My great-uncle never went to university: he had to leave school at 15 or so because he was the only one in his family organized enough to hold down a job. He became a successful businessman, but his deepest interest was in philosophy and psychology. He published serious articles and a book on philosophy, though without a high opinion of them. When I was very small, he discussed philosophical questions with me, not calling them that. As a teenager, I read some interviews with leading philosophers of the day. I felt at home with their elegantly abstract way of thinking, and even thought I could do it better. When I later discovered how hard it is, that just added to its interest.
1955 Born Uppsala, Sweden.
1972-73 Computer programmer, Atomic Energy Research Establishment, Harwell.
1973-76 Studied Mathematics and Philosophy, Balliol College, Oxford.
1976-80 Senior Scholar, Christ Church, Oxford; studied for DPhil on âThe Concept of Approximation to the Truthâ.
1980-88 Lecturer in Philosophy, Trinity College, Dublin.
1988-94 Fellow in Philosophy, University College, Oxford.
1995-2000 Professor of Logic and Metaphysics, University of Edinburgh.
2000- Wykeham Professor of Logic, University of Oxford, and Fellow of New College Oxford.
Visiting positions:
1990, 1995 Visiting Fellow, Australian National University.
1994 Visiting Professor, M.I.T.
1995 Visiting Erskine Fellow, University of Canterbury (New Zealand).
1998-99 Visiting Professor, Princeton University.
2003 Nelson Distinguished Professor, University of Michigan, Ann Arbor.
2004 Visiting scholar, Centre for Advanced Study, Norwegian Academy of Science and Letters.
2006 Townsend Visitor, University of California, Berkeley.
2006 José Gaos Professor, UNAM, Mexico, 2006.
2007 Tang Chun-I Visiting Professor, Chinese University of Hong Kong.
2013-15 Nelson Visitor, University of Michigan, Ann Arbor.
2016- Visiting professor, now Whitney Griswold Visiting Professor Yale University (5 weeks a year).
Distinctions and awards:
1997- Fellow of the British Academy.
1997- Fellow of the Royal Society of Edinburgh.
2004- Foreign member of the Norwegian Academy of Science and Letters.
2004-5 President of the Aristotelian Society.
2005-7 Vice-President then President of the Mind Association
2007- Foreign honorary member of the American Academy of Arts and Sciences.
2008-13 Vice-President of the British Logic Colloquium.
2009-12 Leverhulme Trust Major Research Fellowship
2013- Member of the Academia Europaea.
2014- Honorary Member of the Royal Irish Academy.
2014- Honorary Fellow, Balliol College, Oxford.
2014-18 Senior Adviser to the Chinese Society for Epistemology
2015 Doctor Honoris Causa, University of Bucharest.
2017- Member of the Institut International de Philosophie.
By far my greatest non-academic accomplishments are my three children Alice, Conrad, and Arno, though I canât take credit for their accomplishments. My wife Ana MladenoviÄ is a Serb; much of our family time is spent in Belgrade and on the Adriatic island of Korcula. Iâm not an accomplished mountaineer, but when I can I like to go up not-too-hard mountains, like Gran Paradiso (Italy), ZuckerhĂŒtl (Austria), Toubkal (Morocco), Kosciusko (Australia), and lots in Scotland and Ireland. For an interview see
I love doing philosophy in a place where it has been studied continuously for over six centuries; when I encounter a frustrating problem in my research, a turn around New College garden often gives me the solution.
Research interests
- Logic: modal logic (the logic of possibility and necessity); epistemic logic (the logic of knowledge); the logic of generalizations over absolutely everything, the nature of logical consequence; the methodology of theory choice in logic.
- Epistemology, the theory of knowledge: âunknown unknownsâ, âknown unknownsâ, and âunknown knownsâ; the nature of knowledge and justification.
- Metaphysics, as based on logic.
- Philosophy of language: the nature of vague language and of slurs.
- Metaphilosophy: the philosophical study of philosophy itself, its nature, methods, and aims.
Selected Major Publications
(for a fuller list see )
Books
- Identity and Discrimination. Oxford: Basil Blackwell, 1990; 2nd ed. 2013.
- Vagueness. London and New York: Routledge, 1994.
