A little more than halfway through their 1983 pastoral letter, The Challenge of Peace, the U.S. bishops acknowledge voices calling on them “to raise a prophetic challenge to the community of faith—a challenge which goes beyond nuclear deterrence.” Those prophetic voices rejected the position, embraced at that time by most U.S. bishops and Pope John Paul II, that nuclear deterrence was an acceptable “interim ethic” so long as the ultimate goal was disarmament. One of these voices, Thomas Merton, claimed that “there is simply no ‘good end’ that renders risk [of nuclear war] permissible,” and questioned whether rationalizations for “wielding the threat of nuclear destruction” do not constitute cooperation in evil.

In recent years, leading voices in the Roman Catholic Church, not least Pope Francis himself, have begun to sound more like Merton than like the majority of the U.S. bishops in the 1980s. Prophetic indictment not only of the use but also of the very possession of nuclear weapons is no longer limited to the likes of Merton, the Berrigan brothers, and activist groups like Plowshares. Thus, in a 2017 address, Pope Francis commended the “prophetic voice” of the hibakusha, the survivors of the bombings of Hiroshima and Nagasaki, and condemned the “very possession” of nuclear weapons. In his visit to Hiroshima in late November 2019, Francis extemporaneously reiterated that condemnation. Bishop Robert McElroy of San Diego has claimed that the possession of nuclear weapons “is now condemned, regardless of the intention.” And the Jesuit just-war theorist and former America editor Drew Christiansen has argued in La Civiltà Cattolica that “we should cease to imagine nuclear weapons as tools for us to manage, but rather as a curse we must banish”—language that The Challenge of Peace reserved for the arms race, not nuclear weapons themselves.

Pope Francis’s November 2019 visit to Japan, which included stops in both Nagasaki and Hiroshima, brought attention to the Vatican’s renewed diplomacy on nuclear weapons. But one could argue that more attention now needs to be given to the question of how people who fervently wish for a world without nuclear weapons should go about working for it. As the moral theologian and Commonweal contributor Cathleen Kaveny explains in her book Prophecy without Contempt: Religious Discourse in the Public Square, prophets demand unambiguous compliance with unconditional moral imperatives. By contrast, what she calls deliberators allow that moral rules need to take into account complex circumstances, human weakness, ignorance, and sin. (See also her Commonweal column, “Bridge Burners,” December 2019.)

In her book, Kaveny gives three examples of pressing moral issues that, in her judgment, are not ripe for the rhetoric of prophetic indictment: animal rights, gun control, and climate change. Her reasons for this judgment differ for each of the issues, but a key question is whether would-be prophets can draw on at least some of the fundamental commitments of our present political community, or whether they draw only on the commitments of a utopian community they imagine and hope for. Would-be prophets who cannot draw on commonly recognized moral commitments are not likely to get a hearing. Instead, they’re likely to alienate people and thereby set back their cause.

How do things stand, then, with the pressing moral issue of nuclear weapons in the twenty-first century? Is it ripe for prophetic indictment, or does that rhetorical style risk backfiring?

The would-be prophet can surely draw on widely shared moral commitments to denounce any use of nuclear weapons that directly targets civilian populations, as well as any use that “unintentionally” but foreseeably kills and maims massive numbers of civilians. The would-be prophet can also draw on common moral commitments in denouncing any system, strategy, or policy that would either increase the likelihood of nuclear warfare among the current nuclear powers, or stimulate nuclear proliferation, thereby imperiling peace in unstable regions like northeast Asia and making it more likely that terrorist organizations would acquire a nuclear device. In this regard, the signs of the times have been ominous over the past few years. If, as Pope John Paul II claimed, the “condemnation of evils and injustices...is an aspect of the Church’s prophetic role,” prophets have a lot of material to work with—from North Korea’s expansion of its ballistic-missiles program, to Russia’s violation of the Intermediate-Range Nuclear Forces (I.N.F.) Treaty, to the Trump administration’s withdrawal from the Joint Comprehensive Plan of Action with Iran and abrogation of the I.N.F. Treaty in response to Russia’s violations. The recent agreement between the Biden administration and Vladimir Putin’s Russia to extend the New START Agreement, which limits the countries’ nuclear arsenals, is a rare piece of good news.

