HPhil Seminar: December 11, 2025

The HPhil (History of Philosophy) Research Group of the Centre of Philosophy of the University of Lisbon announces the 2025/26 edition of its permanent seminar on the history of philosophy, devoted to the presentation of conferences by renowned specialists while also creating opportunities to emerging scholars, aiming to promote advanced studies in groundbreaking debates and the permanent training of its academic community.

In this session of the seminar, Matthew Duncombe (University of Nottingham) will present a work of his, entitled “Aristotle, Eubulides and the Liar Argument”. (abstract below)

The session will take place on December 11, 2025 at 5 p.m., in the Room 201.J (Room Mattos Romão, Department of Philosophy). Admission is free

Abstract

Ancient sources agree that Eubulides of Miletus originated the Liar Argument. Unfortunately, they don’t tell us why Eubulides posed the Liar, what it was for, how the argument worked, when he originated it, or the context in which it was originated. But we are not completely in the dark. We have some ancient evidence for how a Liar Argument worked (Cicero A. Pr. II XXIX, 95-XXX,97; Aulus Gellius, XVIII, 2, 20; Lucian Vera Historia I, 4; Ps. Acron, scol. As Hor. Episr, II, 45; Ps. Alexander, In Soph El, 171, 17-20 Wallies) and some possible contextual information discussing a Liar-like argument (Aristotle’s Sophistical Refutations 25, 180b2-7).

Scholars have speculated that Eubulides introduced the Liar to argue for some philosophical thesis, such as the Megaric ‘central dogma’ of Euclides, or the trivialist claim that all statements are true. However, this paper argues that Eubulides’ Liar argument developed as a criticism of Aristotle’s theory of truth. Aristotle is not responding to Eubulides; Eubulides is responding to Aristotle. Eubulides is known to be a critic of Aristotle’s logic; Aristotle’s response to the liar-like argument in the SE can be answered by the self-reference version of the Liar. The self-reference version of the Liar threatens Aristotle’s account of truth, because his principles of semantic ascent and descent licence all the moves needed for the paradox to bite. Moreover, because Aristotle recognises truth-bearers other than sentences, such as beliefs, and even worldly items, we can see why the Liar specifies that this sentence is false. Only sentences can deploy the semantic ascent and descent rules that Aristotle articulates can be subjected to the Liar argument. This also explains why Aristotle does not appear to grasp the gravity of the Liar. He was not in a position to because the Liar responds to him.