- Knowledge and Its Limits. Oxford: Oxford University Press, 2000. Translated into Chinese.
- The Philosophy of Philosophy. Oxford: Blackwell, 2007. Translated into Spanish.
- Modal Logic as Metaphysics. Oxford: Oxford University Press, 2013.
- Tetralogue (Iâm Right, Youâre Wrong). Oxford: Oxford University Press, 2015. Translated into Korean, Chinese, German, Italian, Spanish, Turkish, Persian, Romanian.
- Doing Philosophy: From Common Curiosity to Logical Reasoning. Oxford: Oxford University Press, 2018.
- Suppose and Tell: The Semantics and Heuristics of Conditionals. Oxford: Oxford University Press, 2020.
- (with Paul Boghossian) Debating the A Priori. Oxford: Oxford University Press, 2020.
- P. Greenough and D. Pritchard, eds., Williamson on Knowledge, Oxford: Oxford University Press, 2009.
- M. McCullagh and J. Yli-Vakkuri, eds., Williamson on Modality, Canadian Journal of Philosophy, issues 4-5, vol. 46, and London: Routledge, 2017.
Selected articles
- âMoral anti-exceptionalismâ, to appear in P. Bloomfield and D. Copp (eds.), The Oxford Handbook of Moral Realism, Oxford: Oxford University Press.
- âKnowledge, credence, and strength of beliefâ, to appear in A. Flowerree and B. Reed (eds.), Expansive Epistemology: Norms, Action, and the Social World, London: Routledge.
- âEdgington on possible knowledge of unknown truthâ, to appear in J. Hawthorne and L. Walters (eds.), Conditionals, Probability, and Paradox: Themes from the Philosophy of Dorothy Edgingtonâ, Oxford: Oxford University Press.
- âMore Oxonian scepticism about the a prioriâ, to appear in D. Dodd and E. Zardini (eds.), The A Priori: Its Significance, Grounds, and Extentâ, Oxford: Oxford University Press.
- (with Miroslava Trajkovski), âAbduction, perception, emotion, feeling: body maps and pattern recognitionâ, to appear in Philosophical Perspectives.
- âJustifications, excuses, and skeptical scenariosâ, to appear in J. Dutant and F. Dorsch (eds.), The New Evil Demon, Oxford University Press.
- âThe counterfactual-based approach to modal epistemologyâ, to appear in OtĂĄvio Bueno and Scott Shalkowski (eds.), Routledge Handbook of Modality, London: Routledge.
- âThe KK principle and rotational symmetryâ, Analytic Philosophy (online 2020).
- âNon-modal normativity and norms of beliefâ, Acta Philosophica Fennica, 96 (2020): 101-125 (volume on Normativity, ed. I. Niiniluoto and S. Pihlström).
- âEvidence of evidence in epistemic logicâ, in M. Skipper and A. Steglich-Petersen (eds.), Higher-Order Evidence: New Essays. Oxford: Oxford University Press (2019), 265-297.
- âMorally loaded cases in philosophyâ, Proceedings and Addresses of the American Philosophical Association, 93 (2019): 159-172.
- âCounterpossiblesâ, Topoi, 37 (2018): 357-368.
- âGibbard on meaning and normativityâ, Inquiry, 61 (2018), 731-741.
- âHyman on knowledge and abilityâ, Philosophy and Phenomenological Research, 97 (2018): 243-248.
- âSupervaluationism and good reasoningâ, Theoria, An International Journal for Theory, History, and Foundations of Science, 33 (2018): 521-537.
- âAlternative logics and applied mathematicsâ, Philosophical Issues, 28 (2018): 399-424, edited by Joshua Schechter.
- (with Jason Stanley), âSkillâ, NoĂ»s, 51, 4 (2017): 713-726.
- âSemantic paradoxes and abductive methodologyâ, in Bradley Armour-Garb (ed.), The Relevance of the Liar, Oxford: Oxford University Press, 2017. 325-346.
- âActing on knowledgeâ, in J.A. Carter, E. Gordon, and B. Jarvis (eds.), Knowledge-First, Oxford: Oxford University Press, 2017. 163-181.