The would-be prophet appears to be on shakier ground in denouncing nuclear deterrence as such. In The Challenge of Peace, the U.S. bishops had asked, “May a nation threaten what it may never do?” The argument that the answer to this question must always be “no” typically turns on the claim that it’s morally impermissible to do evil that good may come of it. According to this argument, it is evil for a nation to intend the massacre of civilians either for its own preservation or in retaliation. Yet that has been U.S. policy since the Cold War. It’s not only Catholic ethicists who find this policy evil. In his 2017 book, The Doomsday Machine, Daniel Ellsberg, of Pentagon Papers fame, laments that “what is missing...in the typical discussion and analysis of historical or current nuclear policies is the recognition that what is being discussed is dizzyingly insane and immoral.” An anti-consequentialist thinker like Elizabeth Anscombe (profiled by John Schwenkler in the May 2019 edition of Commonweal) might take the argument a step further: because the use of nuclear weapons would be evil, and because there’s no point in stockpiling weapons that a nation must never use, nations with nuclear weapons should simply get rid of them, without calculating the possible consequences.

There are several objections to this line of argument. First, one might reasonably doubt whether it is really appropriate to describe the choice to use nuclear deterrence so as to avoid being annihilated or subjugated by a foreign power as a choice to do evil that good may come of it. One might argue that it should instead be described as a choice between two evils—which is how the French bishops, for example, saw it in their 1993 document Gagner la paix. In this analysis, nuclear deterrence might be defensible as less evil than annihilation or subjugation. That brings us to a second objection: Is it really as bad to threaten the use of nuclear weapons—while hoping it won’t be necessary—as it is to actually use them? Surely not. In that case, why would a lesser evil (nuclear deterrence) not be permitted if it has the consequence of preventing a greater evil (annihilation or subjugation)? Finally, if we are considering how to counter a threat of aggression, the first question to ask is not what we would be permitted to do after the act of aggression we hope to prevent, but what we are permitted to do in the course of trying to prevent it.

The point of articulating these objections is not to defend current U.S. policy, or that of any of the current nuclear powers. Ellsberg is right: “What is being discussed is dizzyingly insane and immoral.” And Anscombe is right, I believe, to reject consequentialism as a moral theory. Instead, the point is to indicate that the morality of nuclear deterrence is deeply contested. Deep-rooted commitments can be invoked to defend it, such as the conviction that it is a fundamental duty of political leaders to protect citizens from harm. The upshot is that nuclear deterrence as such does not appear ripe for prophetic indictment.

If that is correct, then deliberative discussion about how to reduce the present dangers of nuclear catastrophe is the order of the day. Ellsberg may present a helpful model here to Catholic leaders. His rhetoric against the “modernization” of the U.S. nuclear arsenal is prophetic, but he also allows the legitimacy of maintaining, for now, a minimal nuclear deterrent. His example demonstrates that even prophets should not restrict themselves to prophetic denunciation. Just saying “no” will not do; they must also engage in the debate about what can be done now, starting from where we are.

It’s worth noting that deterrence is hardly a stable equilibrium, especially in our multipolar world where the actions of third parties—say, North Korea or China, or an American president on mind-altering steroids—can introduce new, destabilizing calculations. Nearly fifty years ago, the moral theologian Paul Ramsey presented a thought experiment involving the feud between the Hatfields and the McCoys. In the heat of the moment, when the eldest Hatfield has his gun trained on the youngest McCoy, and the eldest McCoy has his gun trained on the youngest Hatfield, the focus is on the vulnerable children. After a while, however, attention is likely to turn to the weapons themselves, on the grounds that protecting the weapons is protecting the children. Yet, if one side, say the McCoys, protects its weapons so well that the weapons become indestructible, then that side endangers its children anew, because the equilibrium the McCoys had with the Hatfields is now destabilized: the Hatfields’ weapons are vulnerable in a way that the McCoys’ no longer are, which gives the Hatfields a reason to use their weapons before they can be destroyed. Thus, technological breakthroughs improving the speed of delivery systems and the destructive power of the weapons also threaten to destabilize the “ceasefire” between the families. In the end, what had appeared to be a stable, if mad, plan of peace is exposed as a high-risk game of chicken. For all that, until the families can reach a peace based on trust and mutual disarmament, deterrence is their only choice. Whether the policy of deterrence makes trust harder to establish is a good question, but it’s not one that can be answered in the abstract, without attention to how diplomacy actually works.

Once again, the point of articulating objections to prophetic discourse about nuclear deterrence is not to defend current U.S. policy, or the policies of any other nuclear power. Instead, such objections should be understood as an invitation to reflect on the rhetorical style most likely to advance the cause of nuclear disarmament. Jesus instructed his disciples, whom he sent out like sheep among wolves, to be both wise as serpents and innocent as doves (Matthew 10:16). If sheep can also be serpents and doves, perhaps the Church’s leaders can find a way to combine the courage of the prophet with the prudence and humility of the deliberator. Nothing less is likely to succeed in moving us a step closer to multilateral nuclear disarmament.