Ethical Theory and Moral Practice

, Volume 16, Issue 1, pp 35–54 | Cite as

When Is It Right to Fight? Just War Theory and the Individual-Centric Approach



Recent work in the ethics of war has done much to challenge the collectivism of the convention-based, Walzerian just war theory. In doing so, it raises the question of when it is permissible for soldiers to resort to force. This article considers this issue and, in doing so, argues that the rejection of collectivism in just war should go further still. More specifically, it defends the ‘Individual-Centric Approach’ to the deep morality of war, which asserts that the justifiability of an individual’s contribution to the war, rather than the justifiability of the war more generally, determines the moral acceptability of their participation. It then goes on to present five implications of the Individual-Centric Approach, including for individual liability to attack in war.


Individual-centric approach Jeff McMahan Jus ad bellum Just war theory Private contractors 

1 Introduction

The principles of jus ad bellum are typically viewed as directed at rulers, that is, those authorising the use of force. On this view, it is for political and military leaders to decide when and if their state meets the requisite principles and therefore may resort to force. By contrast, those carrying out the use of force—soldiers—should not consider matters of jus ad bellum. Rather, for varying reasons, they should simply implement the ad bellum decisions of their leaders and, consequently, should go to war when ordered. To be sure, soldiers are required to make some individual judgments about warfare, but these are of whether their conduct during the war complies with the principles of jus in bello. For instance, they should question any orders during the war that require them to target civilians, to engage in disproportionate force, or to use means mala in se.

The division of labour that requires leaders to consider jus ad bellum and soldiers to consider jus in bello has been increasingly challenged by recent work in just war theory. This has moved away from the collectivist, convention-based approaches to the ethics of war, such as that famously presented by Michael Walzer (2006). Most notably, in various works, Jeff McMahan offers what he calls an account of the ‘deep morality’ of the rules of war.1 Instead of treating all soldiers the same because of their status as members of the armed forces, McMahan argues that the deep morality of warfare should focus on individuals’ moral responsibility and the objective justifiability of their war. It follows that, on McMahan’s account, the moral foundations of two of the central principles of international humanitarian law are doubtful. The first is the moral equality of soldiers. This principle asserts that combatants are permissible targets, regardless of the justifiability of the war that they are prosecuting because, in Walzer’s (2006, 145) terminology, they are dangerous men. The problem with this view, McMahan (2009, 35) argues, is that it is not clear why soldiers who are prosecuting just wars—wars that meet the requirements of jus ad bellum—are acceptable targets. He suggests that individual liability to attack in war depends on whether the individual is morally responsible for an objectively unjust threat of harm. So, in prosecuting a just war, just combatants do nothing wrong. They do nothing to forgo their right not to be killed. The second is the principle of noncombatant immunity, which asserts that noncombatants cannot be intentionally killed. The problem with this principle, McMahan asserts, is that certain noncombatants may be liable to attack because, by being morally responsible for posing an unjust threat, they forgo their right not to be killed. (That said, for epistemic and consequentialist reasons, McMahan (2008c) thinks that these principles may still be practically justified overall.)

The rejection of the moral equality of soldiers appears to have a major implication for the traditional just war division of labour between soldiers and leaders. Soldiers do not act permissibly simply by virtue of their status as members of the armed forces and by following the laws of armed conflict. Rather, matters of jus ad bellum affect the permissibility of their action and their moral liability to attack. For instance, in killing enemy combatants, they may be murdering the morally innocent and therefore commit grave wrongdoing. It is morally required of soldiers, then, to consider their decision to participate in a war, rather than leaving this up to their leaders. Indeed, a fundamental aim of McMahan’s (2009, vii–viii) Killing in War is to encourage soldiers to consider to a greater extent the moral acceptability of their decision to participate in a war and, hopefully, to discourage soldiers from acting impermissibly (e.g., by helping their states to fight egregious wars).

It is unclear, however, when exactly it is permissible for soldiers to resort to force and, as such, what it is that soldiers should consider when deciding whether to resort to force. Should they look, for instance, to the justice of the war? Should they fight wars only for legitimate institutions? Or can they decide to resort to force if their contribution will be permissible, even if the war is unjust and their institution illegitimate? In this article, I consider these issues.

More specifically, I argue in favour of what I call the ‘Individual-Centric Approach’ to the deep morality of war and then bring out the implications of this approach for several issues in the ethics of war. The Individual-Centric Approach asserts that the justifiability of an individual’s contribution to the war, rather than the justifiability of the war more generally, determines the moral acceptability of their participation. To put this in context, although McMahan and others have done much to challenge the collectivism of the convention-based, Walzerian just war theory, there is still a tendency to judge individuals according to their membership of a particular group. Whereas convention-based just war theory largely judges individuals according to their membership of the armed forces, recent work in just war often judges individuals according to the justifiability of their institution’s war. Those who fight for an institution that is pursuing a just war are deemed as acting permissibly and therefore not liable to attack, whilst those who fight for an institution that is pursuing an unjust war are viewed as acting (objectively) impermissibly and therefore liable to defensive force. Thus, in defending the Individual-Centric Approach, I argue that the rejection of collectivism in just war should go further still—that is, further than the position adopted by McMahan and others—and, in doing so, challenge this (often-implicit) tendency.

I begin by considering an immediate challenge to the claim that soldiers should consider themselves whether to participate in a particular war, which stems from what I call the ‘Deferral View’. I then flesh out the Individual-Centric Approach by offering an account of what I call ‘individual jus ad bellum’, which comprises several principles that an individual should meet when participating in a war. It is these principles, I suggest, that should guide individuals when deciding whether to resort to force rather than the justifiability of the war more generally. Next, I reject both the ‘Institution-Centric Approach’, which I suggest is implied by McMahan, and the ‘Collectivist Approach’. In the last part of the article, I consider five implications of the Individual-Centric Approach, including for individual liability to attack.

Two clarifications are necessary. The first concerns what I mean by the ‘deep morality’ of war. Following McMahan (2007, 104–5; 2008c), the deep morality of war is an approach to the ethics of war that is less concerned with existing conventions and pragmatic considerations; the focus instead is on offering an account of the principles of war which better reflect underlying moral principles and, in particular, individual rights. That said, it is not necessarily an absolutist, deontological perspective; consequences do have some moral import in determining the deep morality of war. But consequentialist and epistemic considerations that relate to noncompliance, lack of information, perverse incentives, and abuse of moral norms are largely excluded. Accordingly, there also exists an ‘applied morality’ of war that reflects such pragmatic considerations. The focus of much of this article, however, will be on the deep morality of war.

Second, it is widely acknowledged that soldiers on the just side can act immorally, such as those who commit in bello abuses,2 and sometimes (although less often) accepted that soldiers on the unjust side can act morally on occasion. I take this point further, beyond particular incidents: I argue that the permissibility of an individual’s participation in a war can be wholly independent of whether their side is fighting a just or unjust war. On the Individual-Centric Approach that I defend, we should look not to whether the individual is fighting for the just or unjust side to determine whether they can permissibly participate, but rather to whether they meet the conditions of individual jus ad bellum that I outline.

