editorial Debunking science denialism Science denialism causes greater harm when left unchallenged. An article in this issue provides evidence for efective rebuttal strategies.

hambo Mbeki, South Africa’s The finding that leaving denialist president between 1999 and 2008, arguments unchallenged has a negative Tbecame infamous for his denial of impact on audiences is particularly the link between HIV and AIDS. Despite important in the current socio-political overwhelming scientific consensus that environment. Although traditionally HIV causes AIDS, he suggested instead science denialism takes on a mantle that the causes of AIDS are poverty-related of pseudoscience, we are witnessing and due to poor nourishment and overall a transformation of public discourse, ill-health. He instituted policies that denied where denialist claims may be entirely antiretroviral drugs to AIDS patients. divorced from a semblance of logic or Instead, his appointed health minister, Manto evidence. It is tempting not to engage Tshabalala-Msimang, recommended garlic, rationally with outlandish denialist beetroot, and lemon juice as treatments for claims, for fear of legitimizing them or AIDS. In a country with the highest HIV Credit: Science Photo Library / Alamy Stock Photo backfiring. In a much discussed example, prevalence worldwide in absolute numbers, Donald Trump tweeted in 2012, “The these policies had disastrous consequences: concept of global warming was created they are estimated to have led to more than by and for the Chinese in order to make 330,000 preventable deaths. the effectiveness of different strategies U.S. manufacturing non-competitive” Science denialism, the rejection of for rebutting science denialism in public (https://twitter.com/realdonaldtrump/ empirically supported propositions discussions on vaccination and climate status/265895292191248385?). The claim despite scientific consensus and the change (https://www.nature.com/articles/ has been retweeted nearly 100 million effort to create the appearance of s41562-019-0632-4). The results of this times and generated thousands of responses. debate when there is none, is not a new work are engagingly described and put The vast majority of these responses phenomenon—think of the Galileo affair into context in an accompanying News & were emotional, whereas fact-based in the 17th century. Surprisingly for most, Views by van der Linden (https://www. rebuttals among those who responded flat-earth beliefs persist well into the 21st nature.com/articles/s41562-019-0631-5). were a slim minority. century. Although flat-earthers may pose A key finding to emerge from this work However, allowing false scientific claims, little risk to humanity and the environment, is that not responding to denialism does no matter how absurd, to float unchallenged the denial of anthropogenic climate change, more harm than good. The authors found by evidence or logic, is worse than engaging the refusal to accept the link between that the negative effect of science denial with them, Schmid and Betsch’s research smoking and lung cancer or HIV and AIDS, on audiences was greater when there was suggests. Their work highlights how vaccine hesitancy, and other denialist claims no science advocate to rebut the claims. important it is to invest in the development have had and continue to have devastating When a science advocate rebutted denialist of a strong body of science-advocacy consequences. How to effectively respond arguments, either by presenting scientific strategies and to patiently persevere in to science denialism, however, is an issue facts or by exposing the logical flaws of the exposing the factual and logical flaws of that scientists and science advocates are arguments, the effects of denialism were even the most absurd denialist claims. ❐ still grappling with. significantly reduced, even among audiences An article in this issue of Nature Human whose beliefs or ideologies are threatened by Published online: 12 September 2019 Behaviour by Schmid and Betsch examines the science advocate. https://doi.org/10.1038/s41562-019-0746-8

Nature Human Behaviour | VOL 3 | SEPTEMBER 2019 | 887 | www.nature.com/nathumbehav 887