The Times (London) (pg. 17), July 27, 2007

ONLY A RECKLESS MIND COULD BELIEVE IN SAFETY FIRST

[Rachel's introduction: "Precaution is now explicitly endorsed by the UN, the EU and Tony Blair, who has claimed that "responsible science and responsible policymaking operate on the precautionary principle". From the genetic modification of crops to speed limits for trains to carbon dioxide emissions, the right policy is claimed to be the careful one. Yet the precautionary principle is not really a maxim of good policy. In fact, it is meaningless."]

By Jamie Whyte

Worrying was considered foolish when I was growing up in New Zealand. Let your fretting show and you received the classic Kiwi response: "She'll be right, mate."

When in doubt, just press on and set your mind at ease.

Times have changed. You never hear "she'll be right" these days, except said ironically. And this new pessimism is not restricted to New Zealand. Across the West, the "she'll be right" principle has been replaced by the so-called precautionary principle. When in doubt, stop and divert your efforts towards minimising the risks.

Indeed, precaution is now explicitly endorsed by the UN, the EU and Tony Blair, who has claimed that "responsible science and responsible policymaking operate on the precautionary principle". From the genetic modification of crops to speed limits for trains to carbon dioxide emissions, the right policy is claimed to be the careful one.

Yet the precautionary principle is not really a maxim of good policy. In fact, it is meaningless. It can provide no guidance when making difficult decisions. Those who invoke it in support of their favoured policies do not display their prudence; they reveal groundless biases.

To understand the precautionary principle and its foolishness, we must first distinguish between what economists call "risk" and what they call "uncertainty".

An outcome is risky when it is not guaranteed but we know its probability. An outcome is uncertain when we do not even know its probability. That a tossed coin will land heads is thus a matter of risk, while the destruction of an ecosystem from the introduction of GM crops is a matter of uncertainty.

Making decisions under risk presents no problem for which the precautionary principle could provide a solution. Suppose that, in return for an annual premium of £ 1, someone promises to pay you £ 1 million if you are abducted by aliens (such insurance exists). You should pay up if your chance of being abducted is greater than one in a million because then the policy is worth more than $1.

The right decision can be determined from the numbers alone, with no help from caution, recklessness or any other attitude.

But suppose that, for all you know, the chance of being abducted could be well under one in a million or well over. What should you do? You lack the information required to know if the insurance is a good deal. It is in such situations of uncertainty that the precautionary principle is supposed to apply.

What does the principle tell you to do? Those who advocate precaution typically favour incurring costs now to reduce the chance of incurring greater costs in the future. That is their reason for wanting to limit carbon emissions, ban GM crops and slaughter livestock with some unknown chance of contracting foot-and-mouth disease.

Applied to our insurance conundrum, this principle tells you to buy the ticket.

You should incur the £ 1 cost of the premium if there is any chance that it will save you from the greater cost of experiencing an uncompensated alien abduction. Whenever the prize is greater than the bet, and you do not know the odds, the principle says you should gamble. Bookmakers must dream of the day when punters bring such wisdom to the racetrack.

Better safe than sorry. This is the verity that the precautionary principle is supposed to bring to policymaking. But the difficult question is never whether it is better to be safe than sorry. Of course it is. The serious question is always which options are safe and which sorry.

The big lie behind the precautionary principle is the idea that we can identify safe options even when we are profoundly ignorant of the probable outcomes. It is nonsense to claim that betting or buying insurance is the safe option whenever you do not know the odds. And it is equally foolish to claim that slaughtering livestock is the safe option when you do not know by how much this will reduce the chance of an epidemic, or that banning GM crops is safe when you do not know its likely ecological effect.

For, as with insurance, such measures are costly. Those currently popular with the cautious lobby run into the billions and, in the case of limiting carbon emissions, perhaps the trillions. It is a strange kind of caution that recommends spending such sums when the chance of success is unknown.

Or, if it is crass to set mere monetary costs against risks to the environment or future generations, then consider the deaths such measures will cause. Banning GM crops, for example, will increase starvation in the third world. More generally, any serious economic cost will cause death because, among other things, less wealth means less nutrition and less healthcare. Economists have estimated that a life is lost for every £ 10 million of cost imposed by regulation.

Sacrificing thousands of lives for uncertain gains takes a very particular notion of caution.

The precautionary principle is either uncalled for, because we know the relevant probabilities, or useless, because we do not know them and so cannot tell whether any policy is a safe or a sorry proposition. So we should hear no more of it. Not only does it lend bogus support to the policies it is fashionable, if arbitrary, to label precautionary. It also promotes the pernicious idea that ignorance is not a serious problem, that a wise policymaker can know that an action is right even when he does not know its likely effects.

Jamie Whyte is the author of Bad Thoughts: A Guide to Clear Thinking