truth definition

A definition of the predicate ‘…is true’ for a language that satisfies convention T, the material adequacy condition laid down by Tarski. The definition of truth provided by Tarski's methods is a recursive definition, enabling us to say for each sentence what it is that its truth consists in, but giving no verbal definition of truth itself. The recursive definition of the truth predicate of a language is always provided in a metalanguage; Tarski is thus committed to a hierarchy of languages, each with its associated, but different, truth-predicate. Whilst this enables the approach to avoid the contradictions of the Liar family, it conflicts with the ideal that a language should be able to say everything that there is to say, and other approaches have become increasingly important.