Catholics and Just War

By Rev. John J. Conley, S.J., Knott professor of philosophy and theology
A grenade with a cross on it

When President Obama received his controversial Nobel Prize, he invoked the doctrine of just war to justify his administration’s military policies.

But the president’s version of just war reduced it to three conditions:“If it [war] is waged as a last resort or in self-defense; if the force used is proportional; and if, whenever possible, civilians are spared from violence.” The Catholic tradition offers a more robust—and far more limiting—version of just war theory.

According to the Catholic Church, going to war can be justified only under the following conditions. 1) It must be a response to grave aggression, such as the actual or imminent killing of innocent persons. 2) It must be a last resort in as much as all other means of protest (diplomatic, economic, nonviolent resistance) have been exhausted. 3) It must be declared by legitimate authority. This criterion is particularly thorny in a democracy where the president is commander-in-chief but Congress alone has the power to declare war. 4) There must be a reasonable hope of success. Recourse to war cannot be used to make a noble but futile point against an aggressor. 5) The military response must be proportionate. The grave nature of the aggression must clearly require a military response to restore the violated order of justice.

The Church also insists that the conduct of war, in the rare cases when it is justified, must meet the following conditions. 1) Warfare must be discriminate. It must aim directly only at military targets, not at civilians. Many philosophers and theologians have argued that the use of biological, chemical, and nuclear weapons would seem to be illegitimate because it is so difficult to keep these weapons discriminate in their impact. 2) The means used must be proportionate to the type of aggression one is trying to remove. The desire to annihilate one’s enemy once a war clearly has a “just cause” must be stoutly resisted. Only if a war meets all these conditions can it be considered just. In the absence of one or several of these conditions, the conscientious citizen must resist the call to war.

Given the horrific results of war in the 20th century and the terrifying prospect of a contemporary war using weapons of mass destruction, the Church has recently strengthened its already substantial set of theoretical roadblocks to war. Many Catholic philosophers and theologians argue that we should consider the conditions of a just peace once a war has been concluded: economic assistance to populations ravaged by war; just treatment of war criminals; support for the development of a postwar regime conducive to human rights; abstention from acts of revenge by the victor. In recent decades, the Church has also grown more sympathetic to the right of conscientious objection to war by individuals, including clergy and members of religious orders, who have traditionally abstained from all acts of homicide in the name of religious principles. Lay people can also invoke ethical and religious considerations to refuse to participate in the military. The Church insists, however, that the state, unlike the individual, cannot adopt a pacifist stance since it has the duty to protect its citizens from internal and external aggression, even by last-resort recourse to lethal force.

While the contemporary Catholic version of just war cannot rule out the recourse to war as a moral possibility, it raises such a high wall against recourse to war as to make the prospect of a moral, contemporary war a very rare and deeply tragic possibility.

Bookmark and Share


  • Posted by Michael P Burruano | April 9, 2011

    Thank you for this article. I had a mini-mester at Loyola January 1973 on Gandhian Non-violence presented by the Baltimore Peace and Justice Center. I still have the books we used. It was a follow up for me to a paper I wrote on conscientious objection my senior year in HS. Fr. Conley’s article is a wonderful reminder of the depth of this commitment for Catholics and hopefully someday, everyone..

  • Posted by Jimmy Otex | January 9, 2016

    I enjoy the information on your website. Much thanks!

RSS feed for comments on this post.

Leave a comment