The term "Cartesian" refers to concepts and ideas derived from the work of the French philosopher and mathematician René Descartes. He is best known for his contributions to philosophy, particularly his method of doubt and the famous statement "Cogito, ergo sum" (I think, therefore I am). Cartesian philosophy emphasizes rationalism and the use of reason as the primary source of knowledge. In mathematics, "Cartesian" often relates to the Cartesian coordinate system, which uses two or three perpendicular axes to define the position of points in space. This system allows for the representation of geometric shapes and algebraic equations, making it a fundamental tool in both mathematics and physics.