Thinking Morally About Intervention

Military intervention into local armed conflicts has emerged in the present international environment as providing the most likely occasion for use of armed force by western nations. In a particular instance, how should a nation decide whether to commit armed forces for the purpose of carrying out or assisting a military intervention? Answering this question requires taking account of various kinds of concerns. Some relate to the nature of the need and the overall circumstances in the society or societies into which the intervention would be made. Other concerns arise from the effect the intervention would have on the nation committing its forces. Still others derive from the nature of the international order. Overarching and including all these, though, are questions having to do with the moral justification of the proposed intervention. In this paper I examine how to think about whether a military intervention is justified or not in terms of the idea of just war. As a framework for this examination I begin by identifying the moral criteria defined in classic just war tradition. Then I briefly examine three important examples of moral argument put forward in the context of American debate over military intervention: those of theologian Paul Ramsey, political theorist Michael Walzer, and the United States Catholic bishops.

Classic Just War Tradition on the Use of Armed Force

Just war tradition approaches the matter of the morality of uses of armed force by raising two fundamental questions: whether the decision to resort to such force is justified and, once this first decision has been made, how justified force should be rightly employed (the two parts of the tradition historically called, respectively, the jus ad bellum and the jus in bello). In terms of the first question, whether resort to force is justified depends on the degree to which it satisfies several criteria, conventionally listed as follows:

  • right authority, historically understood as sovereign political authority, that which has no superior;
  • just cause, classically defined as defense against attack, recovery of persons and property wrongly taken, and punishment of evil;
  • right intention, defined both negatively and positively: negatively, the avoidance of various kinds of wrong intentions, the sort attaching to the modern term «aggression»; and positively, the purpose of establishing an orderly and just peace. This positive side of right intention is often separated out as a distinct criterion, the end of peace.

In Thomas Aquinas’s magisterial listing, only these criteria must be satisfied for a resort to armed force to be just. Subsequent tradition, however, added three other prudential concerns, which are, however, of a somewhat different order than the ones Aquinas termed «necessary»:

  • overall proportionality, the requirement that a judgment be made that the good done by the resort to force will outweigh the evil;
  • reasonable hope of success, a calculation of likelihood that the resort to force would achieve its just purposes; and
  • last resort, the requirement that an assessment be made that no justified means other than force could achieve the just cause.

The jus in bello historically was defined in two ways: by definition of classes of persons as noncombatants, not to be directly and intentionally harmed in a conflict, and by efforts to restrict the means of used in war. There approaches may still be found in the law of armed conflicts, which closely reflects just war tradition on the conduct of war; moral writing today typically reduces these concerns to two principles, discrimination and proportionality of means.

All these concerns are morally important; yet in the decision whether to commit military force for interventionary purposes the moral criteria defining the jus ad bellumare the  ones that must immediately be satisfied.

Let us now examine the three moral arguments on intervention identified above.

Paul Ramsey on Intervention

Ramsey, whose essay, «The Ethics of Intervention»,1Paul Ramsey, «The Ethics of Intervention», Chapter 2 (pp. 19-41) in The Just War (New York: Charles Scribner’s Sons, 1968). first appeared in 1965, wrote in the context of American moral debate over military intervention in Vietnam. Believing, though, that moralists had no business trying to play the role of political authorities, he held his analysis to the theoretical level, not offering any practical advice on its meaning for the case immediately at hand. As a result, the analysis and argument he developed in this particular historical context are not tied to that specific context but apply to moral consideration of intervention in other circumstances as they might arise.

For Ramsey, the central issue in determining the morality of a particular act of military intervention is whether it serves justice or not. In this, on his reasoning, intervention is not different from other possible uses of military force or, indeed, any other form of national power. The political order exists to serve justice in the end of peace, and the means of power the state possesses are morally justified by this fundamental purpose. Thus in principle the state may use military force – indeed, it may experience the need to use such force as a responsibility – when it confronts a situation of extreme injustice that cannot be remedied by other means.

Ramsey’s own language was unambiguous. Military intervention in the cause of justice, he argued, «is among the rights and duties of states unless and until supplanted by superior government».2Ibid., p. 23. If there were such a superior government, then the right and duty of military intervention – as well as of other uses of military force and other forms of governmental power – would rest there; but the existing international order, he judged, does not constitute such a government. Thus the right and responsibility rests with states, and, Ramsey went on to argue, particularly with the United States: «The primary reality of the present age and the foreseeable future is that the United States has had responsibility thrust upon it for more of the order and realized justice in the world than it has the power to effectuate».3Ibid. As a result, for the United States, in the face of extreme injustice,

to choose political or military intervention is to use power tragically incommensurate with what politically should be done, while not to intervene means tragically to fail to undertake the responsibilities that are there, and are not likely to be accomplished by other political actors.4Ibid

Yet a nation also has other responsibilities that flow from the same fundamental normative rationale; thus the decision what to do in the face of a particular injustice always must be reached with care. Ramsey accordingly pushed his reasoning about military intervention further, specifying that a moral decision to intervene must take account of two sorts of justifying grounds, which he called «ultimate» or «just war» grounds and «penultimate» ones.5Ibid., pp. 27-38.

