|Convention T: is part of the theory of truth by A. Tarski, which contains the demand that in the so-called W-schema Tr(x) <> p with the example instance "snow is white" is true, if and only if snow is white, the right side of the equivalence, is so that p is a translation of the expression x on the left side into the meta-language of the theory, whereby the meta-language must be inter alia rich enough to contain the predicate "is true". From this follows a derivability of arbitrarily many other instances of the schema.|
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|Berka I 476f
Def Convention T/original place/Tarski: We will call a true definition of truth a formally correct definition of the symbol "Wr" ("class of all true statements") formulated in terms of the meta language MS if it leads to the following conclusions:
a) all sentences that are gained from the expression "x e Wr iff "p" by inserting for the symbol x a structurally descriptive name of an arbitrary statement in the considered language ((s) of the object language) and for the symbol "p" the expression that is the translation of this statement in the meta language;
b) the statement "for an arbitrary x - if x e Wr, then x e AS" (or in other words ""Wr < AS").
New in relation to Chapter 1: introduction of the meta language.
Logic, Semantics, Metamathematics: Papers from 1923-38 Indianapolis 1983
K. Berka/L. Kreiser
Logik Texte Berlin 1983