 The core concepts of ancient skepticism are belief, suspension of judgment, criterion of truth, appearances, and investigation. Important notions of modern skepticism such as knowledge, certainty, justified belief, and doubt play no or almost no role. This is not to say that the ancients would not engage with questions that figure in today’s philosophical discussions. Ancient debates address questions that today we associate with epistemology and philosophy of language, as well as with theory of action, rather than specifically with the contemporary topic of skepticism. They focus on the nature of belief, the relationship of belief to speech and action, and the mental states of inquiry (on the role of ancient skepticism throughout the history of Western philosophy up to today, cf. Lagerlund 2020; on the relation between ancient skepticism and philosophical debates today, cf. Machuca and Reed 2018, Vlasits and Vogt 2020, and Machuca 2022).