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Just War and Unjust Soldiers: American Public Opinion on the Moral Equality of Combatants

Published online by Cambridge University Press:  06 December 2019


Traditional just war doctrine holds that political leaders are morally responsible for the decision to initiate war, while individual soldiers should be judged solely by their conduct in war. According to this view, soldiers fighting in an unjust war of aggression and soldiers on the opposing side seeking to defend their country are morally equal as long as each obeys the rules of combat. Revisionist scholars, however, maintain that soldiers who fight for an unjust cause bear at least some responsibility for advancing an immoral end, even if they otherwise fight ethically. This article examines the attitudes of the American public regarding the moral equality of combatants. Utilizing an original survey experiment, we find that the public's moral reasoning is generally more consistent with that of the revisionists than with traditional just war theory. Americans in our study judged soldiers who participate in unjust wars as less ethical than soldiers in just wars, even when their battlefield conduct is identical, and a large proportion supported harsh punishments for soldiers simply for participating in unjust wars. We also find, however, that much of the American public is willing to extend the moral license of just cause significantly further than revisionist scholars advocate: half of the Americans in our survey were willing to allow an unambiguous war crime—a massacre of innocent women and children—to go unpunished when the act was committed by soldiers fighting for a just cause. Our findings suggest that incorporation of revisionist principles into the laws of war would reinforce dangerous moral intuitions encouraging the killing of civilians.

Symposium: Just War and Unjust Soldiers
Copyright © Carnegie Council for Ethics in International Affairs 2019

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5 Ibid., p. 39.

6 McMahan, Killing in War, p. 104.

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9 Jeff McMahan, “Rethinking the ‘Just War,’ Part 2,” New York Times, November 12, 2012,

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13 The margin of error for the entire sample is + / –4 percent.

14 Walzer, Just and Unjust Wars, p. 136.

15 Ibid., p. 127.

16 Ibid., p. 39.

17 William Shakespeare, quoted in ibid, p. 39.

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26 See Blum, Gabriella, “The Dispensable Lives of Soldiers,” Journal of Legal Analysis 2, no. 1 (2010)CrossRefGoogle Scholar. Here, Blum extends this argument even further, contending that combatants who pose no threat should be immune from attack and that the principle of military necessity ought to apply to decisions to kill enemy soldiers.

27 McMahan, Jeff, “The Ethics of Killing in War,” Ethics 114, no. 4 (July 2004), p. 718CrossRefGoogle Scholar.

28 McMahan, “Rethinking the ‘Just War.’”

29 McMahan, Killing in War, p. 108.

30 McMahan, “The Ethics of Killing in War,” p. 730.

31 Jeff McMahan, “The Morality of War and the Law of War,” in Rodin and Shue, Just and Unjust Warriors, p. 29.

32 See Sagan, Scott D. and Valentino, Benjamin A., “Not Just a War Theory: American Public Opinion on Ethics in Combat,” International Studies Quarterly 62, no. 3 (September 2018), pp. 548–61CrossRefGoogle Scholar. Sagan and Valentino's study focuses on American public opinion on the just war principles of proportionality, discrimination, and due care.

33 Los Angeles Times, Los Angeles Times Poll #243: War against Iraq—One Month Anniversary, USLAT1991-243, version 2 (Los Angeles: Los Angeles Times, 1991), USLAT.243.R25 (question number), Roper Center for Public Opinion Research, Cornell University,

34 Los Angeles Times, Los Angeles Times/Bloomberg News Poll: George W. Bush/Congress/War in Iraq, USLAT2006-534 (New York: Bloomberg News, 2006), USLAT.092006.R47 (question number), Roper Center for Public Opinion Research, Cornell University,

35 All the results presented in this paper are weighted to match the age, gender, race, and education statistics of the American population by YouGov. See Doug Rivers, “Pew Research: YouGov Consistently Outperforms Competitors on Accuracy,” YouGov, May 13, 2016,

