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On Just Cause in Law and the Morality of War

Between National Defence and Interventionism

Essay 2009 14 Seiten

Politik - Politische Theorie und Ideengeschichte


The sole and only just cause for waging war is when harm has been inflicted.[1]

The dissolution of the bipolar world order at the beginning of the 1990s changed the international security-political surroundings into a multipolar system. Ever since, there was a paradigm shift in the foreign and security policy of western democracies emphasizing the respect for and enforcement of human rights more strongly. Keywords like ‘normative revolution’ and ‘idealistic new world’, which were to finish inhumanity, culminated in the formula of ‘illegal, but legitimate’.[2] This implicates the forcible breach with the post-war consensus of the UN charter, which ties acts of violence down to authorizations of the UN Security Council. But the enforcement, especially with military means, of one UN principle – the principle of human rights – by breaking another – that of sovereignty – is highly precarious. It is not the task of this essay to show that some of these ‘humanitarian interventions’ were far from being actually humanitarian or legitimate at all, but to discuss these legal and moral tensions on a more abstract level. Therefor it is necessary to look beyond the actual positive law and scrutinize the ideas of just war theory deductively.

As the Spaniard Francisco de Vitoria noticed, war can only be justified as response to previous wrongs. The issue here is the extent and manner of inflicted harm justifying the use of violence on behalf of third parties – the legal and moral preconditions for interventions. National defence should remain the central basis for just cause in the law and morality of war, however, in the area of tension between national self-determination and the most fundamental human rights, the prevalent principle of non-intervention reaches its limits and allows for humanitarian interventions as response “to acts ‘that shock the moral conscience of mankind.’”[3] In order to avoid instrumentalization or misemployment of these instruments and guarantee protection of peoples from human rights abuses, an institutionalization is absolutely essential; hence, proper international authority has to be established and has to conduct these interventions on multilateral grounds with care for the cultural circumstances – for the solution of societal problems and of nation-building cannot simply be imposed on nations from outside.

This issue on just cause for waging war with humanitarian purpose is approached within three parts. Part I defines the basic principle of just cause; on this basis, part II justifies war for the sake of human rights; and part III deals with the question of proper authority realizing these moral ideas and shows the limits of interventionist humanitarian acts of violence with a view to the cultural circumstances in the target country.

The most basic distinction in just war theory is the difference between jus ad bellum and jus in bello . The former is the generic concept of substantive reasons to resort to the illegal activity of war, whose legitimate use is limited to at most one side and thereby mainly relegated to the private sense of right and wrong of each sovereign; the later is engaged in the rules of proper conduct in war, which were thought to have a firm legal content, so it is assumed “that war is a law-governed and hence implicitly lawful activity with entitlements and restrictions that accrue equally to both sides.”[4] According to the theory of just war, belligerence may not only be excusable but also justified in some circumstances - so there has to be a just cause to resort to war. However, just war theory’s idea of just cause was challenged in political philosophy by the idea of regular war setting just cause aside and favouring bilateral rights of war. In regular war, the belligerents are viewed as juridically equal opponents that are presumed to have entered the armed conflict in good faith, regardless of the cause having prompted the conflict, and so being entitled likewise to resort to the same armed force because of their mutual status of sovereignty. “[T]his conception of a bilateral jus ad bellum ran directly counter to the central ‘axiom’ of the just war doctrine according to which war could be warranted only as a unilateral response to prior wrongdoing.”[5] By ignoring the idea of just cause, the doctrine of raison d’état would be reinstalled and any attempts to restrict the amount of wars would have been in vain, as each state could decide for itself whether going to war serves its vital interests regardless of any restricting law or morality.

If each side believes in the righteousness of their cause, this contradicts the very logic of just war theory as well, since both belligerents would be innocent and neither would have a justification. But the very notion of just cause implies the impossibility of simultaneous justice. So Vitoria acknowledges that there may be situations in which the wrongful party “believes itself to be innocent, arising from an interplay of factors beyond its voluntary control.”[6] On this basis of ‘invincible ignorance’ (Vitoria), the wrongful party being unaware of its de facto unjust cause should be treated less harshly and would even be entitled to defend itself. However, Vitoria’s doctrine of seemingly simultaneous justice does not endorse equal, bilateral rights of war, for the unjust party is held accountable, yet by invincible ignorance she is excused; thus only one side can possibly be justified to draw upon war.[7]

