It is a truism that we ought to be rational. Despite this (or because of it), it has become popular to think that it is not the case that we ought to be rational. In this paper I argue for a view about rationality—the view that what one is rationally required to do is determined by the normative reasons one possesses—by showing that it can vindicate that one ought to be rational. I do this by showing that it is independently very plausible that what one ought to do is determined by the normative reasons one possesses. Thus, the paper also makes a contribution tos the debate about the nature of our obligations.