Beginning with Plato’s Republic, there is a long philosophical tradition of describing the mind as analogous to a state. The idea is that the lower cognitive faculties are governed and held in check by the higher faculties of which reason is the sovereign. This catalogue of analogies between reason and state is no doubt part of the tradition which Kant intends to evoke in the Critique of Pure Reason. Kant’s legal metaphors are in this sense not historically unique or innovative and he makes no such claim. What is different about Kant’s legal metaphors is that the lawfulness of reason provides the constitutive structure of experience. Because of this focus on lawfulness, the legal metaphors prevail over the political ones.
The legal metaphors give a tangible comprehension of reason. As symbolic hypotyposes, they give us an idea of what reason might look like.