From this vice of radical contradiction, to which both the dualistic theories are committed, the monistic theory is free. Moreover, as we shall immediately find, it is free to combine the elements of truth which severally belong to both the other theories. These other theories are each concerned with what they see upon different sides of the same shield. The facts which they severally receive they severally report, and their reports appear to contradict each other. But truth can never be really in contradiction with other truth; and it is reserved for Monism, by taking a simultaneous view of both sides, to reconcile the previously apparent contradictions. For these and other reasons, which will unfold themselves as we proceed, I fully agree with the late Professor Clifford where he says of this theory—'It is not merely a speculation, but is a result to which all the greatest minds that have studied this question (the relation between body and mind) in the right way have gradually been approximating for a long time.' This theory is, as we have already seen, that mental phenomena and physical phenomena, although apparently diverse, are really identical.
If we thus unite in a higher synthesis the elements both of spiritualism and of materialism, we obtain a product which satisfies every fact of feeling on the one hand, and of observation on the other. We have only to suppose that the antithesis between mind and motion—subject and object—is itself phenomenal or apparent: not absolute or real. We have only to suppose that the seeming duality is relative to our modes of apprehension: and, therefore, that any change taking place in the mind, and any corresponding change taking place in the brain, are really not two changes, but one change. When a violin is played upon we hear a musical sound, and at the same time we see a vibration of the strings. Relatively to our consciousness, therefore, we have here two sets of changes, which appear to be very different in kind; yet we know that in an absolute sense they are one and the same: we know that the diversity in consciousness is created only by the difference in our mode of perceiving the same events—whether we see or whether we hear the vibration of the strings. Similarly, we may suppose that a vibration of nerve-strings and a process of thought are really one and the same event, which is dual or diverse only in relation to our modes of perceiving it.
Or, to take another and a better illustration, in an Edison lamp the light which is emitted from the burner may be said indifferently to be caused by the number of vibrations per second going on in the carbon, or by the temperature of the carbon; for this rate of vibration could not take place in the carbon without constituting that degree of temperature which affects our eyes as luminous. Similarly, a train of thought may be said indifferently to be caused by brain-action or by mind-action; for, ex hypothesi, the one could not take place without the other. Now when we contemplate the phenomena of volition by themselves, it is as though we were contemplating the phenomena of light by themselves: volition is produced by mind in brain, just as light is produced by temperature in carbon. And just as we may correctly speak of light as the cause, say, of a photograph, so we may correctly speak of volition as the cause of bodily movement. That particular kind of physical activity which takes place in the carbon could not take place without the light which causes a photograph; and, similarly, that particular kind of physical activity which takes place in the brain could not take place without the volition which causes a bodily movement. So that volition is as truly a cause of bodily movement as is the physical activity of the brain; seeing that, in an absolute sense, the cause is one and the same. But if we once clearly perceive that what in a relative sense we know as volition is, in a similar sense, the cause of bodily movement, we terminate the question touching the freedom of the will. It thus becomes a mere matter of phraseology whether we speak of the will determining, or being determined by, changes going on in the external world; just as it is but a matter of phraseology whether we speak of temperature determining, or being determined by, molecular vibration. All the requirements alike of the free-will and of the bond-will hypotheses are thus satisfied by a synthesis which comprises them both. On the one hand, it would be as impossible for an unconscious automaton to do the work or to perform the adjustments of a conscious agent, as it would be for an Edison lamp to give out light and cause a photograph when not heated by an electric current. On the other hand, it would be as impossible for the will to originate bodily motion without the occurrence of a strictly physical process of cerebration, as it would be for light to shine in an Edison lamp which had been deprived of its carbon-burner.
The great advantage of this theory is, that it supposes only one stream of causation, in which both mind and motion are simultaneously concerned. The theory, therefore, escapes all the difficulties and contradictions with which both spiritualism and materialism are beset. Thus, motion is supposed to be producing nothing but motion; mind-changes nothing but mind-changes—both producing both simultaneously: neither could be what it is without the other, because without the other neither could be the cause which in fact it is. Impossible, therefore, is the supposition of the materialist that consciousness is adventitious, or that in the absence of mind the changes of the brain could be what they are; for it belongs to the very causation of these movements that they should have a mental side. And equally impossible is the supposition of the spiritualist that the cerebral processes are adventitious, or that in the absence of brain the changes of the mind could be what they are; for it belongs to the very causation of these changes that they should have a material side. Furthermore, the use of mind to animals and to men is thus rendered apparent; for intelligent volition is thus shown to be a true cause of adjustive movement, in that the cerebration which it involves could not otherwise be possible: the causation would not otherwise be complete.
CHAPTER IV.
THE WORLD AS AN EJECT.
In the Introduction to this essay I have sought to show that there are, for the purposes of practical discussion, but three theories of the World of Being. There is, first, the theory of Materialism, which supposes matter in motion to be the ultimate or self-existing Reality, and, therefore, the cause of mind. Next, there is the theory of Spiritualism, which supposes mind to be the ultimate Reality, and, therefore, the cause of matter in motion. Lastly, there is the theory of Monism which supposes matter in motion to be substantially identical with mind, and, therefore, that as between mind and matter in motion there is no causal relation either way. In the foregoing chapters I have considered these three theories, and argued that of them the last-mentioned is the only one which satisfies all the facts of feeling on the one hand, and of observation on the other. The theory of Monism alone is able to explain, without inherent contradiction, the phenomena both of the subjective and objective spheres.
It is my present purpose to extend the considerations already presented. Assuming the theory of Monism, I desire to ascertain the result to which it will lead when applied to the question whether we ought to regard the external world as of a character mental or non-mental. As observed in my Rede Lecture (supra, p. [33]), this question has already been considered by the late Professor Clifford, who decided that on the monistic theory the probability pointed towards the external world being of a character non-mental; that, although the whole universe is composed of 'mind-stuff,' the universe as a whole is mindless. This decision I then briefly criticized; it is now my object to contemplate the matter somewhat more in detail.
I will assume, on account of reasons previously given, that when we speak of matter in motion we do not at all know what it is that moves, nor do we know at all what it is that we mean by motion. Therefore if, as unknown quantities, we call matter a and motion b, all we are entitled to affirm is that a + b = z, where z is a known quantity, or mind. Obversely stated, we may say that the known quantity z is capable of being resolved into the unknown a + b. But, inasmuch as both a and b are unknown, we may simplify matters by regarding their sum as a single unknown quantity x, which we take to be substantially identical with its obverse aspect known as z.