Kant’s doctrine of the Fact of Reason is one of the most perplexing aspects of his moral philosophy. The aim of this paper is to defend Kant’s doctrine from the common charge of dogmatism. My defense turns on a previously unexplored analogy to the notion of ‘matters of fact’ popularized by members of the Royal Society in the seventeenth century. In their work, ‘facts’ were beyond doubt, often referring to experimental effects one could witness first hand. While Kant uses the (...) German equivalent in different contexts, I argue that the scientific analogy opens up a new framework for interpreting his strategy of justification in the Critique of Practical Reason. In the final section, I address a few possible objections to my reading, one of which I anticipate coming from Dieter Henrich and Ian Proops, who have argued that Kant’s Fact of Reason is best understood under a legal analogy. (shrink)