Based on the material in the Lakatos Archive, this paper reconstructs, and then re-assesses, Lakatos’ epistemological project by placing it in the context of the debate on the role of reason in the history of science, and of the justification of rationality as a normative notion. It is claimed that Lakatos’ most fruitful ideas come from a peculiar philosophical combination of Hegelian historicism and Popperian fallibilism. The original tension, however, cannot be ultimately resolved. As a consequence, the problems that Lakatos (...) has to deal with in his attempt to justify a set of genuinely epistemological canons of scientific rationality that are not reducible to psychology or sociology of knowledge stand as a warning for any normative philosophy of science that takes history at its face value.Author Keywords: Lakatos; History; Method; Rationality. (shrink)