n. a fundamental certainty that a human can know everything of the self but not of the other. There is a great divide in human consciousness between the knowing subject (ego) and that of another. The conclusion, therefore, would be: Cogito ergo sum. (I think, therefore, I am.)

CARTESIAN SELF: "In the Cartesian self, Descartes proposes a radical dualism in life where there is the subjective, inner mind on one hand and the objective, outer world on the other."