That Karl Kraus influenced Wittgenstein’s philosophical “work of clarification,” as he called it, is beyond question: “So Boltzmann, Hertz, Schopenhauer, Frege, Russell, Kraus, Loos, Weininger, Spengler, Sraffa have influenced me” (C+V, 19), wrote Wittgenstein in 1931. How he did so is completely unclear. We know from Brian McGuinness’s magisterial biography of the young Wittgenstein what must have interested him personally in Kraus: “It is obvious enough what he liked about Kraus…the style and the man. The satire, the exposure of shabby moral attitudes, the scorn were conveyed by a use and criticism of language which was more ethical than literary. Ludwig all his life had Kraus’s habit of taking his opponent at his word and reading from a single ill-judged sentence a whole moral character.” 1 Moreover, the fact that Wittgenstein ceased to be interested in Kraus in the mid-twenties when, on the philosopher’s view, the satirist’s work ceased to be funny 2 gives us a further clue concerning what drew Wittgenstein to Kraus. However, that information is more about Wittgenstein the man than his philosophy. At best it provides us with clues to the impact Kraus had on his philosophical “work of clarification.” The latter is the important issue. So the present story, unlike the one Toulmin and I told a quarter of a century ago, will bear principally on Wittgenstein’s later philosophy (as it turns out much of what we attributed to Wittgenstein’s “Krausian” background then is more directly traceable to Otto Weininger, although the two streams are anything but incompatible). Lack of documentary evidence as well as the subtle, indirect character of Kraus’s influence upon Wittgenstein, then, implies that our investigation of Kraus’s influence upon Wittgenstein necessarily has a conjectural 186character. However, it should be emphasized that this is nothing strange: we know nothing at all about the decisive role that Piero Sraffa played in stimulating the author of the Philosophical Investigations to his most consequential thoughts (PI, Preface).