Jeff McMahan

McMahan's main contributions to just war theory are made in his book Killing in War (OUP, 2009), which argues against foundational elements of the traditional theory of the just war theory. Against Michael Walzer, he claims that those who fight an unjust war can never meet the requirements of jus in bello.

McMahan has written extensively on normative and applied ethics, especially on bioethics and just war theory. His main work in bioethics include The Ethics of Killing: Problems at the Margins of Life (Oxford University Press, 2002). The book includes five parts, about identity, death, killing, the beginning of life and the end of life. In its first part, McMahan defends a mixed view of personal identity, claiming that individuals are what he calls "embodied minds". In the following parts, he claim that the badness of death and the wrongness of killing depends on our interest in living. He also defends what he calls a "time-relative interest account of living". According to his view, our interest in living depends on our psychological connection to our future selves at each time.

McMahan has also co-edited the books The Morality of Nationalism (with Robert McKim, OUP, 1997), and Ethics and Humanity (with Ann Davis and Richard Keshen, OUP, 2010). In the early 80's, he wrote two books about the political situation at the time: British Nuclear Weapons: For and Against (London: Junction Books, 1981, which included a preface by Bernard Williams), and Reagan and the World: Imperial Policy in the New Cold War (London: Pluto Press, 1984). In more recent times, he has also done work on effective altruism. He is on the editorial board of The Journal of Controversial Ideas.

He taught at the University of Illinois, Urbana-Champaign (1986–2003) and at Rutgers University (2003–2014).

McMahan completed a B.A. degree in English literature at the University of the South (Sewanee). He completed a second B.A. degree in Philosophy, Politics, and Economics then did graduate work in philosophy at Corpus Christi College, Oxford as a Rhodes Scholar. He then earned his M.A. at the University of Oxford. He was offered a research studentship at the St. John's College, Cambridge from 1979 to 1983. He studied first under Jonathan Glover and Derek Parfit at the University of Oxford and was later supervised by Bernard Williams at the University of Cambridge, where he was a research fellow of St. John's College from 1983 to 1986. He received his doctorate in 1986. His thesis title was Problems of Population Theory.

Jefferson Allen McMahan (/m ə k ˈ m ɑː n / ; born 30 August 1954) is an American philosopher. He has been White's Professor of Moral Philosophy at the University of Oxford since 2014.