2 The Deferral View

Before proceeding, it is necessary to consider an immediate challenge to the claim that soldiers should decide themselves whether to resort to force. This comes from what I will call the ‘Deferral View’. This asserts that soldiers are morally required to follow their leaders’ assessment of jus ad bellum, even if they disagree personally with this assessment.3 On this view, the justifiability of a particular soldier’s participation seems irrelevant: the soldier is morally required to obey their leaders’ commands on jus ad bellum, regardless of the merits and demerits of their own particular participation in the war.

There are several potential arguments for the Deferral View. These include: (i) Rulers have access to better information on which to base their judgment of the justifiability of a potential war. (ii) Rulers have the experience of making complex judgments, like that of going to war. (iii) Rulers may be democratically elected and authorised to judge the justifiability of a war on behalf of their citizens. (iv) It is important for both the continuing function of the military and to fight wars successfully that soldiers obey the decision to wage war. A policy of conscientious refusal, whereby individuals can refuse to fight wars or perform actions that they deem unjust, could be detrimental in both respects.

McMahan (2009, 38–103, 138–54) presents several plausible responses to many of these arguments for the Deferral View. Against (i) and (ii), he argues that there is little evidence to show that political representatives are more reliable in their moral judgments about the resort to war than the average person is (McMahan 2009, 76–7). Against (iii), he argues that democracies (or plebiscites) are not necessarily more likely to be epistemically reliable in their decisions about the justifiability of a war than individual soldiers are and, as such, there is not a decisive reason to defer to the judgment of a democratic government or ruling elite (McMahan 2009, 69–70, 77). And, against (iv), he questions whether a policy of conscientious refusal would be disastrous for the military and argues that although individual soldiers may possess institutional and role-based duties to obey their commanders, these duties are outweighed by the duty not to risk killing innocents in an unjust war (McMahan 2009, 72–3).

Although these replies seem plausible, it might be claimed that Deferral View should be maintained. This is because many of McMahan’s responses to the Deferral View are largely provisional in that they depend on empirical circumstances. Most notably, his response to claim (iv) depends, first, on the effects of a policy of conscientious refusal and, second, on the likely justifiability of the particular war in question (and the individual’s role in it).4 That is, when there is a small risk of harming innocents, the duty to avoid harming innocents may not outweigh the reasons for relying on rulers’ assessments of jus ad bellum.5 For instance, the risk of harming innocents might be small because the individual might not be involved in a practice that is likely to (but still could) threaten harm to enemy combatants or civilians (e.g., a soldier is tasked with protecting the home front, when invasion by just combatants would be unlikely, and there are no other combatants available to do so because the other combatants are on the front line). Or, the risk of harming innocents might be small because the war seems quite unlikely to be unjust. In such cases, the reticence that the individual has over the justifiability of the war or their participation should be put to one side. So, it might seem that the Deferral View should still be adopted in certain circumstances.

But, even if we grant this exception, in other instances, when these conditions are not met, the Deferral View will not apply to regular soldiers. Moreover, the Deferral View clearly does not apply to one highly prevalent actor in modern warfare: the private contractor. Private contractors carry out several tasks traditionally performed by the regular military, from the armed guarding of key infrastructure to the supplying of communications and specialist equipment. The scale of their use in the wars in Iraq and Afghanistan has been immense. In March 2010, there were over 250,000 US Department of Defense (DoD) contractors in the CENTCOM area of operations (i.e., in the Middle East), including about 112,000 DoD contractors in Afghanistan and 100,000 DoD contractors in Iraq (Schwartz and Swain 2011). Indeed, at several times there have been a greater number of private contractors operating in Iraq and Afghanistan than regular soldiers. Unlike regular soldiers, private contractors are largely free to select the wars in which they fight since they are largely recruited from online databases by the private military and security companies on a single contract basis. They do not possess an institutional duty to obey state leaders and their conscientious refusal would not be detrimental to the military as an institution because they are not part of this institution. Consequently, they should always look to their own judgment of the acceptability of their participation. To be sure, as I suggest below, contractors and regular soldiers may be required to look to the judgment of the acceptability of their participation by a legitimate institution as well as their own individual assessment. But they must always be confident themselves that their participation is morally permissible. Accordingly, even if we were to accept that the Deferral View applies to regular soldiers on occasion, on other occasions it will not, and at least some individuals—private contractors—should always judge the moral permissibility of their participation in a war.

3 The Individual-Centric Approach

We have seen, then, that some regular soldiers and private contractors are required to consider questions of jus ad bellum. But what is it that these individuals are required to consider? Are they to look simply to whether their state is launching a just war or are matters more complex? More precisely, how should the permissibility of their participation be judged? In what follows, I will consider two alternative views on what it is that should be judged: what I call the ‘Individual-Centric Approach’, which I will defend, and the more dominant ‘Institution-Centric Approach’.

The Individual-Centric Approach asserts that the justifiability of an individual’s participation depends, simply, on the merits and demerits of that contribution, rather than the war more generally. (As I will claim, the justifiability of an individual’s contribution may vary from the justifiability of their institution’s war.) If individuals are required to judge jus ad bellum, this should be of whether this meets the principles of individual jus ad bellum outlined below. It should be noted here that the Individual-Centric Approach does not deny that the moral acceptability of an institution’s war depends on whether the institution meets the principles of jus ad bellum. It simply focuses instead on the moral acceptability of an individual’s participation.

The Individual-Centric Approach can be contrasted with what I will call the ‘Institution-Centric Approach’ to jus ad bellum. For the Institution-Centric Approach, if individual soldiers are required to judge jus ad bellum, their assessment should be of the justifiability of the war about to be waged by their institution. So, on this approach the merits and demerits of an individual’s contribution are largely an irrelevancy because the permissibility of their participation is determined by the justifiability of their institution’s war. This approach asserts that questions of jus ad bellum are a matter solely for states (and state-based institutions) and their rulers, not the individuals under their command. The principles of jus ad bellum—just cause, legitimate authority, proportionality, last resort, right intention, and so on—are all addressed to the institution waging war. If the institution meets these principles and therefore is pursuing a just war, the individual’s participation is just.

It should be noted that there could be both subjective and objective versions of the Individual-Centric Approach and the Institution-Centric Approach. On the subjective versions, what matters is whether an individual’s assessment of the institution’s war (the Institution-Centric Approach) or the individual’s contribution to the justice of the war (the Individual-Centric Approach) is reasonable. On the objective version of these approaches, what matters is the actual justifiability of the institution’s war (on the Institution-Centric Approach) or of the individual’s contribution to the justice of the war (on the Individual-Centric Approach), independent of the beliefs about the war that the individual holds. There can also be a combination of objective and subjective versions of these approaches. For instance, one might hold that whether it is objectively permissible for an individual to use force depends, for the most part, on the objective justifiability of their contribution to the war, but their participation can be excused if it is subjectively permissible for them to use force, that is, if they reasonably (but mistakenly) believe that their contribution to the war is justified.

On the Individual-Centric Approach, for an individual to participate justly in a role that will directly or indirectly involve harm they need to meet several principles. These are what I call the principles of ‘individual jus ad bellum’. These principles have some affinity to the principles of jus ad bellum for institutions, but are largely overlooked by the Institution-Centric Approach. I will consider each of these principles in turn. Note that, for reasons of space, I cannot defend the moral importance of these principles in detail. The aim is simply to outline the principles, which are not meant to be particularly revisionist but rather concern considerations commonly viewed as morally significant. Also note that this list is not meant to be exhaustive since there may be other morally relevant principles; I focus on what seem to be the most morally significant considerations.6

3.1 Principles of Individual Jus Ad Bellum

  1. 1.

    Specific just cause. In order to possess just cause to use force, an individual needs just cause for their specific contribution. The right to use or assist (often-lethal) force, given the harm that it inflicts on others, can exist only when there is a good enough reason to use force. Such a reason could be that they are using force against those who are liable or that they will be likely to achieve significantly more good than harm. Simply taking part in a war in which the institution possesses just cause is not sufficient for this, since the individual may not have just cause for their specific contribution. Their own particular contribution within the war may not lead to the pursuit of the institution’s just cause and therefore fail to justify why that individual can use force. Nor is taking part in a war in which the institution possesses just cause necessary for an individual to possess specific just cause, since the individual may have just cause for their specific contribution, but the institution may lack just cause more generally.7 For instance, a soldier of an intervening force may be in charge of defending a children’s hospital from attack by insurgents—and so have just cause for their specific role—even though their state’s intervention more generally is unjust. To be sure, an individual’s specific just cause will sometimes stem from the broader just cause of the institution, but this will not always be the case.

  2. 2.

    Right intention. This requires that individuals do not possess a wrong intention, such as intending to use force disproportionately or to pursue an unjust end. If they act with a wrong intention, even in response to a just cause, the harm that they will inflict on others is morally problematic. Instead, they should possess a right intention, which I interpret broadly to include all those intentions that are not wrong intentions. This includes intending to achieve the specific just cause and also potentially neutral intentions, such as intending to obey orders.

  3. 3.

    Proportionality. Proportionality as an ad bellum requirement asserts, in short, that those using force must do more good than harm. To be proportionate, an individual’s action needs to be a reasonably effective course of action in terms of the promotion of the good (such as the enjoyment of basic human rights) compared to other potential actions, including the choice not to participate. In addition, proportionality may be sensitive to several considerations, including associative obligations.8 Those who do not advance the good, such as unjust combatants who target enemy civilians, act disproportionately, even if their actions fail to advance their state’s unjust cause.9

  4. 4.

    Pursuit of nonforcible options first. Individuals should be cautious in the resort to force. This may in practice mean that they should sometimes look to other options first, short of the use of force, such as campaigning for the government to pursue other measures rather than war, even if these options are less likely to be effective than the resort to force. This is because of the difference between doing and allowing; it is better to allow harm than to cause it oneself. To be sure, since the difference between doing and allowing is generally not held to be absolute (see Quinn 1989 and Scheffler 2004), individuals can still justifiably resort to force at times. My point, rather, is that the difference between doing and allowing means that they should pursue nonforcible options first, given the harm that these will cause, even if doing so will be less effective than the immediate resort to force.

  5. 5.

    War by a legitimate institution. If one adopts a subjective account of justification, it also tends to be important that individuals fight wars only for legitimate institutions. This is because it can be reasonably expected that an institution, given its resources, will often be in a position to make a more accurate assessment of the justifiability of the individual’s contribution than the individual alone. In addition, if it is the case that a legitimate institution (by which I mean one that upholds basic human rights and is democratic) is less likely than an illegitimate institution to attempt to get its soldiers to fight disproportionately in an unjust role, then an individual’s assessment of their contribution to the war is more likely to be accurate if they look to the assessment of a legitimate institution too. It should be reiterated that, in contrast to the Deferral View, individuals are required to look as well to their own judgment of individual jus ad bellum.

    Notwithstanding, this principle functions only as a prima facie restriction since there may be occasions when an individual’s contribution to a war fought by an illegitimate institution is nevertheless clearly just. Furthermore, if one adopts an objective approach to individual jus ad bellum, this principle will be of little relevance to the assessment of the justifiability of an individual’s contribution. The importance of fighting for a legitimate institution, as I have defended it, is to improve the epistemic reliability of an individual’s subjective assessment of the other principles of individual jus ad bellum. But, on an objective approach, what matters is the actual justifiability of an individual’s contribution. This will be determined by whether an individual’s contribution is, in fact, in response to a just cause, is proportionate, and rightly intended, independent of the reliability of the individual’s assessment of such matters.


4 The Institution-Centric Approach

We have seen that the Individual-Centric Approach asserts that individuals need to meet the principles of individual jus ad bellum in order for their participation to be morally permissible. The Institution-Centric Approach, by contrast, requires only that the individual’s institution be waging a just war. Yet the Institution-Centric Approach may have some prima facie plausibility, since, by participating, soldiers may seem to be contributing to the advancement of their institution’s just war. We may think, for instance, that all Allied Soldiers fighting in the Second World War were justified in fighting, given the just war against the Axis Threat. Although it may not be explicitly defended, the Institution-Centric Approach is often implicitly assumed.10 For certain theorists, this may simply be because it functions as useful shorthand. Rather than considering the moral acceptability of each and every individual’s contribution when considering other issues in the ethics of war, it may be easier to assume that, on the one hand, those who are fighting for an institution that is pursuing a just war make a just contribution and, on the other, those who are fighting for an institution that is pursuing an unjust war make an unjust contribution. Using the Institution-Centric Approach as shorthand is potentially still consistent with holding that the Individual-Centric Approach is ultimately correct: if just combatants make an unjust contribution, they act impermissibly (and vice versa). A stronger version of the Institution-Centric Approach asserts more definitely (rather than assumes) that those who are fighting for an institution that is pursuing a just war make a just contribution and those who are fighting for an institution that is pursuing an unjust war make an unjust contribution.11

It is often unclear whether the Institution-Centric Approach is being employed simply as shorthand or a more definite rule. At times, this is the case for McMahan. For instance, on the one hand, he notes (2004, 710–14; 2009, 134) that an unjust combatant can use force permissibly when in certain situations. But, on the other hand, he also makes several claims where it seems that he is implying the stronger version of the Institution-Centric Approach, and generally Killing in War tends to view unjust combatants as those who effectively contribute to the pursuit of their institution’s unjust war. For instance, in his discussion of the liability to attack of an unjust combatant (who has stopped a just combatant from performing a wrongful action), McMahan argues that

even while he is doing one act that is morally justified, and perhaps even morally required, he is also engaged in a temporarily extended course of action that is wrong: fighting in an unjust war. Because of this—that is, because after he has prevented the just combatants from doing wrong, he will revert to the pursuit of his own ongoing wrongful course of action—he remains a legitimate target of action. His moral status is curiously mixed. Even while he is doing one act for which there is objective justification, he does not cease to be engaged in another course of action that is wrong (2009, 174).12

Although it may be unclear whether McMahan is adopting the Institution-Centric Approach simply as shorthand or a more definite rule, the general thrust of his argument seems to require that the stronger version be true. This is because he faces an objection from contingent pacifism, which runs as follows.13 Many unjust combatants are not liable to attack and, in practice, it is impossible to distinguish between those who are liable and those who are not. Therefore, almost any likely war will involve significant harm to those unjust combatants who are not liable, as well as to just combatants and civilians, and will therefore be unjust.

