The Critique of Pure Reason

Can we know anything about the world independently of experience? Kant's answer turns philosophy around: space, time and basic concepts such as cause are not learned from the world but are the forms through which our minds organise every experience. We can therefore know the world as it appears to us with certainty, but never things as they are in themselves, and reason falls into contradictions when it tries.

Published in 1781 and revised in 1787, the Critique is one of the most important and most difficult books of philosophy. Kant (see his life) was answering David Hume's Enquiry. New readers might begin with a guide, or with Kant's shorter Perpetual Peace.

Immanuel Kant (1724–1804) spent his whole life in and around Königsberg in East Prussia, where he taught at the university for decades and kept such regular habits that, according to legend, neighbours set their clocks by his afternoon walk. He was fifty-seven when he published the Critique of Pure Reason, which changed philosophy.

Answering David Hume, who he said woke him from his dogmatic slumber, Kant asked what we can know, what we ought to do and what we may hope, and gave the world the categorical imperative and the motto of the Enlightenment, 'Dare to know'. His short essay Perpetual Peace is his most accessible work.