Cartesianism is the name given to the philosophical movement initiated by French mathematician and philosopher René Descartes (1596–1650) on the basis of two key innovations. The first is Descartes's claim that material events, including most biological phenomena, can and must be explained without appeal to teleological principles or occult qualities, through laws of motion acting mechanically on microcorpuscular bodies having no properties beyond spatial extension and shape. Descartes's second claim, his dualism, is that the distinctive human properties of selective intentionality and free volition, dramatically manifest in the creative freedom of language, mark human beings off from other animals as innately possessed of an immaterial soul or mind that is ontologically independent of matter, characterized by infinite moral freedom, susceptible of a distinct happiness, and capable of continued existence after the body's demise.

In Descartes's day, the first claim was by far the most controversial: how can living, breathing beings, plants and bees and horses, emerge from purely mechanical laws acting invariably on inert matter? As a program for physics, Descartes's elegant reductionism was fatally undermined when Isaac Newton in 1687 successfully accounted for universal gravitation by adding without metaphysical justification the notion of force. However, Cartesian mechanistic parameters continued fruitfully to guide biology and experimental physiology, shaping the speculative outlook of such diverse scientists as Julien de la Mettrie (1709–1751) and Claude Bernard (1813–1878). Today, Cartesianism survives in the methodological premise, also adopted by Newtonians, that a large part of sensible phenomena derives from causes acting invariably, without intention or free volition.

See also DESCARTES, RENÉ; DUALISM; MATERIALISM; NATURALISM; PHYSICALISM, REDUCTIVE AND NONREDUCTIVE; REDUCTIONISM

ANNE A. DAVENPORT