Skepticism, assertion, and a priori justification

It can easily seem that we do not know that radical skeptical hypotheses---hypotheses according to which we are the unwitting victims of massive deception---are false. This, in turn, makes radical skepticism---the theory that we know almost nothing at all---seductive. I argue that our justification to believe that radical skeptical hypotheses are false cannot come from experience, and defend the idea that we have a priori justification to believe that radical skeptical hypotheses are false. I offer a new explanation for why it seems that we do not know that radical skeptical hypotheses are false. On my view, this is because it is not appropriate to assert that they are false.