Is the Ethic Behind Just War Outdated?

Magnifica Humanitas's Teachings Against the Normalization of War

Photo by Mahmoud Sulaiman on Unsplash

One sentence in Pope Leo XIV’s first encyclical Magnifica Humanitas has received undue attention along with inaccurate interpretation: “Today, more than ever, without prejudice to the right to self-defense in the strictest sense, it is important to reaffirm that the ‘just war’ theory, which has all too often been used to justify any kind of war, is now outdated” (192). While some have quickly concluded that the pope has “repudiated” and “disavowed” just war theory, others – including Catholic philosophers Gregory Reichberg and Edward Feser, as well as myself – observe that Magnifica Humanitas actually uses just war criteria in its analysis of how new technological developments, such as AI-based weapons systems, impact the way that war is justified and waged today.

The deeper problem, according to Pope Leo, is that “a culture of power is taking hold … and grows by normalizing war, pursuing ever-greater military power, taking advantage of the crisis of multilateralism and fueling a false realism that insists that there is no alternative” (188). What he calls the “normalization of war” is evident with the waxing militarism, unilateralism, us-versus-them and might-is-right mentality. “Today … we are witnessing a real paradigm shift in public discourse and in decisions regarding rearmament, with a troubling revival of war as an instrument of international politics,” writes the pope, “while the very ethical principles that had previously limited its use are being eroded” (190). Two paragraphs later, Pope Leo reiterates, “When historical memory fades and the ethical principles that protect civilians and the most vulnerable are weakened, it becomes easier to justify violence as necessary, inevitable or even ‘sanitized’” (192). The ethical principles to which he alludes are undoubtedly what the Catechism refers to as “the strict conditions for legitimate defense,” which are “are the traditional elements enumerated in what is called the ‘just war’ doctrine” (2309).

I wonder, though, whether it is the moral criteria that are corroded and obsolete, or the forgetting and even the denial of the ethic that yielded them and that requires, according to the Catechism, “rigorous consideration” in their application (2309). After all, a few paragraphs later Pope Leo urges, “Concrete criteria for discernment must be established” to address the problems we face with warfare today (199). Again, in these paragraphs the pope clearly refers to the principles of last resort, proportionality, just cause, and noncombatant immunity while carefully applying them to raise questions about AI, weapons, and war.

As Feder suggests, “It is clear, then, that what the pope considers ‘outdated’ is not the principles of just war doctrine themselves, but rather any application of those principles that would permit military action for purposes other than defense in the strictest sense – and in particular, any application of them that ‘normalizes’ war as one ‘instrument of international politics’ alongside others.” The problem, then, isn’t the principles themselves. After all, throughout Magnifica Humanitas, “principles” are mentioned over 70 times and “criteria” nearly 30 times vis-à-vis “the Social Doctrine of the Church [which] is a legacy of wisdom, where we find principles for thought, criteria for discernment and judgment, and concrete guidelines for action” (3).

Curiously, in the sentence preceding his call for the establishment of “concrete criteria for discernment” regarding AI-weapons, Pope Leo asserts, “It is not enough to invoke a generic type of ethics” (199), but what he means by this is unclear to me. If by “generic” he means “general,” he could have in mind an ethic that is “vague,” “popular,” or “predominant,” each of which could be morally problematic by making it “easier to justify violence” (192). But if with “generic” the pope has in mind “universal,” “global,” or “common,” then such an ethic has provided criteria that are established not only in the Catechism and in the Catholic moral tradition but also in military ethics and international law.

As Firdous Syed reminds us, “Long before it was formalized in Christian theology, nearly every major civilization developed its own framework to regulate violence, recognizing both the necessity and the dangers of organized conflict. Each sought to place ethical limits on violence, protect non-combatants, restrain rulers and subordinate force to a higher conception of justice, duty or social harmony.” In fact, just war ethics historically can be found in non-Western and non-Christian cultures, as seen in numerous academic studies by reputable scholars such as Ping-Cheung Lo and Sumner B. Twiss, as well as John Kelsay and Rory Cox.

