Eighty-Five Seconds to Midnight: The Ethics of the Bomb

On August 6, 1945, a uranium bomb called 'Little Boy' destroyed roughly five square miles of Hiroshima; three days later a plutonium bomb, 'Fat Man,' struck Nagasaki. These remain the only wartime uses of nuclear weapons in history. The human toll can only be given as an estimate, and an uncertain one: disrupted wartime records and bodies wholly destroyed in the blast mean no exact count has ever been possible, but credible figures put Hiroshima's dead at around 140,000 by the end of 1945 and Nagasaki's at around 70,000, with combined estimates across the two cities ranging from roughly 110,000 to 210,000. The survivors, the hibakusha, carried elevated rates of cancer, birth defects, and trauma for the rest of their lives. Whether the bombings were justified remains a genuinely live historical dispute. The official case is that they averted a land invasion of Japan projected to cost enormous casualties; critics, following the historian Gar Alperovitz, argue that Japan was already near surrender and that the bombs were meant partly as a demonstration of power to the Soviet Union. The article takes no side on that unresolved question.

What is clearer is what the great just-war thinkers concluded when they applied their own criteria to the bombings. Michael Walzer, in 'Just and Unjust Wars' (1977), and the philosopher Elizabeth Anscombe, who publicly opposed the bombings at the time, judged that they violated the two oldest rules of ethical warfare: distinction, the prohibition on deliberately targeting civilians, and proportionality, the demand that harm not exceed the military gain. Anscombe called it, flatly, the murder of the innocent. That verdict matters for everything that follows, because the modern doctrine of deterrence does not merely regret such acts; it requires the credible promise to commit them on a vastly larger scale.

Worse, the bargain assumes a calm that history has repeatedly failed to supply. Deterrence presumes rational leaders, accurate warning systems, working command and control, and no accidents, and the record is full of moments when one or more of those failed. In 1983 the Soviet officer Stanislav Petrov correctly judged a satellite alarm showing incoming American missiles to be a false alarm, and declined to report a launch that doctrine said should trigger retaliation. That same year, the NATO exercise Able Archer 83 was reportedly read by frightened Soviet leadership as possible cover for a real first strike. In 2018 an emergency alert told the people of Hawai'i a ballistic missile was inbound; it was a mistake, sent by a worker who clicked the wrong option. The political scientist Scott Sagan has argued from cases like these that the stability of deterrence is far more precarious than its defenders assume. The peace it keeps is real. It is also a wager.

Set the strategy aside and ask the older question: can these weapons ever be used justly? Traditional just-war theory splits the question in two, and nuclear weapons fail both halves. On the right to go to war, no aggression seems grave enough to make the devastation of a nuclear exchange a proportionate response. On the conduct of war, nuclear weapons cannot honor distinction, since they inevitably kill civilians in enormous numbers, and cannot honor proportionality, since their destruction outruns any conceivable military objective; even a 'tactical' warhead spreads fallout and fire across the people nearby. Michael Walzer offered the one serious exception, and it is a narrow one: a 'supreme emergency,' a moment of genuine civilizational peril, in which the threat to use nuclear weapons might be reluctantly permitted even though their actual use almost never could be. Other just-war thinkers reject even that, arguing that a threat one may never rightly carry out cannot itself be righteous, and that Walzer's exception quietly dissolves the absolute ban on targeting the innocent that the rest of the theory is built to protect.

Against deterrence stands a serious and growing abolitionist case, and it is not a fringe one. In 2007 and 2008 four hard-nosed American statesmen, George Shultz, William Perry, Henry Kissinger, and Sam Nunn, men who had spent careers inside the nuclear system, argued in the Wall Street Journal that deterrence was becoming too unreliable to trust and that a world without nuclear weapons was both necessary and achievable. The Treaty on the Prohibition of Nuclear Weapons, adopted in 2017 and in force since 2021, makes their goal law for its parties, following the model that outlawed chemical and biological weapons; the campaign behind it, ICAN, won the 2017 Nobel Peace Prize. The churches have largely converged on the same side: the US Catholic bishops in 1983 granted deterrence only a 'strictly conditioned' acceptance as a step toward disarmament and never a permanent home, and during his November 2019 visit to Hiroshima and Nagasaki, Pope Francis went further, calling the use of atomic weapons in war a crime 'against the dignity of human beings and against any possible future for our common home,' and condemning even their possession as immoral.

How bad, exactly, is the worst case? Existential-risk researchers treat nuclear war as one of the few genuine candidates for ending human civilization, though the numbers are more modest and more uncertain than headlines suggest. In 'The Precipice' (2020), the philosopher Toby Ord put the probability that nuclear war causes an existential catastrophe in the next hundred years at roughly one in a thousand, a real and unacceptable risk, but an order of magnitude smaller than some looser claims imply. Whether a full exchange would truly cause human extinction, as opposed to a collapse that survivors eventually climbed out of, depends on contested nuclear-winter modeling and on how resilient scattered remnant populations would prove; this is honestly unresolved in either direction. Between the poles of current arsenals and total abolition, some strategists propose 'minimal deterrence,' cutting to one or two hundred survivable weapons to preserve the deterrent while lowering the odds of accident and arms racing, though critics doubt such a posture would stay minimal for long.

This is a subject that tempts confident verdicts from both directions, and both are overclaims. The first is the 'nuclear peace' thesis: that because no great powers have fought directly since 1945, nuclear weapons have abolished major war and are therefore simply good. It does not follow. The long peace has other plausible causes, nuclear-armed states have still fought each other at the edges (India and Pakistan clashed at Kargil in 1999), and a peace that rests on the permanent risk of accidental or irrational annihilation is not a guarantee but a bet that has not yet lost. A close cousin is the claim that modern weapons could be used 'surgically' without escalating; virtually every war game says otherwise. But the mirror overclaim is equally unearned: that any possession of nuclear weapons is, flatly and settledly, moral monstrosity with nothing more to discuss. That erases the serious, good-faith positions the record actually contains, Walzer's supreme-emergency exception, the Catholic Church's own conditional acceptance of deterrence as a bridge to disarmament, the abolitionists who argue policy rather than accusing every deterrence-minded leader of villainy. The honest verdict refuses both the hawk's certainty and the abolitionist's, and holds the paradox open, because it genuinely is.