- âModel-building in philosophyâ, in Russell Blackford and Damien Broderick (eds.), Philosophyâs Future: The Problem of Philosophical Progress. Oxford: Blackwell-Wiley, 2017: 159-173.
- âDummett on the relation between logics and metalogicsâ, in Michael Frauchiger (ed.), Truth, Meaning, Justification, and Reality: Themes from Dummett (Lauener Library of Analytical Philosophy). Berlin: de Gruyter, 2017. 153-175.
- âAmbiguous rationalityâ, Episteme, 14, 3 (2017): 263-274.
- âKnowing and imaginingâ, in Amy Kind and Peter Kung (eds.), Knowledge through Imagination, Oxford: Oxford University Press, 2016, pp. 113-123.
- âPhilosophical criticisms of experimental philosophyâ, in Justin Sytsma and Wesley Buckwalter (eds.), A Companion to Experimental Philosophy, Oxford: Wiley Blackwell, 2016, pp. 22-36.
- âAbsolute provability and safe knowledge of axiomsâ, in Leon Horsten and Philip Welch (eds.), Gödelâs Disjunction: The Scope and Limits of Mathematical Knowledge, Oxford: Oxford University Press, 2016, pp. 243-253.
- âAbductive philosophyâ, Philosophical Forum, 47, 3-4 (2015): 263-280.
- âA note on Gettier cases in epistemic logicâ, Philosophical Studies, 172 (2015): 129-140.
- âKnowing and believing, acting and intendingâ, Chinese Journal of Philosophy, 42, S1 (2015): 525-539.
- âLogic, metalogic, and neutralityâ, Erkenntnis, 79, 2 (2014): 211-231.
- âVery improbable knowingâ, Erkenntnis, 79, 5 (2014): 971-999.
- âHow did we get here from there? The transformation of analytic philosophyâ, Belgrade Philosophical Annual, 27 (2014): 7-37.
- âGettier cases in epistemic logicâ, Inquiry, 56, 1 (2013): 1-14.
- âHow deep is the distinction between a priori and a posteriori knowledge?â, in A. Casullo and J. Thurow (eds.), The A Priori in Philosophy, Oxford: Oxford University Press, 2013: 291-312.
- âPhilosophical expertise and the burden of proofâ, Metaphilosophy, 42, 3 (2011): 215-29.
- âNecessitism, contingentism and plural quantificationâ, Mind, 119, 475 (2010): 657-748.
- âReference, inference and the semantics of pejorativesâ, in J. Almog and P. Leonardi, eds., The Philosophy of David Kaplan, Oxford: Oxford University Press, 2009: 137-158.
- âConditionals and actualityâ, Erkenntnis, 70, 2 (2009): 135-150.
- âTennantâs troublesâ, in J. Salerno, ed., New Essays on the Knowability Paradox, Oxford: Oxford University Press, 2009: 183-204 .
- âProbability and dangerâ The Amherst Lecture in Philosophy 4 (2009): 1-35.
- âWhy epistemology canât be operationalizedâ, in Q. Smith, ed., Epistemology: New Essays, Oxford: Oxford University Press, 2008: 277-300.
- âOn being justified in oneâs headâ, in M. Timmons, J. Greco and A. Mele, eds., Rationality and the Good: Critical Essays on the Ethics and Epistemology of Robert Audi, Oxford: Oxford University Press, 2007: 106-122.
- âIndicative versus subjunctive conditionals, congruential versus non-hyperintensional contextsâ, in E. Sosa and E. Villanueva, eds., Philosophical Issues, Volume 16: Philosophy of Language, Oxford: Blackwell, 2006: 310-333.
- ââConceptual truthââ. The Aristotelian Society, sup. vol. 80 (2006): 1-41.
- âAbsolute identity and absolute generalityâ, in A. Rayo and G. Uzquiano, eds., Absolute Generality, Oxford: Oxford University Press, 2006: 369-389.
- âStalnaker on the interaction of modality with quantification and identityâ, in J. Thomson and A. Byrne, eds., Content and Modality: Themes from the Philosophy of Robert Stalnaker, New York: Oxford University Press, 2006: 123-147.
- (with Igor Douven), âGeneralizing the Lottery Paradoxâ, British Journal for the Philosophy of Science, 57, 4 (2006): 755-779.