McMahan makes several moves to try to avoid the contingent pacifist position. Notably, he holds that most unjust combatants will, despite subjective permission, be what Seth Lazar (2009, 706) terms ‘agent-responsible’ (they voluntarily choose to do x and meet the criteria for rational agency) for posing an objectively unjust threat. This notion of agent-responsibility broadens out moral responsibility from simply culpability, so that several unjust combatants can be said to be responsible for their contribution to an unjust war even in the face of significant epistemic burdens and notable duress.14 McMahan (2009, 104–54) also places a very high epistemic burden on unjust combatants (arguably more than can be reasonably required (Lazar 2010, 193–203). These moves enable him to assert that most unjust combatants are, at best, what he calls ‘Partially Excused Threats’ and liable to attack.

To avoid the contingent pacifist objection, it also appears necessary that there are not a significant number of unjust combatants who are what McMahan (2009, 174) calls ‘Just Threats’, that is, those who are objectively morally justified in posing a threat of harm to which the victim is liable. Otherwise, even a war against an unjust aggressor may lead to the death of a notable number of Just Threats (i.e., innocent combatants), in addition to civilians (many of whom may also not be liable), and so be wrong. Accordingly, McMahan seems to need a stronger version of the Institution-Centric Approach to be largely true.

To adopt the Institution-Centric Approach simply as a rule of thumb—the weaker version of the approach—would not explain why the deaths of several Just Threats (i.e., innocent combatants), who fall foul of the rule of thumb, would be acceptable. This is because, although he rejects (2010) the radical asymmetry of the difference between doing and allowing, on which pacifism is sometimes based, he still holds that this distinction and the distinction between intentional and unintentional killing has very sizable moral relevance. On his position (as I understand it), the (i) intentional (ii) killing of (iii) several innocents would render war unjust. Thus, it appears that McMahan’s position requires something like the stronger version of the Institution-Centric Approach to be correct, so that those fighting for the side fighting a just war do not intentionally kill several innocents, such as unjust combatants who are Just Threats.15

But why should we reject the Institution-Centric Approach (as McMahan arguably requires) and instead favour the Individual-Centric Approach? I will present two reasons. The first is that the Individual-Centric Approach challenges the assumptions, often implicit in the Institution-Centric Approach, that a just combatant will make an effective contribution to their institution’s just war and that an unjust combatant will make an effective contribution to their institution’s unjust war. This assumption is unfounded. Almost all wars contain unnecessary and unjust phases and aims, as well as agents that contribute very little to the achievement of their institution’s main cause. In short, war is typically wasteful and inefficient.16 To be sure, some individuals will often make an effective contribution, even if only of minor causal (but still of some) significance. But, in many wars, a large number of the soldiers involved do not help to advance their institution’s central just or unjust cause.

More specifically, an individual may be what I will call an ‘Uninvolved Soldier’. An Uninvolved Soldier does not make a causally significant contribution to the pursuit of a just or unjust cause. They may, for instance, provide services to the frontline soldiers that increase the comfort of those fighting (and which do not improve morale), but do not contribute to the war effort. Alternatively, they may be intentionally or unintentionally incompetent, timid, or indolent, and so fail to make a causally significant contribution. In effect, such individuals cannot be regarded as participating in their institution’s just or unjust war. Alternatively, an individual may be what I will call a ‘Tangential Soldier’. A Tangential Soldier does make a causally significant contribution to the war, but does not effectively promote their institution’s main just or unjust aim. They may be disruptive, obstructive, or subversive, and so harm the pursuit of the main aim. Or, they may advance other tangential ends in the war, such as subsidiary just or unjust causes. The first reason in favour of the Individual-Centric Approach, then, is that many individuals in war may not promote their institution’s main aims. In contrast to the Institution-Centric Approach, it should not be assumed that their contribution will be instrumental.

The second and related reason for favouring the Individual-Centric Approach is that the Institution-Centric Approach overlooks several morally relevant considerations that should play a part in whether an individual can justly participate in a war. These are encapsulated by the principles of individual jus ad bellum listed above. Consider, for instance, the moral importance of specific just cause. Suppose that a soldier is considering whether to participate in an all things-considered just war by liberal State A to help protect socialist State B from a genocidal attack by fascist State C. The soldier’s particular contribution, however, would be to subvert the democratic political institutions of the socialist State B in order to establish a liberal regime in State B. On the Institution-Centric Approach, which looks only to the justice of the war fought by the institutions, it would be permissible for the soldier to participate, which seems mistaken. My point, then, is that if the considerations highlighted by the principles of individual jus ad bellum are morally relevant, the Individual-Centric Approach is preferable to the Institution-Centric Approach.

5 The Collectivist Approach

Whereas the Institution-Centric Approach is nevertheless still individualist in that it holds that individuals are morally required to assess whether to participate in war, the ‘Collectivist Approach’ provides a much stronger, more radical objection to the Individual-Centric Approach. It asserts that the problem with the Individual-Centric Approach is that war is fundamentally a collective endeavour and, as such, an individual-focused morality is highly problematic. On the Collectivist Approach, moral responsibility for war (which in turn affects individuals’ liability) and the moral permissibility of resorting to war are at least in part collectively determined (i.e., concern conglomerate rather than aggregative features of groups).

McMahan (2009, 79–84, 208–10) has presented several detailed objections to the Collectivist Approach to warfare, many of which I largely agree with, and I shall not repeat his analysis here. Notwithstanding, it is worth briefly examining why we should prefer the Individual-Centric Approach to the Collectivist Approach and, in particular, to Noam Zohar’s (1993) well-known call for a compromise between collectivist and individualist moral concerns, which he argues is reflected in the War Convention. I will not reject or endorse the need for a compromise between collectivist and individualist moral concerns (which I think depends to some extent on the bigger issue of whether one accepts the notions of collective responsibility and collective intentionality). Rather, I will suggest that, even if one accepts the need for some compromise, the Individual-Centric Approach may still be largely correct.

First, one could accept Zohar’s call for a compromise but deny that the War Convention reflects an adequate compromise. We may think instead that there should be an alternative account of a morally adequate compromise, which may be closer to the Individual-Centric Approach. Second, even if we accept the need for a compromise between collectivist and individualist concerns, it does not follow that these concerns should be weighed equally. On the contrary, we may still instead tip the balance much more in favour of the individual-focussed concerns highlighted by the Individual-Centric Approach because we think that these concerns have greater moral significance than those highlighted by the Collectivist Approach. Third, and related, it may be that individual-focussed concerns should be given greater weight because the conditions required to assign collective responsibility and collective intentionality are not often met in the context of warfare.17 Thus, we may hold that the Individual-Centric Approach is for large part correct as an account of the demands of individualistic morality and that collectivist morality should play only a secondary role for specific issues where the required conditions for collective responsibility and collective intentionality are met. Fourth, much of war is akin to individual confrontations and so can be correctly captured by the Individual-Centric Approach.

