This book concerns the first half of Kant's Critique of Pure Reason; a treatment of the second, half, under the title Kant's Dialectic, is in preparation. The present work ought to be readable by those who know nothing of the Critique. It is in some sense an ‘introduction’, but a selective one which does not expound all the Critique's most important themes. What I hope it provides is one fairly unified way of viewing a good part of Kant's achievement.

To this end I have freely criticized, clarified, interpolated and revised. I make no apology for adopting this approach, for fighting Kant tooth and nail. Had I instead indulged him, or even given him the benefit of every doubt, I could neither have learned from his opaque masterpiece nor reported intelligibly on what it says.

Like all great pioneering works in philosophy, the Critique is full of mistakes and confusions. It is a misunderstanding to think that a supreme philosopher cannot have erred badly and often: the Critique still has much to teach us, but it is wrong on nearly every page.

I have no feelings about the man Immanuel Kant; and in my exploration of his work I have no room for notions like those of charity, sympathy, deference, or hostility.

Because I aim to be clear yet fairly brief, I devote little space to acknowledging debts and pursuing disagreements with previous writers on the Critique.