Cool Logic

Maja Jaakson (ILLC)

What's a Theory to Do? On Classicality with the Purpose of Capturing

October 5th at 17:30, in Science Park D1.113

What do we want in, and from, a formal theory of truth? In his "What Theories of Truth Should Be Like (but Cannot Be)", Hannes Leitgeb presents eight desiderata for such theories, including that the theory have a classical "outer" logic. Leitgeb makes classicality a desideratum because he thinks we reason classically in mathematics, science, and philosophy; and this suggests an ideal theory of truth will capture our inferential practices involving the concept of truth in those disciplines. Thus, for Leitgeb, we go classical with the purpose of capturing.

In this talk, I will argue that Leitgeb's reasons for preserving classical logic are, at the very least, equally good reasons for accepting STTT: a three-valued logic with a non-transitive consequence relation. I will also argue that Leitgeb's criteria present us with a problem when it comes to deciding just which "largely classical" theory of truth is the correct one.