Some thoughts

I found reading the meditations to be interesting but hard to follow at times. In the first meditation he says he cannot rely on his senses because they have deceived him at least once, but then later on he uses them to illustrate examples for why we should believe what he says or to make an analogy to support his line of reasoning.

And I think that Descartes' conclusion of 'I think therefore I am' is ultimately not very well founded, but I think that Descartes goes about as far as one can go in doubting things without going insane (or becoming a madman, as he would put it). If an evil demon were really totally deceiving us all the time (or we were really hooked up to the Matrix, or we were just in one long dream, or...), then we probably wouldn't know we were ever being deceived, and our own thinking that we were being deceived would just be another part of the demon's deception!