Professor Williamson’s research ranges from broad questions about the nature of knowledge to technical work in branches of formal logic such as modal logic and epistemic logic. He has published articles and books on topics including the logic and semantics of vague languages; identity and indiscriminabilty; the relation between knowing how and knowing that; limits on what can be known; the speech act of assertion; unrestricted generality; and philosophical method. He is currently writing a book about the metaphysics of first-order and higher-order modal logic, on whether there could have been more or fewer things than there actually are.
His most recent book, Tetralogue: I'm Right, You're Wrong, uses a fictional conversation between four passengers on a train to explore questions about truth and falsity, and knowledge and belief. It presupposes no prior acquaintance with philosophy, and introduces its concerns in an accessible and light-hearted way.
- Philosophy of language