Scientists and science organizations increasingly use petitions to influence public opinion and government decisions, and the practice is now spilling over into peer-reviewed journals. We question the effectiveness of public petitions, and suggest that ganging up against unpopular research risks damaging scientific discourse.

Petitioners recruit researchers as co-signatories to reinforce their argument, often for people who may not fully understand the debate. Last year, for example, 31,000 scientists signed a petition rejecting the idea of global warming ( — but a counter-petition with 31,001 signatures won't resolve the debate. Numbers and scientific argument generally have little influence on public opinion or political decisions (D. Ding et al. Nature Clim. Change 1, 462–466; 2011), partly because of the difficulty in assessing the authority of individual co-signatories.

'Gang science' is being used to quash unpopular ideas in peer-reviewed journals. For example, 141 scientists mounted an attack on proposals for managing introduced species (D. Simberloff et al. Nature 475, 36; 2011), and 137 others challenged a paper written by three authors on the evolution of eusociality (P. Abbot et al. Nature 471, E1–E4; 2011). In the absence of new data, such huge conglomerates contribute little more than intimidation.

We should judge the validity of scientific ideas on hard, replicable data and not on the number of authors. Otherwise, scientists risk being branded as another advocacy group with its own agenda.