The great change at the turn of the twentieth century, in philosophy in general and in logic in particular, was the transition from the view of logic as the logic of science – of proven informative truths – to the view of logic as the logic of formal languages – of correct speech, of following grammar. In artificial systems, the rules of grammar are worded in advance; proper formulas – strings of words – are well-formed (wff), and then they are true or false (Frege), within the language to which they belong (Tarski). For natural languages this holds only partially; they are given and their grammars are only partially given; and so is synonymy within them (Tarski; Quine). This was progress, as it led from the old concern with concepts to the new concern with statements and contexts. Yet the progress caused some regress: the traditional center of logic with inferences shifted to a concern with tautologies. This led analytic philosophy away from formal logic. It returned to logic, only partly under the influence of Wittgenstein, since his later philosophy was concerned with fragments of language and neither with language as such nor with its global problems, whereas the concern with logic is global by definition. Wittgenstein expressed concern for this – repeatedly and on diverse occasions.