296 ELEMENTS OF SCIENCE 



" Man " is the middle term, because it exists in both 

 premisses and nob in the conclusion. 



The " major premiss " compares the major term with 

 the middle term. 



The minor premiss compares the minor term with the 

 middle term. 



The conclusion compares together the major and minor 

 terms. 



The validity of the whole process reposes upon the 

 truth that, whatever can be affirmed or denied of a class 

 of things (i.e., of every member of it considered as a 

 whole mass) can be affirmed or denied of each individual 

 member which constitutes it. 



The truth of this in each case is signified by the word 

 " therefore" expressed or understood. 



There are ten Rules with respect to syllogisms. 



(i) and (2) affirm that (as before said) there must be 

 neither more nor less than three terms and three 

 propositions. 



(3) The middle term must be distributed at least 

 once. 



(4) No term must be distributed in the conclusion 

 which was not so in the premisses. 



(5) There must not be two negative premisses. 



(6) If there is a negative conclusion there must be a 

 negative premiss. 



(7) If there is a negative premiss there must be a 

 negative conclusion. 



(8) There must not be two particular premisses. 



(9) If there is a particular conclusion there need not 

 be a particular premiss. 



(10) If there is a particular premiss there must be a 

 particular conclusion. 



