Godwin's law, short for Godwin's law (or rule) of Nazi analogies, is an Internet adage asserting that as an online discussion grows longer (regardless of topic or scope), the probability of a comparison involving Nazis or Adolf Hitler approaches 1. In less mathematical terms, the longer the discussion, the more likely a Nazi comparison becomes, and with long enough discussions, it is a certainty. Promulgated by the American attorney and author Mike Godwin in 1990, Godwin's law originally referred specifically to Usenet newsgroup discussions. He stated that he introduced Godwin's law in 1990 as an experiment in memetics. Later it was applied to any threaded online discussion, such as Internet forums, chat rooms, and comment threads, as well as to speeches, articles, and other rhetoric where reductio ad Hitlerum occurs. In 2012, "Godwin's law" became an entry in the third edition of the Oxford English Dictionary. In 2021 Harvard researchers published an article stating the law does not apply in Reddit discussions. ...

Reductio ad Hitlerum (; Latin for "reduction to Hitler"), also known as playing the Nazi card, is an attempt to invalidate someone else's position on the basis that the same view was held by Adolf Hitler or the Nazi Party. One example would be that since Hitler was against smoking, this implies that someone who is against smoking is a Nazi.Coined by Leo Strauss in 1953, reductio ad Hitlerum borrows its name from the term used in logic called reductio ad absurdum ("reduction to the absurd"). According to Strauss, reductio ad Hitlerum is a form of ad hominem, ad misericordiam, or a fallacy of irrelevance. The suggested rationale is one of guilt by association. It is a tactic often used to derail arguments because such comparisons tend to distract and anger the opponent. ...