Since the biblical message is one of peace, can war ever be justified? We begin our exploration of the Church’s just war tradition by offering an overview of how this tradition developed from the early church fathers, through the Scholastics, and into the sixteenth century. We then focus on specific twentieth-century papal documents that have addressed issues of war and peace in our time. We offer this overview to establish the context for the pronouncements of the U.S. bishops in The Challenge of Peace and The Harvest of Justice Is Sown in Peace.
Ambrose of Milan (d. 397), an early church father and mentor of Saint Augustine, taught that war can be justified if its purpose is to defend the weak and oppressed. Ambrose, who was heavily influenced by the Roman philosopher Cicero, also held that war must be legally declared, innocent people must never be killed, and the defeated party must always be treated with justice following the cessation of hostilities.1
Saint Augustine (d. 430) built upon the teachings of his mentor and held that the purpose of war was to bring about peace. For Augustine, the goal of any society is to establish and maintain the tranquilitas ordinis, or “peace of order.” He argued that military force can be used for the purpose of establishing (or reestablishing) the tranquilitas ordinis, but this was only in extraordinary circumstances and only out of necessity. Augustine taught that war can be declared by lawful authority and that it can be waged only for a just cause. Examples of just cause include protecting the innocent from harm or avenging “injury” suffered at the hands of an aggressor. “Injury” for Augustine refers to a situation where one nation refuses to return property it has unjustly taken from another, or when it refuses to rectify injustices perpetrated by its citizens. In cases such as these, the victimized nation has just cause to wage war, but in doing so its motivation must be the restoration of the tranquilitas ordinis. Finally, Augustine speaks of “right” intention. The decision to go to war must not be motivated by cruelty, bloodlust, or a desire for vengeance against an enemy. Correct intention must be grounded in justice and the pursuit of a lasting peace.2
Thomas Aquinas (d. 1274) built upon Augustine’s teachings and identified three criteria necessary for justified war. First, war must be declared by a sovereign authority. The reason for this is that the sovereign is entrusted with the duty to promote the common good, which entails, in part, protecting society from aggressors. Fulfilling this duty could include waging war against those who would cause society harm. Aquinas was careful to point out, however, that individual citizens cannot engage their nation in war with another nation even if there is a legitimate reason for doing so. Only the sovereign has ultimate responsibility for promoting the societal good, and so only the sovereign can legitimately declare war. The second criterion is just cause, understood to mean that one nation can legitimately attack another “on account of some fault” that the perpetrating nation has committed. Here Aquinas explicitly cites Augustine’s teaching that one nation may legitimately punish another if the offending nation refuses “to make amends” for its injustices, or if it fails to restore what it has “seized injuriously.” The third criterion is right intention: the purpose for waging war must be to repress evil and promote the common good. Again citing Augustine, Aquinas teaches that right intention must never involve a “lust to dominate,” a “craving to hurt people,” or any “cruel thirst for revenge.”3
Augustine and Aquinas are often regarded as the “architects” of the Church’s just war tradition, but they are not the only ones who contributed to its development. Bartholomew de Las Casas (d. 1566) forcefully argued against the practice of using military force to “convert” people to Christianity, a teaching formulated in response to the actions of the Spanish Conquistadors in the Americas. Tommaso Cajetan (d. 1534) distinguished between offensive and defensive war, and spoke about “justice after war” or the need to make restitution to one’s enemy after hostilities had ended. Francisco de Vitoria (d. 1546) offered perhaps the most comprehensive treatment of just war theory by stating, in part, that war is not justified when waged due to differences in religion, the desire to enlarge an empire, or for the personal glory of the sovereign. Instead, the sole just cause for war is to redress a harm that has been unjustly inflicted by an aggressor. De Vitoria further maintained that legitimate authority must carefully examine the reasons for going to war, and that it must be willing to negotiate in good faith. In addition, he stressed the importance of non-combatant immunity and insisted that armed forces not inflict more damage than is necessary to achieve victory.4
In light of these historical teachings, we now explore how the topics of war and peace are addressed in twentieth-century papal writings. Pope Saint John XXIII focuses on the establishment of peace in Christianity and Social Progress (1961). Speaking about the gap between wealthy nations and those in the “process of development,” he maintains that “economically advantaged” nations must not ignore the poverty, hunger, and lack of human rights experienced by so many others around the world. He points out that as the world becomes increasingly interdependent, it is difficult, if not impossible, to maintain peace in nations where “excessive imbalances” exist in the economic and social structures. Saint John XXIII then identifies several conditions necessary to achieve and maintain peace: nations have to act with justice in their dealings with one another, particularly wealthy nations in relation to poorer ones; human dignity has to be respected; and a sense of global community and solidarity has to be maintained. Further on in the encyclical, Saint John XXIII warns that regardless of technological or economic advances, when humanity separates itself from God it becomes “monstrous” to itself. For these reasons, human relationships “absolutely require a right ordering” of the person to God, the source of justice and love.5
Christianity and Social Progress was written in 1961, but its teachings remain highly relevant today. We see people in Africa, Asia, the Middle East, and Latin America living in abject poverty. These people have not been treated with justice, their dignity has been ignored, and they are not recognized as equal members of the global community. These factors translate into a lack of hope that fosters hostility and international terrorism. The pope’s warning to remain in right relationship with God is equally relevant as our culture becomes ever more secularized. Even within the Catholic Church we see individuals who, in the name of political correctness, are willing to abandon any notion of faith when debating public policy issues. This is a mistake. Although one certainly should not impose one’s beliefs on another, it is perfectly legitimate, and constitutional, to draw upon one’s faith tradition in order to meet the challenges of our contemporary world.