- âCan cognition be factorised into internal and external components?â, in R. Stainton, ed., Contemporary Debates in Cognitive Science, Oxford: Blackwell, 2006: 291-306.
- âArmchair philosophy, metaphysical modality and counterfactual thinkingâ, Proceedings of the Aristotelian Society 105, 1 (2005): 1-23.
- (with Michael Fara), âCounterparts and actualityâ, Mind 114, 453 (2005): 1-30.
- âContextualism, subject-sensitive invariantism, and knowledge of knowledgeâ, Philosophical Quarterly 55, 219 (2005): 213-235.
- âKnowledge, context and the agentâs point of viewâ, in G. Preyer and G. Peter (eds.), Contextualism in Philosophy: Knowledge, Meaning, and Truth, Oxford: Clarendon Press 2005: 91-114.
- (with Claudio Pizzi), âConditional excluded middle in systems of consequential implicationâ, Journal of Philosophical Logic, 34, 4 (2005): 333-362.
- âKnowledge and scepticismâ, in F. Jackson and M. Smith, eds., The Oxford Handbook of Contemporary Philosophy, Oxford: Oxford University Press, 2005: 681-700.
- âPhilosophical âintuitionsâ and scepticism about judgementâ, Dialectica 58, 1 (2004): 109-153.
- âPast the linguistic turn?â, in B. Leiter, ed., The Future for Philosophy, Oxford: Oxford University Press, 2004: 106-128.
- âSome computational constraints in epistemic logicâ, in D. Gabbay, S. Rahman, J. M. Torres and J. P. van Bendegem, eds., Logic, Epistemology and the Unity of Science (Cognitive Science Series), Oxford and Paris: Hermes, 2004: 437-456.
- âEverythingâ, Philosophical Perspectives 17, 1 (2003): 415-465.
- âUnderstanding and inferenceâ, The Aristotelian Society, sup. vol. 77 (2003): 249-293.
- âVagueness in realityâ, in M. Loux and D. Zimmerman, eds., The Oxford Handbook of Metaphysics, Oxford: Oxford University Press, 2003: 690-715.
- (with AgustĂn Rayo), âA completeness theorem for unrestricted first-order languagesâ, in J. C. Beall, ed., Liars and Heaps: New Essays on Paradox, Oxford: Clarendon Press, 2003: 331-356.
- âNecessary existentsâ, in A. OâHear, ed., Logic, Thought and Language (Royal Institute of Philosophy Supplement: 51), Cambridge: Cambridge University Press, 2002: 233-251.
- âVagueness, identity, and Leibnizâs Lawâ, in A. Bottani, M. Carrara and P. Giaretta, eds.,Individuals, Essence and Identity: Themes of Analytic Metaphysics (Topoi Library, vol. 4), Dordrecht: Kluwer, 2002: 273-303.
- (with Jason Stanley), âKnowing howâ, The Journal of Philosophy 98, 8 (2001): 411-444.
- âVagueness, indeterminacy and social meaningâ, in C. Grant and D. McLaughlin, eds., Language-Meaning-Social Construction: Interdisciplinary Studies (Critical Studies, vol. 16), Amsterdam: Rodopi, 2001: 61-76.
- (with Miroslava AndjelkoviÄ), âTruth, falsity and borderline casesâ, Philosophical Topics 28, 1 (2000): 211-244.
- âScepticism and evidenceâ, Philosophy and Phenomenological Research 60, 3 (2000): 613-628.
- âTennant on knowable truthâ, Ratio 13, 2 (2000): 99-114.
- âOn the structure of higher-order vaguenessâ, Mind 108, 429 (1999): 127-143.
- âExistence and contingencyâ, Aristotelian Society, sup. vol. 73 (1999): 181-203.
- âTruthmakers and the converse Barcan formulaâ, Dialectica 53, 3/4 (1999): 253-270.
- (with Nicolao Bonini, Dan Osherson and Riccardo Viale), âOn the psychology of vague predicatesâ, Mind and Language 14, 4 (1999): 377-393.
- âBare possibiliaâ, Erkenntnis 48, 2&3 (1998): 257-273.
