cartésien

Cartésien (Cartesian in English) denotes relating to René Descartes or his philosophical and mathematical system. Originating in the 17th century, the term is used for Cartesian philosophy, Cartesian geometry, and the broader intellectual movement often called Cartesianism.

Cartesian coordinates: Descartes introduced a system linking algebra and geometry, enabling the description of geometric shapes by algebraic equations. In two dimensions, points are represented by (x, y); in three dimensions, by (x, y, z). This analytic geometry underpins modern physics, computer graphics, engineering, and data analysis.

Cartesian philosophy: The method of doubt seeks to discard unreliable beliefs, culminating in the idea that “I think, therefore I am” (cogito ergo sum) as a certain foundation. Cartesian rationalism emphasizes reason as the primary source of knowledge. Descartes also proposed mind–body dualism, distinguishing res cogitans from res extensa, and he advocated a mechanistic view of nature.

Other uses: The Cartesian product, A × B, is the set of ordered pairs from A and B, known in French as produit cartésien. The term remains influential across disciplines, reflecting Descartes’ unification of algebra and geometry and his emphasis on systematic doubt and rational inquiry.