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Liability and Just Cause

  • Thomas Hurka


This paper is a response to Jeff McMahan‘s “Just Cause for War” (Ethics & International Affairs 19, 2005). McMahan holds, as many have, that there is a just cause for war against group X only if X have made themselves liable to military force by being responsible for some serious wrong. But he interprets this liability requirement in a very strict way. He insists (1) that one may use force against X for purpose Y only if they are responsible for a wrong specifically connected to Y; and (2) that one may use force against an individual member of X only if he himself shares in the responsibility for the wrong. This paper defends a more permissive, and more traditional, view of just war liability against McMahan's claims. Against McMahan‘s first claim it argues that certain “conditional just causes,” such as disarming an aggressor, deterring future aggression, and preventing lesser humanitarian crimes, can be legitimate goals of war against X even if X have no specific liability connected to them. Against McMahan's second claim it argues that soldiers who have no responsibility for X‘s wrong may nonetheless be legitimately attacked because in becoming soldiers they freely surrendered their right not to be killed by enemy combatants in a war between their and another state, so killing them in such a war is not unjust. Though initially a criticism of McMahan, the paper makes positive proposals about conditional just causes and the moral justification for directing force at soldiers.



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1 Jeff McMahan, “Just Cause for War,” Ethics & International Affairs 19, no. 3 (Fall 2005), pp. 1–21; available at http:\\

2 McMahan notes that in some admittedly unusual circumstances a war can lack a just cause, and so be unjust, but nonetheless be morally permissible. I ignore this possibility in this paper.

3 Closely related to these is the reasonable hope of success condition, but as McMahan notes, it can be subsumed under the proportionality condition. On this, see also Thomas Hurka, “Proportionality in the Morality of War,” Philosophy and Public Affairs 33 (2005), p. 37.

4 Jeff McMahan and Robert McKim, “The Just War and the Gulf War,” Canadian Journal of Philosophy 23 (1993), pp. 502–06.

5 Could McMahan hold that the underlying tendency is itself a ground of liability? That would be massively permissive, allowing war when there has been neither any actual aggressive act nor even any intention to perform one.

6 Note that the liability is only more, and not completely, global. While one may imprison a criminal, one may not torture him, use him without his consent in medical experiments, and so on. This parallels the way in which, in just war theory, a state's providing an independent just cause by, say, aggressing, permits other states to seek some goals, such as deterrence, by war against it, but not to pursue others, such as increasing GDP or stimulating art. There too the liability is only more, but not completely, global.

7 G. E. Moore, Principia Ethica (Cambridge: Cambridge University Press, 1903), pp. 27–36; see also Shelly Kagan, “The Additive Fallacy,” Ethics 99 (October 1988), pp. 5–31.

8 Given this condition, the lesser humanitarian wrongs that provide conditional just causes will be situated between two thresholds. They will be below the threshold for being an independent just cause but above the threshold that determines when a humanitarian wrong can be another state's legitimate business.

9 See, e.g., A. C. Ewing, The Morality of Punishment (London: Kegan Paul, Trench, Trubner & Co., 1929).

10 Michael Walzer, Just and Unjust Wars, 2nd ed. (New York: Basic Books, 1992), pp. 34–37; see also Paul Christopher, The Ethics of War and Peace, 2nd ed. (Upper Saddle River, N.J.: Prentice-Hall, 1998), p. 25.

11 Jeff McMahan, “The Ethics of Killing in War,” Ethics 114 (2004), pp. 723–25.

12 See, e.g., Thomas Nagel, “War and Massacre,” Philosophy and Public Affairs 1 (Winter 1972), pp. 139–40; Anthony Kenny, The Logic of Deterrence (London: Firethorn Press, 1985), p. 10; and Walzer, Just and Unjust Wars, pp. 43, 145, n. 145.

13 Walzer, Just and Unjust Wars, p. 145.

14 Christopher, The Ethics of War and Peace, p. 126, n. 23.

15 Robert Nozick, Anarchy, State, and Utopia (New York: Basic Books, 1974), p. 331; and Joel Feinberg, “Voluntary Euthanasia and the Inalienable Right to Life,” Philosophy and Public Affairs 7 (Winter 1978), pp. 122–23.

16 Feinberg, “Voluntary Euthanasia and the Inalienable Right to Life,” pp. 114–18; Feinberg emphasizes this distinction before expressing his skepticism about whether any rights are inalienable.

17 Walzer, Just and Unjust Wars, p. 145.

18 Asa Kasher and Amos Yadlin, “The Military Ethics of Fighting Terror: An Israeli Perspective,” Journal of Military Ethics 4 (2005), p. 17. This is not the only reason they give. They also argue that a state's soldiers deserve priority just as citizens of the state, and that the responsibility for any civilians’ deaths during antiterrorist operations belongs primarily to the terrorists who brought the combat into the civilians’ vicinity (pp. 17–18). But they do not explain how large a role these different reasons play in justifying their final ordering.

19 Jeff McMahan, “The Ethics of Killing in War: The Uehiro Lectures 2006,” Lecture 1, “Unjust Warfare,” p. 6 (forthcoming).

20 1977 Geneva Protocol I Additional to the Geneva Conventions of 12 August, 1949, and Relating to the Protection of Victims of International Armed Conflicts, Art. 51 (5) (b), in Adam Roberts and Richard Guelff, eds., Documents on the Laws of War, 3rd ed. (Oxford: Oxford University Press, 2000), p. 449.

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Ethics & International Affairs
  • ISSN: 0892-6794
  • EISSN: 1747-7093
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