The first two «ultimate» grounds are justice and order, both «terminal goals in (…) proper politics», on Ramsey’s account. As to justice, «The statesman must make a decision about the politically embodied justice he is apt to sustain or increase by his choice to intervene or not to intervene». As to order, the statesman must make «an assessment of order as one of the ends power must serve». The third requirement is to measure the degree to which the contemplated intervention would serve national and international common good. These goods, Ramsey observed, are not always the same, and so good statecraft requires choices that fall in the area of overlap between them. Finally, the statesman must consider the requirements of the domestic legal system and of international law and international institutions before deciding to intervene in a specific instance.

These last two considerations set limits on the quest for justice and order: they are not to be served at all costs. Good statecraft requires careful choices among the possibilities for moral action. Grave humanitarian need, for example, does not by itself justify intervention. The statesman «is not called to office to aim at all the humanitarian good that can be aimed at in the world. Instead he must determine what to do from out of the total humanitarian ought to be». Similarly, while law ultimately must be judged by the degree to which it serves or embodies justice, it must be taken seriously as an effort to establish and maintain a just political order.

This leads Ramsey to the «penultimate» considerations regarding intervention, which turn out to be quite specific grounds provided for in international law: counter-intervention and intervention by invitation. These are never ultimately decisive in themselves, Ramsey argued; good statecraft must always weigh the «ultimate» or «just war» considerations more heavily; yet at the same time, those higher grounds in themselves «are not ordinarily sufficient without having recourse to the secondary justifications». The result of this reasoning is to set serious limits on what at first looks to be virtually an out-and-out moral argument for military intervention as a response to injustice whenever and wherever it appears. There are times when, despite the presence of grave injustice, good statecraft may require a decision against intervention. But the determination must be made individually in each case which presents itself.

Ramsey’s argument recalls the concept of right intention as it was understood by Augustine and adopted by his medieval heirs: not an intention shaped by the potential for gain, the mere possession of superior military force, or any other consideration based on self-interest, but rather the intent to prevent injustice and restore justice in the cause of political order and peace; this is right intention. Ramsey’s position is clearly at odds with political realism, which bases its notion of good statecraft precisely on national self-interest. But on Ramsey’s understanding national interest must be determined by reflection on the fundamental purposes of political life, including justice, order, and the domestic and international common good. Good statecraft is guided by these, while taking account of the empirical resources available and the boundaries of action set by international agreement in international law. Understanding intervention in this way puts the moral issues first, but it also respects the limits of empirical political life and of the international order.

Michael Walzer on Intervention

Walzer developed his position on intervention in his book Just and Unjust Wars, first published in 1977.6Michael Walzer, Just and Unjust Wars (New York: Basic Books, 1977). This places it at the end of American involvement in Vietnam, and in his discussion of intervention Walzer includes a sharp criticism of that involvement as a case of unjustified intervention. No more than Ramsey’s argument, though, does Walzer’s hinge on his judgment about this particular case. The intervention in Vietnam is only one of the various historical cases discussed by Walzer in developing his moral-theoretical approach. While his method is far more dependent on examination of historical cases than Ramsey’s, it is the substance of his moral argument which, in the present essay, requires closest attention.

Walzer effectively begins at the opposite end of the chain of reasoning from Ramsey: with the requirements of the existing international order, which he calls the «legalist paradigm».7Ibid., pp. 61-63. Central to this paradigm is the protection of territorial integrity and political sovereignty of all states, and use of force across national borders therefore «constitutes aggression and is a criminal act». Thus nonintervention across territorial borders is the norm implied by the legalist paradigm. Accordingly, Walzer’s justification of military intervention proceeds as an exploration of how the legalist paradigm may be abrogated. His answer is, as in Ramsey’s case, an appeal to more basic value conceptions that underlie political life as such. In Walzer’s terms, «those conceptions of life and liberty which underlie the paradigm and make it plausible . . . seem also to require that we sometimes disregard the principle» of nonintervention.8Ibid., p. 86. In three sorts of cases, Walzer argues, the prohibition of cross-border use of military force does not «seem to serve the purposes for which it was intended»: intervention is civil wars in states where there are two or more political communities, where one is fighting to secede or for «national liberation»; counter-intervention to offset prior intervention by another outside power; and the case for which Walzer uses the term «humanitarian intervention», intervention to counter extreme violation of human rights by fighters during a conflict or by a government against its people.9Ibid., p. 90.

