PETA (People for the Ethical Treatment of Animals) has a history of (as the old saying goes) using science as a drunk uses a lamppost – for support rather than illumination. In that way they are typical of ideological groups. They have an agenda, they are very open about their beliefs, and they marshal whatever arguments they can in order to promote their point of view.
Favoring information that supports our current beliefs is a cognitive bias common to Homo sapiens, but ideology tends to take this simple bias to a new level. It can lead to the systematic distortion or denial of science, and render belief systems immune to logic and evidence.
PETA provides us with a nice example of how having an ideological agenda can motivate an individual or a group to embrace dubious science. In an article currently on their website, and making the rounds in social media (this is repeating a claim from at least 2008, but the current article is undated), the group warns: Got Autism? Learn About the Link Between Dairy Products and the Disease. They claim:
The reason why dairy foods may worsen or even cause autism is being debated. Some suspect that casein harms the brain, while others suggest that the gastrointestinal problems so often caused by dairy products cause distress and thus worsen behavior in autistic children.
Saying that “how” dairy harms the brain is being debated implies “that” dairy harms the brain is accepted and not being debated. This is misleading. It is not accepted that dairy harms the brain or is in any way linked to autism, and the evidence is largely against it. (more…)