RATIOCINATION, OR SYLLOGISM. 



227 



three figures, by others into four, according to the 

 position of the middleterm, which may either be the 

 subject in both premisses, the predicate in both, or 

 the subject in one and the predicate in the other. 

 The most common case is that in which the middle- 

 term is the subject of the major premiss and the 

 predicate of the minor. This is reckoned as the first 

 figure. When the middleterm is the predicate in 

 both premisses, the syllogism belongs to the second 

 figure; when it is the subject in both, to the third. 

 In the fourth figure the middleterm is the subject of 

 the minor premiss and the predicate of the major. 

 Those writers who reckon no more than three figures, 

 include this case in the first. 



Each figure is subdivided into modes, according to 

 what are called the quantity and quality of the propo- 

 sitions, that is, according as they are universal or 

 particular, affirmative or negative. The following are 

 examples of all the legitimate modes, that is, all those 

 in which the conclusion correctly follows from the 

 premisses. A is the minor term, C the major, B the 

 middleterm. 



FIRST FIGURE. 



SECOND FIGURE. 



THIRD FIGURE. 



AllBisC NoBisC Some B is C All B is C Some Bis not C No B is C 



All Bis A All Bis A All Bis A Some Bis A All B is A Some B is A 

 therefore therefore therefore therefore therefore therefore 



Some A is C Some A is not C Some A is C Some A is C Some A is not C Some A is not C 



Q 2 



