I think you just have to accept external reality period. Exactly how do you "doubt" physical sensation? I mean, I can say that I doubt the existence of my own sensations, but isn't such a statement incoherrent, contradictory and absurd since it is impossible for me not to experience my own sensations?
Some truths we know simply because they are. They are prior to logical proof because they precede ratiocination and in fact are necessary for the possibility of ratiocination.
Descartes big, fat error was to artificially and without reason to bifurcate the human person, body and mind or body and soul.
...it could be a big dream, elaborate simulation etc.
But it can't be. Our central sense tells us whether or not we are dreaming. Besides, if it were literally impossible to distinguish a dream from reality then where did the idea of "dream" come from?
The reasoning Descartes used could lead to the impossibility of doubt? How did you do it?
Descartes big, fat error was to artificially and without reason to bifurcate the human person, body and mind or body and soul.I'm having trouble following this. According to traditional theology, the bifurcation occurs every time someone dies -- that is, the soul separates from the body.