Abstract
the ready availability of wittgenstein's previously unpublished writings from his so-called middle period of 1929 to 1936 has greatly enriched our understanding of the development of his thought. For obvious reasons, however, it has had little effect on the interpretation of Wittgenstein's contemporaries. At the time, few, even amongst those who had by then taken note of the Tractatus Logico-Philosophicus, were apprised of the new avenues Wittgenstein's thought had begun to take. One such rare exception was Moritz Schlick, the nominal head of the Vienna Circle and an eminent philosopher of science. Even before Wittgenstein's return to...