3S2 ANTIENT METAPHYSICS. Book V. 



As we have very many ideas of very many things, it is impof- 

 fible but that our ideas muft have fome relation one to another ; and 

 it is this relation which makes the truth or faH'ehood of any propoii- 

 tion. But what is this relation ? if we can find out this, then we 

 fliiiU know what truth, and its oppofite, faljehood, is. All that Mr 

 Locke has find upon the fubjedt is, that truth confifts in the percep- 

 tion of the agreement or difagreement ot our ideas, meaning, 1 fup- 

 pofe, by the agreement, an affirmative propofition, and, by the difa- 

 gree^ti^eut, a negative propofition. But we are very little the wlier for 

 knayvii,:Vg this, unlefs we know, at the fame time, what kind of agree- 

 ment it is that makes a true affirmative propofition, and what kind 

 of difagreement a true negative ; for it will prefently appear, that it 

 is not every kind of agreement or difagreement that makes a true 

 propofition. 



And, in the jirjl place, in every true affirmative propofition, and, 

 indeed, in every propofition, one of the terms, as we have feen, muft 

 be the praedlcate, the other, ihQ/ubjeSi. Here, therefore, is ib far a 

 difagreement of the ideas in a true affirmative propofition. The two 

 terms of the propofition may, indeed, be the fame, making what is 

 called an identic propofition ; but that is truly no propofition at all, be- 

 ing only a repetition of the fame thing ; as, when we fay, * A man 

 * is a man,' ' An animal is an animal,' ' A triangle is a triangle.' 

 Nor will it alter the cafe, if w^e exprefs the meaning of one of 

 the terms by feveral words, as, when we fay, that man is a ra- 

 tional animal, capable of intelled: and fcience ; or, that a triangle 

 is a figure bounded by three lines ; for that is only explaining the 

 meaning of the word, which is a definition^ not a propofition *. 



Thofe, 



• The difference betwixt a definition and a propofition is, that the definition only 

 tells us what the thing, exprefled by the word, is, without afTirming or denying any 

 thing of it ; whereas, a propofition affirms or denies fomething of it. ^tt Arijiotl, 

 Analytic. Pojier. lib. i. cap. lo. in fine. 



