CH. xxvii.] GENERALISATION. 



595 



men? May we not argue that because some men die 

 therefore he must ? Is it requisite to ascend by induction 

 to the general proposition "all men must die" and ther 



caTo? M 7 rtfr f rJ lmt general P-Position to th^ 



; ase of Mr. Gladstone? My answer undoubtedly is that 



M e must ascend to general propositions. The fundamental 



principle of the substitution of similars gives us no warran 



n affirming of Mr. Gladstone what we know of other men 



because we cannot be sure that Mr. Gladstone is exactly 



similar to other men. Until his death we cannot fijg 



fectly sure that he possesses all the attributes of other 



f'T'f ? S a , r esti 7 of Polity, and I have endeavoured 

 to explain the mode m which the theory of probability is 

 applied to calculate the probability that from a series of 

 similar events we may infer the recurrence of like events 

 under identical circumstances. There is then no such 

 process as that of inferring from particulars to particulars. 

 A careful analysis of the conditions under which such an 

 inference appears to be made, shows that the process is 

 real y a general one, and that what is inferred of a par- 

 ticular case might be inferred of all similar cases. All 

 reasoning is essentially general, and all science implies 

 generalisation. In the very birth-time of philosophy this 

 was held to be so: "Nulla scientia est de individuis sed 

 de sohs timversalibus," was the doctrine of Plato, delivered 

 by Porphyry^ And Aristotle * held a like opinion- 

 Ou6e/ua be re X vn (TKo-rrel TO Kaff ZKCUJTOV . . . TO Se Kaff 

 e<aarov aTreipov K al ot K ^ i(r r v r6 v . "No art treats of 



ticular cases ; for particulars are infinite and cannot be 



nown. No one who holds the doctrine that reasoning 



may be from particulars to particulars, can be supposed 



Have the most rudimentary notion of what constitutes 

 reasoning and science. 



At the same time there can be no doubt that practi- 

 ; ally what we find to be true of many similar objects will 



robably be true of the next similar object. This is the 

 result to which an analysis of the Inverse Method of 

 Irobabihties leads us, and, in the absence of precise data 

 from winch we may calculate probabilities, we are usually 



bilged to make a rough assumption that similars in some 



1 Aristotle's Rhetoric, Liber I. 2. 11. 



Q Q 2 



