380 THE POPULAR SCIENCE MONTHLY. 



of Logic " was a revolution. It hardly needs, of course, to be said 

 that he owed much to his predecessors ; that he borrowed from Whe- 

 well much of his classification, from Brown the chief lines of his 

 theory of causation, from Sir John Herscbel the main principles of the 

 inductive methods. Those who think this a disparagement of his 

 work must have very little conception of the mass of original thought 

 that still remains to Mr. Mill's credit, the great critical power that 

 could gather valuable truths from so many discordant sources, and the 

 wonderful synthetic ability required to weld these and his own con- 

 tributions into one organic whole. 



When Mr. Mill commenced his labors, the only logic recognized 

 was the syllogistic. Reasoning consisted solely, according to the then 

 dominant school, in deducing from general propositions other proposi- 

 tions less general. It was even asserted confidently that nothing 

 more was to be expected that an inductive logic was impossible. 

 This conception of logical science necessitated some general proposi- 

 tions to start with ; and these general propositions heing ex hypothesi 

 incapable of being proved from other propositions, it followed that, 

 if they were known to us at all, they must be original data of con- 

 sciousness. Here was a perfect paradise of question-begging. The 

 ultimate major premiss in every argument being assumed, it could, 

 of course, be fashioned according to the particular conclusion it was 

 called in to prove. Thus an " artificial ignorance," as Locke calls it, 

 was produced, which had the effect of sanctifying prejudice by recog- 

 nizing so-called necessities of thought as the only bases of reasoning. 

 It is true that outside of the logic of the schools great advances had 

 been made in the rules of scientific investigation ; but these rules were 

 not only imperfect in themselves, but their connection with the law 

 of causation was but imperfectly realized, and their true relation to 

 syllogism hardly dreamed of. 



Mr. Mill altered all this. He demonstrated that the general type 

 of reasoning is neither from generals to particulars, nor from particu- 

 lars to generals, but from particulars to particulars. " If from our 

 experience of John, Thomas, etc., who once were living but are now 

 dead, we are entitled to conclude that all human beings are mortal, we 

 might surely, without any logical inconsequence, have concluded at 

 once, from those instances, that the Duke of Wellington is mortal. 

 The mortality of John, Thomas, and others is, after all, the whole evi- 

 dence we have for the mortality of the Duke of Wellington. Not one 

 iota is added to the proof by interpolating a general proposition." We 

 not only may, according to Mr. Mill, reason from some particular in- 

 stances to others, but we frequently do so. As, however, the instances 

 which are sufficient to prove one fresh instance must be sufficient to 

 prove a general proposition, it is most convenient to at once infer that 

 general proposition which then becomes a formula according to which 

 (but not from which) any number of particular inferences may be 



