Descartes claimed that one thing emerges as true even under the strict conditions imposed by the otherwise universal doubt: "I am, I exist" is necessarily true whenever the thought occurs to me. (Med. II) This truth neither derives from sensory information nor depends upon the reality of an external world, and I would have to exist even if I were systematically deceived. For even an omnipotent god could not cause it to be true, at one and the same time, both that I am deceived and that I do not exist. If I am deceived, then at least I am.
Although Descartes's reasoning here is best known in the Latin translation of its expression in the Discourse, "cogito, ergo sum" ("I think, therefore I am"), it is not merely an inference from the activity of thinking to the existence of an agent which performs that activity. It is intended rather as an intuition of one's own reality, an expression of the indubitability of first-person experience, the logical self-certification of self-conscious awareness in any form. http://www.philosophypages.com/hy/4c.htm#cogBut, who translated it into Latin? Descartes himself?
