  The basis for the proposed solution appears in Tarski’s 1966 lecture “What are Logical Notions?” (published posthumously as Tarski 1986a). Here Tarski first makes some remarks about the general nature of his proposal. He says that an answer to a question like the one that gives title to the lecture may take several forms. It may give an account of the prevailing usage of the term “logical notion”, or of the prevailing usage of the term among people who are qualified to use it. It may be a normative proposal, a suggestion that the term be used in a certain way, independently of its actual use. As a third possibility, some other answers 