- Honorary Research Fellowship in Theology and Religious Studies, University of Bristol (from 2010)
- Professor of Philosophy, University of Liverpool (from 1984 to 2009)
- Lecturer in Moral Philosophy, University of Glasgow (from 1974 to 1983)
- Quondam Fellow, All Souls College (from 1975)
- Prize Fellow, All Souls College (from 1968 to 1975)
- Undergraduate, Balliol College, Oxford (from 1965 to 1968)
- Plotinus
- Animals
- Science Fiction
- Philosophy of Religion
- Plotinus: Myth, Metaphor and Philosophical Practice (University of Chicago Press: Chicago 2016), xxii + 344pp
- Can We Believe in People: human significance in an interconnected cosmos (Angelico Press: New Hampshire 2020)
- Plotinus: Ennead VI.9: translation and commentary (Parmenides Press, 2020)
- Cities and Thrones and Powers: towards a Plotinian Politics (Angelico Press: New Hampshire 2022), xix + 305pp
- How the Worlds Became: philosophy and the oldest stories (Angelico Press: New Hampshire, 2023), x + 327pp
- G.K. Chesterton: Thinking Backwards, Looking Forwards (Templeton Foundation Press: West Conshohocken, PA 2006), 256pp
- Understanding Faith: Religious Belief and its Place in Society (St Andrews studies in Philosophy and Public Affairs, Imprint Academic 2009), vi-280pp
- Philosophical Futures (Peter Lang: Frankfurt 2011), 248pp
- Ancient Mediterranean Philosophy (Continuum: London 2013), xiv+246pp