In 1929 Moritz Schlick and those scholars he had brought together came to realize that they had given rise to something entirely new, so the text of the Vienna Circle Manifesto has it. What was novel was the conception of the world, henceforth scientific. Or as we may put it otherwise: a discipline had been established, the philosophy of science, that is a reflection on science no longer subordinate to traditional theory of knowledge and metaphysics. The text goes on to explain why such a conception arose geographically where it did: "That Vienna was specially suitable ground for [the development of the spirit of a scientific conception of the world] is historically understandable" ¹. The Vienna Circle Manifesto proceeds to enumerate the multifarious intellectual movements that were brought together at the beginning of the 20^th century in the city of Vienna. Is it irrelevant or untimely to emphasize this cosmopolitan spirit? I believe, on the contrary, that cosmopolitanism provides both a lesson about philosophical creativity and a key for understanding the vitality of Viennese philosophy: the achievements of the Vienna Circle were the result of an exceptional open-mindedness on the part of its members.