Prof. Boris Kment (Princeton University), will present: “Grounding, Indeterminacy, and the Liar Paradox” on Friday, April 9, 2021, from 2:00-3:45. All are welcome to attend.
Pointing at the reflection of a person in a distant mirror, you say:
(1) What this person is saying is not true.
Unbeknownst to you, the reflection is your own. Is your utterance true? Given seemingly trivial assumptions, either answer to this question leads to a contradiction. This paradox, known as The Liar, can only be solved by giving up some very compelling principles about truth and logic. Such a radical departure from ordinary ways of thinking needs to be independently motivated. I will argue that this can be done by appealing to certain common and plausible views about metaphysical explanation (grounding). Somewhat surprisingly, a natural way of developing these views leads to the conclusion that some aspects of reality are indeterminate, and that certain principles of classical logic should be rejected, including the law of excluded middle and the principle of non-contradiction. Some questions about the world cannot be settled by answering them, but only by ruling out every possible answer. This includes the question whether (1) is true.