w. WUXDT'S LOGIK, n. 453 On the general question as to the nature of Induction, Prof. Wundt inclines to the view that it is the inverse of Deduction. But this needs a little explanation, as his account of their mutual relations does not seem to me to be by any means the same as what is commonly understood by the expression. As I appre- hend the matter, the statement of the inverse relation should be as follows : Deduction starts from given premisses and obtains a certain conclusion ; the inverse process to this is to assume the conclusion as given, and to inquire, What must have been the premisses from which this conclusion was derived ? The answer to this question is, of course, in the majority of cases indeter- minate in character. That this was the view of Jevons, who first introduced the particular technical expression ' inverse ' into use, there can, I conceive, be no doubt : in fact, a section of the Pri/c-l>1.s of Science is devoted, under the heading of " The Inverse or Inductive Problem," to this precise problem, viz., Given a result, what were the propositions from which this result might have been derived ? But such a problem as this, it must be remarked, though indeterminate is absolutely certain ; that is, though different groups of possible premisses might be selected, yet any one of them will necessarily yield the conclusion : there is nothing in this conclusion, as Jevons repeatedly admits, which is wider than the premisses. But in the tabular scheme of Induction and Deduction, given by Prof. Wundt (p. 21), we have them arranged in the familiar plan commonly adopted by inter- preters of Aristotle, viz. : INDUCTION. DEDUCTION. SP MP SM SM MP SP with the express notification that Induction is of the nature of the third figure. I do not see the propriety of terming this an ' inverse ' relation. The view of Jevons, as of Whewell, who had taught substantially the same doctrine though he had not intro- duced an appropriate technical term to designate it was that no rules whatever can be given for Induction. We must simply" "assume our premisses, bypractical and sagacious guessing, reason deductively from them, and test the conclusion by experience. It does not at all seem to me to describe their view to say with Prof. Wundt that " every Induction is a conversion (Umkekneng) of the ordinary syllogism of subsumption of the first figure ". A little further on, the same question is touched upon again. Discussing the methods of Induction, he distinguishes between two operations, viz., (1) that of limiting the possibilities by a due recourse to Analysis and Synthesis, and then (2) arguing hypo- thetically from each such assumption in turn and comparing the result with experience. This latter seems to me exactly what Jevons understands by Induction, but as Prof. Wundt says it is fundamentally of the character of Deduction. 31
