Parallels between the ancient Hellenistic philosophies of the Stoics and Epicureans, on the one hand, and modern cognitive psychotherapy, on the other, are well known and a topic of current discussion. The present article argues that there are also important parallels between Pyrrhonism, the third of the major Hellenistic philosophies, and the currently state-of-the-art “3rd wave” cognitive-behavioral therapies in general, and Acceptance and Commitment Therapy (act) in particular. This provides a crucial insight into Pyrrhonism: understanding Sextus’ term adoxastos using the (...) technical act term ‘defusion’ illuminates the psychological condition of the Pyrrhonist and explains why the apraxia objection against Pyrrhonism is misguided. (shrink)