The Human Condition (book) but the self, Descartes and other moderns thought, could be known. Though his cogito ergo sum was anticipated by Augustine, his dubito ergo sum is original and a hallmark of modernity: beginning from doubt. The notion of common sense as a sense in which the other five were fitted to a common world ceded to a conception of common sense as an inner faculty with no relationship to the world, and the assumption that all humans had faculties like this in common became necessary to get theories going, but without the assumption of a common world, the assumption of faculties
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),