One major problem with most invocations of the precautionary principle is that people tend to apply it to whatever danger they want to prevent, but largely ignore it in considering the potential dangers created by the policies they advocate. For example, Dick Cheney applied a version of the principle to the threat of terrorism, arguing that even a small chance of a catastrophic terrorist attack justified taking sweeping measures to eliminate it. At the same time, he tended to ignore the potential dangers of the anti-terrorist measures themselves. Similarly, environmentalists apply the precautionary principle to global warming, but not to the risks created by policies intended to alleviate global warming.
If we have to take seriously the dangers of a global warming catastrophe, we should give equally serious consideration to the risks on the other side. For example, it’s possible that cutting carbon dioxide emissions by 80%, as some environmentalists advocate, would devastate the global economy, impoverishing millions and causing widespread suffering and death. Moreover, enforcing a worldwide cap and trade regime strong enough to compel obedience by China, India, Russia, and other potentially recalcitrant states might require a global authority with massive powers; even if these states formally agree to a cap and trade system, they might not enforce it aggressively against their own industries, unless compelled. The vast powers necessary to impose compliance could easily be abused in a variety of ways. In the most extreme scenario, the enforcement authority could eventually become an oppressive or even totalitarian world government from which there is no hope of escape. These two scenarios are admittedly unlikely (though the first is improbable largely because an 80% emissions cut is likely to be politically infeasible for the foreseeable future), but they can’t be completely ruled out. If, as Thomas Friedman says, the precautionary principle requires us to “buy insurance” against “a[ny] problem that has even a 1 percent probability of occurring and is ‘irreversible’ and potentially ‘catastrophic,’” these extreme scenarios have to be considered and strong precautions taken to forestall them before any large-scale anti-global warming initiative can be adopted.
Less extreme, but still major catastrophes, are also possible – and far more likely than the worst-case scenarios noted above. For example, as co-blogger Jonathan Adler explains, a cap and trade program could create a bonanaza for interest group rent-seekers who will use it to exploit the general public, while simultaneously falling far short of achieving the level of emission reductions that would be necessary to have a serious impact on global warming. Such large-scale inefficiency might well reduce economic growth. And even small (but persistent) reductions in annual world economic growth would consign millions of people to poverty or an early death, because of the enormous impact of compound growth over time. For example, if India had abandoned its flawed economic policies just a few years earlier than it did in the 1980s and 90s, millions of children who died young might have survived to adulthood. Similar devastating cumulative results could occur if anti-global warming measures slow down Indian or other Third World growth rates today.
Perhaps these dangers could be avoided or minimized if we had a perfectly functioning political system or something close to it; then we could count on policymakers to use their new powers to promote only those emissions-cutting policies that create benefits that outweigh their costs. In reality, government decision-making suffers from systematic flaws caused by widespread voter ignorance, interest group power, and information problems among policymakers. These dangers are exacerbated if the policy in question is complex (and therefore difficult for rationally ignorant voters to monitor), and if decisions are made in a crisis atmosphere. Global warming policy is, of course, both highly complicated and conducted amidst dire warnings that we will have a major crisis on our hands if we don’t act quickly.
None of this proves that global warming isn’t a real danger (even in the wake of Climategate, I think it probably is), or that we shouldn’t take any steps to reduce it. Like Jonathan Adler and James Hansen, I am sympathetic to the idea of using a revenue-neutral carbon tax to counter warming, though I fear that such a plan might not be politically feasible, and also qualify my support by my admitted ignorance of much of the relevant science. These considerations do, however, undercut simplistic arguments claiming that the precautionary principle unequivocally justifies taking immediate drastic measures to prevent global warming.
When there are major potential risks on both sides, the precautionary principle leads to paralysis. Whatever we do (including doing nothing), there is at least a small chance of catastrophe; thus, the principle would lead us to reject all the available options, which isn’t exactly helpful. For that reason, I agree with Cass Sunstein’s view that it is ultimately a poor guide to policy. But those who do believe in it have to be consistent in considering its implications for the possible dangers created by their preferred policies, as well as for the risks those policies are supposed to mitigate.
Meanwhile, those of us who reject the precautionary principle should still take to heart the lesson that we must give serious consideration to the possible dangers policies intended to forestall potential “catastrophic” risks. This is especially the case with policies that would create massive new concentrations of government power. The last century showed all too clearly that concentrated state power has been a major cause of many of our greatest catastrophes.