Kant’s writings on political philosophy do not clearly and conclusively determine its place and significance in his critical philosophy. To address this issue, most accounts of Kant’s political philosophy concentrate on his explicitly political texts that cluster around the second and third Critiques. Although many of these interpretations illuminate different aspects of Kant’s political philosophy, they are silent with regard to a concept of publicness that is implied in the first Critique. This article suggests that Kant’s critical method of metaphysics implies a disciplinary conception of publicness, which is foundational for his political philosophy. It demonstrates how this conception of publicness can be found in the Doctrine of Method of the first Critique, more specifically, in Kant’s argument that all acts of reason must be subjected to the discipline of pure reason.