Genetic Fallacy

Genetic Fallacy

Rejecting (or accepting) something solely on the basis of its origin, without looking at meaning or context. This ignores the fact that even a less credible source is sometimes, or can be, right. Alternately, that a more credible source is sometimes, or can be, wrong.

This is seen in any case where a source is either highly disparaged or esteemed. Sources will commonly be accepted or dismissed out of hand without looking into the actual validity of their facts or arguments.


The ur-example is perhaps Dr. Peter Duesberg. An oncologist at UC Berkeley, he became best known for claiming starting in 1987 that HIV did not cause AIDS, but that it was the result of recreational and or/antiretroviral drug use, with HIV being only a "harmless" passenger virus. Outrage predictably followed, and Duesberg quickly fell from grace. Worse, this view had a major influence on South African President Thabo Mbeki, who failed to provide antiretroviral drugs to AIDS victims (Duesberg claimed such drugs in fact caused AIDS rather than treating it), resulting in hundreds of thousands of preventable deaths. However... Duesberg had discovered a gene that helps cause cancer in 1970, which he continued to conduct research on in the intervening years, including when he was involved with the AIDS controversy. As he was so ostracized and discredited, most of his research was not even read. Ironically, it has potential to save millions of more lives than the deaths his AIDS denialism contributed to. He demonstrates both sides of the fallacy, as many people believed his AIDS denialist theory due to his scientific credentials, while conversely other scientists did not read his work due to that same theory.
  • Stephen Colbert uses quite a few of these. For example, in his June 14, 2012 show, he pointed out that a medication was created by adapting an enzyme used by gangrene-causing (Clostridium spp.) bacteria to tear apart tissues. Of course, this is intentional as he is a comedian.
  • Back to the Future Part III offers two examples of this back to back. Marty and Doc are examining a broken part that was made in Japan. Doc, from the 1950's, commits the first genetic fallacy. He says something like, "No wonder it broke; it was made in Japan." Marty, from the 1980's, counters that all the best stuff comes from Japan. Both are reflecting the views of their respective eras. Doc is obviously committing this fallacy, while Marty flirts with it by implying that the part must be good because it came from Japan.

Looks like this fallacy but is not:

  • When a factual claim is rejected because the sole source of the claim is known to be unreliable. A man who suffers from frequent hallucinations could not be relied upon to accurately report observations of the physical world, for example. Rejecting the claim because it was made by a delusional man would be a Genetic Fallacy, as the man may not have been hallucinating when he made the observation, or even if he did hallucinate, the claim may still be true. But simply saying that the hallucinating man cannot offer useful testimony one way or the other is not this fallacy.
  • When evidence or data must be ignored because it was acquired through illegal or immoral methods. This is the classic "fruit of the poisoned tree." However, this is a legal or scientific standard regarding what evidence can be admitted; it has nothing to do with its truth or falsity. Indeed, the evidence can be completely true but illegally or unethically obtained and thus unusable. The law takes this a good bit more seriously than science; the law is concerned primarily with justice, and an injustice committed in the means by which evidence is discovered may mar any attempt to achieve justice at trial. In science, the paramount virtue is truth, and so evidence acquired unethically or immorally will be accepted so long as it had sufficient controls to guarantee its reliability, but the experiment will not be repeated. The greatest examples are probably the research and significant advances based on Nazi experiments into hypothermia conducted on Holocaust victims, the Japanese experiments by Unit 731 into the effects of biological and chemical weapons, and the Tuskegee Experiment conducted in the United States on black men concerning the long-term effects of untreated syphilis. None of these experiments were ever repeated, but the resultant data was built upon for later, more ethical inquiries.