What if Nuclear Proliferation Reduces the Incidence of War?
Political scientist James Fearon has posted (complete with graphs) the results of his own study of whether nuclear states are more or less likely to engage in war in the years following their acquisition of nuclear weapons. Here’s his bottom line:
[F]or each of the nine states that acquired nuclear capability at some time between 1945 and 2001, their yearly rate of militarized disputes in years when they didn’t have nukes, and the rate for years when they did. Note that for the US we have no data on dispute rate without nukes in this period since we got them in 1945; the rate for non-nuclear years for Russia/USSR is only for 1945-1948; the rate for South Africa (SAF) is for 1982-90; and the dispute data only goes to 2001.
China, France, India, Israel, Pakistan, and the UK all saw declines in their total militarized dispute involvement in the years after they got nuclear weapons. A number of these are big declines. USSR/Russia and South Africa have higher rates in their nuclear versus non-nuclear periods, though it should be kept in mind that for the USSR we only have four years in the sample with no nukes, just as the Cold War is starting.
Now it could be that getting nukes means that other states become more likely to initiate a dispute with you, rather than you becoming more aggressive.
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What happens if you control for other stuff, like aggregate GDP (a proxy for total military capability) or secular change over time for all states, in a statistical model? I’ve done some of this, with a panel data approach using country and year fixed effects and clustering the errors by country. I get that states see on average about one half fewer disputes per year when they have nuclear weapons, an amount that is close to “statistically significant” at p = .10. For various reasons I wouldn’t put a lot of weight on this but it does suggest that the patterns seen above don’t go away, and in fact might be somewhat strengthened, when you control for aggregate capabilities and time trends.
Obviously the fact that the other members of the nuclear club generally didn’t get much more aggressive in their foreign policy behavior after they tested doesn’t mean that Iran won’t.
Interesting results, which tend to support what some IR scholars have been arguing for decades: the presence of more deadly weapons raises the stakes of war, lowering the likelihood states will risk initiating conflict. Others, of course, argue the destabilizing effects of proliferation. So what to do? Fearon hedges his bets a bit on the implications for the debate over preventive war against Iran:
To be clear, I’d strongly prefer that the Iranian regime not get the bomb, mainly because of the risks of further proliferation in the region and attendant risks of preventive war and loss of control of weapons. But attacking Iran seems likely to guarantee pursuit till acquisition, to more effectively license future attacks on Israel, and to greatly increase popular support for the current Iranian regime and a course of nuclear self-defense. (Netanyahu is reported in this NYT article to believe that an attack might actually “be welcomed by Iranian citizens.” If that’s his true view and not purely strategic talk, then sheesh, it looks delusional in light of the historical record on that one.) On the other side of the ledger are vague, weak, or barely developed arguments and claims about terrible things Iran would do if it got nukes.
We’ve heard these same concerns before, regarding Stalin’s USSR, Mao’s China, Kim Jong-il’s North Korea, and about the mortal mutual enemies of India and Pakistan. All these cases have been very scary, and it’s understandable that the prospect of a nuclear Iran is incredibly scary for Israelis. But so far, in none of these prior cases do the more extreme fears look historically justified.
My own question is what does or should this mean for lawyers? Do quantitative studies of this sort — backward-looking, somewhat limited by their own size, with heavy caveats and resulting in some incidents (outliers?) proving the hypothesis– justify shifts in efforts to penalize proliferation? Or are we headed for the same unresolvable arguments about international nuclear proliferation that we hear in U.S. domestic debates over gun control?