In contrast to this fourth claim, Zohar asserts that the problem with individual-focused approaches, such as those based on analogies to private self-defence, is that they deny collectives any separate moral standing. In his words: “[m]oral deliberation about international relations in general, and about the conduct of warfare in particular, must include explicit recognition of the moral status of collectives” (1993, 619). This is because “[t]he reality of international confrontation is not adequately described by reduction to individualistic terms. We are not only individuals facing other individuals but also a nation confronting another nation” (1993, 616).

This picture of warfare is largely mistaken. The general thrust of Mary Kaldor’s (1999) ‘New Wars Thesis’ is that new wars, which are intrastate rather than interstate, blur the lines between war, organised crime, and the violation of human rights. They involve a myriad of transnational connections and so render the distinctions between internal and external, as well as local and global, largely redundant. Unlike ‘old wars’, which were fought by vertically-arranged hierarchical units, new wars are fought by a wide array of—and often highly decentralised—actors. Accordingly, the view that wars involve a clearly identifiable collective against another clearly identifiable collective is mistaken. War is now often more akin to a haphazard series of individual confrontations between agents who possess only weak group identifications.18 The privatisation of warfare, which has gathered significant pace since Kaldor presented her New Wars Thesis, has exacerbated this phenomenon. As noted above, private contractors now sometimes outnumber regular soldiers and are free to pick and choose contracts. Many are ‘third-country nationals’ (individuals who are not from the host state or the sending state) and are employed by an array of actors (including states, communities, and other private actors). The employers typically have little control over the contractors in the field, with weak and sometimes nonexistent lines of effective accountability and regulation, which is worsened by the widespread subcontracting in the industry.19 So, if we accept the New War Thesis and the effects of the privatisation of war, individual morality—and the Individual-Centric Approach—would seem to need to play a major role in the morality of war.

Zohar also argues that a collectivist approach to warfare is the only way of avoiding contingent pacifism, which as noted above is an issue for McMahan (it is the reason why he seems to need to adopt a stronger version of the Institution-Centric Approach). It may seem that the Individual-Centric Approach would also potentially lead to contingent pacifism and the only way to avoid this conclusion is to adopt the Collectivist Approach. The issue is as follows. If the Individual-Centric Approach is correct, we need to look to the moral acceptability of an individual’s contribution in order to determine whether it is permissible for them to act. This will involve complex assessments for each individual. In doing so, we may also need to consider the liability of those who would be subject to their force and, similarly, the liability of those indirectly harmed. This would, again, involve complex assessments for each individual. This is true not only of the ad bellum period, but also (I claim below) of the in bello period. Such assessments, the argument runs, are not feasible either before the war or during it. Any assessment of the justifiability of an individual’s contribution or their liability on the Individual-Centric Approach is likely to be incorrect. Given the Individual-Centric Approach’s claim that many individuals on the unjust side may nevertheless make a permissible contribution, any feasible war will be too indiscriminate. Therefore, war will inevitably involve the impermissible harming of those who are not liable to attack. For this reason, it may seem that the Individual-Centric Approach leads to contingent pacifism. Thus, in his recent defence of contingent pacifism, Larry May (2011, 104) argues that, even in high-tech wars, those on the just side of a war cannot guarantee that they will harm only those who pose an objectively unjust threat. He asserts that

[i]f what makes soldiers liable to be attacked is the threat they pose, then fine-grained determinations need to be made among soldiers, and such determinations make support for fighting in even just wars, where enemy soldiers as well as civilians are normally killed indiscriminately, very difficult to justify because of a concern that those who are innocent not be killed (2011, 104).20

Rather than endorsing pacifism, Zohar argues that we need to accept collectivism: “[o]nly viewing [the enemy] as a collective aggressor can sanction the very killing of combatants, despite the impossibility of determining their individual guilt or innocence, for in fact we cannot act against the enemy as a collective without killing particular persons” (1993, 615–6).

Contingent pacifism is not inevitable on the Individual-Centric Approach, however. For McMahan, the issue (as noted above) is that he seems to hold that the (i) intentional (ii) killing of (iii) several innocents renders war impermissible. By contrast, I hold that the intentional killing of several innocents can be permissible when highly beneficial consequences are likely. As such, I am more willing to give some room to consequences in my value-pluralist approach.21 On my account, although the epistemic difficulties in assessing liability may mean that nonliable individuals are killed in war, this does not mean that all feasible wars will be unjust. When the (even intentional) death of several innocents is likely, war can, on occasion, be morally permissible when highly beneficial consequences are likely, such as the likely prevention of mass killing (e.g., genocide). In other words, the wrong caused by the death of the innocents (intentional or not) is outweighed by the wrong prevented by the tackling of mass killing. As such, it is still possible to endorse the Individual-Centric Approach and reject contingent pacifism.22

6 Implications of the Individual-Centric Approach

I have argued that, instead of the Institution-Centric Approach or the Collectivist Approach, we should prefer the Individual-Centric Approach, which goes further than that adopted by McMahan and others. This approach asserts that the justifiability of an individual’s contribution depends on the merits and demerits of that contribution and, in particular, whether they meet the principles of individual jus ad bellum. I will now turn to consider other implications of this approach for the ethics of war. I should reiterate that my concern is with the deep morality of war; for many of these implications, there may be countervailing practical considerations.

6.1 Jus In Bello, Jus Ex Bello

Thus far, I have concentrated on individual jus ad bellum, that is, on when an individual can justly resort to participation in a war. The Individual-Centric Approach also applies to jus in bello, that is, to an individual’s actions during war. The principles of individual jus ad bellum should also determine when it is acceptable for an individual to use force during war. For particular acts of war, an individual should be sensitive to the requirements above: the act during war should have specific just cause, right intention, and be proportionate, and would be more justified if it were authorised by a legitimate institution and nonforcible options were pursued first.23 This commonality between individual jus ad bellum and jus in bello should not be surprising. The focus of jus in bello is on the justifiability of an individual’s resort to force for particular acts during war; the focus of individual jus ad bellum is on the justifiability of an individual’s resort to force in the first place.24

In addition to ad bellum and in bello considerations, the justifiability of an individual’s decision to continue to participate in a war—what Darrel Moellendorf (2008) calls ‘jus ex bello’—should be subject to principles similar to that of individual jus ad bellum. An individual’s role may change in war. Unlike when they started the war, they may no longer make a proportionate contribution or may come to lack specific just cause. Certain acts that they perform may still be permissible (if the particular acts meet the requirements of jus in bello). However, if for instance their contribution lacks specific just cause overall, is not rightly intended, or is not generally proportionate, their participation will be morally problematic. In such cases, they may be morally required to refuse to fight, abscond, or, if private contractors, break their contracts. (To be sure, although they seem to contravene jus ex bello, soldiers may be sometimes required to fight for similar reasons as highlighted by the defenders of the Deferral View. For instance, a principle of conscientious abandonment may harm the general effectiveness of the agent’s just war effort, even though the particular individual’s contribution is unjust.)

