Michael Shermer goes after climate denial, evolution denial, Holocaust denial, AIDS denial, 9/11 denial, vaccine denial, and tobacco denial:

Scepticism is integral to the scientific process, because most claims turn out to be false. Weeding out the few kernels of wheat from the large pile of chaff requires extensive observation, careful experimentation and cautious inference. Science is scepticism and good scientists are sceptical.

Denial is different. It is the automatic gainsaying of a claim regardless of the evidence for it - sometimes even in the teeth of evidence. Denialism is typically driven by ideology or religious belief, where the commitment to the belief takes precedence over the evidence. Belief comes first, reasons for belief follow, and those reasons are winnowed to ensure that the belief survives intact.

Ronald Bailey adds biotech crop denialism, drug war denialism, and market denialism to the list. Debora MacKenzie also explores the subject:

[O]ther denialisms suggest psychology, not just ideology, is crucial. There is no obvious connection between conservatism and vaccine or AIDS denial, and flu denial was promulgated by a left-leaning group suspicious of the vaccine industry.

Nevertheless, some connections exist that hint at a wider agenda. For example, there is considerable overlap in membership between the vaccine and HIV deniers, says John Moore, an AIDS researcher at Weill Cornell Medical College in New York. Both movements have massive but mysterious funding.

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