which was to argue that knowledge could be analysed into constituent concepts. (Typically this would be justified true belief plus an extra factor.) He agrees that knowledge entails justification, truth and belief, but argues that it is conceptually primitive. He accounts for the importance of belief by discussing its connections with knowledge, but avoids the disjunctivist position of saying that belief can be analysed as the disjunction of knowledge with some distinct, non-factive mental state. Williamson also argues against the traditional distinction of knowing-how and knowing-that. He says that knowledge-how is a type of knowledge-that. Williamson argues that knowledge-how does not relate one's ability. As an example, he gives a ski instructor who knows how to perform a complex move without having the ability to do it himself. In metaphysics, Williamson defends necessitism, according to which necessarily everything is necessarily something, in short, that everything exists of necessity. Necessitism is associated with the Barcan formula: it is possible for something to have a property only if there is something which has that property. Thus, since it is possible for Wittgenstein to have had a child, there is something which is a possible child of Wittgenstein. However, Williamson has also developed an ontology of bare possibilia which he argues alleviates the worst consequences of necessitism and of the Barcan formula. It's not that Wittgenstein's possible child is concrete; rather, it is contingently non-concrete. Publications Identity and Discrimination, Oxford: Blackwell, 1990. Vagueness, London: Routledge, 1994. Knowledge and Its Limits, Oxford: Oxford University Press, 2000. The Philosophy of Philosophy, Oxford: Blackwell, 2007 Modal Logic as Metaphysics, Oxford: Oxford University Press, 2013. Tetralogue: I'm Right, You're Wrong, Oxford: Oxford University Press, 2015. Doing Philosophy: From Common Curiosity to Logical Reasoning, Oxford University Press, 2017. Suppose and Tell: The Semantics and Heuristics of Conditionals, Oxford University Press, 2020. Williamson has also published more than 120 articles in peer-reviewed scholarly journals. References External links Profile at University of Oxford An in-depth autobiographical interview with Timothy Williamson Interview at 3:AM Magazine Università della Svizzera Italiana professors. 1955 births 20th-century British non-fiction writers 20th-century British philosophers 20th-century essayists 21st-century British non-fiction writers 21st-century British philosophers 21st-century essayists Academics of the University of Edinburgh Academics of Trinity College Dublin Analytic philosophers Aristotelian philosophers Atheist philosophers British atheists British logicians British male essayists British social commentators Epistemologists Fellows of New College, Oxford Fellows of the British Academy Fellows of the