36 Ansolabehere, Stephen and Schaffner, Brian F., “Does Survey Mode Still Matter? Findings from a 2010 Multi-Mode Comparison,” Political Analysis 22, no. 3 (Summer 2014), pp. 285303CrossRefGoogle Scholar; Yeager, David S., Krosnick, Jon A., Chang, LinChiat, Javitz, Harold S., Levendusky, Matthew S., Simpser, Alberto, and Wang, Rui, “Comparing the Accuracy of RDD Telephone Surveys and Internet Surveys Conducted with Probability and Non-Probability Samples,” Public Opinion Quarterly 75, no. 4 (Winter 2011), pp. 709747CrossRefGoogle Scholar.

37 All original stories used in our survey from which quotes were taken can be found in the appendix at the end of the article.

38 The full text of all news stories, complete survey question wording, and replication data are available from the Harvard Dataverse,

39 It is possible that some subjects could have concluded that Eastland's counterattack was also unjust if they did not accept that the Westrian invasion gave Eastland a just cause for war. For example, some subjects may have felt that Eastland's counterattack was not a necessary or proportionate response to Westria's seizure of Eastland's territory and oil fields. Although this seems unlikely, a few scholars, such as Rodin (see War and Self-Defense, pp. 127–38), do contend that even an unprovoked military invasion of national territory does not always justify the use of force in self-defense (for a counterargument, see Steinhoff, Uwe, “Rodin on Self-Defense and the ‘Myth’ of National Self-Defense: A Refutation,” Philosophia 41, no. 4 [December 2013], pp. 1017–36CrossRefGoogle Scholar). Empirically, our results confirm that a large majority of subjects did perceive Eastland's counterattack as just. Indeed, more than five times as many subjects agreed that Eastland was justified in its counterattack than thought Eastland was justified when it launched an unprovoked attack on Westria. To the extent that some subjects believed that Eastland's counterattack was unnecessary or disproportionate, however, our results should be considered conservative.

40 The analyst's statement that the troops would “fight hard and do whatever is asked of them” was included in the conditions of both the conscripts and volunteers to ensure that subjects would not assess Eastland's chances of winning differently across the conditions.

41 Although these conditions might appear to be double-barreled, we included a mention of conscription and the degree of Eastland's soldiers’ enthusiasm for the war in order to signal whether Eastland's soldiers have moral agency or are compelled to fight regardless of their personal feelings about the war. Thus, although the comparison between condition C and condition A cannot isolate the effect of conscription from the effect of soldiers’ beliefs in the war, it does allow us to isolate the effect of moral agency of Eastland's soldiers on the public's ethical assessments of the soldiers’ behavior.

42 Subjects who failed the manipulation check were asked to read the story again. On average, 84 percent of subjects answered the manipulation check correctly on the first attempt and all subjects answered it correctly on the second attempt.

43 Although we cannot rule out the possibility that some subjects believed that the unenthusiastic conscripts had a special responsibility not to participate in an unjust war, this kind of moral reasoning would not be consistent with revisionist theory. Future research could explore the relationship between soldiers’ enthusiasm for the war's cause and public views about soldiers’ moral culpability.

44 There were no statistically significant differences on this question between relevant conditions.

45 Since we expected subjects’ beliefs that soldiers behaved unethically to correlate with higher support for legal punishments, we coded “not ethical” using the reverse scale of the dependent variable used in figures 2, 3, and 4.

46 In the just war condition (E), 43 percent of subjects preferred no form of punishment at all, compared to 18.5 percent who preferred no punishment in the unjust war condition (D). In both conditions, more than 80 percent of subjects who supported executing the soldiers who had committed the war crimes also supported prison terms. The small number of subjects who supported execution but not prison sentences may have felt that prison was not a sufficient punishment for participating in war crimes.

47 Crawford, Neta C., “Individual and Collective Moral Responsibility for Systemic Military Atrocity,” Journal of Political Philosophy 15, no. 2 (April 2007), p. 188CrossRefGoogle Scholar.

