In philosophy, the Cartesian Self, part of a thought experiment, is an individual's mind, separate from the body and the outside world, thinking about itself and its existence. It is distinguished from the Cartesian Other, anything other than the Cartesian self. According to the philosopher Rene Descartes, there is a divide intrinsic to consciousness, such that one cannot ever bridge the space between one's own consciousness and that of another.
Descartes did not provide a well-theorized explanation of the self since his views on the subject were primarily found in the first-person narrative in Meditations. However, key features of the concept can be identified such as the way the immaterial thinking self is disembodied and is doomed to isolation. The nature of the self was specifically addressed in the Second Meditation wherein the narrator stated: "I am, then, in the strict sense only a thing that thinks; that is, I am a mind, or intelligence, or reason - words whose meaning I have been ignorant of until now."
Descartes concluded famously that Cogito ergo sum, "I think, therefore I am", but realized that according to his wax argument you could never similarly demonstrate the existence of the 'other'. However, the Cartesian Self, he concluded, is thus almost entirely self-evident: the existence of some being asking about itself necessarily implied that such a being existed. Because of this, while humans can know everything of the self and its mysteries, we cannot actually know anything of anything that is not the self.
It is based on the whole of the Cartesian Pure Inquirer, where cognitive capabilities and methods of achieving knowledge are alike to all knowers. However, the "knower" (particularly to Descartes) is treated as a featureless abstract, and not an actual person.
According to Galen Strawson, the Cartesian self is pure individual consciousness and it was likened to the entity that Hume sought in the flux of perceptions, the Kantian "I think" or the pure formal unity, and Wittgenstein's conception of the subject not as part of the world but its limit.