- March, 2017, University of Oxford: debate with Prof. Jeff McMahan on the morality of assisted suicide.
- October, 2016, University of Buckingham, 'Freedom of Dissociation?'
- June 2016, Senate House, London: 'The Great Unifier: Form and the Unity of the Organism' (conference on Biological Identity). The entire talk is viewable here.
- Feb. 2016, University of Mississippi: 'Further Clarity on Cooperation and Morality'
- Jan. 2015, University of California, Irvine: 'The Metaphysics of Moral Behaviour'
- Dec. 2014, Ecole Normale Supérieure, Paris, conference on continuous creation: 'Divine Premotion'
- Nov. 2014, University of Oxford: 'Finality Revived: Powers and Intentionality'
- Sept. 2014, National University of Singapore: 'Finality Revived: Powers and Intentionality'
- June, 2012, Heythrop College, University of London: conference, 'Is There Purpose in the Universe?'
- March, 2012, Wake Forest University, North Carolina: conference on 'Engineering Human Nature and the Future of Human Values'. Speakers include Robert Audi, Paul Churchland, Patricia Churchland, William Hurlbut.
- September 2011, Institut Catholique, Paris: 'Hume, the Occult, and the Substance of the School' (conference on 'The Legacy of David Hume')
- June, 2011, Univ. of Hertfordshire: 'Disembodied Communication and Religious Experience: The Online Model'; workshop on 'Personal Identities after the Information Revolution', part of an AHRC-funded project on 'The Construction of Personal Identities Online'.
- November 2010, Univ. of Hertfordshire: 'Morality, Religion, and Cosmic Justice'
- June-July 2010, Charles University, Prague: 'Essence and Properties'
- March 2010, King's College, London: 'Why I am not a Consequentialist'
- March 2010, Rewley House, Univ. of Oxford: two lectures on Aquinas
- February 2010, Christ Church, Oxford: 'Appearance and Reality: What Plato can Teach Journalists and the Media' (seminar series 'The Public Responsibility of the Media', organized by Reuters Institute of Journalism and McDonald Centre for Theology, Ethics, and Public Life)
- November 2009, University of Leipzig: on essentialism
- May 2009, Butler Society, Oriel College, Oxford: on the First Way (Audio of the talk)
- February 2009, Southampton: on Peter Singer's bioethics
- October 2008, Oxford: 'The Individuality of the Embryo' (student-sponsored event)
- May 2008, University of Exeter: on concepts and dualism
- April 2008, King's College, London, workshop on philosophy of religion: on Kenny on the First Way
- September 2007, Catholic University of Valencia: lectures on consequentialism and on euthanasia.
- October 2007, University of Birmingham conference: Nature and its Classification, 'The Nature and Classification of Life'
- August 2007, Princeton: Witherspoon Institute Thomistic Seminar; classes for graduate students on essentialism, teleology, dualism, and natural law
- May 2007, University of Lisbon: lectures on consequentialism and euthanasia
- April 2007, Georgetown: 'The Structure of Essence'; workshop on double effect
- December 2006, Princeton: 'Why Peter Singer is Wrong' (student-sponsored event)
- December, 2006, University of Sussex: 'Teleology: Inorganic and Organic'
- March, 2006: University of Navarra, Spain: natural law
- January, 2006: University of Oxford Moral Philosophy Seminar , 'The Metaphysical Foundations of Natural Law'
- September, 2005: Catholic University of America, Washington, DC: 'The Metaphysical Foundations of Natural Law'
- June, 2005: Address to the International Society for Stem Cell Research, San Francisco, on the ethics of human embryonic stem cell research
- May, 2005: Public debate with Prof. Julian Savulescu at the National Portrait Gallery, London, sponsored by The Times Higher, on the ethics of cloning; accompanying article in the Higher available below.
- April, 2005: State University of Valencia, Spain, and Catholic University of Valencia - papers on dualism and on natural law theory
- November, 2004: 'Ordinary and Extraordinary Means', conference on Ethical Issues in Intensive Care, at the University of Reading, in conjunction with the Royal Berkshire Hospital
- November, 2004, University of Saarbrücken: 'A Defence of an Aristotelian/Thomistic Account of Personal Identity'
- June, 2004: University of Brighton: 'Why You Should be a (Certain Kind of) Dualist'
- April, 2004: Bowling Green State University, conference on Personal Identity at the Social Philosophy and Policy Center: 'Hylemorphic Dualism'
- June, 2003: Royal Academy of Arts, Piccadilly, London: 'Perennial Philosophy's Theory of Art'
- July-August, 2003: Visiting Scholar at Bowling Green State University, Ohio, Social Philosophy and Policy Center
- 2003: Royal Institute of Philosophy Annual Lecture Series, Modern Moral Philosophy: 'The Ethics of Co-operation in Wrongdoing'
- November, 2001: American Academy of Religion Annual Meeting: on the Kalam Cosmological Argument (in debate with Wes Morriston)
- October, 2001: Philosophical Society, Oxford: temporal parts and change