Note 3 — Chapter I

"Volitions are not known to produce anything directly except nervous action, for the will influences even the muscles only through the nerves. Though it were granted, then, that every phenomenon has an efficient and not merely a phenomenal cause, and that volition, in the case of the particular phenomena which are known to be produced by it, is that cause; are we therefore to say with these writers that since we know of no other efficient cause, and ought not to assume one without evidence, there is no other, and volition is the direct cause of all phenomena? A more outrageous stretch of inference could hardly be made. Because among the infinite variety of the phenomena of nature there is one, namely, a particular mode of action of certain nerves which has for its cause and, as we are now supposing, for its efficient cause, a state of our mind; and because this is the only efficient cause of "which we are conscious, being the only one of which, in the nature of the case, we can be conscious, since it is the only one which exists within ourselves; does this justify us in concluding that all other phenomena must have the same kind of efficient cause with that one eminently special, narrow, and peculiarly human or animal phenomenon?" It is then shown that a logical parallel to this mode of inference is that of generalising from the one known instance of the earth being inhabited, to the conclusion that "every heavenly body without exception, sun, planet, satellite, comet, fixed star, or nebula, is inhabited, and must be so from the inherent constitution of things." After which the passage continues, "It is true there are cases in which, with acknowledged propriety, we generalise from a single instance to a multitude of instances. But they must be instances which resemble the one known instance, and not such as have no circumstance in common with it except that of being instances.... But the supporters of the volition theory ask us to infer that volition causes everything, for no other reason except that it causes one particular thing; although that one phenomenon, far from being a type of all natural phenomena, is eminently peculiar; its laws bearing scarcely any resemblance to those of any other phenomenon, whether of inorganic or of organic nature."[3]