Conservatives generally think it's best to take enemies at their word, to believe their bombast and threats and make preparations, rather than dismiss them as crackpots and regret it.

Usually, the people who promote that approach invoke Hitler, who was clear about his agenda from the get-go.

George W. Bush compared Saddam Hussein to Hitler. British PM David Cameron compared Vladimir Putin to Hitler. Just about the entire American conservative establishment compared former Iranian president Mahmoud Ahmadinejad to Hitler at one time or another.

So, in the same spirit, let's seriously consider the words of the two men currently leading the race for the Republican presidential nomination, former neurosurgeon Ben Carson and the loudmouth tycoon Donald Trump.

Because it's increasingly possible that one of them will actually be the nominee, and perhaps even president. Their durability has surprised just about everyone.

First, low-key Ben Carson; he just shot past Trump in Iowa, the starting point of the American primary system.

The Washington Post recently called him the biggest fan of Nazi metaphors in contemporary politics.

Carson says America is living in a "Gestapo age," and that the nation has become "very much like Nazi Germany."

The Obama administration, he says, is using the organs of government against its citizenry, and Americans, he says, are as bovine as Germans were in 1933.

That said, Carson has said plenty of Hitler-ish things himself. Beginning with his declaration that a Muslim shouldn't be president.

This of course would violate the U.S. Constitution, which explicitly forbids a religious test for public office, but Carson perceives a threat that must be dealt with. (Hitler, perceiving a nascent Communist revolution, felt obliged to bypass the Weimar Republic's constitution in 1933.)

To give Carson credit, he has now amended his statement to say a Muslim could be considered for the Oval Office, but only if he or she agreed to "reject the tenets of Islam."

Carson also says college campuses should be monitored by the federal government for "extreme political bias." (He would exempt extreme conservative bias.) Sort of the way Hitler purged Communists and leftists from German academia.

(Carson has also likened women who seek abortions to slave owners.

Slave owners saw their slaves as chattels who could be killed at will, he asserted, the same way women regard fetuses they want to abort.

The subtext of this, of course, is that the state should step in if it learns a woman is seeking an abortion.)  

GOP 2016 Carson as Neurosurgeon

A younger Dr. Ben Carson, then-director of pediatric neurosurgery at Johns Hopkins Children's Centre in Baltimore, holds a model of the heads of conjoined twins Tabea and Lea Block of Lemgo, Germany. Carson is the only 2016 candidate for president who has never led a state or company or run for political office, but the retired neurosurgeon maintains that someone who can lead life-or-death operations surely can run a country. (Chris Gardner/Associated Press)

Like Hitler, Carson believes homosexuality is a choice, and a repugnant one at that. (Carson's proof? Straight men who go to prison come out gay. There you have it.)

Marriage equality, he says, is a "Marxist plot" and its supporters are enemies of America. (Hitler wasn't too keen on Marxists, either.)

Oh, and judges who support marriage equality, meaning a majority of the U.S. Supreme Court, should be removed from office. (Hitler was similarly impatient with judges who wouldn't go along with his agenda.)

Trump is rough, Carson 'assuring'

Now, to be fair, Carson unequivocally opposes the Holocaust.

If Jews had only had lots of guns and the courage to use them, he says, they could have resisted the Nazis.

Hitler wouldn't have liked that very much, but maybe he'd agree Carson at least has a point. (Most Jewish organizations don't.)

Now, lest you're beginning to think Carson is just a crank, bear in mind that he's a famed Johns Hopkins-trained neurosurgeon, a brilliant, accomplished man whose "calm manner," according to a long, admiring New York Times profile this week, has him rising in the polls, leaving the rest of the Republican field watching his heels.

He's now right up there, alongside the bellowing jester of the race, Donald "Latino migrants are criminals and rapists" Trump.

"Trump is rough, Carson is assuring," pollster Peter Hart told the Times.  

And yet, outside of Iowa, rough old Trump still holds more Republican voters in his spell than any other candidate.

How does he do it?

Well, for one, Trump has declared that he would, somehow, round up and deport all 11 million or so undocumented immigrants in America, regardless of the effect that would have on the nation's need for cheap labour. And  never mind the consequences for undocumented families with children born on U.S. soil.

Trump seems to accept the idea that there are secret Muslim training camps in America, and has openly suggested Obama himself is a Muslim, and foreign born.

He has called women he doesn't like "pigs, fat slobs and dogs." He's suggested that a female news anchor who called him on that was menstruating.

Some organizations have tried to compare Trump to Hitler, but that really doesn't work. Though you never know, Carson may get there at some point.

Godwin's law

It's tempting to view all this demagoguery as the usual primary-season Republican freak show where the marginal howlers all have their moment in the polls, then the adults step in and nominate a "moderate" with some appeal to mainstream Americans.

And Godwin's law, one of the internet's rules of engagement, states that once Hitler is invoked, the conversation has just ended because rational argument has gone out the window.

But, two points:

Moderation is regarded by the Republican base with suspicion. The main "moderate," Jeb Bush, is wallowing far down in the polls and is now reported to be having trouble raising money.

Second, it may be that the freak show is the show Republicans really want.

Maybe the Tea Party dream is coming true, and the next Republican presidential nominee will be a blunt-object, red-meat down-the-line rightie.

The Tea Party caucus in Congress has just booted out the Republican speaker, John Boehner, and seems to regard his probable successor, Rep. Paul Ryan, as a closet lefty. (A lefty? This is someone who wants to replace Medicare with a voucher system.)

Anyway, nominee Donald Trump or nominee Ben Carson. Think about that, and listen to their words.

And maybe start taking them seriously.