Psychology Dictionary of ArgumentsHome
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| 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._____________Annotation: The above characterizations of concepts are neither definitions nor exhausting presentations of problems related to them. Instead, they are intended to give a short introduction to the contributions below. – Lexicon of Arguments. | |||
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David Wiggins on Extensionality - Dictionary of Arguments
II 306 Inference rule/lambda operator/Grandy/Wiggins: Rl: if l-((xi1 ... xin) (A ↔ B)) and when ---- (λxi1 ... λxin) [A] ----, then ---- (λxi1 ... λxin) [B] ----. Necessary: necessary for predicates. >Operators. II 307 Problems: extensionality: Expressions in a Necessary-sentence are open to substitution of identical and existential generalization but there is a problem: Predicates: E.g. if something was the only ring of Gyges, we do not want to conclude that it was essentially magical. >Substitution, >Existential Generalization, >Identity. Solution: relational view of predication: > participation: >Frege: to fall under a concept. If (λx1) [φX1] and (λx1) [ψx1] do not designate the same property, but are coextensive, then in extensional contexts one will include(entail) the other. Which is maintained when the operator (Necessary) is prefixed. - Whereby the theory does not decide whether it is the same property or not._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. Translations: Dictionary of Arguments The note [Concept/Author], [Author1]Vs[Author2] or [Author]Vs[term] resp. "problem:"/"solution:", "old:"/"new:" and "thesis:" is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition. |
Wiggins I D. Wiggins Essays on Identity and Substance Oxford 2016 Wiggins II David Wiggins "The De Re ’Must’: A Note on the Logical Form of Essentialist Claims" In Truth and Meaning, G. Evans/J. McDowell, Oxford 1976 |
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> Counter arguments against Wiggins
> Counter arguments in relation to Extensionality
