308 INDUCTION. 



" Upon these methods, the obvious thing to remai'k is, that they take for 

 granted the very thing which is most difficult to discover, the reduction of 

 the phenomena to formulaj such as are here presented to us. When we 

 have any set of complex facts offered to us ; for instance, those which were 

 offered in the cases of discovery which I have mentioned — the facts of the 

 planetary paths, of falling bodies, of refracted rays, of cosmical motions, of 

 chemical analysis; and when, in any of these cases, we would discover the 

 law of nature which governs them, or, if any one chooses so to term it, the 

 feature in which all the cases agree, where are we to look for our A, B, C, 

 and a,h,cf Nature does not present to us the cases in this form; and 

 how are we to reduce them to this form ? You say when we find the com- 

 bination of A B C with ab c and A B D with ah d, then we may draw our 

 inference. Granted ; but when and where are we to find such combina- 

 tions ? Even now that the discoveries are made, who will point out to us 

 what are the A, B, C, and a, J, c, elements of the cases which have just been 

 enumerated? Who will tell us which of the methods of inquiry those 

 historically real and successful inquiries exemplify ? Who will carry these 

 formulae through the history of the sciences, as they have really grown up, 

 and show us that these four methods have been operative in their forma- 

 tion ; or that any light is thrown upon the steps of their progress by refer- 

 ence to these formulae ?" 



He adds that, in this work, the methods have not been applied " to a 

 large body of conspicuous and undoubted examples of discovery, extending 

 along the whole history of science;" which ought to have been done in or- 

 der that the methods might be shown to possess the " advantage " (which 

 he claims as belonging to his own) of being those " by which all great dis- 

 coveries in science have really been made." — (P. 277.) 



There is a striking similarity between the objections here made against 

 Canons of Induction, and what was alleged, in the last century, by as able 

 men as Dr. Whewell, against the acknowledged Canon of Ratiocination. 

 Those who protested against the Aristotelian Logic said of the Syllogism, 

 what Dr. Whewell says of the Inductive Methods, that it " takes for grant- 

 ed the very thing which is most difficult to discover, the reduction of the 

 argument to formulae such as are here presented to us." The grand diffi- 

 culty, they said, is to obtain your syllogism, not to judge of its correctness 

 when obtained. On the matter of fact, both they and Dr. Whewell are 

 right. The greatest difficulty in both cases is, first, that of obtaining the 

 evidence, and next, of reducing it to the form which tests its conclusive- 

 ness. But if we try to reduce it without knowing what it is to be reduced 

 to, we are not likely to make much progress. It is a more difficult thing 

 to solve a geometrical problem, than to judge whether a proposed solution 

 is correct: but if people were not able to judge of the solution when found, 

 they would have little chance of finding it. And it can not be pretended 

 that to judge of an induction when found is perfectly easy, is a thing for 

 whiQh aids and instruments are superfluous; for erroneous inductions, false 

 inferences from experience, are quite as common, on some subjects much 

 commoner than true ones. The business of Inductive Logic is to provide 

 rules and models (such as the Syllogism and its rules are for ratiocination) 

 to which if inductive arguments conform, those arguments are conclusive, 

 l^nd not otherwise. This is what the Four Methods profess to be, and 

 'Hvhat I believe they are universally considered to be by experimental phi- 

 losophers, who had practiced all of them long before any one sought to re- 

 duce the practice to theory. 



