Is Nuclear War Inevitable?

Russia's invasion of Ukraine and nuclear saber rattling against the West have revived a debate about nuclear weapons. Last year, when a United Nations treaty to ban such weapons outright entered into force, none of the world's nine nuclear-weapons states was among the 86 signatories. How can these states justify possessing weapons that put all of humanity at risk?

That is a pertinent question, but it must be considered alongside another one: If the United States were to sign the treaty and destroy its own arsenal, would it still be able to deter further Russian aggression in Europe? If the answer is no, one also must consider whether nuclear war is inevitable.

It's not a new question. In 1960, the British scientist and novelist C.P. Snow concluded that nuclear war within a decade was "a mathematical certainty." That may have been an exaggeration, but many believed Snow's prediction would be justified if a war occurred within a century. In the 1980s, Nuclear Freeze campaigners like Helen Caldicott echoed Snow in warning that the buildup of nuclear weapons "will make nuclear war a mathematical certainty."

Those advocating the abolition of nuclear weapons often note that if you flip a coin once, the chance of getting heads is 50%; but if you flip it ten times, the chance of getting heads at least once rises to 99.9%. A 1% chance of nuclear war in the next 40 years becomes 99% after 8,000 years. Sooner or later, the odds will turn against us. Even if we cut the risks by half every year, we can never get to zero.

But the coin-flip metaphor is misleading where nuclear weapons are concerned, because it assumes independent probabilities, whereas human interactions are more like loaded dice. What happens on one flip can change the odds on the next flip. There was a lower probability of nuclear war in 1963, just after the Cuban Missile Crisis, precisely because there had been a higher probability in 1962. The simple form of the law of averages does not necessarily apply to complex human interactions. In principle, the right human choices can reduce probabilities....