It's dangerous to ignore it

Recently Alan Johnson went all Alan Sugar on his chief drugs adviser, David Nutt. But barely had the words "you're fired" left his mouth than the whole thing started to implode in the most unpleasant way for the Home Secretary. Scientists, it would appear, are harder to herd than cats, and their evidence is not so straightforwardly ignored as he might have previously hoped or imagined.

Let's start with three useless facts. A group of 12 or more cows is called a flink, most toilets flush in E flat and ecstasy is no more dangerous than horse riding. What does that last one really mean to anyone? If I had been planning on taking my trusty steed hacking all weekend, can I now instead choose to go clubbing for 48 hours, dropping disco biscuits like they were Smarties, and treat that as an equivalent risk? And yes, I know that Professor Nutt's original paper, published earlier this year, was more nuanced than this. But let's face it: the vast majority of people who choose to use ecstasy rely on newspapers rather than the peer-reviewed literature for their information.

It was the horse riding and ecstasy factoid, and other more recent comments by Professor Nutt about the relative risks of cannabis, alcohol and tobacco, that contributed to his dismissal. One could argue that soundbites of this type in the media are successful in fanning the flame of public debate but do little to genuinely inform it. One could argue further that a seasoned para-politician such as Professor Nutt should know better; that these sorts of stories feed into a press conference like a leg of lamb into a piranha tank. But these acts should not have earned him early sight of his P45.

The second comment, about cannabis and alcohol, appeared to be in part an expression of Professor Nutt's frustration at having made recommendations, based on carefully synthesised lines of scientific evidence, only to see them roundly and repeatedly ignored. The only sackable offence, then, is that committed by the Government, in commissioning independent scientific advice and ignoring the evidence when the truths suddenly appear a little inconvenient.

Politicians are keen to extol the virtues of evidence-based policymaking. This is to be encouraged; the idea that we are governed by policy distilled from objective lines of inquiry should make us all feel warm and cosy. Such an approach reassures the public and lends credence to policy decisions. But the selective and sometimes disingenuous use of evidence does precisely the opposite, and it is of this crime that the Government currently stands accused.

When it comes to issues of policy, the evidence is sometimes incomplete or non-existent; and it is here that there may be room for interpretation and interpolation. Sometimes politicians are expected to earn their pay by making the best call they can, given the available information, and in these circumstances opinion may legitimately conflict with weaker lines of evidence.

But scientific evidence is of a different and higher standard, which is a fact that generations of politicians have repeatedly failed to either understand or accept. In the scientists' vocabulary, the word "proof" is used with great caution, and where political opinion collides with well-sourced scientific evidence, the former must give way.

Failure to do so has grave consequences. And these extend to more than the acute political embarrassment that ensues when it becomes clear that you're the sort of minister who doesn't let a little thing like evidence get in the way of your opinion. Professor Nutt and the Home Secretary have found themselves embroiled in a battle fought over scientific advice and its role in shaping our drugs policy. But if we create a society in which policymakers are at liberty to discard scientific evidence whenever it doesn't suit, there are entire wars that stand ready to be lost. After all, it is arguably the "Armada? What Armada?" attitude to decades of scientific evidence regarding global warming that has left us in the sorry state of potential global catastrophe that we're in today.

There is a move to formally restate the principles that govern the independence of scientists advising government. The Royal Society has begun to pull together new guidelines to protect the independence of advisers offering scientific evidence to inform policy. This is to be welcomed. Recent government moves have eroded the autonomy of science in the academy, and it is time science hardened its stance and fought back.

We've been here before, of course. In 2006, the House of Commons Select Committee on Science and Technology conducted an investigation into scientific advice, risk and evidence-based policymaking. This inquiry recommended that the Government should not overplay the "evidence-based policy" card but rather acknowledge more openly the myriad factors that drive policy. It also called for "a general recognition that changing policy in the light of evidence should be regarded as a strength rather than a weakness".

But quoting evidence lends strength to political argument and none more so than scientific evidence from independently commissioned advisers. Hooked on this drug, the Government has apparently failed to heed the advice either of its science advisers or its select committee; and that, as some have recently discovered to their cost, is something that really is more dangerous than horse riding.