XII.] THE INDUCTIVE OE INVERSE METHOD. 265 



it is usual to have them repeated by different computers ; 

 but a case is on record in which three computers made 

 exactly the same calculations of the place of a star, and 

 yet all did it wrong in precisely the same manner, for no 

 apparent reason.^ 



Summary of the Theory of Inductive Inference. 



The theor}-- of inductive inference stated in this and the 

 previous chapters, was sugi^ested by the study of the 

 Inverse Method of Probability, but it also bears much 

 reseml:)lance to the so-called Deductive Method described 

 by Mill, in his celebrated System of Logic. Mill's views 

 concerning the Deductive Method, probably form the most 

 original and valuable part of his treatise, and I should 

 have ascribed the doctrme entirely to him, had I not 

 found that tlie opinions put forward in other parts of his 

 work are entirely inconsistent with the theory here upheld. 

 As this subject is the most important and difficult one 

 with which we have to deal, 1 will try to remedy the 

 imperfect manner in which I have treated it, by giving a 

 recapitulation of the views adopted. 



All inductive reasoning is but the inverse application 

 of deductive reasoning. Being in possession of certain 

 particular facts or events expressed in propositions, we 

 imagine some more general proposition expressing the 

 existence of a law or cause ; and, deducing the particular 

 results of that supposed general proposition, we observe 

 whether they agree with the facts in question. Hypo- 

 thesis is thus always employed, consciously or unconsci- 

 ously. The sole conditions to which we need conform in 

 fi-arning any hypothesis is, that we both have and exercise 

 the power of inferring deductively from the hypothesis to 

 the particular results, which are to be compared with the 

 known facts. Thus there are but three steps in the process 

 of induction : — 



(i) Framing some hypothesis as to the character of the 

 general law. 



(2) Deducing consequences from that law. 



' Memoirs of the Royal Astronomical Society, vol. iv. p. 290, quoted 

 by Lurdjiei, Ediitharijh Review, July 1834, p. 278. 



