140 EEASONING. 



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 ui'ged by the adversaries of the syllogistic theory, that 

 the proposition, Socrates is mortal, is presupposed in the more general as- 

 sumption. All men are mortal : that we can not be assured of the mortali- 

 ty of all men, unless we are already certain of the mortality of every indi- 

 vidual man : that if it be still doubtful whether Socrates, or any other in- 

 dividual we choose to name, be mortal or not, the same degree of uncer- 

 tainty must hang over the assertion. All men are mortal : that the general 

 principle, instead of being given as evidence of the particular case, can not 

 itself be taken for true without exception, until every shadow of doubt 

 which could affect any case comprised with it, is dispelled by evidence 

 aliundh ; 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 can not infer any particulars, but 

 those which the principle itself assumes as known. 



This doctrine appears to me irrefragable ; and if logicians, though una- 

 ble to dispute it, have usually exhibited a strong disposition to explain it 

 away, this was not because they could discover any flaw in the argument 

 itself, but because the contrary opinion seemed to rest on arguments equal- 

 ly indisputable. In the syllogism last referred to, for example, or in any of 

 those which we previously constructed, is it not evident that the conclu- 

 sion may, to the person to whom the syllogism is presented, be actually 

 and hona fide a new truth? Is it not matter of daily experience that 

 truths previously unthought of, facts which have not been, and can not be, 

 directly observed, are arrived at by way of general reasoning? We be- 

 lieve that the Duke of Wellington is mortal. We do not know this by di- 

 rect observation, so long as he is not yet dead. If we were asked how, 

 this being the case, we know the duke to be mortal, we should probably 

 answer. Because all men are so. Here, therefore, we arrive at the knowl- 

 edge of a truth not (as yet) susceptible of observation, by a reasoning 

 which admits of being exhibited in the following syllogism: 



All men are mortal, 

 The Duke of Wellington is a man, 



therefore 

 The Duke of Wellington is mortal. 



And since a large portion of our knowledge is thus acquired, logicians 

 have persisted in representing the syllogism as a process of inference or 

 proof ; though none of them has cleared up the difficulty which arises from 

 the inconsistency between that assertion, and the principle, that if there be 

 any thing in the conclusion which was not already asserted in the premi- 

 ses, the argument is vicious. For it is impossible to attach any serious 

 scientific value to such a mere salvo, as the distinction drawn between be- 

 ing involved hy implication in the premises, and being directly asserted in 

 them. When Archbishop Whately says* that the object of reasoning is 

 " merely to expand and unfold the assertions wrapped up, as it were, and 



* Logic, p. 239 (9th ed.). 



