Skip to main content Accessibility help
Hostname: page-component-544b6db54f-kbvt8 Total loading time: 0.339 Render date: 2021-10-17T04:27:42.698Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": true, "newCiteModal": false, "newCitedByModal": true, "newEcommerce": true, "newUsageEvents": true }


Published online by Cambridge University Press:  29 April 2016

Claire Finkelstein*
Law and Philosophy, University of Pennsylvania


In his famous book Just and Unjust Wars, Michael Walzer articulates a thesis he calls the “Moral Equality of Soldiers,” namely, the principle that combatants have an equal right to kill other combatants in war, regardless of the justice of the cause for which they are fighting. The Moral Equality Thesis, as I shall call it, is an essential component of traditional Just War Theory, in that it provides the basis for distinguishing the jus in bello from the jus ad bellum. It also plays a crucial role in identifying the nature of the difference between combatants and civilians. The Moral Equality Thesis has recently come under attack by scholars of Just War Theory, notably philosopher Jeff McMahan, on the grounds that killing for immoral purposes cannot be justified, and so it cannot be true that combatants all have an equal right to kill, regardless of the justice of their cause. In this essay, I defend the Moral Equality Thesis in its traditional formulation. Without it, I argue, the rule of law would not apply in war. The failure to recognize the equal right of combatants to kill in war, I suggest, creates an inconsistency between the rules of war and basic concepts in the law and morality of self-defense, an inconsistency that McMahan himself would think undesirable. I argue that McMahan’s argument applies more compellingly to armed conflict in asymmetrical warfare. Arguably, the Moral Equality Thesis does not apply in an armed conflict between combatants and unlawful combatants. In that context, the divergence from the law and morality of self-defense is less of a concern.

Research Article
Copyright © Social Philosophy and Policy Foundation 2016 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)


1 Walzer, Michael, Just and Unjust Wars (New York: Basic Books, 1977; reprint 1992);Google Scholar all page references are to the second edition.

2 Walzer, Just and Unjust Wars, 36.

3 Model Penal Code § 2.10 provides: “It is an affirmative defense that the actor, in engaging in the conduct charged to constitute an offense, does no more than execute an order of his superior in the armed services which he does not know to be unlawful.” This appears to contradict the general approach to war crimes such as was recognized at Nuremberg, for example, according to which following orders is no defense. The two are not, in fact, in contradiction, since the crimes at issue in Nuremberg, which were war crimes and crimes against humanity, were of manifest illegality.

4 In action theoretic terms we would say that the justification for killing an enemy combatant in war does not apply to an act of killing a combatant under a description under which the act was killing a noncombatant. Justification is description-relative, and the status-based privilege of killing combatants simply does not justify collateral damage all by itself.

5 But see Ohlin, Jens, “Targeting Co-Belligerents” in Finkelstein, Claire, Ohlin, Jens, and Altman, Andrew, eds. Targeted Killings: Law and Morality in an Asymmetrical World (Oxford: Oxford University Press, 2012), 6089 CrossRefGoogle Scholar (defending a functionalist account of combatancy).

6 See Chris Kutz, “The Difference Uniforms Make,” Philosophy and Public Affairs 33, no. 2 (2005): 148–80.

7 The International Committee of the Red Cross, however, attenuates this definition by identifying a combatant as follows: “Rule 3. All members of the armed forces of a party to the conflict are combatants, except medical and religious personnel.” While this is still a status-based definition, it has a functional component insofar as it identifies a combatant as someone engaged in armed conflict. Given that “armed conflict” need not imply actual fighting, the definition remains status-based, but on the traditional conception a person need not be actually engaged in armed conflict to be considered a combatant.

8 This is an oversimplification. Civilians can acquire combatant status simply by assisting the military forces. However, unlike true combatants, their status as combatants is dependent on their performing certain actions that assist the war efforts, and that status will disappear as soon as the threatening activity ceases.

9 It is difficult to identify such instances, other than possibly self-defensive acts responsive to excessive use of force. However, in the domain of war, where offensive uses of force are not forbidden, excessive force means only force that is outside the rules of war (in bello rules). Since we are contemplating a world without separate in bello rules, however, it is not clear how we could define force as excessive. Excess would necessarily be relativized to the party’s underlying moral position. For the combatant fighting on the just side, it may be that no force is excessive.

10 Walzer, Just and Unjust Wars, 42.

11 See Walzer’s discussion of Clausewitz at Just and Unjust Wars, 22–25.

12 Jeff McMahan, Killing in War (New York: Oxford University Press, 2009), 1 (arguing “against the view that unjust combatants act permissibly when they fight within the constraints of the traditional rules of jus in bello”).

13 See ibid., 35 (“In contexts other than war, the morality of conflict is invariably asymmetric: those who are in the right may be permitted to use force and violence but those who are in the wrong are not”).

14 On this topic see Finkelstein, Claire, “A Puzzle About Hobbes on Self-Defense,” Pacific Philosophical Quarterly 82 (2001): 332–61.CrossRefGoogle Scholar

15 Excuses are less useful in this regard, both because they do not override criminal prohibitions, and also because they are individualized and cannot therefore be thought of as normative generalizations.

16 There are two sources of objection to this approach. The first are criminal law scholars who see criminal law as having little to do with ordinary morality. Deterrence theorists like Bentham or those in the economic tradition would see it this way. The second are what one might call “legal-moral relativists,” namely those who see so-called moral intuitions as illusory, insofar as such intuitions rely on a kind of realism about moral norms. Nevertheless, many scholars have noted the commonality of intuitions concerning justice across a broad array of peoples and cultures. See Paul H. Robinson and John M. Darley, “Intuitions of Justice: Implications for Criminal Law and Justice Policy,” Southern California Law Review 81, no. 1(2007): 9 (“[A] variety of studies have shown that subjects share both the intuition that actors who engage in serious wrongdoing should be punished and a broad consensus about the relative blameworthiness of different types of transgression”).

17 See generally, McMahan, Killing in War.

18 Ibid., 36 (“[T]here are moral principles that are not restricted to war but are such that the situations to which they apply are extremely rare outside the context of war”).

19 See Model Penal Code § 3.04 (2)(b)(ii) (excluding self-defense where “the actor knows that he can avoid the necessity of using such force with complete safety by retreating . . . ”).

20 I discuss this question at length in my article on the case of Paul Touvier. See Claire Finkelstein, “Changing Notions of State Agency in International Law: The Case of Paul Touvier,” Texas International Law Journal 30 (1995): 261.

21 Hurd, Heidi, Moral Combat (New York: Cambridge University Press, 1999)CrossRefGoogle Scholar, xii.

22 Claire Finkelstein,“Two Men on a Plank,” in Legal Theory, 7 (2001): 279.

23 Hurd, Moral Combat, chap. 2.

24 Shakespeare, William, King Lear, ed. Mowat, Barbara A. and Werstine, Paul (New York: Washington Square Press, 1993)Google Scholar, Act III, Scene IV.

Cited by

Send article to Kindle

To send this article to your Kindle, first ensure is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

Note you can select to send to either the or variations. ‘’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats

Send article to Dropbox

To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

Available formats

Send article to Google Drive

To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

Available formats

Reply to: Submit a response

Please enter your response.

Your details

Please enter a valid email address.

Conflicting interests

Do you have any conflicting interests? *