Augustine's Just War Tradition

Today's Reading

Read Romans 13:1-7 again, since it is the foundation Augustine built on.

Read Luke 3:14, where soldiers come to John the Baptist and ask, "What shall we do?" John does not tell them to leave the army. He tells them not to extort, not to lie, to be content with their wages.

Read Genesis 9:5-6, the post-flood charter that authorizes the shedding of human blood by human authority for the sake of justice ("Whoever sheds the blood of man, by man shall his blood be shed").

Read Matthew 8:5-13, where Jesus heals the centurion's servant, marvels at the centurion's faith, and does not tell him to leave the legion.

Reflection

By the time Augustine sat down to write to a Christian general named Boniface in the year 418, the question that had been theoretical for the early church was urgent. Rome had fallen to the Visigoths in 410. The empire that the church had once viewed as Babylon was now, increasingly, the only civil order standing between the Christian people and chaos. Vandals were crossing into North Africa. Boniface, weary, was contemplating leaving public office for the monastic life. Augustine wrote to ask him to stay.

The letter — Epistle 189 — is the seed text of the Western just-war tradition. Augustine does not celebrate war. He calls it a necessity born of evil. "Peace should be the object of your desire," he writes; "war should be waged only as a necessity, and waged only that God may by it deliver men from the necessity and preserve them in peace." The aim is always peace. War is never the goal. It is, at best, the instrument of a peace that human sin has put out of reach by ordinary means.

The framework Augustine sketched across that letter, City of God (especially Book XIX), and Contra Faustum rests on several convictions. Authority for war belongs to legitimate governing power, not to private individuals. The cause must be just — defending against aggression, recovering what has been wrongfully seized, punishing serious wrong. The intention of the heart must be right — Augustine returns again and again to the warning that the soldier who fights from hatred has already lost, even if his army wins. "The real evils in war," he wrote in Contra Faustum, "are love of violence, revengeful cruelty, fierce and implacable enmity, wild resistance, and the lust of power." The soldier who avoids those things and fights only because he must — and weeps as he does — is, for Augustine, doing something tragic but not damning.

Eight centuries later, Thomas Aquinas systematized the tradition in his Summa Theologiae, II-II, Question 40. Aquinas's three classical criteria are: legitimate authority, just cause, and right intention. He cites Augustine at every step. From Aquinas's foundation, later theologians — Vitoria, Suárez, Grotius — built out the framework that Western Christians have largely operated within ever since.

The tradition divides into two parts. Jus ad bellum — the right to go to war. Jus in bello — the right way to fight a war. Both are necessary. A just cause does not bless an unjust method; a careful method does not redeem an unjust cause.

Jus ad bellum asks whether a war can be entered at all.

Just cause. The war must respond to a grave, actual wrong — typically aggression by another power, the protection of the innocent from massacre, or the recovery of something seriously and unjustly taken. Notice what this rules out. It rules out wars of conquest, wars for prestige, wars for resources, wars for the sake of national glory. It rules out preventive war — striking a nation that has not yet attacked you because you fear it might. It rules out punitive wars in the older sense of bringing imperial discipline to a recalcitrant province.

Legitimate authority. The war must be declared by those who have the lawful right to declare it — historically the sovereign, in modern democracies the constitutional process. Private militias, freelance crusaders, terrorist cells, and rogue commanders have no standing.

Right intention. The aim must be the restoration of just peace — not revenge, not domination, not gain. Augustine is unyielding here. The same act, performed with different intentions, can be the work of God's servant or the work of a murderer.

Last resort. Every reasonable nonviolent alternative must have been exhausted — diplomacy, sanctions, mediation, negotiation. War is the door you open only when every other door is closed.

Reasonable chance of success. A war that has no realistic prospect of achieving its just aim sacrifices lives for nothing. The criterion is not certainty but reasonable expectation; futile bloodshed is its own injustice.

Proportionality (ad bellum). The good expected to be achieved must be proportionate to the harm the war will cause. A war fought to recover a small wrong at the price of millions of lives fails this test, no matter how just the cause in the abstract.

Jus in bello governs how the war, once entered, must be fought.

Discrimination. Combatants and noncombatants must be distinguished. The intentional targeting of civilians is forbidden — always. This is the criterion that has been broken most often in modern wars and the one Christians have been weakest at defending. We will return to it tomorrow.

Proportionality (in bello). Each particular act of war must be proportionate to the military advantage sought. A village burned to deny a few enemy soldiers a hiding place fails. A city destroyed to break enemy morale fails. The criterion has teeth.

The doctrine of double effect — sharpened by Aquinas — addresses the cases where civilian deaths occur as an unintended side effect of an action aimed at a legitimate target. The act must be morally good or neutral in itself; the bad effect must not be the means by which the good effect is achieved; the bad effect must not be intended; and the good effect must be proportionate to the bad. Even read most generously, this is a constraint, not a permission.

Notice what the just-war tradition forbids. Total war — the all-out destruction of an enemy society — is forbidden. Preventive war — striking first because the enemy might one day strike — is forbidden. Targeting civilians is forbidden. Wars of national glory or economic gain are forbidden. Wars without legitimate authority are forbidden. Wars without reasonable prospect of success are forbidden. Wars whose harms outweigh their goods are forbidden.

If you walk through the wars of the twentieth and twenty-first centuries with this list in hand, the tradition is far less permissive than its critics — and many of its alleged adherents — suppose. The American Civil War passes some criteria, fails others. Strategic bombing in World War II — the firebombing of Dresden, the atomic bombs on Hiroshima and Nagasaki — fails the discrimination criterion outright. The Vietnam War's free-fire zones fail. The 2003 invasion of Iraq, on most just-war assessments, fails legitimate authority and last resort. Many of the pacifists' best arguments come from inside the just-war tradition — pointing out that Christians have, over and over, called wars just that the tradition's own criteria would have called unjust.

Augustine knew this. He did not believe most wars in his world were just. He wrote the letter to Boniface as a sober, sorrowful permission for a particular soldier in a particular crisis to remain at his post — not as a celebration of war. Aquinas, building on him, understood that the criteria's job was to constrain.

The just-war tradition is not the obvious reading of Matthew 5. Augustine and Aquinas knew that. They argued, on the strength of Romans 13, Genesis 9, the soldiers who came to John, the centurion whom Jesus commended, and the long testimony of the Old Testament, that the magistrate's calling is real and that a Christian who serves there does not thereby cease to be a Christian. They did not soften the Sermon on the Mount. They drew a line between the disciple's heart, which must always love, and the magistrate's hand, which sometimes must restrain.

Whether they drew that line in the right place is what Christians have argued about ever since. Tomorrow we listen to the voices who have argued they did not.

Going Deeper

Take a recent war you know something about. Walk through the seven jus ad bellum criteria one at a time and ask whether the war passes each. Then walk through the jus in bello criteria for specific actions in that war (a particular battle, a particular bombing). Notice where the criteria do real work — and where they have been, in practice, ignored. The just-war tradition is only worth as much as the church's willingness to apply it honestly.