René Descartes (1596 - 1650) was a French philosopher, mathematician, scientist and writer of the Age of Reason. He has been called the "Father of Modern Philosophy", and much of subsequent Western philosophy can be seen as a response to his writings. He is responsible for one of the best-known quotations in philosophy: "Cogito, ergo sum" ("I think, therefore I am").

He was a pioneer and major figure in 17th Century Continental Rationalism (often known as Cartesianism) later advocated by Baruch Spinoza and Gottfried Leibniz, and opposed by the British Empiricist school of thought of Hobbes, Locke, Berkeley and Hume. He represents a major break with the Aristotelianism and Scholasticism of the Medieval period.