304 ELEMENTS OF SCIENCE 



mere useless trick of art ; for one figure is more useful 

 for some purposes than another, though generally the 

 first figure is the best and most serviceable. It is 

 more convenient, e.g., to say "Our judges are not 

 untrustworthy and corrupt," than it is to say " no 

 men who are untrustworthy and corrupt are judges." 

 If we wish to show how some men will labour 

 earnestly to give just decisions without private reward, 

 we may say : 



Our judges la.bour earnestly to give just decisions. 



Our judges will accept no private reward. 



Therefore some men who will accept no private re- 

 ward will labour earnestly to give just decisions ; 

 which is a syllogism of the third figure and the mood 

 AAI. 



But the utility of the rules concerning syllogisms may 

 perhaps be made more evident by some examples of their 

 violation. Thus : 



The temperate are healthy. 



Some ignorant people are healthy. 



Therefore some ignorant people are temperate. 



This is a syllogism of the second figure and the mood 

 All, but there is no such valid mood, and in fact it is 

 but a syllogism in appearance, for the middle term is 

 not distributed in either premiss. It does not declare 

 that all healthy people are either temperate or igno- 

 rant, and so, for all it says, there may be some (as 

 in fact there are) who are neither the one nor the 

 other. Again : 



Men of science are learned men. 

 Men of science are long-lived men. 

 Therefore all long-lived men are learned men. 