On this point, Lloyd Steffen has referred to “the ancient Western ethics tradition of natural law, which underwrites just war thinking.”¹ As he puts it, there is “a way of ethical thinking,” an “ethic that lies behind just war” that should be “widely applicable to all kinds of ethical issues,” including but going “beyond the particular question of war or the use of force.”² This ethic provides “a system of guidance for deliberating, analyzing, and prescribing action that is good, right, and fitting,” by giving “rise to rules” that function as “normative moral action guides” which are “not intended to rationalize war” but instead meant to “impose restraint, insisting that force be used only in a way that is proportionate to the end of addressing injustice and restoring peace.”³

For Steffen, moral deliberations about “the prospective use of force inevitably involve the content of just war thinking.”⁴ Similarly, in his 1969 book War and Moral Discourse, Ralph Potter observed that when morally evaluating any use of force, including by the police, “some analogue to the just war doctrine emerges, whether it be in non-Western cultures or in the Christian subculture.”⁵

In addition, in Steffen’s view, other human actions that cause harm, even if we do not think of them as uses of force, involve such “just war thinking,” and he illustrates how with end-of-life decision making in bioethics and the death penalty in criminal justice. Similarly, Lisa Sowle Cahill has used just war reasoning and principles to examine embryonic stem cell research, noting: “The task is therefore not to decide ‘prospectively’ whether it is a good idea, but to subject it to moral guidance and restraints, acknowledging its potential for beneficial outcomes while limiting the social damage and moral compromises it involves.”⁶ Likewise, in addition to my own work on just policing, I have proposed a just mining theory with criteria under three categories that parallel just war’s jus ad bellum, jus in bello, and jus post bellum – namely, jus ad extractionem, jus in extractione, and jus post extractionem.⁷

Significantly, Steffen adds that the “ethic that underwrites just war thinking may appear to be focused on the coercive force of violence, but the normative guide against using force applies not only to uses of force that are destructive and violent but to any use of force.”⁸ By this he has in mind active nonviolent resistance, including boycotts, demonstrations, and sit-ins. Steffen argues that just war reasoning and criteria were implicitly embedded in the thought and actions of Gandhi and Martin Luther King, Jr., for even their nonviolent resistance was a use of force, which required justification as well as measured application.⁹

Indeed, over half a century ago, both James F. Childress and Paul Ramsey applied just war thinking and criteria to nonviolent resistance and protests.¹⁰ As Childress observed:

The “just war doctrine” offers a set of considerations for determining when war is justified, and analogous criteria must be employed in determining when civil disobedience is justified, although perhaps it is more accurate to suggest that civil disobedience is subject to the same general demands of morality as any other action rather than that it is illuminated by just war criteria. However that may be, certainly the appropriate criteria for evaluating civil disobedience coincide to a great extent with traditional just war criteria such as just cause, good motives and intentions, exhaustion of normal procedures for resolving disputes, reasonable prospect for success, due proportion between probable good and bad consequences, and right means.¹¹

More recently, in her work on “just peacebuilding,” Maryann Cusimano Love has suggested “just-peace principles” that she acknowledges are implied in just war thinking and resemble its principles.¹²

All of this leads me to suggest that what the Catechism calls “legitimate defense,” along with its “strict conditions” requiring “rigorous consideration,” should encompass both armed and unarmed force. As such, just war theory is far from “outdated.” It may need to be updated, as has happened with work in recent decades on jus post bellum. But when Pope Leo laments, “When historical memory fades and the ethical principles that protect civilians and the most vulnerable are weakened” (192), what is really needed is a remembering and a stronger commitment to – through education and moral formation – the ethic behind just war.

1. Lloyd Steffen, Ethics and Experience: Moral Theory from Just War to Abortion (Rowman & Littlefield, 2012), 16.

2. Steffen, Ethics and Experience: Moral Theory from Just War to Abortion, 15, italics original.

3. Steffen, Ethics and Experience, 33, 37, 40.

4. Steffen, Ethics and Experience, 21.

5. Ralph B. Potter, War and Moral Discourse (John Knox Press, 1969), 50.

6. Lisa Sowle Cahill, Theological Bioethics: Participation, Justice, and Change (Georgetown University Press, 2005), 231.

7. Tobias Winright, “A Just Mining Framework for the Ethics of Extraction of Natural Resources and Integral Peace,” in Catholic Peacebuilding and Mining: Integral Peace, Development, and Ecology, ed. Ceasar A. Montevecchio and Gerard F. Powers (Routledge, 2022), 95-116. This volume is available through open access.

8. Steffen, Ethics and Experience, 52.

9. Steffen, Ethics and Experience, 51-72.

10. James F. Childress, Civil Disobedience and Political Obligation: A Study in Christian Social Ethics (Yale University Press, 1971); Paul Ramsey, Christian Ethics and the Sit-In (Association Press, 1961).

11. James F. Childress, Civil Disobedience and Political Obligation: A Study in Christian Social Ethics (Yale University Press, 1971), 204.

12. Maryann Cusimano Love, “What Kind of Peace Do We Seek? Emerging Norms of Peacebuilding in Key Political Institutions,” in Peacebuilding: Catholic Theology, Ethics, and Praxis, eds. Robert J. Schreiter, R. Scott Appleby, and Gerard F. Powers (Orbis Books, 2010), 56-57.