Denialism: what is it and how should scientists respond?

Excerpts from the article “Denialism: what is it and how should scientists respond?” by Pascal Diethelm, OxyGene`ve, Geneva, Switzerland and Martin McKee, London School of Hygiene and Tropical Medicine published in European Journal of Public Health, Vol. 19, 2009.

Black is white and white is black
HIV does not cause AIDS. The world was created in 4004 BCE. Smoking does not cause cancer. And if climate change is happening, it is nothing to do with man-made CO2 emissions. Few, if any, of the readers of this journal will believe any of these statements. Yet each can be found easily in the mass media.

The consequences of policies based on views such as these can be fatal. Thabo Mbeki’s denial that HIV caused AIDS prevented thousands of HIV positive mothers in South Africa receiving anti-retrovirals so that they, unnecessarily, transmitted the disease to their children. His health minister, Manto Tshabalala-Msimang, famously rejected evidence of the efficacy of these drugs, instead advocating treatment with garlic, beetroot and African potato. It was ironic that their departure from office coincided with the award of the Nobel Prize to Luc Montagnier and Francoise Barre´-Sinoussi for their discovery that HIV is indeed the cause of AIDS.

The rejection of scientific evidence is also apparent in the popularity of creationism, with an estimated 45% of Americans in 2004 believing that God created man in his present form within the past 10 000 years. While successive judgements of the US Supreme Court have rejected the teaching of creationism as science, many American schools are cautious about discussing evolution. In the United Kingdom, some faithbased schools teach evolution and creationism as equally valid ‘faith positions’. It remains unclear how they explain the emergence of antibiotic resistance. Elsewhere, the hand of powerful corporate interests can be seen. It took many decades for the conclusions of authoritative reports by the US Surgeon General and the British Royal College of Physicians on the harmful effects of smoking to be accepted, while even now, despite clear evidence of rapid reductions in myocardial infarctions where bans have been implemented, there are some who deny that second-hand smoke is dangerous. In large part this was due to the efforts of the tobacco industry to deflect attention to other putative causes of smoking-related diseases, from stress to keeping pet birds. The reports of the Intergovernmental Panel on Climate Change have suffered similar attacks from commentators with links to major oil companies.

All of these examples have one feature in common. There is an overwhelming consensus on the evidence among scientists yet there are also vocal commentators who reject this consensus, convincing many of the public, and often the media too, that the consensus is not based on ‘sound science’ or denying that there is a consensus by exhibiting individual dissenting voices as the ultimate authorities on the topic in question. Their goal is to convince that there are sufficient grounds to reject the case for taking action to tackle threats to health. This phenomenon has led some to draw a historical parallel with the holocaust, another area where the evidence is overwhelming but where a few commentators have continued to sow doubt. All are seen as part of a larger phenomenon of denialism.

Defining and recognizing denialism
The Hoofnagle brothers, a lawyer and a physiologist from the United States, who have done much to develop the concept of denialism, have defined it as the employment of rhetorical arguments to give the appearance of legitimate debate where there is none, an approach that has the ultimate goal of rejecting a proposition on which a scientific consensus exists. In this viewpoint, we argue that public health scientists should be aware of the features of denialism and be able to recognize and confront it.

Denialism is a process that employs some or all of five characteristic elements in a concerted way. The first is the identification of conspiracies. When the overwhelming body of scientific opinion believes that something is true, it is argued that this is not because those scientists have independently studied the evidence and reached the same conclusion. It is because they have engaged in a complex and secretive conspiracy. The peer review process is seen as a tool by which the conspirators suppress dissent, rather than as a means of weeding out papers and grant applications unsupported by evidence or lacking logical thought. The view of General Jack D Ripper that fluoridation was a Soviet plot to poison American drinking water in Dr Strangelove, Kubrick’s black comedy about the Cold War is no less bizarre than those expressed in many of the websites that oppose this measure.

In some cases, denialism exploits genuine concerns, such as the rejection of evidence on the nature of AIDS by African-Americans who perceive them as a manifestation of racist agendas. While conspiracy theories cannot simply be dismissed because conspiracies do occur, it beggars belief that they can encompass entire scientific communities.

There is also a variant of conspiracy theory, inversionism, in which some of one’s own characteristics and motivations are attributed to others. For example, tobacco companies describe academic research into the health effects of smoking as the product of an ‘anti-smoking industry’, described as ‘a vertically integrated, highly concentrated, oligopolistic cartel, combined with some public monopolies’ whose aim is to ‘manufacture alleged evidence, suggestive inferences linking smoking to various diseases and publicity and dissemination and advertising of these so-called findings to the widest possible public’.

Responding to denialism
Denialists are driven by a range of motivations. For some it is greed, lured by the corporate largesse of the oil and tobacco industries. For others it is ideology or faith, causing them to reject anything incompatible with their fundamental beliefs. Finally there is eccentricity and idiosyncrasy, sometimes encouraged by the celebrity status conferred on the maverick by the media.

Whatever the motivation, it is important to recognize denialism when confronted with it. The normal academic response to an opposing argument is to engage with it, testing the strengths and weaknesses of the differing views, in the expectations that the truth will emerge through a process of debate. However, this requires that both parties obey certain ground rules, such as a willingness to look at the evidence as a whole, to reject deliberate distortions and to accept principles of logic. A meaningful discourse is impossible when one party rejects these rules. Yet it would be wrong to prevent the denialists having a voice. Instead, we argue, it is necessary to shift the debate from the subject under consideration, instead exposing to public scrutiny the tactics they employ and identifying them publicly for what they are. An understanding of the five tactics listed above provides a useful framework for doing so.