Internet rules and laws: the top 10, from Godwin to Poe [View all]
An old article from 2009 but still a goodie
http://www.telegraph.co.uk/technology/news/6408927/Internet-rules-and-laws-the-top-10-from-Godwin-to-Poe.html
1. Godwins Law
The most famous of all the internet laws, formed by Mike Godwin in 1990. As originally stated, it said: "As a Usenet discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches 1." It has now been expanded to include all web discussions.
It is closely related to the logical fallacy reductio ad Hitlerum, which says Hitler (or the Nazis) liked X, so X is bad, frequently used to denigrate vegetarians and atheists.
Common Godwin's Law appearances include describing women's rights campaigners as feminazis, comparing the former US President George W Bush to Hitler, or saying Barack Obama's proposed healthcare reforms are the new Holocaust.
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More at link above, enjoy !