Timothy Williamson has been the Wykeham Professor of Logic at the University of Oxford since 2000, and Nelson Visiting Professor in Philosophy at the University of Michigan since 2013. He received his doctorate from Oxford in 1981. His previous positions were at Trinity College Dublin, the University of Edinburgh, Oxford, and (as a visitor) at MIT, Princeton, the Australian National University, the University of Canterbury (New Zealand), and the Chinese University of Hong Kong. His main research interests are in epistemology, metaphysics, philosophical logic, the philosophy of language, and metaphilosophy. He is the author of Identity and Discrimination (1990), Vagueness (1994), Knowledge and its Limits (2000), The Philosophy of Philosophy (2007), Modal Logic as Metaphysics (2013), and numerous articles. Williamson on Knowledge (2009) contains fifteen essays on his work with his replies.