In response to Pope Leo XIV’s appeal for leaders of the warring nations to go back to the negotiating table, the Donald Trump administration has appealed to the traditional just war theory to justify its aggressive action. Vice President JD Vance has in fact accompanied his citation of the just war theory with a ridiculous admonition that it is important for the Pope to be careful when talking about matters of theology! Some Catholic archbishops have joined the discourse in asserting that the war against Iran does not meet the criteria set by the just war theory.
The theory is most associated with Saint Augustine, although the attempt to justify waging war vis-a-vis the ideal of peace antedated him. It was formulated when the wars were fought in a face-to-face confrontation and when the weapons were limited to spears and arrows. At any rate, it provided a rigorous set of criteria before any war could be justified. It was not intended to supplant peace as an ideal.
What were some of the conditions? They would include that war must be waged only as a last resort; that the evil engendered by the war cannot be greater than the evil it wishes to eliminate; that there is a serious chance for success, and that the cause must be just.
But there has been an evolution of this theory in more recent Catholic teaching, and it is unfortunate that in the current discourse on the moral justification of the war on Iran, many discussants including American bishops, would fail to bridge the gap between a medieval theory and the reality of modern warfare.
Although this theory is classic, no recent pope has invoked it to justify war. In fact, almost all recent popes have condemned war. Benedict XV was a new pope when World War I started. In his first encylical, Beatissimi Apostolorum, the pope writes, “The combatants are the greatest and wealthiest nations of the earth; what wonder then if, well provided then with weapons which modern military science has devised, they strive to destroy one another with refinements of horror.”
Pope John XXIII, in Pacem in Terris, holds that it is the conviction of contemporary humanity that disputes between states should not be resolved by recourse to arms but by negotiations. He then explains that the basis of this conviction is “the terrible destructive force of modern weapons and a fear of the calamities and the destruction which such weapons would cause,” (Pacem in Terris 126-127). Paul VI, in an address to the General Assembly of the United Nations declares, “No more war, war never again! It is peace which must guide the destinies of people and of all (hu)mankind.” His most important contribution to the advocacy for peace was his insistence, especially on wealthy nations, that “if you want peace, work for justice.”
Pope John Paul II was also strong in his criticism against the American invasion of Iraq. He calls it a “defeat for humanity.” Cardinal Joseph Ratzinger, then the prefect of the Congregation for the Doctrine of Faith, (and who would later become Pope Benedict XVI) explains the stance of Pope John Paul II on the war against Iraq in an interview in 2003, “There were not sufficient reasons to unleash a war against Iraq. To say nothing of the fact that, given the new weapons that make possible the destruction that go beyond the combatant groups, today we should be asking ourselves whether it is still licit to admit the very existence of a just war.”
It is my good friend Danny Pilario who reminds me of what Pope Francis says in Fratelli Tutti. If the reader does not have a printed copy, one is invited to google specifically paragraph 258. Even better yet, read the whole encyclical. But because of space considerations, let me just quote some few sentences, “At issue is whether the development of nuclear, chemical, and biological weapons, and the enormous growing possibilities offered by new technologies, have granted war an uncontrollable destructive power over great numbers of innocent civilians…In view of this, it is very difficult nowadays to invoke the rational criteria elaborated in earlier centuries to speak of the possibility of a just war.”
The just war theory is valuable in that it sets a difficult hurdle for war to be morally justified. But a true disciple of Jesus today must go beyond it and embrace the gospel of peace.
I mentioned above that the theory was formulated when weapons were still primitive. But the atomic bombs dropped in Hiroshima and Nagasaki killed nearly two hundred thousand people, mostly civilians. Today, the available weapons would dwarf the atomic bombs. The atomic bombs in 1945 would be nothing but firecrackers.
