Why is Descartes considered a rationalist?

Descartes is considered a rationalist primarily because he emphasized the role of reason in gaining knowledge and understanding. He famously expressed skepticism about the reliability of sensory experience, arguing that the senses can be deceptive. By prioritizing rational thought and deductive reasoning, he sought to establish a foundation for knowledge that is independent of potentially misleading sensory input. This approach is exemplified in his famous dictum, "Cogito, ergo sum" ("I think, therefore I am"), which showcases his reliance on reasoning as a means to establish certainty. Rationalism, as a philosophical stance, posits that knowledge can be acquired through intellectual and deductive processes, rather than solely through empirical observation, aligning closely with Descartes' perspectives.