After a brief summary of the Copernican revolution in the Preface, where it is advanced as the general solution to the problem of metaphysics, Kant leaves it to the reader to extrapolate the exact nature of his philosophical revolution from the specific doctrines that follow in the Critique. Understanding the arguments of the Critique is however made considerably easier by having in advance a fuller idea of the Copernican revolution than can be gleaned from the Preface. Accordingly, this chapter attempts to set out the line of thought underlying Kant’s Copernicanism, in terms that as far as possible avoid the technicalities of his philosophy.
The place to start is with the letter referred to earlier in which Kant acknowledges the failure of the Dissertation, and first states the Critical problem. Kant is talking about a work that he had previously planned with the projected title, ‘The limits of sense and reason’: