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 to Nazis or Adolf Hitler approaches 1.
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 showing the phenomenon does not occur with statistically meaningful frequency in Reddit discussions.
There are many corollaries to Godwin's law, some considered more canonical (by being adopted by Godwin himself) than others. For example, there is a tradition in many newsgroups and other Internet discussion forums that, when a Hitler comparison is made, the thread is finished and whoever made the comparison loses whatever debate is in progress. This principle is itself frequently referred to as Godwin's law.
Godwin's law itself can be applied mistakenly or abused as a distraction, diversion or even as censorship, when fallaciously miscasting an opponent's argument as hyperbole when the comparison made by the argument is appropriate. Godwin himself has also criticized the overapplication of the law, claiming that it does not articulate a fallacy, but rather is intended to reduce the frequency of inappropriate and hyperbolic comparisons. Godwin wrote that "Although deliberately framed as if it were a law of nature or of mathematics, its purpose has always been rhetorical and pedagogical: I wanted folks who glibly compared someone else to Hitler to think a bit harder about the Holocaust.