 The collapse of the logical empiricist program was in part facilitated by a historical turn in the philosophy of science in the 1960s, associated with authors such as Kuhn, Feyerabend, and Hanson. Kuhn’s highly influential work, The Structure of Scientific Revolutions, played a significant role in establishing a lasting interest in a form of historicism about scientific knowledge, particularly among those interested in the nature of scientific practice. An underlying principle of the historical turn was to take the history of science and its practice seriously by furnishing descriptions of scientific knowledge in situ. Kuhn argued that the fruits of such history illuminate a recurring pattern: periods of so-called normal science, often fairly long in duration (consider, for example, the periods dominated by classical physics, or relativistic physics), punctuated by revolutions which lead scientific communities from one period of normal science into another. The implications for realism on this picture derive from Kuhn’s characterization of knowledge on either side of a revolutionary divide. Two different periods of normal science, he said, are “incommensurable” with one another, in such a way as to render the world importantly different after a revolution (the phenomenon of “world change”). (Among the many detailed studies of these topics, see Horwich 1993; Hoyningen-Huene 1993; Sankey 1994; and Bird 2000.)