cogito, ergo sum, (Latin: “I think, therefore I am) dictum coined by the French mathematician and philosopher René Descartes in his Discourse on Method (1637) as a first step in demonstrating the attainability of certain knowledge. It is the only statement to survive the test of his methodic doubt. The statement is indubitable, as Descartes argued in the second of his six Meditations on First Ph..
