Discourse on the Method Discourse on the Method Discourse on the Method of Rightly Conducting One's Reason and of Seeking Truth in the Sciences () is a philosophical and autobiographical treatise published by René Descartes in 1637. It is best known as the source of the famous quotation ""Je pense, donc je suis"" (English: "I think, therefore I am", or "I am thinking, therefore I exist"), which occurs in Part IV of the work. The similar Latin statement, "Cogito, ergo sum", is found in "Meditations on First Philosophy" (1641) and "Principles of Philosophy" (1644). "Discourse on the Method" is one of the most influential
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),