¹ A recent example was presented by Michael Walzer in Just and Unjust Wars: A Moral Argument with Historical Illustrations, 3rd ed. (New York: Basic Books, 2000). According to Walzer, the “first principle of the war convention is that, once war has begun, soldiers are subject to attack at any time (unless they are wounded or captured)” (p. 138). This represents the standard view of the modern just war tradition, and it corresponds well with current international law.

² Walzer, Just and Unjust Wars, p. 41. According to Walzer there is no license for war-makers, yet he maintains that “there is a license for soldiers, and they hold it without regard to which side they are on; it is their first and foremost war-right” (p. 36).

³ This accords with what Jeff McMahan has labeled the “Orthodox View” in “Innocence, Self-Defense, and Killing in War,” Journal of Political Philosophy 2, no. 3 (1994), p. 195.

⁴ For the view that rights are claims against others, see Ronald Dworkin, Taking Rights Seriously (Cambridge: Harvard University Press, 1977), p. 188, who argues that “most cases when we say that someone has a ‘right’ to do something, we imply that it would be wrong to interfere with his doing it, or at least that some special grounds are needed for justifying any interference.” For a treatment of rights as claims and privileges, see Wesley Newcomb Hohfeld, Fundamental Legal Conceptions as Applied in Judicial Reasoning, Walter Wheeler Cook, ed. (New Haven: Yale University Press, 1966), pp. 35–50.

⁵ McMahan, “Innocence, Self-Defense, and Killing in War,” p. 198.

⁶ See, for example, McMahan, “Innocence, Self-Defense, and Killing in War”; Jeff McMahan, “The Ethics of Killing in War,” Ethics 114, no. 4 (2004); Richard Norman, Ethics, Killing and War (Cambridge: Cambridge University Press, 1995); and David R. Mapel, “Innocent Attackers and Rights of Self-Defense,” Ethics & International Affairs 18, no. 1 (2004).

⁷ Walzer, Just and Unjust Wars, p. 41.

⁸ One could, perhaps, remedy some of these unwelcome consequences by punishing only a low percentage of the culpable unjust soldiers by using a random selection mechanism.

⁹ It may pay to observe that although the soldiers in question might be innocent enough to escape punishment, they might very well be responsible enough in the sense that they ought to take the brunt of the unfortunate situation they have created. Excuses may have different purposes.

¹⁰ David Rodin, “Beyond National Defense,” Ethics & International Affairs 18, no. 1 (2004), p. 95.

¹¹ The right to resort to armed force in the just war tradition has been defined through seven moral concepts: just cause, competent authority, right intention, reasonable hope of success, overall proportionality of good over harm, last resort, and the goal of peace (see James Turner Johnson, Morality and Contemporary Warfare [New Haven: Yale University Press, 1999], pp. 27–38). The observation that people can form private armies indicates that the requirement of right authority should be given up. The focus on right intention on the part of the agent is misleading as well, but is not something I take up in discussion here.

¹² Jeff McMahan, “War as Self-Defense,” Ethics & International Affairs 18, no. 1 (2004), p. 75.

¹³ See Jeff McMahan, “Self-Defense and the Problem of the Innocent Attacker,” Ethics 104 (1994), p. 288.

¹⁴ Mapel, “Innocent Attackers and Rights of Self-Defense,” p. 81.

¹⁵ Ibid., p. 83.

¹⁶ For an earlier account of this proposal, see my “Self-Defense Among Innocent People,” Journal of Moral Philosophy 2, no. 2 (2005).

¹⁷ See Walzer, Just and Unjust Wars, p. 127.

¹⁸ Ibid.

¹⁹ Be aware that no situation of duress generates a right to wrong by the person exposed to it. Although A threatens to kill B or his children unless B kills C, B has not thereby obtained a right to kill C, and C clearly has a right to defend herself.

²⁰ For a similar view, see Mapel, “Innocent Attackers and Rights of Self-Defense,” p. 83. For an opposite view, see David Rodin, War and Self-Defense (Oxford: Oxford University Press, 2002), pp. 88–99.

