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ABSTRACT
Proportionality has long been considered a pillar of just war theory, requiring that the goods achieved in an action outweigh the collateral harms it causes. In this article, I argue that the in bello principle of proportionality cannot serve its intended function of limiting the destructiveness of actions during war. I illustrate the features of war that make the in bello proportionality constraint not merely impossible to follow, but perhaps even self-defeating. I conclude by suggesting ways in which theorists and policymakers concerned with justice in war might attempt to respond to this dilemma.
Acknowledgements
I would like to thank the editors and anonymous reviewers at JME for their insightful comments and suggestions. I would also like to thank the Michael Zuckert, Matthew Hartman, Robert Wyllie, Robert Burton, and Catherine Sims Kuiper for their feedback on earlier versions of this article.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Notes
1 For instance, those used as human shields now enjoy the same status as other civilians when determining proportionality. In addition, the update included new procedures to minimize civilian casualties, such as providing warnings that an attack is coming.
2 As will become apparent, this critique does not apply to ad bellum proportionality. For a good discussion of the difficulties involved in applying that principle, Brown (Citation2011).
3 Unless otherwise noted, subsequent use of the term “proportionality” refers specifically to the consideration of in bello proportionality. For reasons that should become clear, the problem with in bello proportionality discussed in this article does not necessarily implicate its ad bellum counterpart.
4 Although, perhaps not as old as just war thinking itself. Rory Cox (Citation2017) illustrates how ancient Egyptian doctrines of just war placed such overwhelming emphasis on ius ad bellum that no room was left for ius in bello doctrines like proportionality.
5 Cf. Guelff and Roberts Citation1982, 416.
6 McMahan at times distinguishes between the doctrine of proportionality and what he calls the “requirements of minimal force”. However, McMahan himself admits that in war the requirements of proportionality and minimal force blur together (McMahan Citation2009, 23). For the purposes of this argument, I make no distinction between the two.
7 By this, I do not mean to reduce the idea of proportionality to a simple matter of box-ticking. Many reasonably take the purpose of just war theory to be the raising of important questions and issues as starting points to guide the thinking of combatants and policymakers. However, even if one takes this approach to just war theory, just war theorists must make sure that their questions are useful and coherent ones—rather than inherently contradictory. Otherwise, they are unhelpful as guides to thought or action.
8 Cf. Guelff and Roberts (Citation1982), 422-423, 449.
9 See also Fabre (Citation2012).
10 See Lazar (Citation2017) for an account of the general state of the debate between these two strains of just war thinking.
11 See also Lazar (Citation2017, 46).
12 I assume for the purposes of argument that the combatants are adhering to all other elements of just war theory (this is a legitimate target, in service of just ends, undertaken under legitimate authority, etc.).
13 For instance, McMahan (Citation2009, 19, 224-225) and Walzer (Citation2006, 276–277) both introduce special considerations for calculating this, but they do not seem to disagree about the basic logical structure of the doctrine.
14 Although we do not yet have the benefit of retrospect and hindsight to say with certainty, a similar dynamic might be found in the American and allied efforts against ISIS and other terror groups.
15 This is supported by McCarthy’s account of NATO’s campaign in Bosnia. Once Milosevic realized NATO’s rules of engagement, he exploited them by stationing valuable targets in civilian areas—thus prolonging the war by relying on NATO’s self-restraint. More recently, Hamas has been accused by some of using human shields to protect important military targets.
16 One of the most thorough treatments of just war from the perspective of individual human rights is Draper (Citation2015).
17 This is the upshot of ad bellum proportionality considerations. If the victory in the just war is not a very great good—then the whole war fails to be proportional. See Brown (Citation2011).
18 Cox suggests that ancient Egyptian just war theory recognized that ad bellum considerations can work at cross-purposes with in bello restraint (Cox Citation2017, 381).
19 This is assuming the conditions in the previous paragraph are met, i.e., that increased levels of destructive force do make success more likely. In those cases where this does not hold, it is once again not proportionality but some other consideration that does the work of restraint.
20 Moreover, the previous constraints were already quite restrictive, as Crawford (Citation2013, 151–216) demonstrates.
21 Although otherwise a defender of a more traditional just war theory, Walzer also carves out an exception he calls the “supreme emergency,” in which many in bello restraining conditions (not merely proportionality) could be abandoned (Walzer Citation2006, 251–68). However, it seems that if the conditions of ad bellum are met, a just war is more likely than not to be a great emergency (if not, perhaps, a “supreme” one). Moreover, as this article shows, one need not abandon the commitment to the values underlying proportionality (e.g., civilian immunity) for the principle to fail to serve its restraining function.
22 See for instance Goemans and Fey (Citation2009) on the inherently risky nature of war. Both Sidgwick (Citation1897, 254) and Fotion (Citation2007, 21) especially seem to recognize that this fact complicates calculations of proportionality. But, it seems that just war theorists have not considered that it might actually vitiate in bello proportionality altogether.
23 If this assumption does not hold for some reason (for instance, if a commander does not want to level a village because doing so would thwart his future plans), then once again the proportionality requirement is not what is limiting destructive behavior.
24 At least, until considerations other than the proportionality constraint come to bear.
25 For instance, Brown (Citation2003) and McMahan (Citation2011, 143). This is not to say that proportionality has received no direct attention. See Gilbert (Citation2005), Braun and Brunstetter (Citation2013), in addition to the other works discussed above.
26 In a way, this argument resembles that of Valerie Morkevičius (Citation2015), who suggests that ad bellum considerations do not actually have a restraining effect on the number of permissible wars, but may in fact increase their number. Similarly, I argue, the in bello principle of proportionality does not have a limiting effect on the destructiveness of most individual actions in war—and likewise, it may in fact intensify them.
27 Luban (Citation2017) compellingly illustrates this disjunction.
28 See Sullivan and Frase (Citation2009, 25).
Additional information
Notes on contributors
Michael C. Hawley
Michael C. Hawley is an Assistant Professor in the Political Science Department at the University of Houston. He received his Ph.D. in Political Science from Duke University in 2017. His research interests include the history of political thought and contemporary political philosophy. His work has appeared in Journal of Politics, Polis, Philosophy & Theology, History of European Ideas, European Journal of Political Theory, and Polity. His first book, Natural Law Republicanism: Cicero's Liberal Legacy, was published by Oxford University Press in 2022.