Godwin’s Law is also known as Godwin’s Rule of Nazi Analogies. It was created in 1990 by Mike Godwin (later known for his legal work with The Electronic Frontier Foundation).

What it means is this: whenever you are in a discussion, argument, debate, or conversation and someone invokes the name of Hitler or The Nazis, this is probably a good point to stop taking your opponent’s argument seriously.

Example:

Obama is a powerful public speaker.
Hitler was a powerful public speaker.
Therefore, Obama is as bad as Hitler.

It is a form of the Logical Fallacy known as “argumentum ad Hitlerum,” which would state that since Hitler is bad, any regular thing Hitler did must be also be bad. Godwin invented this “Law” because he “wanted folks who glibly compared someone else to Hitler or to Nazis to think a bit harder about the Holocaust.”

From Wikipedia:

• There is a tradition in many newsgroups and other Internet discussion forums that once such a comparison is made, the thread is finished and whoever mentioned the Nazis has automatically “lost” whatever debate was in progress.

• In October 2007, the “Last Page” columnist in The Smithsonian stated that when an adversary uses an inappropriate Hitler or Nazi comparison, “you have only to say ‘Godwin’s Law’ and a trapdoor falls open, plunging your rival into a pool of hungry crocodiles.”

Sources:
Godwin’s Law
Reductio ad Hitlerum
Mike Godwin

Dr. Zoltan is now obsessed with Logical Fallacies. Visit http://www.drzoltan.com/blog to find out more.