3. If consciousness were a mere "epiphenomenon," having no "use" to the organism, it would soon perish (if it ever appeared) according to the law which says that all useless functions perish. But we know that, as a matter of fact, consciousness has grown more and more complex, as evolution has progressed.
4. The Law of Causation is doubtless valid and universal; but to assume that this is invariably physical begs the question at issue. May there not be psychical causation? Only thorough-going materialism can say "No" to this question; but materialism is today out of date.
5. The Philosophy of Nature.—This is a strong argument, a priori, but is subject to re-interpretation, in the light of new facts, to which it must conform. Facts might be adduced which proved this particular view of nature wrong. It is, in short, only a working hypothesis, subject to revision, as new facts are adduced, tending to alter it.
6. Psychology.—Our ignorance of the possible relation of brain and mind is no excuse for our dogmatically asserting that no such connection is possible. It may be a fact, though unintelligible to us. Mental states may influence, partially at least, successive brain-states. We cannot say. If one man asserts that they cannot, another may assert that they do. Hence every one is at liberty to believe what he pleases! Nothing is proved.
If, now, we glance at the preceding arguments, we find that they may be summarized somewhat as follows:
Arguments 2, 3, 5, and 6 are practically valueless, one way or the other. Both sides might claim a victory; none of these arguments would settle the question.
Argument 4 is certainly valid, to a certain extent, and can only be surmounted by assuming that a non-physical energy can affect physical energy. But I do not think that any physicist would be inclined to admit this. So that this argument cannot be used in support of the doctrine of Free Will.
There remains the first argument, drawn from the law of the Conservation of Energy. This is certainly the strongest of all (to my mind), and is, as it stands, valid. Though idealism may maintain that all physical energy may be, in its ultimate analysis, only psychical energy, I do not for a moment believe that any physicist really believes this, or that any man accepts it as a common-sense doctrine—one which can be acted upon in daily life. It is mere philosophical sophistry and hairsplitting, and we must believe, as a matter of fact, that physical energy is really physical, and not psychical, in its nature.
As to the first portion of this argument, although the law of Conservation of Energy has never been shown to be invalid, when applied to the connection of brain and mind, still, every one probably believes that it does actually obtain, and that a brain-state cannot result in consequence of non-physical influences any more than any other physical event could so result. It is tacitly admitted, therefore, that the law of Conservation holds good here also, and that will cannot affect brain, because will is not a physical energy.
We are now in a position to see the tremendous importance of the facts contained in the first part of this chapter. Inasmuch as theory must follow fact; inasmuch as it has been proved experimentally that the human will is a physical energy—this whole question of the relation of brain and mind, of the influence of the former by the latter, and the question of Free Will, must be remodelled in accordance with these facts. The whole Free Will controversy is settled at one stroke (and in favour of Free Will!), and all the books which have been written upon this subject, and all the thought and energy which have been expended in the past are thus shown to be so much waste-paper and wasted effort! For, as we have seen that the whole question resolves itself into the central problem of whether or not the law of Conservation of Energy is valid—whether will or mind can affect brain—it will be seen that the proof that will is a definite physical energy settles the case once and for all. Determinism is routed; Free Will wins the day; and here again, as usual, theory follows fact, instead of dictating what those facts should be! At "one fell swoop" we are enabled to solve and to settle for ever one of the most bitterly disputed points in the whole history of philosophy and metaphysics!