INTRODUCTION ‘natural philosophy’—the removal of Aristotle’s dead hand was a great boon Aristotle’s physics was hopelessly erroneous, and had been shown to be so as early as the sixth century of our era; the deference that was paid to it during the Middle Ages was a great brake on scientiWc progress But for philosophy in the narrow sense—philosophy as it is now practised as a distinct discipline in universities—there were losses as well as gains resulting from the abandonment of Aristotle Our period is dominated by two philosophical giants, one at its beginning and one at its end, Descartes and Kant Descartes was a standardbearer for the rebellion against Aristotle In metaphysics he rejected the notions of potentiality and actuality, and in philosophical psychology he substituted consciousness for rationality as the mark of the mental Hobbes and Locke founded a school of British empiricism in reaction to Cartesian rationalism, but the assumptions they shared with Descartes were more important than the issues that separated them It took the genius of Kant to bring together, in the philosophy of human understanding, the diVerent contributions of the senses and the intellect that had been divided and distorted by both empiricists and rationalists The hallmark of Cartesian dualism was the separation between mind and matter, conceived as the separation of consciousness from clockwork This opened an abyss that hampered the metaphysical enterprise during the period of this volume On the one hand, speculative thinkers erected systems that placed ever greater strains on the credulity of the common reader Whatever may be the defects of Aristotle’s hylomorphism, his substances—things like cats and cabbages—did at least have the advantage of undoubted existence in the everyday world, unlike unknowable substrata, monads, noumena, and the Absolute On the other hand, thinkers of a more sceptical turn deconstructed not only Aristotelian substantial forms, but primary and secondary qualities, material substances, and eventually the human mind itself In the introduction to his lectures on the history of philosophy Hegel warns against dull histories in which the succession of systems are represented simply as a number of opinons, errors, and freaks of thought In such works, he says, ‘the whole of the history of Philosophy becomes a battleWeld covered with the bones of the dead; it is a kingdom not merely formed of dead and lifeless individuals, but of refuted and spiritually dead systems, since each has killed and buried the other’ (LHP, 17) xiii