RATIOCINATION, OR SYLLOGISM. 



185 



the minor. This is reckoned as the first figure. When the 

 middleterm is the predicate in both premises, 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 premise and the predicate of the major. Those 

 writers who reckon no more than three figures, include this case 

 in the first 



Each figure is divided into moods, according to what are 

 called the quantity and quality of the propositions, that is, ac- 

 cording as they are universal or particular, affirmative or nega- 

 tive. The following are examples of all the legitimate moods, 

 that is, all those in which the conclusion correctly follows from 

 the premises. A is the minor term, C the major, B the middle- 



No B is 

 Some A is B 



therefore 

 Some A is not C 



All C is B 

 Some A is not B 

 therefore 



term. 



FIRST FIGURE. 



All B is No B is C All B is C 



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



therefore therefore therefore 



All A is No A is C Some A is C 



SECOND FIGURE. 



No C is B All C is B No C is B 

 All A is B No A is B Some A is B 

 therefore therefore therefore 

 No A is C No A is C Some A is not C Some A is not C 



THIRD FIGURE. 



All B is C No B is C Some B is C All B is C Some B is not C No B is C 



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



FOURTH FIGURE. 



AllCisB AllCisB SomeCisB No C is B NoCisB 

 All B is A No B is A All B is A All B is A Some B is A 



therefore therefore therefore therefore therefore 



SomeAisC Some A is not C Some A is C SomeAisnotC SomeAisnotC 



In these exemplars, or blank forms for making syllogisms, 

 no place is assigned to singular propositions ; not, of course, 

 because such propositions are not used in ratiocination, but 

 because, their predicate being affirmed or denied of the 

 whole of the subject, they are ranked, for the purposes of the 

 syllogism, with universal propositions. Thus, these two syllo- 

 gisms 



