ABSTRACT
The prospect of global climate change has prompted a remarkable mobilization of the scientific community. That effort typically has sought a politically neutral science-estimating the impacts that might matter to members of various publics, then letting them decide what to do. Some scientists, though, have been not just messengers but also advocates for the implications of climate science. Most of these scientists stress the expected severity of the impacts. A few downplay the problem. Most volunteer their time and energy, hoping to help others see the science as they do. Such advocacy makes many scientists uncomfortable. Of course, science itself entails advocacy, as researchers make the case for the importance of their studies, the soundness of their methods, and the robustness of their results. However, that advocacy follows the familiar norms of the scientific community. Those norms compel scientists to, for example, identify uncertainties, consider all data (and not just supporting evidence), and update their beliefs as new evidence arrives. Public advocacy, however, follows the norms of politics. Claims should be based on fact. However, they need not include all the facts. Evidence is assembled to make a case, not to provide a full picture-let the other side provide what is missing. Uncertainty is avoided-let observers infer it from the clash of certain views. Positions are defended, come what may. Scientists typically resort to public advocacy after concluding that, without it, the science will not get a fair hearing. One way or another, the public is blamed for this failure. It might be blamed directly, for not understanding the science, or indirectly, for falling prey to the other side’s advocates, who exploit its scientific illiteracy. Such advocacy runs the risk of winning battles over what science says, while losing the war over what science is.
