There is considerable discussion about how exactly Descartes thought this argument functions. There are two strains of interpretation that derive directly from his texts. In the Second Replies, Descartes observes that ‘when we become aware that we are thinking things, this is a primary notion which is not derived by means of any syllogism’. This suggests that the Cogito Argument is known immediately by direct intuition. In the Principles (Part I §10), however, Descartes notes that before knowing the Cogito, we must grasp not only the concepts of thought, existence and certainty, but also the proposition that ‘it is impossible that that which thinks should not exist’. This suggests that the Cogito is a kind of syllogism, in which I infer my existence from the fact that I am thinking, and with the premise that whatever thinks must exist. Recent analytic philosophers have also been attracted to the Cogito, trying to understand its obvious allure through speech act theory and theories of demonstratives (Hintikka 1967; Markie 1992 ). These accounts, however, are distant from anything that Descartes himself conceived.
There is also some confusion