 The 5th century sophists develop forms of debate which are ancestors of skeptical argumentation (Bett 2020b). They take pride in arguing in a persuasive fashion for both sides of an issue and in developing an agonistic art of refuting any claim put forward. Further, the sophists are interested in the contrast between nature and convention. The formative roles of custom and law were discussed by some of the earliest Greek authors (consider Pindar’s “law is king” and its many interpretations, for example in Herodotus). The sophists explore the idea that, if things are different for different cultures, there may be no fact of the matter of how those things really are. The skeptics engage with both legs of the distinction between nature and convention. Pyrrhonian skepticism employs an argument to the effect that, if something is by nature F, it is F for everyone (affects everyone as F) (see sections 4.2 and 4.4). Pyrrhonism further associates convention with appearances, so that the sceptic, by adhering to appearances, can lead an ordinary life (see section 4). However, the contrast between nature and convention does not figure importantly in ancient skepticism, and there is no skeptical school that would confine itself to ‘moral’ skepticism, or skepticism about values.