convention T a criterion of material adequacy (of proposed truth definitions) discovered, formally articulated, adopted, and so named by Tarski in connection with his 1929 definition of the concept of truth in a formalized language. Convention T is one of the most important of several independent proposals Tarski made concerning philosophically sound and logically precise treatment of the concept of truth. Various of these proposals have been criticized, but convention T has remained virtually unchallenged and is regarded almost as an axiom of analytic philosophy. To say that a proposed definition of an established concept is materially adequate is to say that it is ‘neither too broad nor too narrow,’ i.e., that the concept it characterizes is coextensive with the established concept. Since, as Tarski emphasized, for many formalized languages there are no criteria of truth, it would seem that there can be no general criterion of material adequacy of truth definitions. But Tarski brilliantly finessed this obstacle by discovering a specification that is fulfilled by the established correspondence concept of truth and that has the further property that any two concepts fulfilling it are necessarily coextensive. Basically, convention T requires that to be materially adequate a proposed truth definition must imply all of the infinitely many relevant Tarskian biconditionals; e.g., the sentence ‘Some perfect number is odd’ is true if and only if some perfect number is odd. Loosely speaking, a Tarskian biconditional for English is a sentence obtained from the form ‘The sentence ——— is true if and only if ——’ by filling the right blank with a sentence and filling the left blank with a name of the sentence. Tarski called these biconditionals ‘equivalences of the form T’ and referred to the form as a ‘scheme.’ Later writers also refer to the form as ‘schema T.’ See also FORMAL SEMAN- TICS , GÖDEL’ S INCOMPLETENESS THEOREMS , MATERIAL ADEQUACY, SATISFACTION , TARSKI , TRUT. J.Cor.