This is not to deny that individuals can perform multiple roles during war. For each role, they should ensure that their contribution is permissible. In addition, the same action may have unjust and just elements. For instance, a soldier may defend a hospital from attack, but by doing so weaken the attacking side’s ability to achieve their main just cause. It follows that the various aspects of a particular act may be able to be described differently. But this does not mean that there should be multiple judgments of the act. The individual should weigh up the different elements of the act and decide if the act is, all told, permissible. It may be, for instance, that the soldier should not defend the hospital, despite this leading to some innocent deaths.

It should also be noted that institutional acts might change the permissibility of an individual’s contribution. Consider, for instance, a soldier whose task is to refuel planes that initially bombed enemy barracks but that now target hospitals. In such cases, the soldier should re-evaluate their contribution if they are aware of the changes. More generally, individuals should attempt to keep abreast of any potential changes and periodically re-evaluate the permissibility of their contribution.

6.2 Just Combatants May Be Liable to Attack

The Individual-Centric Approach also affects individual liability to attack in war. As we saw above, on the Individual-Centric Approach, the justifiability of an individual’s contribution may differ from the justifiability of their war more generally. It seems, then, that whether individuals are liable to attack should depend not on the morality of their institution’s war, for which they may not be morally or causally responsible, but on the permissibility of their own contribution. In short, they need to meet the requirements of individual jus ad bellum (and, during the war, jus in bello and jus ex bello).25 To be sure, those using force against those who are liable would themselves need to meet these principles. If those using force against the liable individuals do not meet these principles, they cannot act permissibly.

It follows, then, that just combatants might be liable to attack if they act impermissibly.26 Suppose, for instance, that a soldier agrees to assist the UN to undertake humanitarian intervention, but does so to gain access to diamond mines. Suppose further that the soldier thereby undermines the effectiveness of the UN’s intervention with their own self-interested actions. Consequently, the UN is unable to halt the violation of hundreds of civilians’ human rights (say the soldier jeopardises an operation to protect a school). In such a case, it seems that they would be liable to attack.

6.3 Unjust Combatants May Not Be Liable to Attack

It also follows from the Individual-Centric Approach that the soldiers of an institution that is pursuing an unjust war might not be liable to attack. An unjust soldier may simply be an Uninvolved Soldier who does not make a causally significant contribution to the pursuit of their institution’s unjust war. Since an Uninvolved Soldier does not contribute to an objectively unjust threat, they do nothing to render themselves liable to attack. Although they may be in uniform and near the battlefield, they are, in effect, a bystander. Alternatively, an unjust soldier may be a Tangential Soldier who advances a subsidiary just end and thereby makes a permissible contribution. By making a permissible contribution, they too do nothing to forgo their right not to be killed. Thus, some unjust combatants may, in fact, be Just Threats—those who are objectively morally justified in posing a threat of harm to which the victim is liable.

It is worth considering two responses to this argument. First, against the permissibility of the Tangential Soldier from acting, it may seem that it is worse if an individual decides to resort to force to thwart the promotion of an unjust end than them doing nothing to prevent the unjust end. But, in response, consider a pilot who is deliberately ineffective at hitting unjust targets; he drops all of his bombs on fields rather than the schools he is ordered to hit. If he would be replaced by another, more ruthless pilot if he does not carry out the bombing missions, it seems better that he conduct the mission than stay at home and do nothing. He is therefore not liable to attack. As such, despite the import of the doing and allowing distinction, inaction can sometimes be worse than collaboration. The example of Kurt Gerstein presented by Walzer is relevant here. According to Walzer (citing Saul Friedländer), Gerstein “disavowed the Nazi regime, even hated it inwardly, but collaborated with it in order to combat it from within and to prevent worse things from happening” (2006, 295). In doing so, he seemed to act permissibly and so, likewise, was not liable to attack.

The second response is from McMahan, who holds that unjust combatants who are Just Threats are liable to attack. He argues (2009, 174) that an unjust combatant, even when acting in a morally justified way, has a mixed moral status because he is still engaged in an objectively wrongful course of action—the pursuit of the larger unjust cause—and so is liable. McMahan’s argument for holding that the unjust combatant retains a mixed moral status could be interpreted as the view that, although unjust combatants act permissibly in terms of jus in bello, they act impermissibly in terms of individual jus ad bellum (i.e., they wrongly commence their participation in the war) and/or individual jus ex bello (i.e., they wrongly continue their participation in the war). That is, the unjust combatant is still posing an objectively unjust threat in their general role as an unjust combatant and, as such, they are liable to attack.

Yet, there will be cases when unjust combatants act permissibly in terms of jus in bello and individual jus ad bellum and/or jus ex bello, and so do not pose such a threat. This means that unjust combatants, pace McMahan, may not always be liable to attack.27 Suppose, for instance, that State A is pursuing an unjust war. Bob, who is a soldier of State A, agrees to perform a clearly demarcated role. This is not to help State A pursue its main unjust aim, but instead to engage in a just civilian protection mission (assume that otherwise the civilians would go unprotected). It does not seem that Bob should be held liable to attack.

In response, we might think that because Bob may, at any point, be deployed by State A to a role in which he will contribute to the institution’s main unjust cause, he is liable to attack. To that extent, McMahan (2009, 183–4) claims that there is reason to think that the liability of combatants is ‘strict’ in the sense that they can be liable to attack even though they have not done anything wrong yet. They choose to make themselves instruments of their government, and their government may well use them to fight in an unjust war, which can make them liable to even a preventative attack. Thus, McMahan (2008a, 141) presents two reasons for holding that unmobilised soldiers of a state may be liable to attack: (i) the soldiers have committed themselves to fighting (or have at least given others good reason to believe that they are committed to fighting), either by making a choice to enlist in the military or by allowing themselves to be conscripted; (ii) they have had the ‘bad moral luck’ of having political leaders who are plotting aggression—they are ‘agents of injustice’.

These conditions for preventative war are, however, too permissive because they could radically expand liability to attack. Take the first criterion—that the soldiers have committed themselves to fighting. In the case above, Bob has committed himself only to the civilian protection mission. He has not committed himself to fight in any other part of the war. He may well conscientiously refuse if asked to do so. It should not be assumed that Bob would fight for another end and should therefore not be held liable to attack. Likewise, despite an oath of allegiance when signing up, regular soldiers may not have necessarily committed to fight in an unjust war that their leaders are plotting—they may decide to refuse to act (as several soldiers did before the War in Iraq).

Notwithstanding, if the first criterion is interpreted more broadly to be agent-responsibility (which would cohere with McMahan’s general account of liability to attack), it might be argued that any unjust combatant who has failed to make it clear that they will refuse to fight for an unjust end is liable to attack. Almost all unjust combatants would then be liable since they either volunteer or allow themselves to be conscripted, and may pose an unjust threat in the future. Yet the problem is that many noncombatants would be liable to preventative force as well because they will also perform a voluntary act that it is foreseeable might result in an unjust attack.28 For example, they pay taxes which it is foreseeable may be used to fund an unjust war. They could be targeted when leaders are plotting a war because it can be expected that civilians will continue to pay their taxes during this war and that these taxes are necessary for the unjust war to be prosecuted.

