Re-evaluating the Church’s Approach to Nuclear Weapons

Since the end of World War II, two camps have vied to define, once and for all, the Catholic Church’s doctrine on nuclear weapons. The first of these, let’s call it the deterrence camp, holds that nuclear weapons have their place in the geopolitical order and are legitimate weapons of war. Deterrence is a means of preventing wars of aggression, not of preparing to launch them. As such, it is broadly consistent with the Church’s desire to promote peace. As the Compendium of the Social Doctrine of the Church proposes, possession of weapons of mass destruction (WMDs) is morally acceptable, though it also proposes (somewhat ominously, if not contradictorily) that “those who possess them have an enormous responsibility before God and all of humanity” (no. 508). The possession of nuclear weapons, therefore, is not inherently evil, though it may become evil if a country violates the “principle of sufficiency, by virtue of which each State may possess only the means necessary for its legitimate defense” (no. 509).

During the Cold War, the logic of deterrence led to mutually assured destruction (MAD), a strategy both dangerous and baleful. But, deterrence advocates maintain, that was a hard reality that had to be managed through arms-control and non-proliferation practices, not a grave sin requiring the penance of comprehensive nuclear disarmament.

Deterrence proponents do not believe that nuclear war is inherently evil. To be sure, they recognize that such a war would be catastrophic, perhaps even apocalyptic. But so too were the world wars of the 20th century; indeed, in a moral sense, so too are all wars. Deterrence advocates acknowledge the intrinsic balefulness of war but argue nonetheless that in a postlapsarian world populated by fallen men, in which the libido dominandi that St. Augustine spoke of is always prevalent and in which the institutions of global governance are fundamentally and irredeemably ill-equipped to meaningfully mitigate these realities, the possibility of war is ever-present. Given that the natural law warrants the use of force for self-defense, and that the use of nuclear weapons may be necessary for self-defense, a nuclear war cannot be ruled out absolutely.

As the Church has taught from the time of Augustine, states are entitled to use force to defend themselves against attack. This means that preparing to fight a nuclear war — and, in extremis, actually fighting one — is not morally impermissible. Indeed, to the extent that it preserves the peace by enhancing the credibility of deterrence threats, preparation for nuclear war might even be morally commendable. Simply put, though deterrence advocates, like all rational people, abhor the prospect of nuclear war, they also maintain that, provided such a war is fought for a just cause and conducted according to the ius in bello (“right of armed conflict”) principles of Catholic just-war doctrine, there are simply no moral grounds on which to condemn it tout court.

The second of these camps, the disarmament camp, takes a very different view. It holds that nuclear war is inherently evil and can never be morally justified, no matter its cause or how it is fought. The use of nuclear weapons would be a violation of both Catholic morality and just-war doctrine if only because such use would, by its very nature, be indiscriminate and needlessly injurious. As these are two of the key criteria of licitness in the Catholic ius in bello tradition, disarmament advocates claim that such a stern moral judgment is logically unavoidable. Just-war doctrine is not a user manual for the prosecution of a morally justifiable nuclear war, they argue. Instead, read appropriately and in light of the signs of the times, it is a sweeping summary judgment that anathematizes both the use and possession of nuclear weapons — without qualification.