Run a search on the words 'just like Hitler' and marvel. That string yields more than 60,000 hits, many directly comparing the failed artist and successful mass-murderer to modern bigwigs, among them former US vice-president Al Gore. Gore makes the cut thanks to his green treatise An Inconvenient Truth, which has been pilloried by CNN Headline News host Glenn Beck. 'When you take a little bit of truth and then you mix it with untruth, or your theory, that's where you get people to believe,' Beck is quoted as saying before he goes into overdrive. 'It's like Hitler,' he continues, then pursues the analogy hard, dragging the Jews in. Another online source inflicting the toothbrush-moustache treatment on targets ranging from Mother Teresa and anti-terror laws to Scientologists, Israel and American Democrats is moveon.org. Lambasting the last, analyst 'Frank J' writes: 'Propaganda: check! Belief in superiority: check! Blames all their problems on others: check!' The sweeping antics of Frank J and others inspired to throw the H-word around demonstrate the salience of a formula called Godwin's Law. Devised by American lawyer Mike Godwin in 1990, the law addresses logical fallacies such as 'reductio ad Hitlerum', where an idea is rejected because of its association with people widely deemed 'evil'. 'As an online discussion grows longer,' the law says, 'the probability of a comparison involving Nazis or Hitler approaches inevitability.' In a variation, some libellers liken their enemies to gulag-building Soviets and the members of crazed regimes such as the Khmer Rouge. The comparison is liable to crop up early on if the issue at stake is something really touchy - abortion, homosexuality or gun control, say. Another fertile subject is Microsoft, which faces intense competition in the blackshirt slander stakes from Apple. I've seen Apple chief executive Steve Jobs compared to Joseph Stalin, and Bill Gates to Hitler. Or was it the other way round? Whatever. It's only a matter of time before the Dalai Lama falls prey to the association as the internet displays every angle the human mind can find. In theory, the comparison backfires because whoever makes it in a thread automatically loses whatever debate was underway, the law says rightly. The comparison almost always seems daft. I wonder if it's stretching reality to say that its stubborn frequency proves the argument set out in the upcoming non-fiction book Triumph of the Airheads. Claiming the world has been taken over by idiots, author Shelley Gare cites how some students don't know who Mao Zedong was. If they did, they would doubtless liken each other to him, should they tire of Hitler gibes - although the iconic Nazi dictator makes for juicier material than other candidates. Satirical website Beautiful Atrocities ( www.beautifulatrocities.com ) logs how even global warming has earned the comparison, as have the Republican Party, smokers and Pope Benedict. A visitor to the site, Jake Smith, calls for a halt: 'I think all this comparing people to Hitler crap is just stupid. No one can be like Hitler unless they can slaughter as many millions of people as he did.' Maybe. But in expressing himself with such bite, Smith may have blundered, overstepping the boundaries of semi-civilised debate. The next and final message in the thread hits back at the denier with six choice, cutting words: 'You are obviously worse than Hitler!' Check.