Type: Guilt by Association
Unfortunately, it does not go without saying that in our examination we must avoid the fallacy that in the last decades has frequently been used as a substitute for the reductio ad absurdum: the reductio ad Hitlerum. A view is not refuted by the fact that it happens to have been shared by Hitler.
Source: Leo Strauss, Natural Right and History (1976), pp. 42-43.
[T]he ideas of ecologists about invasive speciesalien species as they are often calledsound similar to anti-immigration rhetoric. Green themes like scarcity and purity and invasion and protection all have right-wing echoes. Hitler's ideas about environmentalism came out of purity, after all.
Source: Interview of Betsy Hartmann by Fred Pearce, "The Greening of Hate", New Scientist, 2/20/2003
In almost every heated debate, one side or the otheroften bothplays the "Hitler card", that is, criticizes their opponent's position by associating it in some way with Adolf Hitler or the Nazis in general. This move is so common that it led Mike Godwin to develop the well-known "Godwin's Law of Nazi Analogies": "As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches one."
No one wants to be associated with Nazism because it has been so thoroughly discredited in both theory and practise, and Hitler of course was its most famous exponent. So, linking an idea with Hitler or Nazism has become a common form of argument ascribing guilt by association.
Some instances of the Hitler card are factually incorrect, or even ludicrous, in ascribing ideas to Hitler or other Nazis that they did not hold. However, from a logical point of view, even if Hitler or other Nazis did accept an idea, this historical fact alone is insufficient to discredit it.
The Hitler Card is often combined with other fallacies, for instance, a weak analogy between an opponent and Hitler, or between the opposition political group and the Nazis. A related form of fallacious analogy is that which compares an opposition's actions with the Holocaust. This is a form of the ad Nazium fallacy because it casts the opposition in the role of Nazi. Not only do such arguments assign guilt by association, but the analogy used to link the opposition's actions with the Holocaust may be superficial or question-begging.
Other arguments ad Nazium combine guilt by association with a slippery slope. For instance, it is sometimes argued that the Nazis practised euthanasia, and therefore even voluntary forms of it are a first step onto a slippery slope leading to extermination camps. Like many slippery slope arguments, this is a way of avoiding arguing directly against voluntary euthanasia, instead claiming that it may indirectly lead to something admittedly bad.
Playing the Hitler Card demonizes opponents in debate by associating them with evil, and almost always derails the discussion. People naturally resent being associated with Nazism, and are usually angered. In this way, playing the Hitler Card can be an effective distraction in a debate, causing the opponent to lose track of the argument. However, when people become convinced by guilt by association arguments that their political opponents are not just mistaken, but are as evil as Nazis, reasoned debate can give way to violence. So, playing the Hitler Card is more than just a dirty trick in debate, it is often "fighting words".
Germany today bans capital punishment, but the history of this ban is surprising: The government of the former West Germany adopted the ban in 1949 and it continues in effect today in the reunited Germany. The law that banned the death penalty was proposed by a politician sympathetic to the Nazi war criminals who were being executed after World War 2, and was intended to block such executions. Should the disreputable historical origins of the ban influence those Germans who today oppose capital punishment to reconsider their views? Should the ban be repealed simply because it was the brainchild of a Nazi sympathizer? Capital punishment is either right or wrong. If it is right, then the ban should be repealed, regardless of its origins; if it's wrong, then the ban should be continued, despite its origins. While the history of the origins of Germany's ban on capital punishment is interesting, it is irrelevant to the moral and legal question of whether the ban should continue. Those Germans who support capital punishment should resist the temptation to play the Hitler card.
Thanks to Michael Koplow for the Example, to Dominic Sisti for pointing out the Caplan editorial, and to Joanna Roberts for reminding me about Godwin's Law.