Chrysippus Confronts the Liar: The Case for Stoic Cassationism

Abstract

The Stoic philosopher Chrysippus wrote extensively on the liar paradox, but unfortunately the extant testimony on his response to the paradox is meager and mainly hostile. Modern scholars, beginning with Alexander Rüstow in the first decade of the twentieth century, have attempted to reconstruct Chrysippus’ solution. Rüstow argued that Chrysippus advanced a cassationist solution, that is, one in which sentences such as ‘I am speaking falsely’ do not express propositions. Two more recent scholars, Walter Cavini and Mario Mignucci, have rejected Rüstow's thesis that Chrysippus used a cassationist approach. Each has proposed his own thesis about Chrysippus’ solution. I argue that Rüstow's view is fundamentally correct, and that the cassationist thesis gains greater plausibility when viewed in light of a passage in Sextus Empiricus’ Adversus mathematicos that the previous commentators have ignored, and when understood within the broader context of Stoic logical theory and philosophy of language. I close with a brief remark on the significance of Chrysippus’ work for the modern debate on the semantic paradoxes.