Philosophy Lexicon of Arguments

General validity: within a calculus a formula that is satisfied by any interpretation (variable assignment with expressions for objects) is valid. See also satisfaction, satisfiability, interpretation.
Author Item Excerpt Meta data

Books on Amazon
HC I 65 ~
Validity / Hughes / Cresswell: No structural property of formulas, no relation between formulas - in contrast: derivability relation between formulas - yet the set of the derived and the valid formulas in a system are identical
HC I 119
Validity / propositional calculus: truth tables are not sufficient for an evaluation of formulas in the p.c. - because we can not assign truth values to individual variables and predicate variables.

Cr I
M. J. Cresswell
Semantical Essays (Possible worlds and their rivals) Dordrecht Boston 1988

M. J. Cresswell
Structured Meanings Cambridge Mass. 1984

> Counter arguments against Cresswell

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Ed. Martin Schulz, access date 2017-05-28