The 5 characteristics of scientific denialism

A fascinating paper well worth reading is Denialism: what is it and how should scientists respond? (Diethelm & McKee 2009) (H/T to Jeremy Kemp for the heads-up). While the focus is on public health issues, it nevertheless establishes some useful general principles on the phenomenon of scientific denialism. A vivid example is the President of South Africa, Thabo Mbeki, who argued against the scientific consensus that HIV caused AIDS. This led to policies preventing thousands of HIV positive mothers in South Africa from receiving anti-retrovirals. It's estimated these policies led to the loss of more than 330,000 lives (Chigwedere 2008). Clearly the consequences of denying science can be dire, even fatal. 

The authors define denialism 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". They go on to identify 5 characteristics common to most forms of denialism, first suggested by Mark and Chris Hoofnagle:

  1. Conspiracy theories
    When the overwhelming body of scientific opinion believes something is true, the denialist won't admit scientists have independently studied the evidence to reach the same conclusion. Instead, they claim scientists are engaged in a complex and secretive conspiracy. The South African government of Thabo Mbeki was heavily influenced by conspiracy theorists claiming that HIV was not the cause of AIDS. When such fringe groups gain the ear of policy makers who cease to base their decisions on science-based evidence, the human impact can be disastrous.
  2. Fake experts
    These are individuals purporting to be experts but whose views are inconsistent with established knowledge. Fake experts have been used extensively by the tobacco industry who developed a strategy to recruit scientists who would counteract the growing evidence on the harmful effects of second-hand smoke. This tactic is often complemented by denigration of established experts, seeking to discredit their work. Tobacco denialists have frequently attacked Stanton Glantz, professor of medicine at the University of California, for his exposure of tobacco industry tactics, labelling his research 'junk science'.
  3. Cherry picking
    This involves selectively drawing on isolated papers that challenge the consensus to the neglect of the broader body of research. An example is a paper describing intestinal abnormalities in 12 children with autism, which suggested a possible link with immunization. This has been used extensively by campaigners against immunization, even though 10 of the paper’s 13 authors subsequently retracted the suggestion of an association.
  4. Impossible expectations of what research can deliver
    The tobacco company Philip Morris tried to promote a new standard for the conduct of epidemiological studies. These stricter guidelines would have invalidated in one sweep a large body of research on the health effects of cigarettes.
  5. Misrepresentation and logical fallacies
    Logical fallacies include the use of straw men, where the opposing argument is misrepresented, making it easier to refute. For example, the US Environmental Protection Agency (EPA) determined in 1992 that environmental tobacco smoke was carcinogenic. This was attacked as nothing less than a 'threat to the very core of democratic values and democratic public policy'.

Why is it important to define the tactics of denialism? Good faith discussion requires consideration of the full body of scientific evidence. This is difficult when confronted with rhetorical techniques which are designed to distort and distract. Identifying and publicly exposing these tactics are the first step in redirecting discussion back to a focus on the science.

This is not to say all global warming skeptic arguments employ denialist tactics. And it's certainly not advocating attacking peoples' motives. On the contrary, in most cases, focus on motives rather than methods is counterproductive. Here are some of the methods using denialist tactics in the climate debate: 

  1. Conspiracy theories
    Conspiracy theories have been growing in strength in recent months as personal attacks on climate scientists have intensified. In particular, there has been accusations of manipulation of temperature data with the result that "the surface temperature record is unreliable" has been the most popular argument over the last month. This is distracting people from the physical realities of global warming manifesting themselves all over the world. Arctic sea-ice loss is accelerating. Antarctic and Greenland ice sheets are losing ice mass at an accelerating rate. Spring is coming earlier each year. Animal breeding and migration are changing in response. Distribution of plants are shifting to higher elevations. Global sea level is rising. When one steps back to take in the full body of evidence, it overwhelmingly points to global warming.
  2. Fake experts
    A number of surveys and petitions have been published online, presenting lengthy numbers of scientists who reject man-made global warming. Close inspection of these lists show very few qualifications in climate science. On the contrary, a survey of climate scientists who actively publish climate research found that over 97% agree that human activity is significantly changing global temperature.
  3. Cherry picking
    This usually involves a focus on a single paper to the neglect of the rest of peer-review research. A recent example is the Lindzen-Choi paper that finds low climate sensitivity (around 0.5°C for doubled CO2). This neglects all the research using independent techniques studying different time periods that find our climate has high sensitivity (around 3°C for doubled CO2). This includes research using a similar approach to Lindzen-Choi but with more global coverage.
  4. Impossible expectations
    The uncertainties of climate models are often used as an excuse to reject any understanding that can come from climate models. Or worse, the uncertainty of climate models are used to reject all evidence of man-made global warming. This neglects the fact that there are multiple lines of empirical evidence that humans are causing global warming .
  5. Logical fallacies
    Strawmen arguments abound in the climate debate. Often have I heard skeptics argue "CO2 is not the only driver of climate" which every climate scientist in the world would wholeheartedly agree with. A consideration of all the evidence tells us there are a number of factors that drive climate but currently, CO2 is the dominant forcing and also the fastest rising. Logical fallacies such as "climate has changed before therefore current climate change must be natural" are the equivalent of arguing that lightning has started bushfires in the past, therefore no modern bushfire is ever started by arsonists.

Update 16 April 2012: Many thanks to Mark Hoofnagle for pointing out that the 5 characteristics of science denial didn't originate in Diethelm and McKee's paper but in an article written by Mark and Chris Hoofnagle. This is an article very worth reading for anyone interested in climate change and public discourse about science. Credit has been updated accordingly.

Posted by John Cook on Wednesday, 17 March, 2010

Creative Commons License The Skeptical Science website by Skeptical Science is licensed under a Creative Commons Attribution 3.0 Unported License.