Hugh Pennington: Scientists – 'on tap but never on top'

Scientists who advise Government swim in shark-infested waters, as Professor Nutt's fate proves. But it was ever thus. The semi-independent inspectors used by the first chief medical officer, John Simon, were such sanitary enthusiasts that in 1871 they were castigated by the Secretary to the Treasury for "unlimited missionary activity". Simon eventually resigned.

The Times said: "There is obviously no place for Mr Simon under a government, by which science is held to be superfluous except ... as a reserve force for the rectification of blunders, or as a means of securing in an imposing manner the door of a stable from which the steed has already been stolen."

Today the influence of science on policy is enormous. But how many of our elected members understand double differential equations, or the forces that drive the climate, or the genome structure of influenza viruses? The politician needs scientists as never before. For many the call will come to join an advisory committee. But beware. The Harvard academic Don K Price identified the big problem in his 1954 book Government and Science. He described the British civil service as "a profoundly conservative force – not in the sense of being opposed to left-wing economics but in the sense of looking on the Government and its programme as a single coherent machine in which inconsistencies cannot be permitted. Any novel idea is an inconsistency that could cause temporary waste and disorder and inefficiency".

He also identified the limits of scientific advice: "Scientific methods are the most useful in determining how a specific thing is to be done; the more precise the thing, the more precise the determination. They are less often and less immediately useful in determining whether or when such things are to be done and how much effort or money is to be spent on them. But these are the controlling decisions, the decisions that must be made in the upper levels of the hierarchy if a government is to have any unity of purpose or action."

The Government uses scientists not just as sources of information – when they are on tap but not on top – but also to "depoliticise" its actions (this is when "the science" is invoked as the policy justification). Gongs await the safe pairs of hands. But to change policy, a scientist has to become a practitioner of politics without being identified as one. Clearly, this is not easy.

Hugh Pennington is an emeritus professor of bacteriology at the University of Aberdeen. He chaired the public inquiry into the 2005 South Wales E. Coli outbreak