‘Descartes's Ghost’ considers his influence. His writings were placed on the Index by the Roman Catholic Church in 1663. Some decades later, Newton's physics superseded Descartes', and revisionary interpretations of his metaphysics, and elaborations of his logic and ethics, began to be put forward. Cartesians carried out observations and experiments in an attempt to support Descartes's theories, but their research programme petered out when serious anomalies in the Cartesian theory of gravity, and of planetary motion and position, were corrected by Newton. Leibniz, Spinoza, Locke and Hume were all influenced by Descartes and the Descartes who still haunts people today is the ghost of a philosopher.