What is (can there be) a just war?

An invitation to discuss the just-war tradition

What does the Church teach about justice in warfare? Let’s explore that question together.

“Just war theory” is often invoked, but rarely explained, by partisans who support or oppose a particular conflict. How should we evaluate their competing claims?

The Catechism of the Catholic Church (2302- 2330) explains the moral teachings that underlie the just-war tradition, and #2309, in particular, offers a quick summary of the main principles of just-war teaching. But those few pages contain only a small sample of the rich tradition of thought on the subject. St. Augustine was a pioneer in the field, and St. Thomas Aquinas (who relied heavily on St. Augustine), is cited frequently. But there are many other important contributors: from 16^th-century scholastics like Vitoria and Grotius and Suarez to 20^th-century Catholic (William O’Brien, James Turner Johnson) and non-Catholic (Paul Ramsey, Michael Walzer) scholars.

While all of these just-war theorists can enrich our understanding, none can be characterized as the official arbiter of the just-war tradition. The Catechism can be taken as the formal teaching of the Catholic Church, but it its treatment of the subject is not detailed, and it offers few definitive judgments. In fact the Catechism leaves that the final decisions on just warfare to “the prudential judgment of those who have responsibility for the common good.”

Why are there so few clear moral rules about justice in warfare? Mainly because every moral judgment about armed combat must be made in the context of specific circumstances. Prudential judgments are based on the understanding of facts, and in the heat of conflict, facts are often distorted, misinterpreted, or misunderstood. Competing claims— about rights and wrongs, about a potential enemy’s strength and intentions, about the likely consequences of different actions— cannot be evaluated in a vacuum.

Moralists and historians can make their judgments at leisure. National leaders and military officers do not have that luxury. Invariably they would like to have more time, more information, and more certainty. But they must make choices and take actions now, based on the best information they have; the failure to choose can itself be a choice, and a costly one.

Still the uncertainty that inevitably clouds military decisions— the “fog of war”— should not deter intelligent citizens from discussing the moral principles that their leaders should consult. Nor should we, as voters in a democratic republic, absolve ourselves of the moral duty to make our own views known. We may not have the benefit of daily national-security briefings, but we should be able confidently to say: If X is the case, then action Y is morally unjustifiable; Y is licit only if Z occurs.

Over the course of the next several months, beginning in August I propose to host an exploration of just-war principles, inviting readers to join in the discussion. (In order to keep that discussion under control, active participation will be limited to paid subscribers to this Substack.) Each week I will post a short essay on one aspect of the just-war tradition, roughly following the outline of a college seminar that I taught for several years, and suggesting some further readings. (See the outline below.) My experience has been that this topic invites lively debates; it should be a fascinating and enlightening conversation.

One caveat: I do not intend for this seminar to become a debate on the morality of current military conflicts— or of past wars, for that matter. Inevitably there will be references to past and present wars, but I hope we can avoid becoming bogged down in political arguments. Apart from that, my only requirement is that participants show respect for each other and for the tradition of Christian morality. We don’t all need to agree; in fact I feel certain we won’t; but we can treat each other’s arguments seriously.

Thinking about justice in warfare presumes some prior consideration of warfare in particular and foreign policy in general. For that matter, the moral options available to a nation in a time of crisis are limited by the decisions that country has made before the crisis developed. Si vis pacem, para bellum, runs the old Roman adage: “If you wish for peace, prepare for war.” The preparation for warfare, the preparation of a practical war-fighting capability, the construction of a realistic foreign-policy outlook: all these are means of preserving a just peace— which is always the goal of a just war. So I propose to start our exploration with a brief discussion of one of the all-time classics of military strategy: The Art of War, by Sun Tzu.

Course outline (tentative)

“Thou Shalt Not Kill.” The words of Decalogue are clear; the prohibition seems absolute. But the Catholic Church has always recognized the individual’s moral right to self-defense, and the nation’s right to wage war under certain circumstances. What are the conditions that justify warfare, and what limits can be placed on the legitimate use of lethal force? Can the classic principles of just-war theory apply to the realities of 21^st-century conflicts?

This Substack Seminar will explore those questions, offering participants a chance to engage in the debate.

Each week I will post a new essay (with an accompanying podcast to cover the same points) on some aspect of the just-war tradition, together with some recommended reading, as a jumping-off point for general discussion. (See the proposed schedule— which may change, as our discussion develops— below.)

All paid subscribers to this Substack are welcome to participate; I ask only that participants be respectful of each other and of the tradition of Christian morality.

- Week 1: War in the context of foreign policy

o The Art of War, by Sun Tzu

- Week 2: Is Just War Still Possible

o War and the Christian Conscience, by Paul Ramsey

- Week 3: War in History

o The Face of Battle, John Keegan

o On War, Carl von Clausewitz

- Week 4: Moral foundations of just-war tradition

o City of God (selections) St. Augustine,

o Summa Theologica (selections), St. Thomas Aquinas

- Week 5: Fundamental principles of just-war theory

o Catechism of the Catholic Church (selections)

- Week 6: Revolution and Legitimacy

o Declaration of Independence

- Week 7: Efforts toward international law

o On the Law of War and Peace, Hugo Grotius

o Perpetual Peace, Immanuel Kant,

- Week 8: World Wars and new challenges

o Guns of August, Barbara Tuchman

- Week 9: Colonialism, liberation, terrorism

o The Wretched of the Earth, Frantz Fanon

o (viewing) The Battle of Algiers

- Week 10: Asymmetrical war; proxy war

o The Conduct of Just and Limited War, William O’Brien

- Week 11: Terrorism and Jihad

o Terrorism and Communism, Leon Trotsky,

- Week 12: Nuclear deterrence and disarmament

o Thinking about the Unthinkable, Herman Kahn,

o Strategy: the Logic of War and Peace, Edward Luttwak,

o The Challenge of Peace, US Conference of Catholic Bishops

- Week 13: Just-war theory today

o Just and Unjust Wars, Michael Walzer

Please join us!