Pope Paul VI speaks to the relationship between justice and peace in three well-known social documents of his papacy. In On the Development of Peoples (1967), he reiterates the words of Saint John XXIII by stating that the excessive economic, social, and cultural inequalities among nations pose a “danger to peace.” It is vitally important, Paul VI maintains, to promote cooperation among nations with the goal of improving conditions for those living in poverty.6 Four years later, in A Call to Action (1971), he warns that international relations must not be based on force, whereby developed or powerful nations dictate to weaker ones what they can and cannot do in the international realm. He argues that such relationships never forge “true and lasting” justice and thus cannot foster peace. In fact, the use of force by one party actually breeds resentment in the other, thus leading to further conflict.7 Finally, in his 1972 Message for the World Day of Peace, he argues that if we seek to form a genuine peace, we need to recognize a “true respect” for humanity. Stated differently, those who want peace must work for justice. For Paul VI, justice includes recognizing the rights and duties that insure the stability of all social, cultural, and economic relationships. It also means enabling every nation “to promote its own development in the framework of cooperation,” free from any economic or political domination.8
Pope Saint John Paul II addresses the relationship between justice and peace by focusing on the need for greater international solidarity. In On Social Concern (1987) he asserts that developed nations have a moral obligation to aid their less fortunate neighbors, and to establish an international system that recognizes the fundamental equality of all people. These actions, he argues, will lead to increased solidarity among nations, rich and poor alike, and world peace is impossible without them. The pope firmly believed that world peace could only be achieved through the establishment of international justice, and international justice could only be achieved through solidarity. Thus, in practice, solidarity demands the tearing down of all political blocs, the end of all forms of economic and political imperialism, and the transformation of mutual distrust into collaboration.9
In On the Hundredth Anniversary of Rerum Novarum (1991), Saint John Paul II makes an even more impassioned plea for an end to armed conflict. Writing in the immediate aftermath of the Persian Gulf War, he implores:
Never again war! No, never again war, which destroys the lives of innocent people, teaches how to kill, throws into upheaval even the lives of those who do the killing and leaves behind a trail of resentment and hatred, thus making it all the more difficult to find a just solution to the very problems which provoked the war.10
Several important truths are embedded within this statement. War destroys innocent people caught up in a conflict they do not desire. War also causes great stress on those who are fighting, both during the battle and afterward when they return home. War further leads to resentment on the part of those who “lose,” militating against efforts at reconciliation. Following this impassioned plea for an end to all warfare, the pope reiterates that true peace is possible only when all people have the opportunity to share equitably in the world’s resources, and when international economic structures are directed toward the common good. These are moral responsibilities of the world community as a whole. Thus, just as there is a collective responsibility to avoid war, there is a reciprocal responsibility to promote the integral development of all people, the pathway to true peace.11
1. Ambrose is discussed in Gregory Reichberg, Henrik Syse, and Endre Begby, eds., The Ethics of War: Classic and Contemporary Readings (Malden, MA: Blackwell Publishing, 2006), 67–68. See also J. Daryl Charles, Between Pacifism and Jihad: Just War and the Christian Tradition (Downers Grove, IL: Inter Varsity Press, 2005), 37–40; and Joseph Fahey, War and the Christian Conscience (Maryknoll, NY: Orbis Books, 2005), 86–87.
2. See Paul Weithman, “Augustine’s Political Philosophy,” in The Cambridge Companion to Augustine, ed. E. Stump and N. Kretzmann (Cambridge: Cambridge University Press, 2001), 245–47. See also Reichberg et al., eds. Ethics of War, 70–82; Charles, Between Pacifism and Jihad, 40–45; and Fahey, War and the Christian Conscience, 88–89.
3. Summa Theologica, II–II, q.40 a.1.
4. Reichberg et al., eds., Ethics of War, 240–43 and 288–332. See also Charles, Between Pacifism and Jihad, 57–60; and Fahey, War and the Christian Conscience, 100–101, 161–67.
5. Pope Saint John XXIII, Christianity and Social Progress, in O’Brien and Shannon, eds., Catholic Social Thought, numbers 157 and 215. In Peace on Earth (1963), Saint John XXIII reiterates and expands upon these themes by arguing that international relations must be governed by the norms of justice. Every nation has the right to exist, develop according to its own devices, procure the resources necessary for development, and defend its “good name and honor.” Justice demands that these rights be recognized by the world community as their recognition forms the foundation for peace. See Peace on Earth, in O’Brien and Shannon, eds., Catholic Social Thought, number 92.
6. Pope Paul VI, On the Development of Peoples, in O’Brien and Shannon, eds., Catholic Social Thought, number 76.
7. Pope Paul VI, A Call to Action, in O’Brien and Shannon, eds., Catholic Social Thought, number 43.
8. Pope Paul VI, Message for the Celebration of the Day of Peace(January 1, 1972), available at www.vatican.va/holy_father/paul_vi/messages/peace/documents/hf_p-vi_mes_19711208_v-world-dayfor-peace_en.html.
9. Pope Saint John Paul II, On Social Concern, in O’Brien and Shannon, eds., Catholic Social Thought, number 39.
10. Pope Saint John Paul II, On the Hundredth Anniversary of Rerum Novarum, in O’Brien and Shannon, eds., Catholic Social Thought, number 52.