Extensionality and Propositional Identity

A. N. Prior

in Objects of Thought

Published in print April 1971 | ISBN: 9780198243540
Published online October 2011 | e-ISBN: 9780191680694 | DOI:
Extensionality and Propositional Identity

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This chapter focuses on a particular error: the treatment of truth-values as the denotata of sentences, and the confusion of propositional identity with material equivalence. It begins with a discussion of the fallacy of extensionalism. It then discusses Frege on functions and values, equivalence and propositional identity, the ‘quotation-marks’ objection, and the parallel between truth-values and classes.

Keywords: extensionalism; Frege; function values; propositional identity; truth-values

Chapter.  6884 words. 

Subjects: Philosophy of Mathematics and Logic

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