A second fundamental tenet of Christian just war theory is that peace is the natural and desirable state for human beings and that the sole aim of just war is "a certain earthly peace." (Augustine, City of God, XIV.4) Statecraft that regards war as nothing more than a gambit in the great game of geopolitics or a tool of national power is unjust and immoral. The Times article quotes National Security Advisor Thomas Donilon's view that Obama is "a president who is quite comfortable with the use of force on behalf of the United States." By contrast, just war theory is not comfortable with the use of force, and regards it as at best a necessary evil. As for the view that combativeness is part of human nature, like head-butting among rams, Augustine would concede it only because we are fallen, sinful creatures. In his view, "if the earthly city observes Christian principles, even its wars will be waged with the benevolent purpose that better provision might be made for the defeated to live harmoniously together in justice." (Letter 138 to Marcellinus, ch. 2, sec. 14; translation slightly altered.)
At the same time, traditional just war theory is a long way from pacifism. One of Augustine's most important works on just war theory is a letter to his friend Marcellinus, a Roman official in North Africa and a devout Christian. He aimed to persuade Marcellinus that the pacifism of some early Church Fathers, grounded in Christ's injunction to turn the other cheek, was a mistake. Just war theory may be about justice, but it is also very much about war, and it never says that all war is unjust. It limits violence, but it also licenses it.
The most important criterion of just war is possession of a just cause, the paradigmatic example being self-defense. In the wake of the September 11 attacks, there can be little doubt that the United States could morally use force in self-defense. There is a strong case that the U.S. drone campaign against al Qaeda in the Arabian Peninsula is genuine self-defense, given AQAP's relentless series of (fortunately thwarted) attacks against the American homeland-the underwear bomber, the printer-cartridge bombs, the attempt at a second underwear bombing in May with explosives designed to evade airline security. Even those who favor the use of law enforcement rather than military action in the struggle against al Qaeda accept that force employed to defend against terrorist attacks is justified when lesser measures don't work.
Another condition of just war, emphasized by Aquinas, is "rightful authority." Not just anyone can launch a war; only a legitimate ruler can. It follows that non-state actors such as al Qaeda by definition are unjust warriors. (Granted, by this criterion the same would be true of the American revolutionaries, and those who believe that freedom fighters can wage just struggles will reject the "rightful authority" criterion for its bias in favor of the status quo.) One of the most controversial aspects of the use of military commissions at the Guantánamo Bay detention facilities was treating mere membership in al Qaeda as an offense against the laws of war. In my view this treatment is a legal and moral mistake, but the "rightful authority" strand of just war theory supports it.
