An Introduction to Modem Loyic. By RUTBBT CLHD6H LODOB, M.A., A-intent Professor of Philosophy in the University of Minnesota, some time John Locke Soholar in Mental Philosophy in the University of Oxford. The Perine Book Co., Minneapolis. Pp. xiv, 361. Th9 author tells u» that what he meaus by Modern Logic is what he finds, for example, in the views of Lotze, Bradley, Dewey, and Wundt. He purposely omits "Aristotelian " and also Symbolic Logic, seemingly for the sake of securing unity in his
... troductory treatise. Thus what he offers is a plain account of Judgment, Inference, and the Method of Science, in three successive books, without any reference to logical technicalities, excepting sach general terms as analysis, induction, identity, organisation. His plan, I think, is a good one. What he is really doing throughout is to trace, in successive ranges of expansion, the process of introducing in connexion with sensory data the intellectual "ideals" or "standards" of "identity," " difference," "internal " and " external organisation ". In the first Book these are applied successively to the four types of " perceptual," " experiential," " symbolic," and " transcendent" judgment (I think here we are on thin ice philosophically speaking, but the author is not intending to deal with philosophy) ; and in the second and third Books respectively to the theory of inference and to the method of Boienoe; in both of which they develop into accounts of synthesis and analysis, and other factors of method. The description of the method of science is the longest part of the work, and obviously follows the headings of Wundt's AUgemtine Mtthodenlthrt (chapters i. and ii. of his Logik, vol. ii.). Proof, «.#., is separated from inference and discovery, and treated as a method of exposition. I think the sub-division and lengthening of the book thus effected is unfortunate, for the bouk is long considering its character, though it is in Appearance a small volume. I wish the Method of Science could be omitted, and its best chapters, xxi. and xxvi., where there is a good acoount of analysis and synthesis taken together, and so too of induction and deduction, fused with the acoount of inference in Book II. In the pursuit of knowledge through the application of the " ideals " or " standards " we oonstruct " mental models, i.e., mathematical or causal schemes intended to interpret this or that set of data; and those may have perfect validity ("objectivity" and "completeness") when applied to "mind-made entities" (anything from a puzzle-box to a triangle), but there is always a gap between them and "natural phenomena". All this raises problems which I cannot now discuss. The illustrations are extraordinarily copious and ingenious. One, for instance, points oat that a cipher may have a group of five letters to each letter indicated, so that if you begin by analysing it into single letters your analysis will be wholly irrelevant. They are a good deal drawn from the psychological laboratory, where, it seems, you have puzzle-boxes, "artificial crimes," and many other dodge*. The mathematical beginning of a science is illustrated by a trick in experimental fBsthetic. You have a celluloid dachshund, which you can lengthen and shorten at pleasure by an apparatus which admits of exact measurements in millimetres. The problem is how long a dachshund should be ctttiu paribut in order to give the most eesthetical 'satisfaction. Tou collect judgments and treat them mathematically, and so make a beginning of "experimental (esthetics". These illustrations partly suggest what the author means by "mind-made entities".