Descartes is sitting at a bar. The bartender asks him if he wants another drink. "I think not," says Descartes. Suddenly, Descartes disappears.And remember also, the reason that the joke was horrible: Descartes famously said, "I think, therefore I am," but he didn't say, nor does it follow, nor is it true, that "I do not think, therefore I am not" would be a valid inference. But I was reading Meditation Two today, and I do see that he did say the following:
I am; I exist -- this is certain. But for how long? For as long as I am thinking; for perhaps it could also come to pass that if I were to cease all thinking I would then utterly cease to exist. At this time I admit nothing that is not necessarily true. Descartes, Meditations on First Philosophy, Meditation Two, 27In light of this passage, I feel that I ought to add one more to my list of more-acceptable Descartes-in-a-bar-joke alternatives: Descartes is sitting in a bar. He finishes his drink, and the bartender asks him if he'll have another. "I think not," says Descartes. Suddenly, Descartes disappears for all he knows. Ok, so the other ones are funnier.