This paper develops a novel, functionalist, unified account of the epistemic normativity of reasoning. On this view, epistemic norms drop out of epistemic functions. I argue that practical reasoning serves a prudential function of generating prudentially permissible action, and the epistemic function of generating knowledge of what one ought to do. This picture, if right, goes a long way towards normatively divorcing action and practical reasoning. At the same time, it unifies reasoning epistemically: practical and theoretical reasoning will turn out to be governed by the same epistemic norm—knowledge—in virtue of serving the same epistemic function: generating knowledge of the conclusion.