Hugo Grotius points out that “a war cannot be just on both sides”[8], but having established a necessity for just cause in order to gain the justification to resort to war, this still leaves open the question of moral equality in the jus in bello . According to the traditional just war theory, the justification for killing in war is both independent of, and incompatible with, the idea that there is an asymmetry of moral status between attackers and defenders, or between just and unjust combatants for “the soldiers of the aggressive state have as much right to kill defending soldiers as the defending soldiers have to kill them.”[9] Revisionists like Rodin, Hurka and McMahan want to challenge just war theory in being against the independence thesis of a separation of jus in bello from the fulfilment of jus ad bellum conditions. Thus they argue against moral equality applying to both sides: “soldiers, and not just sovereigns, are responsible for the aggressive wars in which they engage. […] soldiers fighting an unjust war have no permission to kill, and there is no ‘moral equality’ between soldiers.”[10] McMahan sees the basic distinction determining who might become an acceptable target for attacks between “the morally guilty and the morally innocent.”[11] And he even claims that it is justifiable to kill prisoners to avoid their rejoining and therewith strengthening their armies.[12] But this would undermine any war conventions and would not be compatible to justice or the absolute validity of human rights; such entirely pragmatic considerations like denying prisoners any trial seem more like a massacre or counter-terrorism than just war.

The solution of this moral equality problem is more subtle than McMahan’s either/or approach suggests. “[T]he enemy soldier, though his war may well be criminal, is nevertheless as blameless as oneself.”[13] Soldiers fighting in an unjust war are not responsible for this war “their lives [being just] nationalized […] by the modern state” and they remain blameless as long as they adhere to the rules of proper conduct in war, for “war is still, somehow, a rule-governed activity, […] a moral world […] in the midst of hell.”[14] The notion of soldiers as nationalized instruments is crucial here and Hurka’s approach of discounting soldiers death might be helpful – not to challenge moral equality, but to refine it. He implies that soldier’s lives count less than civilians’ and the moral weight of their death’s diminishes by choices they took in the past, that volunteering to military service is tantamount to give up the right not to be killed and making one’s death not unjust, and that conscript’s lives have more weight than the lives of full volunteers.[15] This is still compatible to Walzer’s view on moral equality in the standard case of wars between sovereign states leaving the soldiers guiltless: “when soldiers fight freely, choosing one another as enemies and designing their own battles, their war is not a crime; when they fight without freedom, their war is not their crime.”[16] However, just war theory has also to be adaptable to the modern non-standard cases of war – the so-called ‘asymmetric warfare’.[17] With regard to them, McMahan’s revisionist individualist approach to war merges with Walzer’s collectivizing view. Then moral equality depends on the kind of war being conducted: in wars between states, moral equality applies fully; soldiers in guerrilla warfare are also still excused or even justified; but terrorists – in killing deliberately innocent people – are a clear case of individually unjust, criminal warriors and therewith not subject to moral equality, as in terms of terrorism, the responsibility for all activities depends fully on the individual. Unlike combatants, terrorists – unless in case of state terror – have to bare the responsibility of a missing just cause in both jus ad bellum and jus in bello .


[1] Francisco de Vitoria: De jure belli ( On the Law of War ), qu. 1, art. 3, § 4. Cited in Reichberg, Gregory M./Syse, Henrik/Begby, Endre (2006): The Ethics of War. Classic and Contemporary Readings . Oxford: Blackwell, p. 314.

[2] See Chomsky, Noam (2005): ‘Illegal, doch legitim. Eine dubiose Doktrin unserer Zeit.’ Blätter für deutsche und internationale Politik , 8/2005, 925-938.

[3] Walzer, Michael (1977): Just and Unjust Wars. A Moral Argument with Historical Illustrations . New York, NY: Basic Books, p. 107.

[4] Rodin, David (2002): War and Self-Defense . Oxford: Clarendon Press, p. 166; see also Reichberg, Gregory M. (2008): ‘Jus Ad Bellum.’ In Larry May (ed.): Essays in Political Philosophy . New York, NY: Cambridge University Press, pp. 11-29: 11.

[5] Reichberg 2008, 17.

[6] Ibid., 19.

[7] See ibid., 19-20.

[8] Grotius, Hugo (1964): De Jure Belli Ac Pacis . New York, NY: Classics of International Law, book II, p. 565.

[9] Rodin 2002, 128.

[10] Ibid., 173.

[11] McMahan, Jeff (1994): ‘Innocence, Self-Defence, and Killing in War.’ Journal of Political Philosophy 2 (3), 193-221: 205.

[12] McMahan, Jeff (2006): ‘Killing in War: A Reply to Walzer. Philosophia 34, 47-51: 49-50.

[13] Walzer 1977, 36.

[14] Ibid., 35, 36.

[15] Hurka, Thomas (2008): ‘Proportionality and Necessity.’ In Larry May (ed.): Essays in Political Philosophy . New York, NY: Cambridge University Press, pp. 127-144: 136-139.

[16] Walzer 1977, 37.

[17] See e.g. Münkler, Herfried (2002): Die neuen Kriege . Hamburg: Rowohlt.


ISBN (eBook)
ISBN (Buch)
428 KB
Institution / Hochschule
University of Birmingham – Department of Political Science and International Studies
Just Cause Morality War Intervention Human Rights National Defence Selfdetermination Gerechter Krieg Menschenrechte Selbstbestimmung



Titel: On Just Cause in Law and the Morality of War