face of this significant admission, "is absolutely distinct from the nonliving world, and, instead of being a necessary outcome of it, is, compared with the antiquity of matter, probably a very recent addition to it—not, of course, an addition of mere transformed or modified matter and energy, but of transcendent power conferred on matter, by which both matter and its forces are controlled, regulated, and arranged, according, it may be, to laws, but not the laws of inert matter." This additional agent is, of course, our old acquaintance—the vital force. Dr. Beale adds: "It may be freely admitted that, if we attribute to vital power certain phenomena of the living world which have not been, and can not be, explained or accounted for by any physical laws yet discovered, we thereby assume an agency which we are unable to isolate or demonstrate, and the existence of which we can not in any way prove. On the other hand, it is only fair to observe that, if we assume that phenomena peculiar to life will some day be explained by physics, we certainly act in a manner which is not sanctioned by science—we assume, we prophesy; and prophetic assumptions of every kind are contrary to the spirit of science. . . . But is it not in accordance with reason," he concludes, "to assume the existence of a peculiar power to account for phenomena which are peculiar to living beings, which differ totally from any known physical phenomena, and which can not be imitated—and is it not contrary to reason to prophesy that such phenomena will one day be explained by ordinary forces or powers? "Such is his statement of the case, and such the argument by which he supports his side of it.
A few words, I think, will suffice to show the invalidity of the argument. The question, fortunately, hinges on a point which science has determined definitively.
A genuine hypothesis, in the scientific sense, is capable of proof or disproof; for an hypothesis capable of neither must always remain an hypothesis, and, instead of leading to an explanation of phenomena, serves to block the way to it. I may say here, parenthetically, that too much verbal respect, as it seems to me, is usually paid by scientific thinkers to assertions of this transcendent sort; strictly speaking, an assertion, of which it is said that it can be "neither proved nor disproved," is disproved by denying it, for the denial, being of equal validity with the assertion, nullifies it, leaving zero as the logical result, and an assertion reduced to zero is effectually disproved. But to return. An unverifiable hypothesis, as incompetent to lead to certainty, has no reason of being; and, consequently, science pronounces it illegitimate. But the hypothesis of a vital force, Dr. Beale admits, is unverifiable. It assumes "an agency," he owns, "which we are unable to isolate or demonstrate, and the existence of which we can not in any way prove." It is, therefore, illegitimate on his own showing.
Moreover, a genuinely scientific hypothesis does not assume an unknown cause, much less an unknowable one, before the inadequacy of