Against the standard interpretation of Kant's ‘Copernican revolution’ as the prioritization of epistemology over ontology, I argue in this paper that his critique of traditional metaphysics must be seen as a farewell to the perfectionism on which early modern rationalist ontology and epistemology are built. However, Kant does not simply replace ‘perfection’ with another fundamental concept of normativity. More radically, Kant realizes that it is not simply ideas but only the relation of ideas that can be subject to norms, and (...) thus he shifts the focus from the reality of ideas to the validity of judgments. Section 1 of this paper clarifies the pre-Kantian role of the concept of perfection and examines Kant's critical response to that concept. Section 2 identifies Kant's point of departure from the Cartesian ‘way of ideas.’ Section 3 explains the key problem of his novel account of epistemic normativity. I conclude that Kant's anti-perfectionism must be seen as the driving force behind his ‘Copernican revolution’ in order to fully appreciate his mature account of epistemic normativity. (shrink)