Self-reference, truth, and provability

Speaker: Prof. Volker Halbach (School of Philosophy, Oxford University, UK) Time: 2021-06-02, 19:00-21:00 Beijing Time（UTC 11:00-13:00） Organizer: School of Philosophy, Wuhan University Host: Prof. Albert Visser (University of Utrecht, Member of the Royal Netherlands Academy of Arts and Sciences, Netherlands) Interlocutors: Dr. Balthasar Grabmayr (Humboldt University of Berlin, Germany) Prof. Graham Leigh (The University of Gothenburg, Sweden) Abstract: Philosophers have struggled for centuries with sentence that make claims about themselves such as the "liar sentence". The following is an example of a liar sentence: THE SENTENCE IN CAPITALS IS NOT TRUE.The liar sentence is a threat to any theory of truth, and has been taken as evidence that the entire notion of truth and perhaps even realism have to be rejected. In the talk I will look at this and similar sentences. In particular, I will consider sentences that say about themselves that they are not provable (Gödel sentences) and sentences that say about themselves that they are true (truth teller sentences). I will look at consequences of the analysis of self-reference for the theory of truth and its paradoxes and for the Gödel incompleteness phenomena.