Descartes

René Descartes (1596–1650) was a French philosopher, mathematician, and scientist whose work helped establish modern Western thought and analytic geometry. Born in La Haye en Touraine, he studied law at the University of Poitiers but pursued mathematics and philosophy, spending much of his life in the Dutch Republic. His method of doubt and emphasis on reason aimed to secure knowledge on a certain foundation, a program articulated in his writings and correspondence.

In philosophy, Descartes is known for radical doubt and the search for an indubitable starting point. The outcome of his method is the famous proposition “I think, therefore I am” (cogito, ergo sum), found in the Meditations on First Philosophy (1641). He advanced mind–body dualism, distinguishing res cogitans (the thinking mind) from res extensa (the physical world), and he argued that knowledge should be built on clear and distinct ideas attained by reason. His rationalist approach influenced the development of modern epistemology and metaphysics.

In mathematics, Descartes created analytic geometry, linking algebra and geometry and introducing the Cartesian coordinate system, which allows geometric figures to be described by algebraic equations. This work, embedded in the Discourse on Method (1637) with the appended La Géométrie, helped launch a new mathematical language for science.

Major works also include Principles of Philosophy (1644) and, later in his career, writings on optics and the physiological aspects of emotion. Descartes’ ideas shaped subsequent rationalist philosophy and the method of scientific inquiry, leaving a lasting impact on both philosophy and mathematics.

He died in Stockholm in 1650 during a visit to Queen Christina of Sweden, leaving a profound and enduring legacy in thought and method.