Brendan Nyhan suggests that liberal blogger Josh Marshall is guilty of a "smear" when he compares Guiliani's speech at the recently concluded RNC convention to a speech by Josef Goebbels. Nyhan notes that "casual Nazi analogies demean and cheapen the discourse -- it's an easy way to active a series of unflattering associations and attach them to a public figure that you don't like." He then compares Marshall's Nazi analogies to Bush's arguably comparing the Democrats to Vietnamese Communists in his video address to the convention.
Here's my problem with so rapidly dismissing the left side of this, which is comparing the current Republicans to Nazis or fascists. I regard it as a genuinely open empirical question how far these guys are willing to go to destroy American democracy. For my money, the discourse at the RNC convention truly was Nazi or fascist-style: demeaning opponents as less than fully human or at least not American, militarism, outrageously over the top lying (Palin on the Bridge to Nowhere, Guiliani denouncing cosmopolitans, Romney denouncing Eastern elites), claiming that only people from small towns are real Americans, etc. Then there's the executive authoritarianism, the claims the president can lock up anyone indefinitely, lying to get us into wars, government secrecy for everything (including indefensible legal opinions embracing torture), the use of torture itself when its intelligence payoff has pretty much been proven to be negative, complete politicization of the executive branch, use of the Justice Department to throw political foes such as Don Siegelman in jail, and repeated, systematic attempts to intimidate the media and prevent it from questioning even demonstrably false claims (whether about Guanatanamo or Palin's earmark record), etc.
I feel they are destroying civil society and the rule of law, and I honestly don't know how far they would go. Explicit dictatorship? Jailing of the opposition? Reichstag fire style fake terror attacks? (Bush and Cheney have both been quoted considering the equivalent in foreign affairs to create casus bellis with Iraq and Iran.) I don't think that leading Republicans themselves know what they would do or where they are headed beyond the next news cycle, but that doesn't mean that they aren't, via their incentives and inclinations and the pressure of events, headed somewhere very nasty.
At this point, I feel there are reasonable arguments to be made on both sides of this - yes, they are something new in American politics and there really is no limit to how far they would go; or no, it's pretty much still business as usual and neither politics nor government have ever been pretty.
But Nyhan is guilty of simply assuming the no side here. He might be right, but at this point I feel we genuinely don't know.