  Moritz Schlick is primarily remembered as the leader of the Vienna Circle of Logical Positivists, which flourished in the early 1930s. Few philosophers of science today would deny that their views have been influenced – one way or the other – by the positions which emerged from the group of philosophers, mathematicians, and social scientists who gathered in between-wars Vienna. And while it cannot be denied that other Circle members were more prominent and influential over the long-term, none contributed more unity and cohesion to the Vienna group during its brief existence. Indeed, long before 1930, when the Circle’s Manifesto, “Wissenschaftliche Weltauffassung: Der Wiener Kreis”, appeared, Schlick had already made contributions to scientific epistemology which exerted a profound influence on subsequent generations of philosophers (Neurath 1973, Ch. 9). And while other Circle members quite deservedly continue to receive a great deal of attention, there has always been a steady interest in Schlick’s views on a range of issues, for there is much of lasting value to be discovered in them. 