- Member Banno http://forums.philosophyforums.com/threads/descartes-i-think-therefore-i-am-vs-kants-i-think-53397-2.html Here's where the muddle comes to the fore. "I think, therefore I am" is valid because it is an example of existential instatiation, thus presupposing a language in which the instatiation can take place. Languages are never private(Wittgenstein). Hence his certainty is built on his membership of a linguistic community.
Member Scg8866t seems to grasp the circularity problem.
- http://forums.philosophyforums.com/members/scg8866t-45023.html What exactly is this “I” that Descartes uses in his argument? Can Descartes have knowledge of it? One might naturally assume that this “I” refers to the self as a thinking subject. But if the “I” refers to a thinking subject, then Descartes argument is flawed in that it commits the fallacy of begging the question. Descartes is trying to prove that he exists as a thinking subject, but by stating that ‘I think’ (in the premise), he automatically presumes that he exists as a thinking subject...
From "Cogito, Ergo Sum" to the Exponential Function: A Derivation via the Principle of Evolution (1997)