2. That man _resembles_ the lower animals does not prove that he is _identical_ with them. On the contrary, the observed differences constitute the very differences about which the argument rages. Further, recent theories of organic evolution are tending to prove that interior (spontaneous) forces play a part, as well as exterior forces. 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 Only thorough-going materialism can say "No" to this question; but materialism is today out of date. 5.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.