- âConditionalizing on knowledgeâ, The British Journal for the Philosophy of Science 49, 1 (1998): 89-121.
- âIterated operatorsâ, in T.J. Smiley, ed., Philosophical Logic, Oxford: Oxford University Press, 1998, Proceedings of the British Academy 95 (1998): 85-133.
- âIndefinite extensibilityâ, in J. Brandl and P. Sullivan, eds., New Essays on the Philosophy of Michael Dummett, Amsterdam and Atlanta GA Rodopi, 1999: 1-24.
- âThe broadness of the mental: some logical considerationsâ, Philosophical Perspectives 12 (1998): 389-410.
- âKnowledge as evidenceâ, Mind 106, 424 (1997): 717-741.
- (with Lloyd Humberstone) âInverses for normal modal operatorsâ, Studia Logica 59, 1 (1997): 33-64.
- (with Claudio Pizzi), âStrong Boethiusâ Thesis and consequential implicationâ, Journal of Philosophical Logic 26, 5 (1997): 569-588.
- âImagination, stipulation and vaguenessâ, in E. Villanueva, ed., Philosophical Issues 8: Truth, Atascadero, CA: Ridgeview, 1997: 215-228.
- âKnowing and assertingâ, The Philosophical Review 105, 4 (1996): 489-523.
- âCognitive homelessnessâ, The Journal of Philosophy 93, 11 (1996): 554-573.
- (with Hyun Song Shin) âHow much common belief is necessary for a convention?â, Games and Economic Behavior 13 (1996): 252-268.
- âThe necessity and determinacy of distinctnessâ, in S. Lovibond and S. Williams, eds., Essays for David Wiggins: Identity, Truth and Value, Oxford: Blackwell, 1996: 1-17.
- âWhat makes it a heap?â, Erkenntnis 44, 3 (1996): 327-339.
- âIs knowing a state of mind?â, Mind 104, 415 (1995): 533-565.
- âDefiniteness and knowabilityâ, Southern Journal of Philosophy 33 (1995, Spindel Conference supplement): 171-191.
- âNon-genuine MacIntosh logicsâ, Journal of Philosophical Logic 23, 1 (1994): 87-101.
- (with Hyun Song Shin) âRepresenting the knowledge of Turing machinesâ, Theory and Decision 37 (1994): 125-146.
- âNever say neverâ, Topoi 13, 2 (1994): 135-145.
- âSome admissible rules in non-normal modal systemsâ, Notre Dame Journal of Formal Logic 34, 3, (1993): 378-400.
- âOn intuitionistic modal epistemic logicâ Journal of Philosophical Logic 21, 1 (1992): 63-89.
- âAn alternative rule of disjunction in modal logicâ, Notre Dame Journal of Formal Logic 33, 1 (1992): 89-100.
- âInexact knowledgeâ, Mind 101, 402 (1992): 217-42.
- âVagueness and ignoranceâ, Aristotelian Society, sup. 66 (1992): 145-162.
- âTwo incomplete anti-realist modal epistemic logicsâ, The Journal of Symbolic Logic 55, 1 (1990): 297-314.
- âFirst order logics for comparative similarityâ, Notre Dame Journal of Formal Logic 29, 4 (1988): 457-481.
- âAssertion, denial and some cancellation rules in modal logicâ, Journal of Philosophical Logic 17, 3 (1988): 299-318.
- âEquivocation and existenceâ, Proceedings of the Aristotelian Society 88 (1987/8): 109-127.
- âKnowability and constructivismâ, The Philosophical Quarterly 38, 153 (1988): 422-432.
- âBivalence and subjunctive conditionalsâ, Synthese 75, 3 (1988): 405-421.
- âInvertible definitionsâ, Notre Dame Journal of Formal Logic 28, 2 (1987): 244-258.
- âAnthropocentrism and truthâ, Philosophia 17, 1 (1987): 33-53.
- âCriteria of identity and the Axiom of Choiceâ, The Journal of Philosophy 83, 7 (1986): 380-394.
- âConverse relationsâ, The Philosophical Review 94, 2 (1985): 249-262.
- âThe infinite commitment of finite mindsâ, Canadian Journal of Philosophy 14, 2 (1984): 235-255.

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