What Kind of Possibility Allows for Kant's History of Pure Reason

Chapter 4 of Kant's "Transcendental Doctrine of Method" in the First Critique has the title "The History of Pure Reason". Hence, a history of pure reason exists and, hence, is possible. Yet, if pure reason is to be understood generally as the sum of a priori structures which make possible our thinking, understanding, judgement and sensibility (and this is how Kant uses the expression 'pure reason'), then a history of this pure reason cannot take place. This is because a history of pure reason would need to make sense of it topic without relying on the conditions which make possible thinking, judging, understanding, perceiving. In this paper I aim to explore the kind of possibility, if any, which would allow Kant to provide a history of pure reason. Such an account would also have implications for how we understand political change at a deep level - not only simply in terms of changing a state of affairs to move closer to the norms of a rightful condition, but in terms of changing our view of how we make sense of the rightful condition.