 In his own philosophical work, Mates defends a stance akin to Pyrrhonian skepticism.He argues that the major problems of philosophy (such as the liar paradox, the existence of an external world, and free will) are intelligible and non-trivial yet utterly defy solution.Unlike the classical Pyrrhonists, however, Mates finds that skeptical arguments lead to unsatisfactory perplexity rather than ataraxia.