128 REASONING. 



CHAPTER III. 



OF THE FUNCTIONS, AND LOGICAL VALUE, OF THE SYLLOGISM. 



§ 1. We hav« shown what is the real nature of the truths \%'itli 

 which the Syllogism is conversant, in contradistinction to the rriore- 

 supei-ficial manner in which their import is conceived in the common 

 theory ; and what are the fundamental axioms on which its probative 

 force or conclusiveness depends. We have now to inquire, whether 

 the syllogistic process, that of reasoning from generals to particulars, 

 is, or is not, a process of inference ; a progi-ess 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 an- 

 swering this question. It is universally allowed that a syllogism is 

 vicious if there be anything more in the conclusion than was assumed 

 in the premisses. But this is, in fact, to say, that nothing ever was,' or 

 can be, proved by syllogism, which was not kno^vn, 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 

 represented to be exclusively appropriate, not really entitled to be 

 called reasoning at all I This seems an inevitable consequence of the 

 doctrine, admitted by all writers on the subject, that a syllogism can 

 prove no more than is involved in the premisses. Yet the acknowl- 

 edgment so explicitly made, has not prevented one set of writers from 

 continuing to represent the syllogism as the coiTect analysis of what 

 the mind actually performs in discovering 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 syllogism to its 

 legitimate corollary, have been led to impute uselessness and frivolity 

 to the syllogistic theory itself, on the gi'ound 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 

 attention of the reader to certain considerations, without which any 

 just appreciation of the true character of the syllogism, and the func- 

 tions it performs in philosophy, appears to me impossible ; but which 

 seem to have been either overlooked, or insufficiently adverted to, 

 both by the defenders of the syllogistic theory and by its assailants. 



§ 2. It must be granted that in every syllogism, considered as an 

 argument to prove the conclusion, there is a petitio principii. Wlien 

 we say, 



All men are mortal, 

 Socrates is a man, 



therefore 

 Socrates is mortal ; 



it is unanswerably urged by the adversaries 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 were previously certain of the 



