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The Precautionary Principle and Global Warming

How much risk from climate change should there be before we spend trillions of dollars to address the problem?

by
Rand Simberg

Bio

December 16, 2009 - 12:06 am
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Those advocating that we upend the global (and particularly the U.S.) economy to stave off climate change resort to a concept called the “precautionary principle“. Simply stated, it is that if there is some risk of an irreversible disaster in taking an action, then that action should be foregone.

In this formulation, the risk is climate change that will be disastrous for humanity, and the action to be foregone is continuing to add the carbon dioxide that is ostensibly causing it to the planetary atmosphere. The beautiful thing about the principle (at least for them) is that, because it doesn’t assign any particular probability to the risk (i.e., it is uncertain), then it doesn’t matter whether the science backing it up is known to be valid, because even if the science has only a small probability of being correct, the principle applies.

The original advocate of the precautionary principle was the mathematician Blaise Pascal, who came up with a famous “wager.” To wit: we can’t calculate the probability of the existence of God, but if he exists, the cost of believing in him is small, and the wages for not doing so is eternal damnation. Therefore, it makes sense to believe.

Many in the centuries since have pointed out the flaws in the argument. For instance, there is a non-zero probability that God will consign you to perdition if and only if you believe in him. Thus, to avoid this fate, the only safe course is to be an atheist.

Which points out the flaw in the principle in general. While it doesn’t require a precise accounting of the odds, it also doesn’t necessarily provide guidance as to what to do if there’s any chance that the proposed cure (or “insurance policy”) is worse than the feared disease. And a good case can be made (as has been by people such as Bjorn Lomborg) that in fact there is not just an excellent chance, but almost a certainty that this is the case with most of the proposed solutions to anthropogenic global warming.

Despite those logical flaws (not that he has ever been a stranger to illogic), the latest AGW hystericist to employ the concept is Tom Friedman:

When I see a problem that has even a 1 percent probability of occurring and is “irreversible” and potentially “catastrophic,” I buy insurance. That is what taking climate change seriously is all about.

Well, I do that, too. But I buy insurance that has a price commensurate with the expected value (i.e., the cost of the disaster times the probability that it will occur). For instance, I’ll pay a few hundred bucks for a million-dollar policy against the small chance that I’ll kick off tomorrow. Presumably, Friedman assumes that the proposed palliatives of cap’n’tax or carbon taxes meet that criterion, but he doesn’t do the calculations for us, because he can’t. Warm mongers like him propose to spend trillions of dollars now to prevent an unknown amount of cost later, in defiance of the basic economic principle of discounting the value of future expenditures.

There is a variation on this fallacy, in fact. It goes: There is a crisis; something must be done! What we propose to do is something. Therefore, it must be done!

This invalid argument is otherwise known as false choice, of course, because the alternative to the particular something being proposed is not nothing (even if one accepts the initial premise that there is a crisis about which something must be done) — it is a variety of other somethings, some of which may be the something that is actually key to solving the problem, even if their own is not necessarily.

We saw this last January when many of the same people promoting AGW hysteria also used it to ram through the failed “stimulus” bill without reading it. It is now being used to justify taking over the sixth of the US economy represented by the health care industry. All the while, these people have been lambasting their political opponents who offer more sensible alternatives as proposing that we do “nothing.”

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