Just Cause for War Jeff McMahan* erhaps it should be rather hearten- widely accepted as just, such as the pun- ing that democratic leaders who ishment of wrongdoing and the spread of Pwish to take their countries to war the Christian religion. are now obliged to advertise the war as In this essay I advance a conception of having a “just cause.” Politicians now the requirement of just cause that is revi- routinely invoke this rather quaint sionist in the context of contemporary phrase drawn from the traditional theory just war theory, but that has roots in an of the just war. Indeed, when the admin- older tradition of thought about the just istration of George H. W.Bush decided to war with which contemporary theorists invade Panama, it christened its war have lost touch to a considerable extent. “Operation Just Cause,” thereby appro- This revisionist conception has various priating a label that George W. Bush heterodox—indeed, heretical—implica- might later have found serviceable had it tions that I will highlight and defend: for still been available. But despite the example, that a just cause is necessary for increasing prominence of the notion of the satisfaction of any of the other condi- just cause in political discourse, there are tions of a just war, that there can be var- few serious discussions of it, and those ious just causes for war other than there are tend to be perfunctory. The defense against aggression, that both usual practice is to offer a simple charac- sides in a war can have a just cause, and terization of the requirement of just so on. The conception of just cause for cause—for example, that it is the require- which I will argue must ultimately be ment that there be a good or compelling assessed by reference to the moral plausi- reason to go to war—and then to observe bility both of these implications and of that, at least until quite recently, contem- the larger understanding of a just war in porary just war theory and international which the conception is embedded. As I law have recognized only one just cause will make clear below, I mean by a just for war: self- or other-defense against war something more than merely a aggression. It is then often noted that the morally justified war. consensus on this point is currently being challenged by those who claim that the prevention of large-scale violations of people’s human rights by their own gov- ernment also provides just cause for war. *I am deeply grateful to Christian Barry, Allen Occasionally, skeptics of just war theory Buchanan, David Lefkowitz, Larry May, Ron will also, for satirical effect, cite instances McClamrock, David Mellow, and Derek Parfit for penetrating comments on an earlier draft of this from the classical literature of causes for essay, and to Thomas Hurka for illuminating discus- war that are now rejected but were once sion. 1 RESORT TO WAR, CONTINUATION goal, such as collective self-defense, there is OF WAR, AND TERMINATION OF no reason to suppose that a war may have WAR only one just cause. Even if the requirement of just cause applied only to the resort to In the just war tradition, just cause is one of war, there could in principle be two or more the requirements of jus ad bellum—that is, just causes. It is even possible that, if there one of the conditions of justification for the were two or more just causes, no one on its resort to war. Contemporary just war theo- own would be sufficiently important to rists often assume, therefore, that the make the resort to war proportionate, requirement of just cause applies only to the though all together would be. And assuming initial resort to war, and that after war has that the requirement of just cause applies begun all that matters is how the war is con- not only to the initial resort to war but also ducted. But this cannot be right. It is possi- to the continuation of war, it is also possible ble that a war can begin without a just cause for there to be different just causes for the but become just when a just cause arises same war at different times. Consider, for during the course of the fighting and takes example, a war that has self-defense against over as the goal of the war. When this hap- unjust aggression as its initial just cause. It pens, it would be absurd to say that an unjust might be justifiable to continue the war even war has concluded and a new, just war has after the initial aggression had been defeated begun. Rather, one and the same war may in order to protect people in a justly occu- cease to be unjust and become just—just as pied area or to ensure the effective disarma- a war that begins with a just cause may con- ment of the aggressor. These would be just tinue after that cause has been achieved or causes that, while not part of the justifica- has simply disappeared on its own.1 But if a tion for the recourse to war, may legitimately war in progress can either acquire or cease to be pursued by the continuation of the war. have a just cause, then the requirement of The idea that war may not be continued just cause must apply not only to the resort in the absence of a just cause explains why it to war but also to the continuation of war.2 cannot be permissible to demand that an A just cause is, indeed, always required for adversary surrender unconditionally. For engaging in war. Just cause specifies the ends the idea that it could be permissible to for which it is permissible to engage in war, demand unconditional surrender presup- or that it is permissible to pursue by means poses that the denial of any condition that of war. the other side might set for surrender would One important implication of the idea that any engagement in war requires a just 1 Grotius observed that “a war may be just in its origin, cause is that when the just cause of a war has and yet the intentions of its authors may become unjust been achieved, continuation of the war lacks in the course of its prosecution.”See Hugo Grotius, The justification and is therefore impermissible. Rights of War and Peace (1625), trans. A. C. Campbell Just cause thus determines the conditions (London: M. Walter Dunne, 1901), p. 273. But a shift of intention does not entail the disappearance of the just for the termination of war. cause. Thus, Grotius goes on to say that “such motives, There are, however, complexities here of though blamable, when even connected with a just war, which it is important to be aware. Although do not render the war ITSELF unjust.” 2 Here I am in agreement with David Mellow, A Critique theorists in the just war tradition often write of Just War Theory (Ph.D. dissertation, University of as if just cause were always a single, unitary Calgary, 2003), p. 201. 2 Jeff McMahan itself be a just cause for the continuation of simply that war must have a just or worthy war. And that cannot be the case. Suppose goal. Nor is it a requirement that there be a the enemy insists on something perfectly worthy goal, the achievement of which reasonable as a condition of surrender—for would outweigh the bad effects of war. In the example, that the victors pledge not to kill just war tradition, the task of assessing the the prisoners of war they are holding. If it comparative importance of the goal or goals were permissible for the victors to insist on of war is assigned to the independent jus ad unconditional surrender and to continue bellum requirement of proportionality. Pro- the war until they secured it, that would pre- portionality requires, roughly, that the rele- suppose that it is permissible for them to vant bad effects attributable to the war must assert by means of war their alleged right to not be excessive in relation to the relevant withhold a pledge not to kill prisoners. good effects.3 According to the view I accept, This of course leaves open the question of it might in principle be possible for consid- what may be done when an adversary who erations of proportionality to be fully sub- has fought without justification demands as sumed within the requirement of just cause. a condition of surrender something to Many just war theorists would resist this which they are not entitled, yet the demand suggestion, however, because they believe is also of a type that it would not be permis- that the goods that count in the proportion- sible to resist by means of war. Suppose, for ality calculation are not restricted to those example, that an adversary who has been specified by the just cause. But unless just largely defeated militarily demands as a con- cause fully accounts for considerations of dition of surrender that they be allowed to proportionality, it ought not to say anything continue certain unjust domestic practices, about the scale, magnitude, or comparative such as certain forms of religious discrimi- importance of the goods to be achieved by nation (for example, providing state fund- war. For it would be uneconomical and ing for schools that promulgate the state indeed pointless to divide the work of religion, but not for others). Just as it may be weighing and measuring values between necessary for an individual not to resist cer- two requirements—for example, by having tain forms of wrongdoing when the only just cause stipulate that the goal of a war effective response would be inappropriate or must be to achieve some very great good, excessive in relation to the offense, so it may while proportionality would require that the be necessary in war to grant certain unde- served concessions when the only alterna- tive is to continue to fight without sufficient 3 justification.