At one point, McMahan (2008a, 143–5) seems to agree that this account may be too permissive. He argues that a preventative attack would be ruled out on his account because such an attack could not discriminate between unmobilised soldiers who are liable and those who are not. Certain unmobilised soldiers, he argues, would not be liable to attack because (i) the degree of duress on them may have been irresistible, (ii) they may later go on to refuse to fight and so no longer pose a threat, and (iii), given the turnover of the military, they may not be on active duty when the unjust attack would occur. It is questionable, however, whether these three exceptions are consistent with what he says elsewhere. To start with, in Killing in War, he argues (2009, 183) that even if unjust combatants are subject to irresistible duress (and so are ‘Innocent Threats’), they may still be liable to attack since they are agent-responsible for their action (even if not morally culpable). The second and third points raise doubts over whether the threat posed by unjust combatants will actually materialise into an unjust attack. But this is not at issue. Rather, the concern is whether the unjust combatants currently pose an unjust threat of a nonimminent, but certain, attack. If they do, they would seem to be liable on the logic of McMahan’s account. That unjust combatants may conscientiously refuse and be rotated shows that there is a lower probability of them contributing to an unjust attack, which may in turn reduce their degree of liability. However, it does not refute the fact that they currently pose some threat—and so still are liable—given that their leaders are plotting an unjust attack and that they are committed to fighting. This is the case even if it is only a distant (but certain) threat of a nonimminent attack. Accordingly, a preventative attack is not ruled out by the principle of discrimination on McMahan’s account.

McMahan’s account of preventative force seems to be too permissive then. On the one hand, we may reject his account of liability to attack more generally. For example, Lazar (2009) rejects McMahan’s reliance on agent-responsibility rather than culpability partly because of the problems with what he calls the ‘Risk Argument’ (essentially, McMahan’s account of preventative force). On the other hand, even if we accept McMahan’s view of preventative attack, and hold that unjust combatants who make a just contribution (and potentially several nonculpable civilians) are, in fact, liable to attack, this may be of little relevance, since their liability will be so minimal that in most cases it would be disproportionate to attack them. That is, although they make an unjust contribution, it is a small unjust contribution, and therefore there would be little chance that a military action, given its general destructiveness, in response to this small unjust contribution would do more good than harm.29 Either way, unjust combatants cannot be justly attacked if they are making a just contribution.

6.4 Jus Post Bellum

A fourth implication of the Individual-Centric Approach is for the deep morality of jus post bellum, that is, justice after the war. I will focus on three aspects of jus post bellum: termination, punishment, and rehabilitation.

A central principle of jus post bellum for institutions is that the war be terminated once its objectives have been largely met. Individuals may be required to terminate their participation before this. Once they have made their just contribution, they should forego their role. This is a corollary of the argument above that individuals need to meet the requirements of jus ex bello. They need a continuing reason for maintaining their threat. Once this ceases to exist, they no longer make a just contribution.

Let us now consider post-war punishment. There is a case for holding that individuals should be punished for their violations of not only jus in bello, but also individual jus ad bellum and jus ex bello. If they have violated individual jus ad bellum, jus in bello, or jus ex bello, individuals should be prosecuted for making an unjust contribution, even if their institution has been fighting a just war (except if their action is excused). Thus, prosecutions for violations of individual jus ad bellum should not necessarily be limited to leaders. If the arguments for the Deferral View considered above are unpersuasive, certain regular soldiers, and, more straightforwardly, private contractors, should be punished for their wrongful resort to war. They may, for instance, be required to pay reparations to those whom they have harmed by their unjust participation.

To be sure, there may be countervailing reasons against holding that individual soldiers should be punished. For instance, soldiers may have had no choice but to fight and prosecuting soldiers for making an unjust contribution may harm military morale. Similarly, Steve Viner (2010) argues that unjust combatants should not be punished for several reasons, including the appearance of victor’s justice, the randomness of which unjust combatants will be punished (given the practical difficulties of punishing all unjust combatants), and the potential for punishment to be counterproductive.

Although these considerations may often tell against the case for punishment, they will not always be decisive. Consider, for instance, the punishment of a group of soldiers who decide to seize diamonds from a local diamond mine—an unjust ad bellum operation—during an otherwise just war and all of them are then (rightly) punished by their own state. This does not seem to fall foul of the problems identified by Viner, but would cohere with the Individual-Centric Approach. This approach asserts that any post-war punishment should not ultimately depend on who is victorious, or on which institution’s war was just, but should depend on the permissibility of the particular contribution made by the individual, regardless of the side for which they fought.

Similarly, postwar rehabilitation to avoid the unjust threat that prompted the war should be sensitive to the concerns highlighted by the Individual-Centric Approach. In fact, it should not simply be sensitive to the unjust threat that prompted the war, but also particular unjust threats by individuals throughout the war. As a result, a just settlement may require rehabilitation of both fighting parties, such as the removal of a tyrannical dictator on the one side and the reassessment of aerial bombing campaigns on the other.

6.5 Filibustering30

A fifth implication of the Individual-Centric Approach is that it may sometimes be permissible for individuals (even if soldiers) to fight for almost any agent worldwide if they would make a just contribution, even if the agent is illegitimate and its main cause unjust.31 A private contractor may, for instance, be able to provide armed guarding for an individual who improves the targeting of a terrorist organisation so that the organisation kills fewer innocent civilians. What ultimately matters is that the individual’s contribution is a just one, rather than the justice of the larger cause or the legitimacy of the institution fighting the war.

To be sure, given the importance (when adopting a subjective account of justification) of the fifth ad bellum principle—‘war by a legitimate institution’—outlined above, the burden of proof that falls on individuals who want to filibuster may need to be high to ensure that their contribution will be justified. There are, of course, further, more practical arguments for a legitimate authority principle. For instance, by reducing the number of actors that can legitimately wage war, the principle makes easier the development of legal and political instruments to govern and to limit warfare (Pattison 2008; under contract). Such considerations may mean that there should be an international norm that prohibits filibustering, but may not necessarily render it impermissible for a particular individual to filibuster in every case.

7 Conclusion

I have argued, then, that the rejection of collectivism in just war theory should go further still. Rather than focusing on the justifiability of an institution’s war, I have claimed that we should often look to the justifiability of an individual’s contribution. Thus, I have defended the Individual-Centric Approach to the deep morality of war. This asserts that the merits and demerits of an individual’s contribution is what matters and, in particular, whether they meet the principles of individual jus ad bellum. My point, then, is a simple one: individuals should judge and be judged by what they do as individuals, not by what their institutions do.

But is the Individual-Centric Approach too utopian? Individuals may be highly likely to assume, first, the efficacy of their participation and, second, that they will be acting permissibly if their institution has just cause. In addition, given the emphasis placed on the importance of civilian control of the military, soldiers may tend to assume that moral judgments about their contribution in war should be made by their political rulers. The Individual-Centric Approach is therefore unlikely to be universally internalised in the near future. Nevertheless, even if only a few more individuals begin to question the permissibility of their contribution, this would be a positive development. What matters is ultimately that individuals should make contributions to war that are morally permissible and even the partial internalisation of the Individual-Centric Approach should be beneficial in this regard.


  1. 1.

    See, especially, McMahan (2004, 2009). Also see Fabre (2009) and, generally, Rodin and Shue (2008).

