David Chalmers

Speaking for myself, I don’t think there’s anything special about thinking per se. Descartes could have said, “I feel, therefore I am,” or “I see, therefore I am,” or “I worry, therefore I am.” All of these are claims about his mind that he can be certain of and that aren’t threatened by the evil demon. At least, he can be certain about these claims if they’re understood as states of consciousness, or subjective experience.

In my view, the best statement of the cogito is “I am conscious, therefore I am.”

Faced with an argument that we have knowledge of the external world, the Riposte counters: That’s what someone in a simulation would say.