with inconceivable rapidity, certainly do not constitute one thing. They do not, then, by molecular constitution and activities, constitute a physical basis conceivable as a representative or correlate of one thing." (Ladd, Phys. Psychology, p. 595.)

{8} Bain, Mind and Body, p. 130; cf. Maudsley, op. cit. c. ii.

{9} Of the theory of certain scientists, "that all mental phenomena, whatever their varied characteristic shading, have exact equivalents, as it were, in specific forms of the nerve-commotion of the living brain," Professor Ladd remarks: "Our first impression on considering the foregoing way of accounting for mental phenomena is that of a certain surprising audacity. The theory, standing on a slender basis of real fact, makes a leap into the dark which carries it centuries in advance of where the light of modern research is now clearly shining." He shows that even in such comparatively simple problems as the determination of the physiological conditions of variations in the quantity, quality, and time-rate of sensation, "almost everything needed for an exact science of the relations of the molecular changes in the substance of the brain and the changes in the states of consciousness is lamentably deficient;" whilst as regards the neural conditions of spiritual acts, such as the conviction of the principle of causality, or the idea of substance, he shows that science must remain in absolute ignorance. (Cf. Physiological Psychology, pp. 592-597.)

{10} Janet, Materialism of the Present Day, p. 134.

{11} "Since evidently the absolute weight of the brain cannot be the measure of intelligence, because if so the elephant and the whale ought to excel the greatest human genius, therefore refuge has been taken in greater relative weight. . . . Since again in this respect man is surpassed by several of the smaller birds (e.g., the titmouse), and the adult by the child, the multiplicity, complexity, and thickness of the convolutions on the surface of the brain are to afford the solution. But since on this principle the ox ought to distinguish itself by mental capacity, appeal is made to the chemical constitution of the cerebral substance, and the excellence of man's intellect attributed to the richness of his brain in phosphorus; but here again the superiority of the human cerebrum is disputed by two proverbially stupid animals, the sheep and the goose." (Gutberlet, Psychologie, p. 255.) On the relative weight, size, etc., of brains, cf. Ladd, op. cit. Pt. II. c. i.; also Surbled, Le Cerveau, cc. iv.-xii. The latter writer gives some very interesting statistics on this point. Thus, the average cubic capacity of Parisian skulls -- which are larger than those of most European nations -- is estimated to-day at about '1559cc' whilst six skulls of "Cave-men," assigned to the Palaeolithic period, average 1,606cc, and a collection of skulls of ancient Gauls reach 1,592cc. This does not seem very favourable to Evolution. Again, as regards the weight of the brain: Cuvier used to be triumphantly cited by materialists, as an example of great intellect, due to a very heavy brain -- 1,830 grammes (about 4 lbs.). The average British brain is about 1,400 grammes (3 lbs.). But in recent times cases of brains exceeding that of Cuvier have been found combined with very moderate abilities. A still more surprising fact is that Gambetta, whose mental gifts French materialists, at all events, will be the last to deny, was possessed of actually only 1,160 grammes (2 1/2 lbs.) of cerebral material, an endowment inferior to that of the lowest tribes of savages. Undoubtedly, great intellectual power is, as a rule, accompanied by a large brain, but there are very serious exceptions to the law.

{12} Cf. The Metaphysic of Experience (1898), Vol. II. p. 283.

{13} Op. cit. Vol. I. p. 446.

{14} Vol. II. pp. 315-318.

{15} "When molecules are so combined as to form the film on the under-side of a jelly-fish, the elements of mind-stuff which go along with them are so combined as to form the faint beginnings of sentience. When the molecules are so combined as to form the brain and nervous system of a vertebrate, the corresponding elements of mind-stuff are so combined as to form some kind of consciousness. . . . When matter takes the complex form of the living human brain, the corresponding mind-stuff takes the form of human consciousness, having intelligence and volition." (Lectures and Essays, 2nd Edit. p. 284; also Mind, Vol. III. pp. 64, 65.)

{16} Op. cit. p. 262.

{17} Mind and Body, p. 131.

{18} Op. cit. pp. 131, 132.

{19} Principles of Psychology, Vol. I. 62.

{20} Op. cit. p. 140.

{21} Cf. Mallock, Is Life worth Living? p. 180.

{22} Cf. Herbert, Modern Realism Examined, p. 71. Sects. 7-12 contain some very good criticism of this theory.

{23} Cf. Metaphysic, § 241, and Microcosmus, Bk. II. c. i. §§ 5, 6.

{24} Op. cit. pp. 358-60. The italics and capitals are those of Professor James himself. His argument here is, it seems to us, perfectly sound, but, notwithstanding his disclaimer (p. 362), fatal to his own theory. How can "the present section of consciousness" the merely "passing thought" act as "bystander" to sum up the series of long past states into the unity of a Self? Or if James chooses the other alternative and says that the present thought in which I cognize the unity of my past states, is "an effect on an entity external to the sum itself" (of these states); is not this "entity" after all very like the vulgar common-sense soul contemptuously discarded because it "explains nothing and guarantees nothing." On this question see also pp. 47. 48, above.

{22} The idealist may maintain the real efficiency of mind, but he does so by denying the independent reality of matter -- with the disastrous results already indicated. (pp. 113-116.)

{26} "Sentient existence can evolve only on condition that pleasure-giving acts are life sustaining acts." (Data of Ethics, p. 83.) "During the evolution of life pleasures and pains have necessarily been the incentives to and deterrents from, actions which the conditions of existence demanded and negatived . . . The pleasures of sympathy exceeding its pains lead to an exercise of it which strengthens it." (Ibid. p. 245.)

