PROPOSITIONS. 47 



considered such propositions purely accidental, and came 

 to the extraordinary conclusion, that ' Singulars cannot be 

 predicated of other terms/ 



Propositions may also express the identity of extensive 

 groups of objects taken collectively or in one connected 

 whole ; as when we say 



* The Queen, Lords, and Commons = The Legislature 



of the United Kingdom/ 



When Blackstone asserts, * The only true and natural 

 foundation of society are the wants and fears of indi- 

 viduals/ we must interpret him as meaning that the whole 

 of the wants and fears of individuals in the aggregate form 

 the foundation of society. But many propositions which 

 might seem to be collective are but groups of singular pro- 

 positions or identities. When we say ' Potassium andsodium 

 are the metallic bases of potash and soda/ we obviously 

 mean 



Potassium = Metallic base of potash ; 



Sodium = Metallic base of soda. 



It is the work of grammatical analysis to separate the 

 various propositions often combined in a single sentence. 

 Logic cannot be properly required to interpret the forms 

 and devices of language, but to treat the meaning or 

 information when clearly exhibited. 



Partial Identities. 



However numerous and important may be propositions 

 expressing simple identity of one term or class with 

 another, there is an almost equally important kind of 

 proposition which I propose to call a partial identity. 

 When we say that ' All mammalia are vertebrata/ we do 

 not mean that mammalian animals are identical with 

 vertebrate animals, but only that the mammalian form a 

 part of the class vertebrata. Such a proposition was 

 regarded in the old logic as asserting the inclusion of one 



