The main aim of the paper is to reconstruct Wittgenstein's criticism of the possibility of holding the skeptical position we traditionally call Cartesian doubt. According to Wittgenstein, the concept of this position is unintelligent because of the specific way language works. In any system of linguistic signs, there is a constitutive – unique – connection between what competent users take to be unassailable about the external world on the one hand, and what the signs they use mean, on the other. As a result, it is not possible to comprehend a scenario in which I am not sure whether or not there is an external world all around me, and, at the same time, am able to understand the language I use. It looks as though what this scenario aimed to describe does not, in fact, represent a meaningful step in our game.