"Metaphysics has been often revisionary, and less often descriptive. Descriptive metaphysics is content to describe the actual structure of our thought about the world, revisionary metaphysics is concerned to produce a better structure. The productions of revisionary metaphysics remain permanently interesting, and not only as key episodes in the history of thought. Because of their articulation, and the intensity of their partial vision, the best of them are both intrinsically admirable and of enduring philosophical utility. But this last merit can be ascribed to them only because there is another kind of metaphysics which needs no justification at all beyond that of inquiry in general. Revisionary metaphysics is at the service of descriptive metaphysics. Perhaps no actual metaphysician has ever been, both in intention and effect, wholly the one thing or the other. But we can distinguish broadly: Descartes, Leibniz, Berkeley are revisionary, Aristotle and Kant descriptive. Hume, the ironist of philosophy, is more difficult to place. He appears now under one aspect, now under another."
-- P. F. Strawson, Individuals.