War has been a constant, more or less, for all of human history. Yet many wars are unjust, often gravely and manifestly so.

In the face of this injustice, what is one to do? Many people, the realists, accept it. War and its injustices, they reason, are inevitable. If war will ever be overcome, that moment is not presently imaginable. Politicians across the world seem to endorse such realism, even if there is not much to recommend it ethically.

In rejecting realism, we must ask, “How can war be just?” Pacifism insists that it cannot be, so all war must be avoided no matter the cost. Just war theory, on the other hand, provides conditions defining the circumstances in which military conflict can occur justly. These conditions could, obviously, take a number of forms, but historically, answers have been relatively stable. The conditions can be divided under two headings restricting the right to go to war (jus ad bellum) and delineating what constitutes right conduct during war (jus in bello).

The Catechism of the Catholic Church provides one formulation for just war theory—what it calls “legitimate defense by military force.” There are four necessary criteria for jus ad bellum:

-The damage inflicted by the aggressor on the nation or community of nations must be lasting, grave, and certain; -All other means of putting an end to [the conflict] must have been shown to be impractical or ineffective; -There must be serious prospects of success; -The use of arms must not produce evils and disorders graver than the evil to be eliminated.

With regard to the last condition, the Catechism helpfully adds, “The power of modern means of destruction weighs very heavily in evaluating this condition.”

During war, the Catechism demands humane treatment for noncombatants, wounded soldiers, and prisoners, while also ruling out all murderous acts. Moreover, each military action must be necessary and cannot cause disproportionate, even if unintended, harm. Thus the second, third, and fourth criteria for jus ad bellum essentially continue to apply in bello.

It isn’t necessary to be Catholic, however, to recognize the independent plausibility of these principles. Is it possible that a war could be justified? Since self-defense and the use of force by some entities, such as law enforcement, are both justifiable, it is hard to imagine an argument that war is unjustifiable in principle, even if the opportunities for just war are exceptionally rare in practice.

The question then is, “What would it take for a proposed war to be just?” The principles enumerated above, basically, prohibit wars that are pointless, ill-motivated, or ill-conceived. A war must be a response to something serious; moreover, it must not cause more damage than it averts.

Yet just war theory has been critiqued recently. For instance, the Vatican hosted a conference in Rome from April 11 to 13 to discuss what should replace just war theory, which the conference organizers allege is obsolete. I will focus on the suggestion that the reality of modern war has rendered just war theory obsolete, and on the related contention that there is something deeply paradoxical in anything called a “just war.” Both critiques miss the point of just war theory. Moreover, the conference organizers’ position is susceptible to Elizabeth Anscombe’s famous critique of pacifism.

The Problem of Modern Wars

There are two problems modern warfare might pose for just war theory. On the one hand, perhaps modern wars are counterexamples to just war theory. But this approach is a non-starter: Just war theory provides necessary conditions for a war to be just, so a counterexample would be a war that meets those conditions and is still unjust. I claim that no such counterexample could exist, since an unjust war would necessarily violate one of the conditions—that is what it would mean for the war to be unjust.

In any case, the critics I have in mind concede that modern wars are not counterexamples to just war theory, for they contend that no modern war even meets its criteria. This leads us to the second problem, expressed by Terrence Rynne, a Marquette University theologian presenting at the conference, who writes, “Even what just war theory sets out to do—discriminate justified from unjustified wars—has been rendered null and void by the massive, indiscriminate violence of modern wars.” To Rynne, the reality of modern war makes just war theory irrelevant. All modern wars are unjust by its standards, so the theory no longer applies. In particular, “Key criteria of the theory, namely, proportionality and protection of noncombatants, are never met by modern wars.” Rynne cites some historical evidence for his claim: “Civilian deaths in World War I were 10 percent of the deaths. In modern wars, such as the internal conflict in Syria or the US invasion of Iraq, civilian deaths now range from 80 percent to 90 percent of all war casualties.”

Whether or not this claim about twentieth-century wars is true, this argument makes two mistakes. The more obvious one is the failure to perceive that just war theory is normative and not descriptive: It says something about which wars should be engaged in, not about which wars are or will be engaged in. Wars are frequently unjust—which is why we need a theory about just wars—but that does not render just war theory irrelevant. In fact, just war theory applies to such twentieth-century wars because, if Rynne is right, it evaluates them as unjust. Just war theory, like Christianity by Chesterton’s lights, “has not been tried and found wanting. It has been found difficult; and left untried.”

In response to this point, an objector might press, “Sure, just war theory is normative. Still, if it has not applied to any twentieth-century war, it cannot be of much help practically.” This objection, too, is mistaken.

To show that just war theory does not apply in the modern era, it is insufficient to claim that no twentieth-century war met the conditions for a just war. Rather, the claim needed is that no conceivable twentieth-century war could have met the conditions for a just war. This would involve analyzing the conflicts to which the wars of the twentieth century were responses, and showing that any possible military action addressing them would have been unjust by just war theory’s criteria. This is a tall order, and needless to say, it has not been done.

