The College Beat: Article XII
. . .
In the last year, morning, afternoon, and night consistently brought sobering headlines from Israel and Iran, while war raged on in Russia, Ukraine, Myanmar, and many parts of Africa. Isolationists cautioned against war while hawks urged further intervention, both for US interests. What united much of the news commentary was the tendency to frame the question of American involvement in foreign war in utilitarian terms, with analysts considering material and economic arguments more seriously than ideals of justice and peace.
What the world at large misses—and the Church offers through just war doctrine—is a way to think about war that prioritizes peace and upholds the dignity of all people while supporting the duties of states to protect and defend their citizens. The Catholic Church neither forbids war outright nor supports a nation’s “right” to wage war. Rather, it teaches that for a war to be justified, the conflict must meet a rigorous set of established criteria. Just war doctrine uses the principles of natural law (the moral law inscribed on every human heart) to provide a philosophy of international politics for Catholics and non-Catholics alike.
Some Catholics, recalling God’s law “You shall not kill” and Christ’s command to turn the other cheek, assume fidelity to the Gospel precludes armed conflict, military involvement, and even self-defense (Exod 20:13, Matt 5:39). Yet, when John the Baptist addressed the crowds that had flocked to him to be baptized, a group of soldiers asked him, “What is it that we should do?”
“‘Do not practice extortion, do not falsely accuse anyone, and be satisfied with your wages,’” John tells them (Luke 3:14).
As numerous scholars have pointed out, the Baptist does not tell them to leave their occupations as part of their repentance. Nor does Jesus do so when a centurion comes to him and requests a servant’s healing. In fact, he praises the man’s trust.
Although Augustine approves of a limited violence to defend the innocent, he—and the whole Church with him—emphasizes the great suffering that is war.
“‘Amen, I say to you, in no one in Israel have I found such faith . . . as you have believed, let it be done for you,’” Christ says (Matt 8:10–13).
Together, Jesus and John’s silence on the matter signals that involvement with the military is not sinful in and of itself.
St. Augustine, the fourth- and fifth-century bishop and Doctor of the Church, developed a systematic just war theory influenced by the writings of Cicero and St. Ambrose. In his philosophical work City of God, Augustine decried the violence and tragedy of war, while asserting that in very specific scenarios, war could be the just way for a state to defend its citizens.
“They who have waged war in obedience to the divine command, or in conformity with His laws, have represented in their persons the public justice or the wisdom of government, and in this capacity have put to death wicked men; such persons have by no means violated the commandment, You shall not kill,” Augustine wrote (City of God, 1.21).
The fifth commandment orders men to guard and respect all life, and so it may come as a surprise that Augustine seems to condone violence. Two principles underlie his thinking. The Old Testament clarifies God’s prohibition against killing, saying, “Do not slay the innocent and the righteous” (Exod 23:7). And per the principle of double effect, a just war permits violence and death as unintended but foreseen side effects of defending the “innocent and the righteous.”
Later, in chapter 19 of City of God, Augustine coined the term “just war.”
“For it is the wrongdoing of the opposing party which compels the wise man to wage just wars; and this wrong-doing, even though it gave rise to no war, would still be matter of grief to man because it is man’s wrong-doing,” Augustine wrote. “Let every one, then, who thinks with pain on all these great evils, so horrible, so ruthless, acknowledge that this is misery.”
So although Augustine approves of a limited violence to defend the innocent, he—and the whole Church with him—emphasizes the great suffering that is war.
In the thirteenth century, St. Thomas Aquinas, another Doctor of the Church, took up Augustine’s theory of just war in his Summa theologiae. To explain how the Church can reconcile Christ’s commandment of peace with a state’s duty to protect its citizens, Aquinas quotes a letter of Augustine’s about peace.
“War is waged in order that peace may be obtained,” Augustine writes. “Therefore, even in waging war, cherish the spirit of a peacemaker, that, by conquering those whom you attack, you may lead them back to the advantages of peace.”
In line with the principle of double effect, both Augustine and Aquinas see peace—and not the devastation of the enemy—as the only correct intention, or end, for war.
“Those who wage war justly aim at peace,” Aquinas writes. “So they are not opposed to peace.”
Aquinas enumerated specific conditions under which a war could be justified. As the Catechism of the Catholic Church cautions, “All citizens and all governments are obliged to work for the avoidance of war” (CCC 2308). Yet if all possible avenues of peacekeeping have been pursued and danger still looms, a government may wage war as legitimate societal self-defense.
“Jus ad bellum” conditions limit the circumstances in which a nation may go to war. There must be a just cause for entering war—danger to a nation that is “lasting, grave, and certain,” while at the same time all alternate means of resolving the conflict are proven “impractical or ineffective” (in other words, war is waged as a last resort). The nation must assess whether the human and material cost of the war is proportional to the expected outcome and have reasonable hope of success. The rights and principles at stake must be critical enough to justify violence. Only the proper authorities may declare war (CCC 2309). Augustine and Aquinas add another condition: that the intention of the nation be justice and peace, not cruelty or vindictiveness.
Catholics should note these conditions forbid nations from violent aggression. Just war is limited to self-defense. The Second Vatican Council—which took place after the two world wars and during the Cold War—especially emphasized the duty to avoid war (Gaudium et Spes 79–82). It warned about weapons of mass destruction, cautioning against even the practice of arms buildup which is so common today (GS 81).
“Insofar as men are sinful, the threat of war hangs over them, and hang over them it will until the return of Christ.”
“Jus in bello” conditions govern a nation’s conduct in war. During the conflict itself, moral law still applies. In concordance with Augustine and Aquinas, the Catechism specifies that a nation cannot directly attack civilians and must treat noncombatants, prisoners, and wounded soldiers fairly. A nation may only use as much force as necessary (CCC 2312–2314).
Like Augustine and Aquinas, the Catechism begins and ends its teaching with peace, which the Catholic Church sees as a divine reality capable of restoring order to men.
“Insofar as men are sinful, the threat of war hangs over them, and hang over them it will until the return of Christ,” reads Gaudium et Spes. “But insofar as men vanquish sin by a union of love, they will vanquish violence as well” (GS 78).
Disorders of the human heart like pride, envy, or anger bring about the spiritual sickness of war. Thus, the solution to war must also begin within the human heart and encompass more than basic safety.
“Peace is not merely the absence of war, and it is not limited to maintaining a balance of powers between adversaries,” reads the Catechism. “Peace cannot be attained on earth without safeguarding the goods of persons, free communication among men, respect for the dignity of persons and peoples, and the assiduous practice of fraternity” (CCC 2304).
It is up to Catholics to apply the principles of just war doctrine to past and present conflicts. Though just war doctrine provides objective criteria in matters that are otherwise complex and seemingly subjective, we should not be surprised if some moral ambiguity remains. E. Christian Brugger, a moral theologian, writes that it is difficult for ordinary citizens to determine whether a conflict meets the criteria for a just war without having access to military intelligence.
“In the absence of publicly available information that allows us to reply to the questions above with moral certainty, citizens should not be quick to judge harshly the military actions taken by their authorities, since factors unknown to them may play decisive roles in decision-making,” Brugger writes. “This does not mean that we shouldn’t judge our leaders’ actions when facts come to light.”
The absence of certainty is all the more reason for Catholics to pray for peace, as Pope Leo XIV has persistently urged his flock.
“Peace be with you!” Leo greeted the crowds awaiting the new pope. “It is the peace of the risen Christ. A peace that is unarmed and disarming, humble and persevering. . . . God loves us, God loves you all, and evil will not prevail!”