 From a historical standpoint, the positivist model collapsed the distinction between synchronic and diachronic reduction, that is, between reductive models of the structure and the evolution, or succession, of scientific theories. By contrast, historicism, as embraced by Kuhn and Feyerabend, drove a wedge between the two dimensions and rejected the linear model of scientific change in terms of accumulation and replacement. For Kuhn, replacement becomes partly continuous, partly non-cumulative change in which one world—or, less literally, one world-picture, one paradigm—replaces another (after a revolutionary episode of crisis and proliferation of alternative contenders) (Kuhn 1962). This image constitutes a form of pluralism, and, like the reductionism it is meant to replace, it can be either synchronic or diachronic. Here is where Kuhn and Feyerabend parted ways. For Kuhn synchronic pluralism only describes the situation of crisis and revolution between paradigms. For Feyerabend history is less monistic, and pluralism is and should remain a synchronic and diachronic feature of science and culture (Feyerabend, here, thought science and society inseparable, and followed Mill’s philosophy of liberal individualism and democracy).