Walzer’s reasoning for the first two sorts of cases is similar: though these two kinds of cases are different, the only proper aim for intervention is to establish a kind of balance so that the parties to the civil conflict can work out their future on their own. In counter-intervention into a civil conflict, the aim is to offset the prior intervention; in intervention to assist a struggle to secede, the aim is to establish a kind of balance between the secessionist movement and the existing government – which can be assumed to have military resources superior to those of the secessionists if the latter are unaided. Walzer comments:

The problem with a secessionist movement is that one cannot be sure that it in fact represents a distinct community until it has rallied its own people and made some headway in the «arduous struggle» (Mill’s phrase) for freedom. The mere appeal to the principle of self-determination isn’t enough; evidence must be provided that a community actually exists whose members are committed to independence and ready and able to determine the conditions of their own existence.10Ibid., pp. 93-94.

As an example, Walzer cites anti-colonial warfare: «imagine a small nation successfully mobilized to resist a colonial power but being slowly ground down in the unequal struggle. Mill [John Stuart Mill, whose analysis Walzer has been following] would not insist, I think, that neighboring states should stand by and watch its inevitable defeat».11Ibid., p. 94. Intervention in such a case would be aimed at balancing the odds, allowing the weaker power to establish its worthiness for self-rule without being overwhelmed by the stronger.

Humanitarian intervention, by contrast, does not aim at creating a balance of forces, but at stopping the abuses of human rights that justify such intervention. Where «the bare survival or the minimal liberty» of significant numbers of people are at stake, Walzer writes, «we don’t want the local balance to prevail».12Ibid., p. 101. In the particular case of a government’s repression of such groups as political opponents, national minorities, and religious sects, such repression in effect forfeits the right for that government to be protected by the principle of non-intervention.

While Walzer, unlike Ramsey, did not employ the specific language of just war tradition, he clearly understood his position on intervention to be in accord with the general aim of Just and Unjust Wars, which he described as «to recapture the just war for political and moral theory».13Ibid., p. xiv. Thus as with Ramsey, Walzer’s concern is the use of national power to serve values on which all political life, rightly understood, depends. National self-interest may play a part in a decision to intervene, and the presence of self-interested motives does not remove the moral right to intervene. Walzer notes that he has not been able to identify any historical cases of purely unself-interested humanitarian intervention, for example, but only ones involving mixed motives. The claim of a humanitarian purpose must accordingly be tested by other considerations, namely, who are the targets of the intervention, how destructive the intervention will be of the society in question, and how quickly the intervening force withdraws after it has ended the humanitarian violations. These tests go to the question of the intentionality of the intervening power and, as with Ramsey’s argument, recall the classic just war definitions of just cause and right intention: use of political authority and power to serve justice, punish evil, and restore rights wrongly taken away, not for self-interested motives but for the sake of the underlying purposes of political life itself, including for Walzer the right to enjoy life and liberty in peace.

The United States Catholic Bishops on Intervention

In the context of the American debate the position on intervention laid out by the United States Catholic bishops in their 1993 collective statement, The Harvest of Justice Is Sown in Peace,14National Conference of Catholic Bishops, The Harvest of Justice Is Sown in Peace (Washington, D.C.: United States Catholic Conference, 1993). is important not only as a representation from the largest American religious denomination but also as a reflection of attitudes widely shared among other denominations, particularly the mainline Protestant churches. The 1993 statement is further of interest because it was prepared to mark the tenth anniversary of the U.S. Catholic bishops’ widely read and debated 1983 collective pastoral letter focused on the moral issues related to nuclear war and deterrence, The Challenge of Peace.15National Conference of Catholic Bishops, The Challenge of Peace (Washington, D.C.: United States Catholic Conference, 1983). Though these two documents are connected historically, thematically, and in their reliance on the bishops’ understanding of Catholic teaching on just war, the 1993 statement, unlike its predecessor, includes a discussion of military intervention. Moreover, while both documents regard the resort to military force as limited by a moral «presumption against war», the 1993 statement sets out a strikingly positive position on use of military force in humanitarian intervention.

