Known for his philosophical writings on identity, metaphysics, and morality, he argued for objective morality in a 2006 publication titled Ethics: Twelve Lectures on the Philosophy of Morality.
During his time at Brasenose College, University of Oxford, he was tutored by classical scholar and philosopher J. L. Ackrill.
His full-length published works include such titles as Identity and Spatio-Temporal Continuity and Sameness and Substance.
A native of England, he taught at the University of Oxford and presided over the Aristotelian Society in London.
He and American philosopher Richard Brandt both wrote numerous essays on the subject of morality.