If you ask the man on the street what’s the biggest threat to the continued existence of human civilization, he’ll probably say global nuclear war. And yet, even as someone who worries a lot about threats to civilization, I don’t spend much time thinking about nuclear war.
Global nuclear war is a lot like a cataclysmic asteroid collision. There’s a non-zero probability of it happening, and the expected damage is huge. Multiply the low probability by the high expected damage and, for the sake of argument, let’s say it turns out to be the single greatest threat the world faces over the next 500 years in expected value terms. Even so, there’s not much point in worrying.
The thing about asteroid collisions is, they’re freak events. They happen without any influence from what we do on the ground, and barring the return of a supergroup helmed by Bruce Willis, there’s not much one can do about it in any case.
So, worrying about asteroid collisions, as compelling as it might be in expected value terms, looks like a sort of neurosis. “Grant me the serenity to accept the things I cannot change…”
Now, you’re probably saying, nuclear war isn’t at all like that. Sure there’s nothing to be done about a giant asteroid that’s completely external to the earth. But nuclear weapons are built by humans, deployed by humans, for human purposes, and can be dealt with using human methods. Far from a freak occurrence, nuclear war is possible to avert, and profitable to worry about.
Suppose we had the power to move the earth to a solar system where the probability of asteroid strikes was zero. Would we want to do it? Would we want to have done it?
Human civilization certainly benefited from asteroid collisions. Mammals would be of little account if not for the mass extinction of larger lizards – primates likely wouldn’t exist, let alone be a dominant species. So, at the very least, we wouldn’t want to have lived in a solar system without asteroid collisions.
Similarly, the global order that has resulted in a more or less peaceful equilibrium with only one territorial annexation1 since the end of World War II is largely the result of the decisive nuclear victory by the Allies in that war. This is a phenomenal accomplishment in the age of nation-states. The construction of global governance institutions has been relatively successful in maintaining global peace, and spurred in large part by the prospect of nuclear annihilation.
Indeed, the case for life with nukes is even stronger than the case for life in an asteroid field. Even if we did turn out to benefit ex post from an asteroid collision, it would still be in our interest, were it possible, to move to a safer solar system now. Living with the prospect of asteroids is still undesirable ex ante. This isn’t true of nuclear war! Not only did humanity happen to benefit ex post from the single use of a nuclear weapon, we continue to benefit ex ante from the continued prospect. Global institutions were not only constructed in response to nuclear weapons, but derive their continuing justification in large part from that continued threat. Disarmament, more than likely, results in a return to the pattern of opportunistic annexation and constant petty war that characterized nation-states in the pre-atomic age.
Now, obviously, there’s a limit to this logic. Cooperation becomes much harder to sustain, even with a huge downside, as the number of players increases – especially if you add unstable players like Iran or North Korea without much of a downside. For this reason nuclear consolidation, say into NATO, could make things safer – certainly safer than disarmament – assuming that NATO is less likely to unilaterally disarm than the US, which I doubt.
But granting that the existence of nuclear weapons is necessary to sustain much that’s worth preserving about modern human civilization in the first place, once we’ve settled into an equilibrium where civilization is sustained by the threat of its annihilation, the actual realization of nuclear war starts to look like a freak occurrence in the same way as an asteroid collision. The threat has to be real for it to work, and a real threat implies a non-zero probability of realization. If the prospect of moving to a different solar system (disarming) is off the table, as it should be, there’s not a lot of sense in worrying about collisions.