Oakeshott's tradition-centric account of rational-ity in Rationalism in Politics is usually considered in its capac-ity as a major part of his political philosophy, forming as it does so the constructive part of his critique of 'rationalism'. The present article, in contrast, considers it as a methodologi-cal notion, since it forms too the core of a theory of rational explanation that is at the same time a theory of social expla-nation. In this, Oakeshott argues that the sociologist or politi-cal scientist explains human behaviour by identifying the reasons for her subjects doing what they did, with the right kind of reasons being those that concern not any expressed motivations on the original agents' part, but how they could only have acted relative to a certain 'tradition'. Seeking to both expound and analyse Oakeshott's theory, this article high-lights how it involves a not uncontroversial 'externalist' con-ception of practical reason that, nonetheless, is open to sympathetic reconstruction. Even so, the imperialistic preten-sions of Oakeshott's argument--and in particular, his claim that his tradition-centric conception of rational explanation is fundamentally superior to its more orthodox 'instrumentalist' rival--is found questionable, the sheer variety of his own examples misleading him about his theory's real scope.