 Laudan opened Progress and Its Problems (1977) with the claim that providing an adequate model of rationality is the primary business of the philosopher of science but that no extant methodologies fit actual science. In this book his idea of good fit was fit with a selection of intuitively strong historical instances that any adequate theory must explain. (Laudan 1984 and 1996: ch. 7, later rejected the intuitionistic elements that gave normative punch to this model.) His response to the rationality question was to propose a thoroughgoing, explicitly pragmatic, problem-solving account of science. Problem-solving had been an important element in previous accounts, notably those of Kuhn and Popper, but Laudan reversed the usual account of scientific progress as a temporal succession of atemporal rational decisions.  Instead of defining progress in terms of rationality, we should define rationality in terms of progress. We cannot measure progress in terms of approach to an unknowable, final, metaphysical truth, but we do have reliable markers of progress in terms of numbers and relative importance of both empirical and conceptual problems solved by long-term “research traditions”. Just as Lakatos’s research programs were a compromise between Popper and Kuhn, we can read Laudan’s “research traditions” as incorporating elements of his major historicist predecessors, while departing sharply from other tenets of their work.