1. _The Law of Conservation of Energy_ tells us that no energy can be added to or abstracted from the total stock of physical energy in the universe. If the will be a non-physical energy (as it is conceived to be, by psychologists), it cannot affect the physical world, for if it did the law of Conservation of Energy would be overthrown. Hence, the will cannot affect the material world: hence, it cannot be a true cause. 2. _Biology_ contends that heredity and environment alone are capable of explaining the actions and movements of the lower organisms, without postulating any "will." Inasmuch as man is connected with these lower organisms by an unbroken line of descent, why should not these factors explain man's actions also? 3. _Physiology_ teaches that in-coming nerve stimuli give rise to certain physical changes in the nerve cells or centres, which, in turn, give rise to out-going (afferent) currents. There is here an arc or loop of unbroken physical causation; and there is no "room" for consciousness, save as an "epiphenomenon," as postulated by Huxley. 4. The _Law of Causation_ tells us that an effect must have a cause, and that the cause must, in a certain sense, resemble the effect--since the effect _is_, in a sense, the cause translated. But, inasmuch as the effect is a physical event, the cause must also be physical in its nature; hence will (supposedly a non-physical event) cannot possibly play a part, or be a true cause. 5. _Philosophical Science_ contends that Nature is a "closed circle." Mechanical causation holds supreme sway. Everything happens according to law and order. If Free Will were allowed a place in the scheme of things, chance and caprice would immediately be introduced into our world--which could never be tolerated for a moment! 6. _Psychology_ holds that every mental state has its equivalent or counterpart in a corresponding brain-state. But each brain-state is not caused by the state of consciousness, but by the preceding brain-state. Here, again, there is no room for "free will" to play any part. (Inasmuch as we are approaching this subject from a purely scientific point of view, the arguments drawn from sociology, ethics, and theology need not here be discussed. The interested reader is referred to Professor H. H. Horne's excellent little book, _Free Will and Human Responsibility_, for an extremely clear summary of this problem.) The reply of the Libertarian to these problems is usually somewhat as follows: 1. The doctrine of Conservation has not been experimentally proved with regard to the relation of mind and brain; it is only assumed. Still, granting it to exist, all energy may, in its ultimate analysis, be psychical, instead of physical, in its nature--the doctrine of idealism, which is today gaining wider and wider acceptance, seeming to support this view.