Skip to main content

About this free course

Download this course

Share this free course

The moral equality of combatants
The moral equality of combatants

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

I The doctrine of the moral equality of combatants

There’s a well-known scene in Shakespeare’s Henry V in which the King, disguised as an ordinary soldier, is conversing with some of his soldiers on the eve of the battle of Agincourt. Hoping to find or inspire support among them, he remarks: ‘Methinks I could not die anywhere so contented as in the King’s company, his cause being just and his quarrel honorable.’ One soldier replies: ‘That’s more than we know,’ whereupon a second says: ‘Ay, or more than we should seek after; for we know enough if we know we are the King’s subjects: if his cause be wrong, our obedience to the King wipes the crime of it out of us.’ Footnote 1

I don’t know whether Shakespeare recognized the now familiar legal distinction between justification and excuse. But if he had meant for this soldier to be claiming only an excuse, he probably would have had him say that the King’s authority wipes the guilt from them. But instead he says that it clears them of the crime : that is, even if the cause for which they fight is wrong, they commit no crime, or do no wrong, in fighting for it.

This has been the dominant view about participation in an unjust war throughout history. And it’s central to the theory of the just war in its currently orthodox form. According to contemporary just war theory, the principles governing the conduct of war make no distinction between soldiers whose war is just and those whose war is unjust. These principles are held to be equally satisfiable by all those who fight. According to the theory, combatants do wrong if they violate these principles, though not if their war contravenes the principles that determine whether a war is just. For these latter principles apply only to those who have a role in deciding whether to resort to war, or to keep a war going.

Michael Walzer, the most distinguished proponent of the just war theory in its contemporary form, refers to the idea that combatants on all sides in a war have the same rights, immunities and liabilities as the ‘moral equality of soldiers’. I will refer to this as the ‘moral equality of combatants’, since the term ‘soldiers’ doesn’t obviously include air and naval personnel. All combatants, he says, have an ‘equal right to kill’. Although Walzer is asserting a moral claim, he might equally have been citing international law, which holds that it’s not a crime merely to participate in an unjust war. Combatants act illegally only if they violate the laws that regulate the conduct of war.

A war can be unjust for various reasons. It might, for example, be fought for a just cause but be unnecessary for the achievement of that cause, or disproportionately destructive relative to the importance of the cause. Usually, however, wars are unjust because they’re fought for a cause that’s unjust. I’ll refer to combatants who fight for an unjust cause as ‘unjust combatants’ and to combatants who fight in a just war as ‘just combatants.’ These categories are not exhaustive because they leave out combatants who fight in unjust wars which have just causes.

My remarks will focus on the more common cases in which war is unjust because the cause for which it’s fought is itself unjust. Though many of my subsequent claims will apply to combatants who fight in wars that are unjust for other reasons, I’m restricting the focus of my argument because it’s in cases in which a war’s goals are unjust that the doctrine of the moral equality of combatants is least plausible. If it can be shown that the doctrine is indefensible in these cases, that will be sufficient to refute it, since it’s supposed to be universal in scope and application. No one, to my knowledge, claims that it’s impermissible to fight in a war with an unjust cause yet permissible to fight in a war that has a just cause but is unnecessary or disproportionate, or in a war that has a good aim that doesn’t rise to the level of a just cause. Footnote 2

Although the doctrine of the moral equality of combatants has been the dominant view throughout history, it’s hard to see how it could be correct as a matter of basic morality. In part that’s because it’s hard to see how any means to the achievement of an unjust end could be anything other than wrongful – unless, perhaps, it were simultaneously an end in itself that was just, or a means to another end that was just, and achieving the just end would morally outweigh bringing about the unjust end.

But an equally important reason why participation in an unjust war seems wrong is that those against whom unjust combatants fight are innocent in the relevant sense. This may seem a strange claim. For in the context of war, ‘innocent’ is usually treated as synonymous with ‘civilian’. Yet ‘innocent’ has two distinct uses in discourse about war that are commonly assumed to coincide. My claim invokes the other sense, which is acknowledged by Walzer when he notes that ‘ innocent [is] a term of art’ that we apply to people when ‘they have done nothing, and are doing nothing, that entails the loss of their rights.’ Footnote 3 The reason that the two senses are generally thought to coincide is that civilians aren’t engaged in the activity of war and thus are assumed to have done nothing to lose their right not to be attacked.

But even if all civilians are innocent in this second sense, that doesn’t mean that only civilians have this status. Suppose that a malicious person attacks you unjustly. Would you lose your right not to be attacked by him simply by trying to defend yourself? No. People don’t lose moral rights by justifiably defending themselves or other innocent people against unjust attack; therefore, unless they lose rights for some reason other than acquiring combatant status, just combatants are innocent in the relevant sense. So, even when unjust combatants confine their attacks to military targets, they kill innocent people. Most of us believe that it’s normally wrong to kill innocent people even as a means of achieving a goal that’s just . How, then, could it be permissible to kill innocent people as a means of achieving goals that are unjust ?

In effect, what I’m asserting is that unjust combatants can’t satisfy the traditional requirement of discrimination in its generic formulation – that is, the requirement to attack only legitimate targets. I’ve argued elsewhere that they also can’t satisfy the other principal constraint on the conduct of war: the requirement of proportionality. Footnote 4 Acts of war by unjust combatants can’t in general satisfy this requirement because any good effects they might have can’t serve to justify, and therefore can’t weigh against, the killing or maiming of innocent people.

These objections seem obvious enough. I believe that they conclusively demonstrate the moral inequality of combatants at the level of basic morality. Yet even after considering them, most people remain convinced that unjust combatants do not act wrongly merely by fighting in an unjust war. So, rather than further developing the arguments against the doctrine of the moral equality of combatants, I propose to explore the reasons why people are reluctant to accept that unjust combatants act wrongly in fighting. My concern here is with normative rather than explanatory reasons, and in what follows I’ll examine the most cogent arguments that I’ve been able to find or to devise in support of the orthodox doctrine of the equality of combatants. Footnote 5


  1. 1 IV.i.128–35.Back to main text
  2. 2 For the distinction between a good cause and a just cause, see Jeff McMahan, ‘Just cause for war’, Ethics and International Affairs , 19 (2005), 1–21. Back to main text
  3. 3 Michael Walzer, Just and Unjust Wars (Harmondsworth: Penguin, 1977), p. 146. Back to main text
  4. 4 Jeff McMahan, ‘The ethics of killing in war’, Ethics , 114 (2004), 693–733, especially pp. 708–18. Back to main text
  5. 5 In The Ethics of Killing in War I will identify some confusions that I believe motivate people’s commitment to the doctrine of the moral equality of combatants. Back to main text