René Descartes (1596–1650) was a French philosopher and mathematician, credited as a foundational thinker in the development of Western notions of reason and science. ... doing the doubting and believing its perceptions, hence the famous formulation, 'I think therefore I am', or in Latin, the cogito—'Cogito ergo sum'. read more
Cogito, ergo sum: Cogito, ergo sum, (Latin: “I think, therefore I am) dictum coined by the French philosopher René Descartes in his Discourse on Method (1637) as a first step in demonstrating the attainability of certain knowledge. read more
"Cogito ergo sum." The why of it was that Descartes was an anti-skeptic. He did not doubt his actual existence, and he believed the sole purpose of life revolved around thinking. read more