{27} "It is admitted that the feelings of others cannot themselves be perceived by any sense; certain bodily movements only are perceived, which are supposed to indicate feelings. It is admitted, further, that these movements proceed with the strictest physical sequence; in other words, that in the absence of feelings they would take place just as they do. It follows that mind leaves no trace of its presence in the movements by which alone it is revealed. What is this but to say it is a pure supposition, without a single vestige of evidence? The only evidence science can have of anything is that it is, or effects some change, some movement. Whatever effects no change, makes no sign in the material world, is to physical science non-existent." (Herbert, op. cit. p. 113.)

{28} This argument is stated with much force by Herbert. (Ibid. p.133.) It should be borne in mind that the present argument does not involve any particular metaphysical theory of causality. Accepting even Mill's definition of causation as invariable succession, our contention would still retain its force. The defender of the double-aspect doctrine may of course instinctively attribute minds to other human bodies, but he has no rational grounds for believing in such minds; consequently he cannot maintain mental states to be constant concomitants or conditions of physical actions. The latter, he asserts, are unaffected by the former, and so might have occurred precisely as well without them. If the mind cannot modify or influence bodily movements, then, clearly, it contributes nothing to the wonderful works of civilization, and, so far as these latter are concerned, might never have been. This is one of those curious but strictly logical consequences of this theory, which its supporters do not care to obtrude on public attention.

{29} Cf M. Guthrie, On Mr. Spencer's Unification of Knowledge, p. 248.

{30} The law of inertia is here mis-stated. As given above (p. 517) in Newton's words, it does not assert that the movement of a body can be affected only by the influence of another material agent. Newton himself would never have admitted such a principle. Yet it may be conceded that physical science prescinds from all but material agencies.

{31} Were Höffding not committed to this view we doubt if he would write thus to-day. The best authorities in biological science now admit that the attempt to explain life mechanically -- so much in vogue twenty-five years ago -- has failed all along the line; and that the present tendency is universally back towards vitalism. Cf. Prof. Haldane, "Vitalism," Nineteenth Century (Sept. 1898).

{32} Here is a truly naive petitio principii. After copiously proving universally admitted facts, the writer slurs over the crucial question, and devotes just two lines, plus an abusive epithet, to establish the fundamental thesis on which his attack upon dualism rests! The two lines are either a puerile and irrelevant truism, or a formal begging of the whole question in dispute. The assumption that a physical movement is modified only by a physical force is a truism for the astronomer, chemist, physicist, &c., who abstract from all but physical forces; but it is the precise point to be proved in regard to the moral sciences, ethics, economics, aesthetics, psychology, which all assume, -- and find the same sort of verification for the assumption, that non-physical forces -- motives and volitions -- direct physical movements. What the Monist has to prove is, e.g., that the ideas of "Independence" or British supremacy" have had no real influence in originating or in directing that special commotion of material particles and transmutation of physical energy called "the Boor war." For this, neither a question-begging epithet, nor an irrelevant truism will suffice. Assuredly the fact that the physical scientist may justly assume this law of inertia with only approximate proof in regard to lifeless matter does not compel the moral scientist to admit it without any proof, rigid or approximate, regarding living conscious beings.

{33} Surely the parallelism of two activities would point not to one but to two distinct substrata. Again: are they parallel in space, or in time? Or how? Are both continuous? Experience affirms mental states accompany only a fraction of neural processes; and present science professes profound ignorance of the character of the cerebral correlate of the higher rational activities. What, then, is the precise signification of this "parallelism" of the activities, except their incapacity to meet -- which is scarcely a reason for their identification? Does the "proportionality " -- e.g., of a reasoning process to its concomitant nerve-commotion -- refer to variation in intensity, or spatial area, or rapidity, or duration? Or has this half-conceived metaphor -- on which the whole weight of the monistic inference here rests -- any consistent intelligible meaning whatsoever? This is a specimen of the clearness and accuracy of thought of that "scientific" psychology which contemns the "metaphysician."

{34} Cf. Ladd, Philosophy of Mind, pp. 209-219 .

{35} "As far as we can judge, life is always associated with machinery of a certain kind, in virtue of which an extremely delicate directive touch is magnified ultimately into a very considerable transmutation of energy." (Balfour Stewart, On the Conservation of Energy, p. 263.)

{36} G. Fonsegrive, Le Libre Arbitre (1896), pp. 315-326.

{37} Cited by Tait and Stewart, The Unseen Universe, p. 180. These eminent physicists, however, prefer a different solution. (Ibid. §§ 111, 112.) MM. Cournot, de Saint-Venant, Boussinesque, and others, have also invented various ingenious solutions based on more or less abstruse mathematics. To our mind, however, the chief value of these attempts is that they make prominent the complexity, obscurity, and uncertainty of the assumptions involved in applying the doctrine of Conservation to the living organism, and prove the groundlessness of the dogmatism of Monism.

{38} La Liberté et la Conservation de l'Energie (Paris, 1897), Livre IV.

{39} "La volonté peut éveiller et tirer de leur torpeur les forces disponibles de l'organisme, auquel elle est unie. Elle ne pent les accroître. Ces forces ont une limite, quand elle est atteinte, elles s'arrêtent ou fléchissent. Et il n'y a pas de tension de la volonté qui puisse les porter en avant on les soutenir. . . . La fonction de la vie est de placer les forces physico-chimiques dans les conditions où peuvent se produire les combinaisons d'où résulte le tourbillon vital. La vie est directrice. Mais elle ne peut ni altérer ni perfectionner les éléments qui sont mis sa disposition par la nature." (Couailhac, op. cit. p. 226.)

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