The UK government's chief scientist, John Beddington, has done much to promote the potential of science to address pressing global imperatives. But in a straight-talking speech last month, he urged his audience of 300 government scientists to be “grossly intolerant” of “pernicious” and “fatuous” “pseudoscience”. In this he included: scepticism of genetic modification technology; “illegitimate” advocacy of environmental precaution in response to unknowns; and suggestions that science is subject to morality. This approach is a rejection not just of irrational denial but of entirely reasonable social scepticism concerning science itself.

It is ironic that defence of scientific rationality is often so emotive. Science does not monopolize social rationality. Although imperfectly realized, the principal distinctions between science and, say religion, politics, commerce or the media are arguably social practices of organized scepticism. Open publication, peer review, experimentation and critical respect for evidence help promote reasoned argument. But rational scepticism is as important outside as inside the social practices of science. Hence the motto of Britain's Royal Society, 'Nullius in verba': take nothing solely on authority — even from scientists.

Suppression of rational scepticism of science is also potentially undemocratic. Allocation of research priorities depends on contending interests and values. Technologies are partly shaped by social and political factors, not simply determined by unfolding knowledge. Economic, institutional, military and political pressures help to drive world science in particular directions. The internal dynamics of disciplines and universities are not immune to personality, privilege, prejudice or power. Intrinsic scientific uncertainties underscore the role of democratic debate.

Inhibiting reasonable social questioning of science can foster disingenuity, polarization and untrustworthiness. The progressive social potential of science is therefore supported, not hindered, by greater political tolerance for scepticism.