What Is a Just War?

Michael Walzer
Michael Walzer; drawing by David Levine

Jus in Bello

The traditional theory of the just war covers three main topics—the cause of war, the conduct of war, and the consequences of war. Or, in the Scholastic tags: jus ad bellum, jus in bello, and jus post bellum. But most attention is given now to the middle term, the conduct of war. That is where clear offenses are most easily identified, though only occasionally reported and even more rarely punished. The two main rules of jus in bello have to do with discrimination between combatants and noncombatants, the latter to be spared as far as possible, and proportionality, so that violence is calibrated to its need for attaining the war’s end. The claims of morality here are recognized with difficulty in actual combat, and disputed when recognized. Why should that be?

In Tolstoy’s War and Peace, Prince Andrey is an enlightened, humane, reforming, disciplined man. He has had experience in war without becoming embittered—he was badly (almost mortally) wounded at the Battle of Aus- terlitz—and has tried to improve the military system. But by the Battle of Borodino, even this estimable man has snapped. After riding past his destroyed estate, he ruminates:

I wouldn’t take prisoners. What sense is there in taking prisoners? That’s chivalry. The French have destroyed my home and are coming to destroy Moscow; they have outraged and are outraging me at every second. They are my enemies, they are all criminals to my way of thinking…. Playing at war, that’s what’s vile; and playing at magnanimity and all the rest of it…. They plunder other people’s homes, issue false money, and, worse than all, kill my children, my father, and then talk of the laws of warfare…. If there were none of this playing at generosity in warfare, we should never go to war, except for something worth facing certain death for…. The object of warfare is murder.1

Andrey has attained the state Clausewitz says is necessary to war—Hass, hatred for the foe. There is in all sane people a hesitation to kill, whether from timidity, disorientation, or scruple. That is why so many bullets are fired in war but not at the target, why so many bombs are dropped but not where they were supposed to be. It is the task of those in charge of war to override these hesitations, and the only sure way of doing that is to demonize the enemy, so that hating him is not only condonable but commendable.

Clausewitz says that war is fueled by emotion (Gefühl), which always outruns intent (Absicht). And once this begins there is a constant ratcheting-up (Wechselwirkung) of hatred. Hate produces atrocities, which provoke answering atrocities from the other side, and so on in a reciprocal upward spiral. This means, says Clausewitz, that war by its basic nature drives onward to extremes. Shakespeare was almost scientifically accurate when he had…

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