  The first question about Arcesilaus’ skepticism is thus whether it involved any commitment to doctrines at all. A negative answer to this question—based on something like the two difficulties given above—yields what is called a dialectical interpretation of Arcesilaus (adopted by e.g., Couissin 1929 and Striker 1980; see Castagnoli 2018 on the senses of ‘dialectical’). The primary drawback to this interpretation is that it involves the rejection of a central claim about him in all of our major sources except Philodemus: Cicero, Numenius, Sextus, Diogenes and Plutarch ascribe some degree of commitment to at least one of these doctrines—that of universal suspension ([ii] above). Rejecting this evidence might be justified by the lateness of these sources and their associations with later Academic developments; but this seems hard to maintain when we learn that Arcesilaus’ contemporary opponents, including Chrysippus, also ascribed universal suspension to him (see Plutarch On Stoic Self-Contradictions 1036a with 1037a, and Against Colotes 1122a). A dialectical interpretation also risks failing as an interpretation: it cannot explain why Arcesilaus argued as he did, whether because it denies him any commitments or because it claims they are entirely opaque to us (see Perin 2013).