Taking Regulative Principles to Be True

Kant identifies regulative principles of cognition both in the Critique of pure reason and the Critique of the power of judgment. While it seems that assuming a principle regulatively implies forming an attitude such that we take a certain proposition to be true, it is not clear what the nature of this attitude is. In this paper, I approach this problem by focusing on the third Critique and on our assumption of the principle of purposiveness in exercises of the reflective power of judgment directed at extending our empirical cognition of nature. I argue that Kant’s account of this assumption suggests that a new form of taking-to-be-true should be added to his classification in the Canon of the first Critique. I call this form practical opinion, which is a taking-to-be-true that is based on practical considerations, but is below the level of subjective sufficiency. Furthermore, I argue that identifying this form has consequences for the story we tell regarding the evolution of Kant’s notion of belief. While Kant recognizes moral belief as the only type of belief in the third Critique, this does not mean that moral belief is the only form of taking-to-be-true justified on practical grounds.