  2. 2.

    Consider, in this context, Walzer’s approval of the dishonouring of Bomber Harris after the Second World War. He suggests that “it went some small distance toward re-establishing the commitment to the rules of war and the rights they protect” (2006, 325).

  3. 3.

    See, for instance, Estlund (2007).

  4. 4.

    As McMahan (2009, 75, 99) notes, there is little empirical evidence whether a policy of conscientious refusal would be disastrous for the military.

  5. 5.

    McMahan (2009, 74–5) admits this possibility, but claims that it is merely hypothetical (and that such combatants would be liable to attack). Also see McMahan (2004, 707–8).

  6. 6.

    As I will discuss below, on the Individual-Centric Approach individuals are required to consider whether their contribution will meet the principles of individual jus ad bellum throughout the war. In particular, they should consider the permissibility of their contribution not only when they resort to force, but also when their role changes.

  7. 7.

    McMahan (2004, 713–14) also asserts that a war can have numerous aims, some just and some unjust, and that unjust combatants may have a just aim even in a war that is unjust overall.

  8. 8.

    For a detailed discussion of the principle of proportionality, see Hurka (2005) and Pattison (2010b, 74–94).

  9. 9.

    It should be emphasised that, if one adopts a subjective account of the individual jus ad bellum principle of proportionality, the permissibility of an individual’s contribution depends on whether their assessment of the proportionality of their contribution was reasonable. It is not judged in hindsight according to whether it was actually proportionate.

  10. 10.

    See, for instance, for Coady (1980), Mapel (1998), and Toner (2010) (although Toner does note some of the nuances that I consider).

  11. 11.

    To be sure, some just war theorists do acknowledge the importance of an individual’s contribution—as the Individual-Centric Approach highlights—for specific issues and particularly in their accounts of liability to attack. They hold, for instance, that an unjust combatant’s liability to attack depends on the moral acceptability of their own contribution. See, for example, Fabre (2009, 57) and Lazar (2010).

  12. 12.

    Also see McMahan (2008b, 232).

  13. 13.

    This objection is discussed in more detail in Lazar (2010).

  14. 14.

    For criticisms of McMahan’s invocation of agent-responsibility, see Lazar (2009).

  15. 15.

    It should be noted that since writing this article, McMahan (2011, 547) has explicitly stated that on his account liability depends on what an individual does, not on their membership of a particular group. Notwithstanding, it is questionable whether he can avoid the contingent pacifism objection without endorsing the stronger version of the Institution-Centric Approach. Although I cannot pursue them here, his (2011) responses to this point depend on debatable empirical claims about the efficacy of unjust combatants’ contributions to a war and their likelihood of appearing to pose a threat, and rely on a problematic interpretation of the prohibition on intentionally killing innocents (he claims that the prohibition would not be violated by an attack on each member of a group that comprises 99 innocents and one culpable threat).

  16. 16.

    Similarly, Lazar argues that “[w]hether through fear, disgust, principle or ineptitude, many combatants are wholly ineffective in war” (2010, 190).

  17. 17.

    For instance, given the fragmentation of the private military industry, the conditions that are commonly required for collective responsibility (that groups have representative decision-making procedures, that group members have common interests and shared solidarity, and/or that there exist shared attitudes between group members) do not seem to apply to private contractors. For a clear overview of these conditions, see Smiley (2011).

  18. 18.

    The main objection to the New Wars Thesis is that the ‘old wars’ also possessed these features. See, for instance, Newman (2004). Even if this objection is correct, it does not undermine my point here, which does not depend on the newness of these features.

  19. 19.

    I consider these issues in detail in Pattison (2008, 2010a, 2010c, forthcoming).

  20. 20.

    Lazar (2010, 211) makes a similar claim.

  21. 21.

    I outline this view in much more detail in Pattison (2010b; under contract).

  22. 22.

    Alternatively, it might be claimed that contingent pacifism would be an upshot of the Individual-Centric Approach because individuals will often decide not to participate in war for fear of making an unjust contribution, which will make it very difficult for their institution to go to war. It is correct that the Individual-Centric Approach, if internalised, may make it more difficult for wars to be launched—this might be a further attractive feature of this approach. But I think that it can also be reasonably expected that, even if the Individual-Centric Approach were internalised, individuals may still be motivated on occasion to make what they judge to be just contributions to wars. Individuals’ fear of making an unjust contribution, I believe, will be outweighed by the desire to make a just contribution. Consider, for instance, the number of civilians who, with a heavy heart, take up arms in rebellions with the belief that, despite the risks of harming fellow citizens, their doing so is necessary to advance the cause of justice within their state.

  23. 23.

    Similarly, Toner (2010), claims that the jus in bello principles should have the same structure as the principles of jus ad bellum and McMahan (2004, 713–14) argues that just cause and other ad bellum requirements should be continuously applied throughout the course of war to individual acts of war.

  24. 24.

    There may be some moral differences, however. The role-based moral duties to perform a particular function may be stronger, for instance, during a war than before it commences, which, in turn, may reduce (although not eliminate) the overall wrongness of an in bello violation.

  25. 25.

    Several theorists get close to this position. See, especially, Fabre (2009) and Lazar (2010).

  26. 26.

    McMahan (2004, 712) notes that a just combatant may act wrongly in two ways. The first is to pursue a just cause by wrongful means and the second is to pursue a subordinate, unjust aim within a war that is just overall. In these two circumstances, he argues, an act of war by unjust combatants against just combatants could potentially be proportionate and permissible, presuming that they are unable to avert the wrongful action by terminating their own unjust war. However, as discussed further below, in Killing in War he still regards unjust combatants engaged in such actions as liable to attack.

  27. 27.

    In a similar vein, Lazar (2010, 189–93) argues that McMahan generalises in his assumption that unjust combatants will make a sufficiently large enough contribution to render them liable to be killed. Many combatants, Lazar argues, are so ineffective that they do not pose a ‘micro-threat’ against individuals or contribute to the larger ‘macro-threat’ posed by their side.

  28. 28.

    Likewise, Lazar asserts that many noncombatants on McMahan’s account would be liable as they (i) are agent-responsible and (ii) make some (small) contribution to the war (2010, 192–3).

  29. 29.

    That said, it may still be of some relevance, given that small differences may still make a difference in near-symmetrical, forced-choice situations.

  30. 30.

    I use filibustering in the sense of taking part in a private war in a foreign land.

  31. 31.

    See, further, Fabre (2008), who defends the view that individuals may wage war alone, even in the absence of legitimate authority.



I would like to thank David Boucher, Mark Evans, Joe Femia, Mervyn Frost, Helen Frowe, David Karp, Seth Lazar, Graham Long, Cian O’Driscoll, Tom Porter, Jon Quong, Mark Reiff, Peri Roberts, Hillel Steiner, Peter Sutch, Milla Vaha, Steve de Wijze, and two anonymous reviewers for their helpful comments on earlier versions of this article. This article was written whilst in receipt of funding from the Economic and Social Research Council (RES-000-22-4042). I am very grateful for their support.


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© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Politics, School of Social SciencesUniversity of ManchesterManchesterUK

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