HEX ERA LIZA TIOX. 243 



we not know that Mr. Gladstone must die, because he is like 

 other 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 then 

 descend by deduction from that general proposition to the 

 case of Mr. Gladstone 1 My answer will be undoubtedly 

 that it is necessary to ascend to general propositions. 

 The fundamental principle of the substitution of similars 

 gives us no warrant in afiirming of Mr. Gladstone what 

 we know of other men, simply because we cannot be 

 sure that Mr. Gladstone is exactly similar to other men. 

 Until his death we cannot be perfectly sure that he 

 possesses precisely all the attributes of other men ; it is 

 a question of probability, and I have endeavoured to 

 explain the mode in which the theory of probability is 

 applied to calculate the probability that from a series 

 of similar events we mav infer the recurrence of like 



/ 



vents under identical circumstances. There is then no 

 such process as that of inferring from particulars to par- 

 ticulars. A careful analysis of the conditions under which 

 such an inference appears to be made, shows that the 

 process is really a general one, and that what is inferred 

 of a particular case might be inferred of all similar cases. 

 All reasoning is essentially general, and all science implies 

 generalization. In the very birth- time of philosophy this 

 was held to be so : ' Nulla scientia est de individiis, sed 

 de solis universalibus,' was the doctrine of Plato, delivered 

 by Porphyry. And Aristotle a held a like opinion 



Ove/j.ia 3e Te^i't] aKOTret TO KO.& 1 eKacrrov ... TO ^e Katf eKaarrov 



eipov, Kal OIK eTTKTTijTov. 'No art treats of particular 

 sases ; for particulars are infinite and cannot be known.' 

 No one who holds the doctrine that reasoning may be 

 from particulars to particulars, can be supposed to have 



a Aristotle's 'Rhetoric,' Liber I. 2. n. 

 R 2 