The bishops’ argument on intervention forms part of a lengthy section of the 1993 statement – approximately half the document – laying out «An Agenda for Peacemaking».16National Conference of Catholic Bishops, The Harvest of Justice, pp. 8-18. Early in this section attention is called to a «challenge» to the international community by Pope John Paul II singling out the cause of justice as linked to peace; this is followed by an activist list of what needs to be achieved in the service of justice and peace: establishing and protecting human rights, sustaining equitable economic development, restraining nationalism and eliminating religious violence, building cooperative security, and shaping responsible leadership by the United States as the preeminent world power. The bishops’ discussion of humanitarian intervention closely follows from this beginning.

Humanitarian intervention, for the bishops, is «the forceful, direct intervention by one or more states or international organizations in the internal affairs of other states for essentially humanitarian purposes», including alleviating «internal chaos, repression, and widespread loss of life». Such intervention properly aims «to protect human life and basic human rights» in such contexts. The document observes that such intervention has been termed «obligatory» by Pope John Paul II in cases «where the survival of populations and entire ethnic groups is seriously compromised». In such cases intervention, according to the Pope, is «a duty for nations and the international community».17Ibid., p. 15. This is unusually broad and strong language, which the bishops reinforce with a further quote from the Pope: when diplomatic and other procedures short of force have failed, and

nevertheless, populations are succumbing to the attacks of an unjust aggressor, states no longer have a «right to indifference». It seems clear that their duty is to disarm the aggressor if all other means have proven ineffective. The principles of sovereignty of state and of noninterference in internal affairs (…) cannot constitute a screen behind which torture and murder may be carried out.18Ibid.

Such language clearly compares to Ramsey’s on the responsibility of states to intervene where there is flagrant injustice and even more closely to Walzer’s explicit reference to protecting human rights in justifying humanitarian intervention. It is clear that the Pope in these statements was not simply speaking abstractly or theoretically, but had in mind contemporary conflicts in which the suffering of noncombatant populations had magnified and in which noncombatatants had sometimes themselves been targeted directly and intentionally as a means of war. The American bishops added their own list of contemporary conflicts in which the humanitarian need was great and, as a result, intervention seemed justified: «Haiti, Bosnia, Liberia, Iraq, Somalia, Sudan and now Burundi»19bid. – a list that they might well extend today, six years later.

In their elaboration of their own theoretical position the bishops draw on their understanding of just war principles. The justifying cause for humanitarian intervention is protection of «human life, human rights, and the welfare of the human community», including the aim «to ensure that starving children can be fed or that whole populations will not be slaughtered». Such aims, they argue, «represent St. Augustine’s classic case: Love may require force to protect the innocent». As to the question of authority, the bishops’ main concern is with immoral actions that revoke moral authority to govern and remove the protections normally associated with state sovereignty: sovereignty and nonintervention, they write, are not absolutes. As to right intention, in addition to the purpose of serving the just cause as identified above the bishops make the right to intervene dependent on the degree to which the intervention seeks to strengthen international law and the international community. Finally, as to last resort, in cases in which intervention is justified, nonmilitary forms of intervention should take precedence over military ones.20Ibid., p. 16.

As a result, the bishops conclude,

humanitarian intervention need not open the door to new forms of imperialism or endless wars of altruism, but could be an exceptional means to ensure that governments fulfill the purposes of sovereignty and meet the needs of their people.21Ibid.

That is, intervention should serve the interests and purposes of political order rightly understood, a position that recalls Ramsey’s and reflects earlier just war tradition on the relation of military force to ensuring and main­tain­ing a just, peaceful political order.


As these examples show, the concern for justice at the heart of the just war idea leads to a conception of international order in which the responsibilities of states do not stop at their own borders or with their own interests as defined by political realism, but may extend to intervention into the territories of other states in situations where there are major violations of justice and grave humanitarian need. At the same time, just war thinking also imposes significant restraints on the actions of states, even in such situations. In the classic tradition, the difference between these two tendencies – and the tension between them – is visible in the contrast between the deontological and consequentialist concerns that together define the jus ad bellum: the fundamental moral meanings underlying the ideas of right authority, just cause, and right intention (including the end of a just, peaceful order) versus the calculations required by consideration that any military action contemplated should do more good than harm, that it be a genuine last resort, and that it have a reasonable expectation of succeeding in its aim. That is, a full understanding of the moral obligation of a state when confronted by grave injustice and humanitarian need does not stop with establishing the authority to act by reference to the justice of the cause and the state’s having the right intentionality; it must also include reasoned judgment of the consequences of acting in a specific way, acting in some other way, or not acting at all.

