406 THE SCIENCE OF LOGIC 



knowing that it has three sides : it must be three-sided in order to be a triangle. 

 The fallacy is here committed not in the major, but in the minor ; and it is 

 committed when the major is a merely verbal proposition, a proposition which 

 gives some attribute that belongs to the connotation of its subject-term (M) 

 and in the absence of which from any object (S) this latter would not receive 

 the class name (M) or be admitted into the class. We have no other way of 

 determining the truth of the minor &quot; 5 is M &quot; than by seeing whether it has 

 all the attributes (including P, therefore) the possession of which entitle it to 

 be called M. 



If, then, our major is a mere nominal definition (complete or partial) of 

 our middle term, we commit the fallacy in the minor premiss. If, however, 

 P is a property, or an accident, of M, so that we can know that S is M without 

 knowing whether 6&quot; is P or not, we escape the fallacy. It is sometimes 

 urged that there is no real subsumption, or bringing of S under the condition 

 of a rule, as the first figure demands (168), whenever the major &quot;states a con 

 nexion seen to be necessary between P and M as such . . . [because] in this 

 case no one can judge that S is M without eo ipso recognizing it to be P as 

 well.&quot; * This indeed, is so, and it is in this recognition precisely that the 

 force of the syllogism lies. And no one accuses the syllogism &i petitio principii 

 on this score. But neither can we deny that there is a real subsumption of 

 a case under a rule. It matters not that the rule is here apprehended as em 

 bodied in the case, instead of being applied as an extrinsic and independent 

 rule. This point will come up again in connexion with Demonstration (258). 

 We must next inquire whether the fallacy is committed in the syllogism 

 much more commonly met with in which the major premiss is the converse 

 of a definition, or of part of a definition ; the middle term being, not the subject 

 defined (the res definienda\ but either the whole or part of the definition of 

 the latter ? For example, is this syllogism a petitio principii : 

 All three-sided figures are triangles ; 

 ABC is a three-sided figure ; 

 therefore, ABC is a triangle ? 



It is not a. petitio principii : for the major is the expression of a strict, ab 

 stract, universal judgment, of this general form : &quot; Whatever is conceived to 

 have certain attributes is a thing of a certain nature or kind or class &quot; ; and the 

 minor is discovered or known independently of the conclusion. It must, 

 however, be admitted that this type of syllogism, considered in itself, expresses 

 an inferential step which is exceedingly small in comparison with the mental 

 labour needed to establish the minor premiss. An example of the following 

 kind will illustrate this better : 



All substances which have modes of operation and a mode of existence 

 independent of, and higher than, those of matter, are spiritual substances ; 

 The human soul has such modes of operation and existence ; 

 Therefore, the human soul is a spiritual substance, 



This syllogism is typical of quite an extensive class of arguments 

 familiar to students of philosophy. It would be childish, of course, to put 

 forward such a syllogism as embodying in itself a complete proof of the 

 spirituality of the human soul. It merely gives the one final descending 

 (inferential) step to the desired conclusion, from the commanding position we 



JOSEPH, op. cit., p. 307 with other symbols. 