48 Approximately half of these subjects, however, also indicated that they believed that Eastland's war was unjust, roughly twice the percentage of those who did not support prison for leaders and soldiers in this condition.

49 Unsurprisingly, subjects who supported the death penalty were significantly more likely to approve of executing the soldiers who committed war crimes in condition D.

50 Liberman, Peter, “An Eye for an Eye: Public Support for War against Evildoers,” International Organization 60, no. 3 (Summer 2006), pp. 687722CrossRefGoogle Scholar; and Sagan and Valentino, “Revisiting Hiroshima in Iran,” pp. 41–79.

51 For research on vicarious retribution, see Liberman, Peter and Skitka, Linda, “Vicarious Retribution in US Public Support for War against Iraq,” Security Studies 28, no. 2 (January 2019), pp. 189215CrossRefGoogle Scholar; and Lickel, Brian, Miller, Norman, Stenstrom, Douglas M., Denson, Thomas F., and Schmader, Toni, “Vicarious Retribution: The Role of Collective Blame in Intergroup Aggression,” Personality and Social Psychology Review 10, no. 4 (November 2006), pp. 372–90CrossRefGoogle ScholarPubMed.

52 See Greene, Joshua, Moral Tribes: Emotion, Reason, and the Gap between Us and Them (New York: Penguin, 2013)Google Scholar; and Haidt, Jonathan, The Righteous Mind: Why Good People Are Divided by Politics and Religion (New York: Pantheon, 2012)Google Scholar.

53 Greene, Joshua D., “Beyond Point-and-Shoot Morality: Why Cognitive (Neuro)Science Matters for Ethics,” Ethics 124, no. 4 (July 2014), pp. 695–96CrossRefGoogle Scholar.

54 Herrmann, Richard K., Voss, James F., Schooler, Tonya Y. E., and Ciarrochi, Joseph, “Images in International Relations: An Experimental Test of Cognitive Schemata,” International Studies Quarterly 41, no. 3 (September 1997), pp. 403–33CrossRefGoogle Scholar.

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56 Benbaji, Yitzhak, Falk, Amir, and Feldman, Yuval, “Commonsense Morality and the Ethics of Killing in War: An Experimental Survey of the Israeli Population,” Law & Ethics of Human Rights 9, no. 2 (November 2015)CrossRefGoogle Scholar.

57 Gallup, Gallup/Newsweek Poll #1971-7145: Calley Trial, USAIPOSPGONEW1971-7145, version 3 (Washington, D.C.: Gallup, 1971), USGALNEW.71CLLY.R1 (question number), Roper Center for Public Opinion Research, Cornell University,

58 Louis Harris & Associates, Harris survey (Rochester, N.Y.: Louis Harris & Associates, 1971), forthcoming survey (31107588), Roper Center for Public Opinion Research, Cornell University. Only 53 percent of respondents said he was not justified (12 percent chose “Not sure”).

59 Gary Jonathan Bass, Stay the Hand of Vengeance: The Politics of War Crimes Tribunals (Princeton, N.J.: Princeton University Press, 2000).

60 Gallup, Gallup/CNN/USA Today Poll: Congress/Bush/War in Afghanistan/Enron/Business/Slavery, USAIPOCNUS2002-03 (Washington, D.C.: Gallup, 2002), USGALLUP.02JA25.R18, USGALLUP.02JA25.R19 (question numbers), Roper Center for Public Opinion Research, Cornell University,

61 McMahan, Jeff, “On the Moral Equality of Combatants,” Journal of Political Philosophy 14, no. 4 (November 2006), pp. 392–93CrossRefGoogle Scholar.

62 Lazar, “Responsibility Dilemma for Killing in War,” p. 188.

63 George C. Marshall, quoted in Luke Mogelson, “A Beast in the Heart of Every Fighting Man,” New York Times, April 27, 2011,

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