There is a meme from the old days of the Usenet that will be familiar to people who frequent blogs and boards. It is known as Godwin’s Law. Follow the link for details, but it essentially says that as any online discussion thread increases in size, the probability of someone making a comparison to Hitler or Nazis approaches 1. Since initially invented, the meme has expanded somewhat to include the proviso that the point where Hitler is first mentioned, all further discussion becomes irrelevant and the person who raised Hitler is immediately considered to have lost the debate. argumentum ad Hitlerum.
May I humbly suggest it is time to suggest a new Corollary?
Anyone in the least bit interested in the science and politics behind Anthropogenic Global Warming will recognize this. Any online discussion about AGW inevitably results in someone raising the spectre of Al Gore, usually as a purportedly stunning rebuke against an actual rational point. At that point, any further discussion becomes irrelevant.
…argumentum al Gorium.