Appeal to just war tradition does not yield a neat, one-size-fits-all answer; rather, it guides responsible statecraft to the consideration of all the moral concerns that need to be satisfied in order to have a just use of military force. Further, whether these concerns are satisfied is not likely to be a matter of black and white in a given case. What degree of humanitarian need must there be in order for a just cause to exist? What degree of oppression must have been reached before a state implicitly sacrifices its right to be treated as sovereign, so that other states may intervene to right the wrongs it is perpetrating? What measure of national interest may be added to humanitarian intention before this intention is fatally flawed? These questions show that even the deontological criteria of the just war jus ad bellum require moral judgment, even before the consequentialist calculations enter the picture. Just war thinking provides a valuable guide to such moral judgment; it does not in itself determine the outcome in any given case.

This is further illustrated by the tensions visible in the three recent examples I have treated. In retrospect, Ramsey’s evaluation of the implications of just war reasoning must have seemed in the context in which he wrote to provide a moral justification for the policy choice for United States military intervention in the conflict in Vietnam – even though he insisted that his analysis was on the level of theory, not practical policy decisions. Yet Walzer, using theoretical reasoning very much like that of Ramsey but writing after the Vietnam intervention had gone sour, made his own practical moral judgment that this had been an unjust action. Within Walzer’s own field of analysis, one may observe that even when the justifying principles have been carefully laid out, there remains the necessity of decision, and different decisions may be made on the basis of the same principles. For example, in a civil war over an ethnic or religious community’s desire to secede from a larger state, prudential judgment may vary as to what measure of interventionary force simply creates a balance that will allow the secessionists to succeed or fail by their own degree of virtue, and what measure of force would amount to tilting the balance in the direction of the secessionists. This seems to be very much the current problem in NATO thinking about autonomy for Kosovo, for example. Finally, when we consider the use of just war reasoning by the United States Catholic bishops, it almost seems as if the tension I have identified between the right to use military force and caution over that use has been resolved in favor of the permission – even obligation – to intervene in cases of great injustice and humanitarian need. The language of the bishops’ argument in their discussion of humanitarian intervention, taken by itself, certainly points in this direction. Yet the bishops’ overall position is heavily conditioned by their understanding of Catholic just war teaching as beginning with a «presumption against war»22Ibid., p. 5. and their clear reservations – more pronounced in their 1983 pastoral letter than in their 1993 statement – as to whether states and the state system can be trusted to fulfill the obligations of justice rather than simply being guided by self-interest.

These contemporary cases of just war-based moral reasoning thus reveal the same internal tension that I identified in classic just war tradition: on the one hand the concern for justice in the face of grave injustice establishes a moral justification for intervention, while on the other hand considerations requiring practical moral reasoning tend to restrain the actual decision to act on this justification. Left to itself, the justification creates not only a responsibility but a moral obligation; yet the limiting considerations bring other responsibilities, other moral obligations, into the picture as well. Finally, moral judgment is called for, and in any given case reasonable people, all searching for a moral solution, may reach different final judgments. Moral judgment is art, not science. Further, judgments in different cases may rightly differ, even where there is grave humanitarian need or other injustice. As Ramsey observes, the responsibility of good statecraft is not to aim at all the humanitarian good that might be done in the world – for example, to intervene with armed force wherever there is grave oppression – but to choose what to do «from out of the total humanitarian ought to be». Every act of intervention has wide-ranging consequences, not only in the targeted society but in the international order and one’s own society as well, and Ramsey, again, recognizes this in his requirement that a moral decision must take account of the domestic and international common good.

For a moral intervention, a moral intention is not enough; a just cause is not enough. These are necessary but not sufficient. Just war tradition broadens and nuances the moral debate, making for a statecraft that is neither idealistically utopian nor nationally protectivist in what it seeks to accomplish when confronted by grave evil.

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1. Paul Ramsey, «The Ethics of Intervention», Chapter 2 (pp. 19-41) in The Just War (New York: Charles Scribner’s Sons, 1968).
2. Ibid., p. 23.
3, 18, 21. Ibid.
4. Ibid
5. Ibid., pp. 27-38.
6. Michael Walzer, Just and Unjust Wars (New York: Basic Books, 1977).
7. Ibid., pp. 61-63.
8. Ibid., p. 86.
9. Ibid., p. 90.
10. Ibid., pp. 93-94.
11. Ibid., p. 94.
12. Ibid., p. 101.
13. Ibid., p. xiv.
14. National Conference of Catholic Bishops, The Harvest of Justice Is Sown in Peace (Washington, D.C.: United States Catholic Conference, 1993).
15. National Conference of Catholic Bishops, The Challenge of Peace (Washington, D.C.: United States Catholic Conference, 1983).
16. National Conference of Catholic Bishops, The Harvest of Justice, pp. 8-18.
17. Ibid., p. 15.
19. bid.
20. Ibid., p. 16.
22. Ibid., p. 5.