Kant on the Unity of Theoretical and Practical Reason

Abstract

is ONE AND THE SAME, whether it is applied theoretically, to the realm of what is, or practically, to the realm of what ought to be.His view that theoretical and practical reason are two different applications of "one and the same reason" 1 is known as the doctrine of the unity of reason.Yet Kant himself seems to contradict this doctrine in two ways.In some passages in the very same works in which he asserts the unity of reason, he also states that this unity has yet to be demonstrated.According to the Foundations of the Metaphysics of Morals, demonstrating the unity of practical and theoretical reason is one of the tasks of a critique of practical reason. 2 In the Critique of Practical Reason, Kant further postpones this task by saying that we can expect this unity only to be demonstrated "some day." 3 Moreover, Kant also claims that theoretical and practical reason are "united" through the idea of the purposiveness of nature, suggesting an original disunity. 4Thus, it seems that Kant defends three