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5. Theory of Logic / I. Semantics of Logic / 6. Intensionalism

[semantic system built on reference to properties]

4 ideas
Frege is intensionalist about reference, as it is determined by sense; identity of objects comes first [Frege, by Jacquette]
     Full Idea: Intensionalism of reference is owing to Frege (in his otherwise extensionalist philosophy of language). Sense determines reference, so intension determines extension. An object must first satisfy identity requirements, and is thus in a set.
     From: report of Gottlob Frege (On Sense and Reference [1892]) by Dale Jacquette - Intro to 'Philosophy of Logic' §4
     A reaction: The notion that identity of objects comes first sounds right - you can't just take objects as basic - they have to be individuated in order to be discussed.
Frege moved from extensional to intensional semantics when he added the idea of 'sense' [Frege, by Sawyer]
     Full Idea: Frege moved from an extensional semantic theory (that countenances only linguistic expressions and their referents) to an intensional theory that invokes in addition a notion of sense.
     From: report of Gottlob Frege (On Sense and Reference [1892]) by Sarah Sawyer - Empty Names 2
     A reaction: This was because of Frege's famous 'puzzles', such as the morning/evening star. Quine loudly proclaimed himself an 'extensionalist', implying that he had extensional solutions for Frege's Puzzles.
Intension is not meaning, as 'cube' and 'square-faced polyhedron' are intensionally the same [Putnam]
     Full Idea: Intension cannot be identified with meaning. ..'Cube' and 'regular polyhedron with six square faces' are logically equivalent predicates. The intension is the same (the function giving the cubes in any possible world) but there is a difference of meaning.
     From: Hilary Putnam (Reason, Truth and History [1981], Ch.2)
Intensionalists say meaning is determined by the possession of properties [Jacquette]
     Full Idea: According to intensionalist semantics the meaning of a proposition is determined by the properties an object possesses.
     From: Dale Jacquette (Intro to 'Philosophy of Logic' [2002], §4)
     A reaction: This sounds good to me. Extensionalist don't seem to care what sets they put things in, but if property possession comes first, then things will fall into their own sets without any help for us. We can add silly sets afterwards, if we fancy.