Rynne’s second mistake is confusing the object of evaluation in just war theory. It is not really “World War I” that should be evaluated. Just war theory evaluates decisions to wage and conduct war, and these decisions are made by each participant in a war. Thus a defensive war might be just even if the aggressor’s participation is unjust. Consequently neither the proportion nor the volume of civilian deaths directly indicates a war’s justice or injustice, since an attack resulting in a large number of civilian casualties might legitimate—indeed, might require—violent defense.

Further, it is incorrect to suppose that only full-blown wars can be evaluated. The criteria for jus in bello permit fine-grained evaluation of individual military actions. Someone who wants to argue that just war theory was inapplicable in the twentieth century would have to argue that, for instance, the United States could not have taken any possible military action of any scale in response to the Holocaust. Is it obvious that the Holocaust could have been stopped without taking up arms? Or, if it could not have been, should we have declined to stop it?

Rynne’s insistence on “the recent track record of nonviolent action campaigns” is no evidence of the inadequacy or irrelevance of just war theory. Perhaps lots of conflicts have reasonable nonviolent resolutions; that is a great blessing. Just war theory obliges people of good will to pursue those nonviolent means rather than violent means. This is no mark against just war theory.

Just War: A Paradox?

Rynne raises a related concern, regarding the emphasis of just war theory: “Its focus is war, not peace.” Other conference organizers insist:

While clear ethical criteria are necessary for addressing egregious attacks or threats in a violent world, moral theologians and ethicists should no longer refer to such criteria as the “just war theory,” because that language undermines the moral imperative to develop tools and capacity for nonviolent conflict.

This objection, however, is multiply ambiguous. Is the “language” that undermines nonviolent efforts the mere use of the term “just war,” or is it the language of just war theory’s criteria? The latter proposal would make little sense, for the criteria mandate seeking nonviolent solutions; someone who has not honestly discerned that all nonviolent alternatives are “impractical or ineffective” cannot wage a just war.

On the other hand, it is rather superficial to object to the name “just war theory.” It is not as though the phrase “just war” thoughtlessly lulls people into associating war and justice; neither Rynne nor anyone else defends this implausible causal claim. If it’s really important to imbue war with iniquity, then just war theory could be renamed “unjust war theory”—since the jointly necessary criteria for a just war, answered in the negative, are also individually sufficient criteria for an unjust war. Or one could, with the Catechism, refer to “legitimate defense by military force”—a name that, although clunky, signals that just war theory can make very restricted judgments of legitimacy.

In its final statement, the conference’s participants affirm, “Too often the ‘just war theory’ has been used to endorse rather than prevent or limit war.” The suggestion is that just war theory is usually used to rationalize what are in fact unjust wars. If this is true, then it is no reason to discard just war theory. It would only mean that sinful humans often fail to meet its demands and twist it to their selfish purposes.

Elizabeth Anscombe on Pacifism

Another ambiguity in the conference organizers’ statement is their qualification that “clear ethical criteria are necessary for addressing egregious attacks or threats in a violent world.” This seems intended as a concession, but of what? It admits that the world remains violent and that war must, at least, be worked around. But can these “egregious attacks or threats” be “addressed” with violence, or can they not?

If the answer is yes, then clearly we need a just war theory to weed out unjust responses. If the answer is no, then the conference organizers are endorsing some sort of pacifism. This pacifism would reject the idea of a just war and the associated criteria; consequently it is subject to an important argument made by the Catholic philosopher Elizabeth Anscombe.

In 1956, Oxford University awarded President Harry Truman an honorary degree for his role in World War II. Anscombe, then a professor at Somerville College, Oxford, protested his degree on the basis of his repugnant decision to drop the atomic bomb on Hiroshima and Nagasaki, in order to elicit “unconditional surrender.” “For men to choose to kill the innocent as a means to their ends is always murder,” she wrote, “and murder is one of the worst human actions.”

My concern here is the critique of pacifism that Anscombe develops in the course of her protest. She thought pacifism contributed to Truman’s readiness to drop the bomb and the world’s readiness to congratulate him for it. For those unfamiliar with her pamphlet, this is probably a surprising claim. What worried her was the acceptance of indiscriminate killing in times of war:

It is characteristic of nowadays to talk with horror of killing rather than of murder, and hence, since in war you have committed yourself to killing—for example “accepted an evil”—not to mind whom you kill. This seems largely to be the work of the devil; but I also suspect that it is in part an effect of the existence of pacifism, as a doctrine which many people respect though they would not adopt it.

The problem, then, is with proposing pacifism as an ideal. Pacifism elides the distinction between killing and unjust killing—murder. Since war is sometimes necessary, those who find pacifism impossible become cynical realists rather than just war theorists—having forgotten the distinction that made the latter intelligible—with deadly consequences for the world.

I intend no blanket condemnation of the conference, and I concur with Pope Francis’s opening statement, which repeats the Second Vatican Council’s acknowledgement of a government’s right to legitimate defense. Moreover, nonviolence, whenever possible, is mandated by just war doctrine, so the conference’s inquiry into nonviolence is surely valuable.

Alas, not all of the modern world’s problems admit of reasonable nonviolent solutions. Consequently one should be prepared to say which military actions are just and which unjust. To throw out the principles that make this decision possible is to stand on the precipice between pacifism and realism—and from there, it is too easy to fall into the chasm.