chapter  5
Intensional versus extensional logic and semantics
Pages 44

If in logic we must ultimately have to do with objects and their properties, then it is not surprising to nd some logicians and philosophers choosing or being intuitively compelled to begin with objects, making objects logically more basic than properties as the most basic, and others beginning instead with properties, for whatever contrary reasons or impulses, making properties logically more basic than objects. ose who begin with objects, and thus necessarily with entities or existent objects, are extensionalists in logic and semantics; those who begin with properties and thus unavoidably both with instantiated and uninstantiated combinations of properties, or, in any case, with logically possible properties in the abstract, are intensionalists.