Summary |
Alfred Tarski's theory of truth, also called the semantic theory of truth, holds that truth is a property of sentences (that is, that sentences are truth bearers). It is two-part, consisting of a minimal and a substantial theory. The minimal theory is not itself a theory about the nature of truth, but rather a theory about theories of truth. It provides adequacy conditions: effectively, a filter for candidate theories of truth by which to verify their acceptability. There are two conditions: formal correctness and material adequacy. Formal correctness means that an acceptable theory of truth must not be circular or lead to paradoxes. Material adequacy means that an acceptable theory of truth must entail all instances of Tarski's T-schema. Namely, the sentence S is true if and only if p, where S is the sentence in the object language and p is the sentence in the meta-language. Tarski's substantial theory of truth, which satisfies his own adequacy conditions, defines truth in terms of 'satisfaction' (Tarski seems to treat the concept of satisfaction as a primitive, undefinable concept in his semantic theory). For example, the monadic predication 'a is F' is true if and only if a satisfies 'is F'. |