René Descartes, often known by his Latin name, Renatus Cartesius, from which the adjective "Cartesian" is derived, was the prime mover behind the mechanistic conception of the human body. He was born the son of a wealthy magistrate in La Haye, Touraine, France. From 1606 to 1614, he studied logic, mathematics, scholastic theology, Aristotelian philosophy, and the classics at the Jesuit school of La Flèche in Anjou. In 1616, he took a law degree from the University of Poitiers, but never practiced law. Dissatisfied with his education in France, he enrolled in the Dutch military academy at Breda in 1618. There he studied mathematics and mechanics under Isaac Beeckman (1588-1637), whom he acknowledged as his mentor.
Descartes served in the Thirty Years War, first in the Dutch army, then in the Bavarian army. Because of his chronic ill health, he did no fighting, but contributed his mathematical and engineering skills to the war effort. After 1627, he spent hardly any time in his native France. He lived mostly in the Netherlands from 1629 to 1649, then moved at the request of Swedish Queen Christina (1626-1689) to Stockholm, where he died shortly after arriving.
Writing sometimes in French, sometimes in Latin, and sometimes translating one into the other, Descartes published Discourse on the Method of Rightly Conducting the Reason and Seeking Truth in the Sciences, Dioptrics, Meterology, and Geometry in 1637; Meditations on First Philosophy with six sets of objections and replies in 1641; Principles of Philosophy in 1644; and Passions of the Soul in 1649. His posthumous works include Treatise on Man and on the Formation of the Fetus in 1664 and Rules for the Direction of the Mind in 1701. In the 1630s, he planned a treatise called The World, but, recalling what the Roman Catholic Church had recently done to Nicolaus Copernicus (1473-1543), Giordano Bruno (1548-1600), and Galileo Galilei (1564-1642), he abandoned it out of fear.
Descartes saw all knowledge as a tree. His most fundamental fact, cogito ergo sum (literally, "I think, therefore, I am"), his absolute certainty that he existed as a thinking thing, was his basis of metaphysics, the roots. Physics was the trunk. Medicine, mechanics, and morals were the branches.
This view of knowledge committed him to a strict metaphysical dualism between res cogitans ("thinking substance") and res extensa ("extended substance"). This dualism brought into sharp focus a philosophical problem which was implicit in Plato's (ca. 427 B.C.-ca. 347 B.C.) Phaedo and in the spirit/flesh (pneuma/sarx) or word/flesh (logos/sarx) dualism in the Gospel of John, namely, how can any causal relationship exist between mind and body? This problem, typically just called "the mind/body problem," has intrigued philosophers ever since, has never been solved, and was not even sufficiently argued until Gilbert Ryle (1900-1976) published The Concept of Mind in 1949. For Ryle, the Cartesian mind was "the ghost in the machine."
Cartesian dualism immediately wrought a crisis in Continental Rationalism, prompting Baruch Spinoza (1632-1677) to attempt a monistic solution and Gottfried Wilhelm Freiherr von Leibniz (1646-1716) to attempt a pluralistic solution. The rigid natural difference between body and soul entailed separate sets of rules for each. The laws of physics and especially mechanics governed the body but did not affect the soul; while principles of psychology and individual free will determined the nature of the soul and affected the body only in an occult way, as Descartes believed, through the "animal spirits" in the pineal gland. His studies of the pineal gland and his dissections of sheep brains inspired later research in cerebral localization.
Descartes propounded iatromechanism, the belief that physiological and medical processes were reducible to problems of physics and mechanics. Opposed to this school was the iatrochemism of Franciscus de le Boë Sylvius (1614-1672), who claimed that these processes were essentially chemical. Descartes accepted the mechanistic explanation of blood circulation proposed by William Harvey (1578-1657) in 1628. The Cartesian view that only humans have souls, and that all other animals are merely reactive automatons that feel no pain and cannot think, justified vivisection and other cruelty to animals in the name of science.
Descartes believed in divine foreknowledge, but not in predetermination, as he explained with a story in a famous letter to Princess Elisabeth of Bohemia. A king sent two of his subjects, mortal enemies of each other, on simultaneous errands, one to travel from point A to point B, the other from point B to point A. He knew that they would meet and fight. He caused them to meet, but did not force them to fight. The free will of the two enemies was fully preserved even though the orchestrator of their actions knew in advance what would happen.
Descartes discovered analytic geometry, the system of solving problems in plane geometry by graphing algebraic equations as "Cartesian coordinates" on a grid defined by a horizontal x-axis and a vertical y-axis. This standard and indispensable part of mathematics is sometimes called either "coordinate geometry" or "Cartesian geometry." In set theory and formal logic, the "Cartesian product" of any two sets is a third set whose elements are all the pairs such that the first half of each pair is an element of the first set and the second half of each pair is an element of the second set.
This is the complete article, containing 871 words
(approx. 3 pages at 300 words per page).
