“I think, therefore I am” is perhaps not the best way to state the premise that, if I am able to perform an action, I must first exist, but it is short and to the point. It is only redundant if you interpret it to mean, “I am because I think”. Descartes chose thinking to be his action because it required no interaction with an unproven environment (other than what was going on in his own head one could argue - see wood on ground above). Sartre chose nausea because it was an experience that no one would choose to undergo.

My take on the matter is that the whole argument is interesting, but overly academic. Premise A: Everything I percieve to be a real part of my environment is real. Premise B: Everything is an illusion. If premise A, and I treat it as real, no problem. If premise B and I treat it as real, no problem. If premise B and I treat it as unreal, I starve, I die, I am institutionalized and force-fed, etc. This makes the safest course of action for continued existence to treat everything as being real. In other words, it makes no difference whether it is real or not; I can either go catatonic, or I can go for a nice bike ride.

My brother, who’s starting college, says he’s taking a philosophy course. I sincerely hope he doesn’t say stuff like this when he comes home.