Just War: Catholicism’s Contribution to International Law

That the moral and theological issues discussed in what follows are not “academic” matters, we are reminded by an exchange that moved theater-goers four centuries ago.

king henry

Methinks I could not die anywhere so contented as in the king’s company,—his cause being just and his quarrel honourable.

william

That’s more than we know.

bates

Ay, or more than we should seek after, for we know enough if we know we are the king’s subjects: if his cause be wrong, our obedience to the king wipes the crime of it out of us.

william

But if the cause be not good, the king himself hath a heavy reckoning to make when all those legs and arms and heads, chopped off in a battle, shall join together at the latter day and cry all, We died at such a place; some swearing; some crying for a surgeon; some upon their wives left poor behind them; some upon the debts they owe; some upon their children rawly left. I am afeared there are few die well that die in a battle, for how can they charitably dispose of anything when blood is their argument?

Shakespeare, King Henry V, iv. i.

The Origins of Just War Theory

It has become a commonplace to assert that “just war theory” arose from a Christian tradition formulated by St. Augustine and St. Thomas Aquinas. This half-truth conceals both the indebtedness of each to earlier thinkers as well as the profound differences between them that have important consequences. It is also often claimed that just war theory has been developed in order to justify wars favored by authors of the theory. This claim is confuted by the historical circumstances in which Christian thinking on this subject reached its fullest development. In what follows, I hope to stimulate constructive doubt about these opinions. I wish to indicate that as just war doctrine matured it also progressively departed from Augustine’s point of view. Augustine makes a significant contribution to moral wisdom about war, but he does not contribute to a theory of war’s justice. I shall also suggest that just war doctrine was both a distinctively Catholic achievement and one that could, for that very reason, be appropriated by all conscientious persons.

Fatuous as it may be to assign provenance to great movements in human thought, international law has been repeatedly assigned either of two originators. The more widely known is the seventeenth-century Dutch Calvinist scholar, jurist, and diplomat, Hugo Grotius.¹ The other candidate is the sixteenth-century Spanish Dominican philosopher and theologian, Francisco de Vitoria.² By a winsome irony there exists at The Hague a plaque dedicated to “The Founder of International Law.” The plaque was erected by the Grotius Society. The person it honors is Vitoria. My present interest in this amicable question of origins is the symbolic focus it provides. For between the sixteenth and seventeenth centuries, a progressive though erratic Catholic doctrinal development reached its maturity. It subsequently shed its ecclesiastical particularities and entered upon a new tradition, secular and juridical.³ Finally, after two world wars, the theory has gained firmer footing in practice through the League of Nations and the United Nations.

I hope to indicate two things in this condensed account: first, how just war theory originated as a moral doctrine; and second, how it was modified by the principles of authoritative thinkers and refined in controversy generated by unforeseen events. I shall stop at the period commonly labeled Renaissance and Reformation because it was then that just war theory, in essence nearly complete, ceased to be part of specifically Christian intellectual history and became part of the new jurisprudence of international law. After that time, Catholic just war theory participated in a general stagnation of post-Reformation Catholic moral and political thought that continued to the nineteenth century. During the same period, mainstream Protestant religious thinkers paid it little attention beyond insisting, against Protestant pacifists, that wars certainly could be just and—at least when conducted by Protestant rulers—were best presumed to...