René Descartes

1596-1650
French philosopher and mathematician whose ideas included early and significant contributions to the field of psychology.

Descartes was born in France, near the small village of Le Haye. From the age of 10, he attended the most prestigious school in France, the Royal Collège of La Flèche, graduating at the age of 16. After spending some time sampling the amusements of Parisian society, followed by a period of solitary studies in philosophy and mathematics, Descartes briefly served as a soldier on the eve of the Thirty Years' War, joining first the Protestant and then the Catholic forces. Returning to the study of science and philosophy after the war, he spent several more years in Paris before moving to Holland at the age of 32. There Descartes wrote his most important works, Discourse on Method (1637), Meditations on First Philosophy (1642), and Principles of Philosophy (1644). Because his books aroused controversy among the Dutch Protestant clergy, Descartes, already wary after Galileo's condemnation by the Inquisition, published little for the remainder of his life, confining his thoughts largely to unpublished manuscripts and letters. His last published work was the Passions of the Soul (1649). Descartes remained in Holland for most of his life, although he moved frequently during his time there. In 1649, he left for Sweden at the invitation of Queen Christina and undertook to tutor her in philosophy. Only months after arriving in Sweden, Descartes died at the age of 53.

Descartes's philosophy is known for its glorification of human reason. He began with the premise that the only way to be sure of anything is to doubt everything ("I resolved to reject as false everything in which I could imagine the least doubt, in order to see if there afterwards remained anything that was entirely indubitable"). In so doing, Descartes arrived at the conclusion that the one thing he could be sure of was his own act of doubting—a mental process. From the certainty expressed in the famous statement, "I think, therefore I am," he built a philosophy that gave to the workings of the individual mind priority over both immediate sensory experience and received wisdom. Descartes postulated a radical mind-body dualism, claiming that the universe consisted of two utterly distinct substances: mind ("thinking substance" or res cogitans) and matter ("physical substance" or res extensa). Thus, he separated mental phenomena from the comprehensive mechanistic explanation he gave for the workings of matter and material things, including the human body, which he divided into ten physiological systems. These included such faculties as memory and

René Descartes (The Library of Congress. Reproduced by permission.)

imagination, along with the purely physiological functions of digestion, circulation, and respiration.

Descartes believed the primary site of interaction between mind and body to be the pineal gland (which he incorrectly thought to be unique to humans). He held that the will, an aspect of the mind, can move the pineal gland and cause the transmission of what he called animal spirits, which produce mechanical changes in the body; and, similarly, that changes in the body are transmitted to the pineal gland and can there affect the mind. His rationalistic ideas provided a basis for the Enlightenment and became the dominant system of philosophy until the work of David Hume (1711-1776) and Immanuel Kant (1724-1804). While many of Descartes's individual arguments have since been discredited, his overall view of the dualism between mind and body has been a powerful influence on succeeding generations of philosophers and psychologists.