LOGIC 303 



If the minor was negative, as, e.g., " All mammals are 

 not furnished with gills," we could not thence conclude 

 that " Some creatures not furnished with gills have warm 

 blood," because the . term " furnished with gills " is dis- 

 tributed in the conclusion but not in the minor premiss, 

 since there may be and are creatures " not furnished 

 with gills " which are not " mammals." This would be 

 an " illicit process of the minor." 



Similarly, there must be a particular conclusion, as 

 otherwise our conclusion would be "All air-breathers 

 have warm blood," in which case the term " air- 

 breathers" would be distributed in the conclusion, but 

 not in the minor premiss, which only says that "All 

 mammals are air-breathers," for all which it may be 

 the case (as it is) that many air-breathers are not 

 mammals. 



The valid moods of the fourth figure are, AAI, AEE, 

 EAO, EIO, IAI. 



In this figure, when the major is affirmative, the minor 

 must be universal ; and when the minor is affirmative, 

 the conclusion must be particular. Thus : 



All apes are mammals. 



All mammals have backbones. 



Therefore some backboned mammals are apes. 



If for the minor, we only had " some mammals have 

 backbones," we could not know from our syllogism 

 whether apes might not be mammals without backbones. 

 In order that a conclusion in this figure should be uni- 

 versal, we require a negative minor. Thus : 



All apes are mammals. 



No mammals breathe by gills. 



Therefore no creatures breathing by gills are apes. 



The division of syllogisms into these figures is not a 



