The French philosopher and theologian Nicolas Malebranche (1638-1715) was a noted Cartesian. His analysis of the fundamental presuppositions of Descartes's philosophy led to a set of doctrines that is known as occasionalism.

Born in Paris, Nicolas Malebranche was educated at the Collège de la Marche and at the Sorbonne. In 1660 he entered the Oratorian order, which had been founded by Cardinal Pierre de Bérulle, an early supporter of René Descartes. Sometime after his ordination in 1664, Malebranche chanced upon a copy of Descartes's On Man. This incomplete treatise was an attempt to explain man's physiology as part of a system of universal mechanics. On the strength of this work, Malebranche devoted the next 10 years of his life to the study of science and of Descartes's philosophy.

Occasionalism is a theory of causal interaction. Descartes's metaphysics culminates in an extreme dualism according to which matter...