The prominent writer and philosopher often called the “father of modern philosophy” is René Descartes. His work laid the groundwork for much of contemporary Western philosophy through his method of critical analysis. Descartes is best known for his phrase “Cogito, ergo sum” ("I think, therefore I am"), which emphasizes doubt and reasoning as a path to knowledge. His principles shifted the focus to the importance of individual thought and inquiry, influencing numerous fields such as metaphysics, mathematics, and science, and establishing the foundation for later philosophical developments.