|Extensionality, philosophy: (also extensionality principle, extensionality thesis) an attempt to make the language distinct by taking complete sets of denoted objects as the meaning of the referring words. See also extensions, intensions, extensional language, ambiguity, propositional attitudes.|
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Extensional/Intensional/Extensionality/(s): 2nd order properties: non-extensional - "of" intensional E.g. "the redness-of-x" - Vs 2nd order logic - Field: e.g. rename real numbers as new properties of a certain kind.
Realism, Mathematics and Modality Oxford New York 1989
Truth and the Absence of Fact Oxford New York 2001
Science without numbers Princeton New Jersey 1980