Cogito, ergo sum though not explicitly as "cogito, ergo sum" in Meditation II: In 1644, Descartes published (in Latin) his "Principles of Philosophy" where the phrase "ego cogito, ergo sum" appears in Part 1, article 7: Descartes's margin note for the above paragraph is: Descartes, in a lesser-known posthumously published work dated as written ca. 1647 and titled ("The Search for Truth by Natural Light"), wrote: The proposition is sometimes given as . This fuller form was penned by the eloquent French literary critic, Antoine Léonard Thomas, in an award-winning 1765 essay in praise of Descartes, where it appeared as In English, this
Cogito, ergo sum "Meditations", Descartes phrases the conclusion of the argument as "that the proposition, "I am, I exist," is necessarily true whenever it is put forward by me or conceived in my mind." ("Meditation" II) At the beginning of the second meditation, having reached what he considers to be the ultimate level of doubt—his argument from the existence of a deceiving god—Descartes examines his beliefs to see if any have survived the doubt. In his belief in his own existence, he finds that it is impossible to doubt that he exists. Even if there were a deceiving god (or an evil demon),