What is the name of the fallacy where one implies something is false simply because someone evil supported it?

Question

Creationists sometimes argue that Darwinism is wrong because the Nazis used it as a rationale for their eugenics program.

We call it a "genetic fallacy" if we try to claim that a theory is wrong because the person who discovered it was evil or unworthy. The theory has to be judged on its own without regard to who or what discovered it.

In this case the Nazis did not discover evolution, but (by many accounts) picked it up and adopted it as the truth, and possibly even employed its principles.

Just because Hitler liked it does not in any way imply that the theory is wrong. This might be a red herring because it is simply immaterial to whether evolution is true or not. But it seems that this is a special way of insinuating that something is evil because it was adopted and used by something or someone evil. It is a kind of "sin by association"

I looked through a couple of lists of fallacies and did not find one that captured this idea.

Answer 1

One might view this fallacy as guilt by association or ad hominem. Here is how Bo Bennett describes it:

When the source is viewed negatively because of its association with another person or group who is already viewed negatively.

Bennett notes a potential exception if one can demonstrate that the "association is causally linked, or the probability of taking on a characteristic would be high, then it would be valid".

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Bennett, B. "Ad Hominem (Guilt by Association)" Retrieved from Logically Fallacious on May 2, 2019 at https://www.logicallyfallacious.com/tools/lp/Bo/LogicalFallacies/10/Ad-Hominem-Guilt-by-Association

Answer 2

What is the name of the fallacy where one implies something is false simply because someone evil supported it?

I would add the fallacy of appeal to authority; here, however, the appeal is inverted. The argument is not that Darwinism is defensible because of authority; rather, it is indefensible because of negative authority.

The appeal to authority is

Insisting that a claim is true simply because a valid authority or expert on the issue said it was true, without any other supporting evidence offered. [Logically Fallacious > Appeal to Authority]

Here is the same definition, modified for purposes of this answer:

Insisting that a claim is false simply because an invalid authority or expert on the issue said it was true...

That fallacy describes the Darwinism/Nazism argument.

Answer 3

Pinning down the fallacy

For the reason you give, the genetic fallacy is not at work here - alone or in combination - since that fallacy concerns the origin of an idea, theory or argument. The Nazis did not originate the idea of evolution in any of its protean forms.

But they used the idea. Or may have done - some doubts are aired in the second part of the answer.

I should call the case in question one of argument - 'refutation' - by false or misleading association. The behaviour of the Nazis is irrelevant to the truth or otherwise of Darwin's theory : abusus non tollit usum - misuse does not prove that there is no proper use. Use - or attribution of the use - of the theory by a particular group in pursuit of a particular policy at a particular time has nothing to do with the cogency and coherence of the theory.

But were the Nazis Darwinians ?

For the record - the Nazis and evolution

... the Nazis did not discover evolution, but (by many accounts) picked it up and adopted it as the truth, and possibly even employed its principles.

The topic is complex and contentious, as shown by this passage :

Many historians recognize that Hitler was a social Darwinist, and some even portray social Darwinism as a central element of Nazi ideology. Why, then, do some historians claim that Nazis did not believe in human evolution? George Mosse argued that human evolution was incompatible with Nazi ideology, because Nazis stressed the immutability of the German race. More recently Peter Bowler and Michael Ruse have argued that the Nazis rejected human evolution, because they upheld a fixed racial type and racial inequality. (Richard Weikart, 'The Role of Darwinism in Nazi Racial Thought', German Studies Review, Vol. 36, No. 3 (October 2013), pp. 537-556: 537.) I don't attempt to adjudicate but simply indicate that there are respectably rivalrous views.