Sir

We read with some concern the views of M. J. Hsu and G. Agoramoorthy in Correspondence, that “Scientists and teachers should ignore politics” (Nature 431, 627; 200410.1038/431627c). They argue that scientists help society most effectively through teaching and research, rather than by taking part in election campaigns. In the current political climate in the United States, this well-intentioned argument represents a grave threat to both science and society.

The politicization of science threatens to undermine the value of science to society by obscuring scientific consensus and misleading policy-makers and the public. Although the threat is external — and most apparent in the suppression and manipulation of science by the Bush administration — the resolution is largely internal. More than 5,500 scientists have signed the Union of Concerned Scientists' statement of protest, and more than 1,800 environmental scientists have signed a separate statement at http://www.scienceinpolicy.org. But it will take a greater outcry from the scientific community to bring this issue to the prominence it deserves. Scientists must step forward to protest against the manipulation of their results, or the obfuscation of accepted science will become an enduring tactic in political manoeuvring.

Already, scientific information is often clouded in the public arena. Evidence from competing expert witnesses in court cases, for example, makes it difficult for juries to decipher scientific evidence.

Attempts at journalistic balance similarly give equal weight to ideas that have unequal scientific support. This practice — which is neither good journalism nor an effective presentation of scientific knowledge — often creates the misconception that there is serious scientific debate about a particular issue when, in reality, there is virtually none.

For example, journalists gave roughly equal attention to the views of isolated scientists, including those funded by stakeholding industries, long after the wider scientific community reached consensus over the health threat posed by smoking and over the likelihood of human-induced climate change. In the former case, outcry from physicians and scientists finally penetrated the disinformation campaign by the tobacco industry (to society's great benefit). Yet in the climate-change arena, the naysayers still have a significant voice despite the consensus against them.

Politicians increasingly employ a similar misrepresentation of science in public policy debates. If such manipulation is allowed to continue, scientists' constructive provision of unbiased, realistic assessments to policy-makers will be compromised.

Unfortunately, calling on scientists to defend their work from political manipulation bumps squarely against a deep reluctance among scientists to appear partisan. After all, the impartiality of science is largely responsible for the confidence most Americans have in scientific information. Scientists are legitimately concerned that advocacy may undermine the public perception that scientists are relatively apolitical and concerned primarily with facts. But what use is a voice that is held in high esteem but never raised?

We argue that the current assault on science sufficiently threatens the role of science in society to merit the risk of speaking out. Advocacy is less dangerous than sitting quietly on the sidelines while politicians and interest groups undermine the scientific method by perpetrating junk science.