That something is profoundly wrong with the way in which enlightenment has unfolded has widely been taken to be the main thrust of Dialectic of Enlightenment. In this paper, I propose to defend that to understand the book and shed light on some of its most puzzling features, one should rather take Horkheimer and Adorno's critical claim at face value: through their criticism they contend to have prepared a positive concept of enlightenment. How this can be so is the question I want to answer. I defend that what we need is an account that works out the conceptual grounds on which their critique can operate. The focus of my attempt will consist in understanding (1) what they mean when they assert that rationality is intrinsically social and (2) how they conceive of rationality as being reflective at its core.