Abstract This article divides philosophical skepticism into two basic forms. The “Academic Skeptic” proposes that one cannot have knowledge of a certain set of propositions. The “Pyrrhonian Skeptic,” on the other hand, refrains from opining about whether one can have knowledge. This article outlines two arguments for Academic Skepticism: a “Cartesian-style” argument based on the claim that knowledge entails the elimination of all doubt; and a “Closure Principle–style” argument based on the claim that if x entails y and S has justification for x, then S has justification for y. It turns to contextualism and outlines the background of Pyrrhonian Skepticism, pointing out that the Pyrrhonist withholds assent concerning one's knowledge-bearing status because reason cannot provide an adequate basis for assent. It assesses three possible patterns of reasoning (foundationalism, coherentism, and infinitism), and concludes that the Pyrrhonist view, that reason cannot resolve matters concerning the nonevident, is vindicated.