Monday, 8 February 2010

We might err, but science is self-correcting

If claims about climate change need to be debunked, you can rely on scientists to do it. Scepticism is what we are all about
John Krebs

My non-scientist friends are beginning to ask me “What’s gone wrong with science?” Revelations about melting glaciers and potentially dodgy emails about global warming, the resurfacing of Andrew Wakefield and the MMR scare, and the sacking of the Government’s drugs adviser, have created the impression for some people that science is in a mess.
Of course science isn’t in a mess, nor has anything changed. But the stories underline two important features of scientists and science. First, scientists, just like every other trade — bus drivers, lawyers and bricklayers — are a mix. Most are pretty average, a few are geniuses, some are a bit thick, and some dishonest.
Second, science itself is often misunderstood. Scientists tend to be portrayed as voices of authority who are able to reveal truths about arcane problems, be it the nature of quarks or the molecular basis of ageing. In fact, science is almost the opposite of this. In The Trouble With Physics, physicist Lee Smolin considers how to describe science and concludes that Nobel Prize winner Richard Feyman’s phrase says it best: “Science is the organised scepticism in the reliability of expert opinion.”
An Oxford colleague, one of the world’s top climate scientists, made the same point last week when he said to me: “It’s odd that people talk about ‘climate sceptics’ as though they are a special category. All of us in the climate science community are climate sceptics. It’s our job to question and challenge everything.” Any scientist will tell you that when you turn up at a conference the audience will do its best to tear your findings to pieces: no one takes anything for granted.
This philosophy of science was formally instituted 350 years ago in London by the small band of men, including Christopher Wren and Robert Boyle, who founded the Royal Society, the world’s oldest national academy of science. Their motto, Nullius in verba (“Take nobody’s word for it”) embodies the Royal Society’s founding principle of basing conclusions on observation and experiment rather than the voice of authority. Scientists don’t have all the answers, but they do have a way of finding out, and the fact that our lights come on, our computers compute and our mobile phones phone are among the myriad daily reminders that the scientific way works.
You might retort that science and scientists often don’t live up to this ideal. And you would be right. Scientists, like everyone else, have human frailties and are susceptible to fashion and orthodoxy. Nevertheless, over time, science is self-correcting because someone will have the courage to challenge the prevailing view and win the argument, provided he or she has sufficient evidence.
There is, of course, no excuse for scientists who over-egg or massage their results, or who underplay the uncertainties in their conclusions. The prevailing view in many areas of science will include significant uncertainties (as with climate change), so challenge is central to the progress of understanding. The claim that Himalayan glaciers would melt in the next 30 years is an example of this self-correction. It was debunked from within the scientific community and not by outside commentators, it does not undermine the core conclusions about man-made global warming, and the mistake that the Chairman of the Intergovernmental Panel on Climate Change made was to dismiss this challenge without studying the evidence.
Scepticism is fine but science is not a free-for-all. Whether or not you accept the sceptics’ view should depend on careful weighing of the evidence. Dr Wakefield had no good evidence to support his claim of a link between the MMR vaccine and autism. Equally, the Department of Health’s claim that the “MMR vaccine is perfectly safe” is wrong. No vaccine is perfectly safe, but not vaccinating your children exposes them to a far bigger risk than the tiny risk associated with the vaccine.
Given what I have said, it is not surprising that the interaction between science and government can be edgy. Ministers look to their expert advisers for clear-cut answers, a unanimous view, and preferably one that is politically convenient. Scientific advisers are prone to disappoint on all fronts. “I am sorry minister, but science is not clear-cut, what is more, different experts take a different view, and our best advice is to do X” (where X is not a vote winner). When I was asked to advise, in 1996, on whether or not to kill badgers as a way of controlling bovine tuberculosis, I said that without a proper experiment it is not possible to tell whether or not the policy would work. To its credit, the Ministry of Agriculture set up what was perhaps the largest ecological experiment ever carried out in this country. The result showed that killing is not a cost-effective policy, and disappointed farmers.
Last year David Nutt, Chairman of the Advisory Committee on the Misuse of Drugs, was sacked by the Home Secretary for being too outspoken about the Government’s rejection of his committee’s advice on the classification of cannabis and Ecstasy. If ministers are going to reject expert advice, they should explain why. What they should definitely not do, as both the Prime Minister and the Home Secretary did in this case, is to announce, before they have received the expert advice, that they have made up their mind.
Equally, independent experts should not be gagged by ministers, even if their views are inconvenient. Science, warts and all, is still the best way of finding out, and is absolutely vital in informing government policy. That is why the Government must strongly reaffirm its commitment to freedom of expression for independent scientific advisers. At the same time, if scientists have a right to be heard, they have a responsibility to be scrupulously honest and not to claim more than is justified by the evidence.
Lord Krebs is Principal of Jesus College, Oxford