²¹ Rodin, War and Self-Defense, p. 88.

²² People lacking the required mental capacity to evaluate their actions can be regarded as innocent aggressors or threats, depending on their level of incapacity.

²³ As for innocent threats, there might be reasons for singling out innocent threats who ultimately have become threats through responsible actions—for instance, by taking up driving and thereby taking the risk of becoming a threat to others if one's brakes fail, and those who have done nothing to become a threat to others (see Jeff McMahan, “The Ethics of Killing in War,” and “The Basis of Moral Liability to Defensive Killing,” Philosophical Issues 15 [2005]). To support this view, imagine that you can survive by killing either of two people. One is an innocent threat hurtling toward you in his car; the other is an innocent threat being thrown against you. In this case, one better kill the person in the car. Imagine next, however, that one is an innocent aggressor who falsely but reasonably believes that he must kill you in order to save others; the other is again an innocent threat being thrown against you. In this case, McMahan's view seems to propose that you better kill the innocent aggressor. That seems wrong. There should be no reason for you to choose to kill the one rather than the other; deciding by a coin toss could be appropriate.

²⁴ By saying that we should give priority to the defending party when there is a question of equal harm, I take it to mean that it is permissible to use (proportional) defensive force against the initiator; that if the defending party acts for the right reason he or she is justified in doing so; and that third parties would have to intervene on the side of the defending party.

²⁵ This third goal could admittedly be achieved by taking an expansive conception of responsibility—for example, by saying that those who initiate a threat are not fully innocent unless they have taken every reasonable precaution against becoming initiators, and saying further that only fully innocent initiators are without liability. This would give people the same incentive to take all reasonable precautions not to become initiators, and would treat only those who have done so as innocent. I owe this observation to Jeff McMahan.

²⁶ There could be, if some parties had such a high probability of ending up among the initiators that the contractual reasons alluded to would not suffice to give them reason to support a rule that gave priority to the defendant. That procedure is only in the interest of all participants if it increases the survival chance for all. If that were not the case, a second-best option for all participants would be a coin toss.

²⁷ For a related discussion, see McMahan, “Self-Defense and the Problem of the Innocent Attacker,” p. 281.

²⁸ I have the term “culpable cause” from McMahan, “Self-Defense and the Problem of the Innocent Attacker.”

²⁹ We should also observe that some features that help excuse soldiers do not excuse civilians. Civilians do not, for example, tend to be young and uneducated, nor do they vote under duress.

³⁰ See Gerhard Øverland, “Killing Civilians,” European Journal of Philosophy 13, no. 3 (2005).

³¹ One might wonder why third parties should assist at all. Why not simply let sleeping dogs lie? Well, we might imagine that if they do not intervene all four will be killed.

³² See George Fletcher, “The Individualization of Excusing Conditions,” in Michael Louis Corrado, ed., Justification and Excuse in the Criminal Law (New York: Garland Publishing, 1994), p. 145.

³³ Roderick T. Long, “The Irrelevance of Responsibility,” in Ellen F. Paul, Fred D. Miller, and Jeffrey Paul, eds., Responsibility (Cambridge: Cambridge University Press, 1999), pp. 145, 125.

³⁴ It might, as well, look as if we have a reason to accept more harm to innocent third parties when attempting to prevent innocent aggressors without killing them, than when the aggressors are culpable.

³⁵ Be aware that accepting that soldiers have an equal right to kill does not imply that one holds that soldiers always have a right to kill other soldiers. Necessity and proportionality may very well make it impermissible to do so. Proponents of an equal right to kill may therefore also regret that “the Iraqi army disintegrated in a chaotic retreat from Kuwait, and were mown down by Allied air strikes as they retreated. Iraqi military casualties were estimated by the U.S. Defense Intelligence Agency to be between 50, 000 and 150, 000” (Norman, Ethics, Killing and War, p. 202).

³⁶ Observe that even though you might not think soldiers in general should be deemed fully innocent, you might accept that they should be judged innocent to such a degree that it will have implications for what permissibly may be done toward them as partially excused aggressors.