Genetic Logic. Vol. II. Experimental Logic, or Genetic Theory of Thought.
By James Mark Baldwin. Pp. 436. New York: The Macmillan Co. $2.75 net.
CSP, identification: MS 1509. See also: Burks, Bibliography.
The author here continues the working out of his purpose with the same industry, and with the same quality of ability, if not perhaps in so full measure, as in the first volume (see the Nation of February 28, 1907, p. 203). But it now becomes quite clear that, however desirable the main inquiry of the work may be in itself, the project of connecting it with the science of logic was very unfortunate for the one subject and for the other.
The main motive of logic has always been to get possession of a method for determining the values of arguments. Now, it is obvious that whatever bearing the truth of one thought may have upon the truth of another will depend exclusively upon what the states of things are which the two thoughts represent to be real, and not at all upon the psychical or linguistic forms in which they are dressed, nor upon the psychical processes by which that dress is given to them. Whether we say that among sea-animals will be found some that give milk to their young or whether we say that among animals that give milk to their young will be found some that inhabit the sea, is for all purposes of argumentation quite indifferent; and the equivalence is here so evident that the school of "exact," or mathematical, logicians are almost unanimous in adopting, as their standard, or canonical, form of expressing the same fact, substantially this: "There is an aquatic mammal." Newton's great discovery is usually stated in elementary books, and is thought of by ordinary people in the form that each separate body in the solar system has an instantaneous component acceleration toward every other proportional to the mass of that other and inversely proportioned to the square of the distance between them, but is otherwise constant for all and at all times. But in writings on celestial mechanics (as in Equation 15 on p. 175 of Dr. Moulton's admirable little "Introduction" to the science), the form in which the same fact is often stated and intended to be thought is that the sum of the vires viva (or their halves, according to the old definition) of all the bodies of the system subtracted from the sum of the reciprocals of the distances between the several bodies, each reciprocal being multiplied by the product of the masses of the pair of bodies concerned and these masses being expressed in terms of a gravitational unit, remains unchanged. Since these two statements represent, and would in all conceivable cases represent precisely the same state of things, they are for all purposes of reasoning interchangeable. It follows that for logic they are equivalent, although, since this equivalence is not self-evident, they cannot strictly he called identical. From such considerations it follows that, in general, logic has nothing to do with different dresses of thought which cannot possibly represent different states of things; or at most has no more to do with them than to demon-