Reductio ad Hitlerum
- Hitler believed P was true.
- Hitler was a horrible man who waged bloody war upon Europe and killed millions in concentration camps.
- P is false.
When saying, "P is false" SOME people generally mean, P is bad, P is evil, P should be avoided at all costs.
Similar arguments occasionally arise centered around other infamous historical individuals, but Hitler is the most common. Frequently, the first premise is challenged when significant evidence to the contrary exists, but even if it is true, the conclusion does not follow the premises. Hitler likely believed that the Earth was round and that it revolved around the Sun, beliefs unrelated to his actions. Even if his actions were directly caused by his holding certain beliefs, it doesn't follow that the beliefs are false. This is the fallacy of the Argument from adverse consequences.