t20 



HEASONlNa. 



ceived in the common theory ; and 

 what are the fundamental axioms on 

 which its probative force or conclusive- 

 ness depends. We have now to in- 

 quire whether the syllogistic process, 

 that of reasoning from generals to 

 particulars, is, or is not, a process of 

 inference ; a process from the known 

 to the unknown : a means of coming 

 to a knowledge of something which 

 we did not know before. 



Logicians have been remarkably 

 unanimous in their mode of answering 

 this question. It is universally allow- 

 ed that a syllogism is vicious if there 

 be anything more in the conclusion 

 than was assumed in the premises. 

 But this is, in fact, to say that nothing 

 ever was, orcanbe, proved by syllogism 

 which was not known, or assumed to 

 be known, before. Is ratiocination, 

 then, not a process of inference ? And 

 is the syllogism, to which the word 

 reasoning has so often been represent- 

 ed to be exclusively appropriate, not 

 really entitled to be called reasoning 

 at all ? This seems an inevitable con- 

 sequence of the doctrine, admitted by 

 all writers on the subject, that a syl- 

 logism can prove no more than is 

 involved in the premises. Yet the 

 acknowledgment so explicitly made, 

 has not prevented one set of writers 

 from continuing to represent the syl- 

 logism as the correct analysis of what 

 the mind actually performs in discover- 

 ing and proving the larger half of the 

 truths, whether of science or of daily 

 life, which we believe ; while those 

 who have avoided this inconsistency, 

 and followed out the general theorem 

 respecting the logical value of the syl- 

 logism to its legitimate corollary, have 

 been led to impute uselessness and 

 frivolity to the syllogistic theory itself, 

 on the ground of the petitio principii 

 which they allege to be inherent in 

 every syllogism. As I believe both 

 these opinions to be fundamentally 

 erroneous, I must request the atten- 

 tion of the reader to certain considera- 

 tions, without which any just appre- 

 ciation of the true character of the 

 syllogism, and the functions it per- 



forms in philosophy, appears to me 

 impossible ; but which seem to have 

 been either overlooked, or insuffi- 

 ciently adverted to, both by the de- 

 fenders of the syllogistic theory and 

 by its assailants. 



§ 2. It must be granted that m 

 every syllogism, considered as an 

 argument to prove the conclusion, 

 there is a petitio principii. When we 

 say, 



All men are mortal, 



Socrates is a man, 

 therefore 



Socrates is mortal ; 

 it is unanswerably urged by the adver- 

 saries of the syllogistic theory, that 

 the proposition, Socrates is mortal, 

 is presupposed in the more general 

 assumption. All men are mortal : that 

 we cannot be assured of the mortality 

 of all men, unless we are already cer- 

 tain of the mortality of every indi- 

 vidual man : that if it be still doubt- 

 ful whether Socrates, or any other 

 individual we choose to name, be 

 mortal or not, the same degree of 

 uncertainty must hang over the asser- 

 tion, All men are mortal : that the 

 general principle, instead of being 

 given as evidence of the particular 

 case cannot itself be taken for true 

 without exception, until every shadow 

 of doubt which could affect any case 

 comprised with it, is dispelled by evid- 

 ence aliunde ; and then what remains 

 for the syllogism to prove ? That, in 

 short, no reasoning from generals to 

 particulars can, as such, prove any- 

 thing, since from a general principle 

 we cannot infer any particulars, but 

 those which the principle itself assumes 

 as known. 



This doctrine appears to me irre- 

 fragable ; and if logicians, though 

 unable to dispute it, have usually 

 exhibited a strong disposition to ex- 

 plain it away, this was not because 

 they could discover any flaw in the 

 argument itself, but because the con- 

 trary opinion seemed to rest on argu- 

 ments equally indisputable. In the 

 syllogism last referred to, for example, 



