Self-knowledge, externalism, and skepticism: I - Brian P. McLaughlin

In recent years, some philosophers have claimed that we can know a priori that certain external world skeptical hypotheses are false on the basis of a priori knowledge that we are in certain kinds of mental states, and a priori knowledge that those mental states are individuated by contingent environmental factors. Appealing to a distinction between weak and strong a priority, I argue that weakly a priori arguments of this sort would beg the question of whether the skeptical hypothesis under assessment is true, and that the prospect of a sound strongly a priori argument of this sort seems dim.