Latin word meaning “I think” (Cogito ergo sum – I think, therefore I exist).
Cogito is a term borrowed from the modern French philosopher Rene Descartes and used to denote the Self, especially the Thinking Self. It is also a symbol of the primacy of subjectivity in the perspective of the Self, which is seen as unique and everything else is derived from it (especially the world and language).
Because Descartes does not acknowledge the unconscious, the term Cogito is often used to denote the Self, both unified and transparent in itself.
Some new theories of subjectivity (such as those of Jacques Lacan, Julia Kristeva, and Luce Irigaray) emphasize the exact opposite, the ego as a divided entity (conscious/unconscious) and something vague about itself.
Descartes also did not accept the importance of language, especially as a factor in what is commonly called the engendering of subjectivity. The Self is, after all, something that can be self-proclaimed, that can use language reflexively.
The ability for self-identification, self-description, self-relation, etc. is essential to what is generally called subjectivity. But this ability is linguistic, as Emil Benveniste points out, only in and through language do we construct ourselves in a subjectivity. While modern theories of subjectivity emphasize language, Descartes neglects its importance.
In short, Cogito is the name for a mistake, at least for many semioticians it is. Or a series of mistakes that we have not yet completely got rid of.