There are many important questions still unresolved concerning the philosophical and personal relations between Ludwig Wittgenstein and the members of the Vienna Circle, and there are also current views on those relationships that do not bear closer scrutiny. For instance, in the last few decades, it has been fashionable to emphasize the differences between the philosophical views of Ludwig Wittgenstein and those of the members of the Vienna Circle. It has even been suggested that the members of the Vienna Circle misunderstood or otherwise misinterpreted Wittgenstein's Tractatus. For instance, in a recent book we find the statement that the "members of the so-called Vienna Circle ... had founded logical positivism partly on a deep misunderstanding of the Tractatus".¹