In the Critique of practical reason, Kant invokes the moral law as an underived fact of reason. The aim of this article is to explore the highly debated role of the fact of reason and the nature of this fact, which apparently defies the senses of factuality commonly associated with empirical facts and objective entities. Following David Sussman’s interpretation, I argue that the fact of reason not only marks the abandonment of deduction of the moral law but illustrates that the failure to ground the moral law does not undermine its unconditional authority. Therefore, I claim that rather than signifying a methodological maneuver to get out of the circle that Kant admits to be entrapped, it operates as an imminent, dynamic and an aporetic facticity. This perspective allows seeing its heuristic function for keeping intact the aporia that structures morality and offers a way of coming into the circle of morality.