Truth & self-reference

A 3D maze with white and blue walls on a dark background. The maze has the text 'PLAYING WITH TRUTH' and the name 'Stefan Wintein' on it.

My PhD thesis (Playing with Truth, Tilburg University, 2012, Cum Laude) was concerned with theories of truth and the paradoxes that are caused by sentences such as the Liar, which says, of itself, that it is not true. Classical logic must be given up in light of these paradoxes and I develop various non-classical logics as an alternative: different logics are obtained by specifying different assertoric norms, i.e. norms for assertion and denial. My thesis sheds novel light on the notions of assertion, denial and truth. In particular, in On the Strict-Tolerant Conception of Truth (2014), I explain the upshot of obtained results for bilateralism.

In case you’re interested in a hard-copy of my thesis (including its beautiful cover), just send me an e-mail.

In Assertoric Semantics and the Computational Power of Self-Referential Truth (2012), I show that by asking self-referential questions to a computer database, one can retrieve information more efficiently than without self-reference. Hence, I shed novel light on the age-old problem of self-referential sentences such as the Liar: self-referential truth has computational power. In On the Behavior of True and False (2012) I show how self-referential questions allow for more efficient solutions to Raymond Smullyan’s well-known knight-knave puzzles, in particular to the so-called Hardest Logic Puzzle Ever, which had received independent attention in the academic literature. In A Framework for Riddles about Truth that do not involve Self- Reference (2011) I develop a logical framework in which Smullyan’s puzzles can be formally represented and their solutions discussed. With or without self-reference, knight-knave puzzles can be used to illustrate various technical logical concepts. In addition, they are plain fun. One of Smullyan’s puzzles made an appearance in the movie Labyrinth: see the video in which Sarah solves the riddle.

After my PhD I continued to work on non-classical logics, but now from a more general perspective than in my PhD thesis: self-referential truth is not the only topic that invites one to adopt a non-classical logic. In particular, my work in this period deals with many-valued logics (a specific type of non-classical logics) that, in contrast to classical logic, recognize more than two truth-values. More in particular, to a large extent my work deals with sub-logics and extensions of the well-known logic of First Degree Entailment (FDE), a 4-valued logic that was originally developed to reason with incomplete and inconsistent information.

Non-classical logic

Publications Truth & Self-reference

Publications Non-classical logic