The aim of this paper is to show that it is not irrational to doubt one’s own existence, even in the face of introspective evidence to the effect that one is currently in a certain mental state. For this purpose, I will outline a situation in which I do not exist, but which cannot be ruled out on the basis of any evidence available to me—including introspective evidence about my current mental states. I use this ‘superskeptical scenario,’ as I will (...) call it, to formulate an argument to the conclusion that I do not know that I exist. In order to substantiate my argument, I draw upon Terence Parsons’ theory of non-existent objects. I conclude that, inasmuch as Parsons’ theory is reasonable, doubts about one’s own existence are reasonable as well. (shrink)