The Case for Just War Theory

It's time for our foreign policy to return to first principles.


Texas Gov. Rick Perry and Kentucky Sen. Rand Paul, both GOP presidential aspirants, recently had what one might call a frank exchange of views on foreign policy. After Paul wrote an op-ed in The Wall Street Journal opposing further intervention in Iraq, Perry suggested Paul is (paraphrasing here) a hopeless naïf whose fraidy-cat isolationism presents a standing invitation for terrorists to bomb America into rubble. Paul replied that Perry is a shoot-first maniac who would send American sons and daughters to their deaths because he refuses to learn from the past. "Any future military action by the United States," Paul wrote, "must always be based on an assessment of what has worked and what hasn't."

That would be a good start. But only a start. The foreign policy debate shouldn't end there — although, unfortunately, it often does.

Perry's and Paul's concern over what works and what doesn't ignores an equally important consideration: what's right and what's wrong. Except for one brief clause, in which he credits Ronald Reagan with "moral and strategic clarity," Perry ignores the question. So does Paul, aside from arguing that the best approach is one that "seeks peace, faces war reluctantly, and when necessary acts fully and decisively."

Maybe they both ignore the question because they assume the U.S. can do no wrong. It's lovely to think so. It's also treacherous. Nothing guarantees that future presidents and congresses will always choose wisely. What's more, assuming they will could increase the odds they won't: Certainty breeds arrogance. Arrogance is dangerous, and doubly so when military force is at issue.

Unless you think nations are little more than rival mafia families, which wage peace and war only to gain tactical or strategic advantage, you need an ethical framework for thinking about the role of force in the world. Fortunately, history has provided one: just-war theory, a body of thought that began (roughly) with St. Augustine and that others have improved upon over time.

Just-war theory's two prongs are jus ad bellum, which judges the entry into conflict, and jus in bello, which judges the conduct of it. Briefly, the theory holds that no war is justified unless it meets several criteria:

(1) It must be launched for morally justifiable reasons, such as self-defense or protecting the innocent from genocide.

(2) It must be waged with the right intention. Even a war begun in self-defense can be unjust if the defending nation intends to exterminate every citizen of the aggressor country.

(3) It must be commenced by the proper authority. In the U.S., this means Congress. (Almost by definition, an illegitimate government, such as North Korea's, cannot be a proper authority.)

(4) It must be a last resort.

(5) It must have some reasonable chance of success.

(6) It must be proportional: The harm done by the war must be, in some sense, "worth it." While the Soviet occupation of Afghanistan was wrong, it would not have justified global thermonuclear Armageddon.

Failure to meet any one of those criteria renders a war unjust. Likewise, failure to meet the criteria for rightful conduct within the war also renders it unjust. Those criteria are:

(1) Discrimination. As Michael Walzer, a widely regarded contemporary just-war theorist, has put it, soldiers should target only those who are "engaged in harm." Never intentionally target innocent civilians, or butcher soldiers who have surrendered, and strive always to minimize the unintended harm inflicted on the innocent.

(2) Proportionality. Leveling an entire city to destroy one munitions factory is not proportional.

This is the barest summary of a subject that fills whole library shelves, and different sources present the subject in different ways. Some, for instance, include prohibitions against methods malum in se, or evil in themselves, such as poison gas, and some include jus post bellum, or justice in the conclusion of warfare (e.g., war crimes of the victors should be punished as well as those of the losers).

Just-war theory sometimes takes heat from "realists" who consider it excessively idealistic, and from more pacifist types who think it tries to put a moral face on an intrinsically evil business. If an unwilling conscript fights only because a tyrannical regime will kill his entire family if he does not, it is fair to ask whether killing him — even in a firefight — ever could be considered an act of justice.

Most people, however, intuitively accept some, if not all, of the just-war tenets: We understand that unprovoked aggression is wrong; that slaughtering people because you hate who they are, or covet what they have, is heinous; that it is one thing to shoot a soldier who is shooting at you, and something different to shoot a soldier who is shaving outside his tent. Just-war theory offers a systematic framework for thinking about such questions.

What's more, it also helps to clarify contemporary situations that can get muddied by ancestral disputes. We do not have to re-litigate the 1667 Treaty of Andrusovo to consider Vladimir Putin's incursions in Ukraine unjustified aggression. We don't have to dissect the entire history of the Middle East to find the ethical calculus of the current Israeli-Hamas conflict highly asymmetrical. (And — attention, Rand Paul — applying just-war ideas to relations between the government and the individual also can offer a grounding for libertarian domestic policy. When is the state ever justified in initiating force against a person who is peaceably minding his own business?)

Just-war theory shows that, throughout history, most wars are unjust. Most of them are, in fact, little short of cold-blooded murder. Which is why politicians should concern themselves with far more than "what has worked and what hasn't." Any common cutthroat can ask himself that.