We have come to a point where we should really discuss the issue of the "unity of the sciences," a central issue of debate, it seems, within the Vienna Circle -- and in the philosophy of science (or the sciences?) to this day. This was an issue central to their philosophizing. When they became a big enough of a deal to organize international conferences, those conferences were to be known as the International Congress for the Unity of Science. At one of the conferences that they gave that title, at Prague in 1934, Alfred Tarski made his appearance on the stage of the history of philosophy. Tarski (portrayed above) gave a lecture on the ideas of truth and falsity in which he tried to resolve the ancient Liars' paradox. His efforts, Edmonds tells us, "caused so much buzz that an additional session was hastily arranged to discuss it further." Tarski's reaction to the Liar Paradox was to suggest a formal language with a hierarchy of truths. At the bottom level...