For the sake of argument let's assume Donald Trump is, in American parlance, an ass.
So the question is: why is an ass - and not just any old ass but someone widely regarded as a gigantic ass, one of the world's biggest - holding a commanding poll lead over his rivals for the Republican presidential nomination?
There are immediate political reasons:
• The first Republican primary is five and a half months away so voters can take the irresponsible option now in the knowledge there's still plenty of time to get real. If you look at it this way, Trump's like a marathon runner who takes off like a bat out of hell and is usually last seen being loaded into an ambulance around the halfway mark.
• Trump has extraordinary name recognition, a particularly valuable asset in a crowded field. (There are 17 Republican candidates.) As a writer on Politico.com put it this week: "For all the flak Trump receives about littering his name on swag and skyscrapers the way a feral cat marks its territory, doing so is one of the reasons he's trouncing his rivals in the polls. He's been carpet-bombing the electorate with it for the better part of three decades."
• Of the others, only Jeb Bush has anything like that level of name recognition and, in his case, it's a mixed blessing. There's Ted Cruz, but he looks and acts like he's just emerged from a Transylvanian vault; there's Mike Huckabee, but his surname sounds like a term of abuse; and there's a bunch of interchangeable middle-aged white men with bland, forgettable names like Walker, Perry and Graham. (For no other reason Marco Rubio, the telegenic Cuban-American from the swing state of Florida, may be worth keeping an eye on.)
Then there are big picture reasons. Trump has been an ass for so long that it's taken for granted, hence he gets away with stuff that would bury any other candidate. As is the case with his hair, familiarity has bred resignation, thus making his behaviour less confronting and offensive.
Second, there's the fact that there are a lot of asses in America (population around 320 million). Even if the ass ratio is much the same as in other countries - and it's fair to say the global consensus is that America, being the spiritual home of the ass, has a higher per capita ratio than anywhere else - that's an awful lot of asses.
More than enough to tilt the polls in Trump's favour.
Sure, some minor league asses have run for President but, rather than revel in their ass-iness, as Trump does, they saw it as a liability and wasted resources trying to persuade the electorate that they weren't in fact assholes.
Trump isn't making that mistake. In the words of the Denis Leary song that should be his campaign anthem: "Maybe I shouldn't be singing this song/Ranting and raving and carrying on/Maybe they're right when they tell me I'm wrong/ Nah - I'm an asshole."
Think about what makes an ass.
Racism: check. When Trump described Mexican immigrants as rapists and criminal scum, asses from Anchorage to Austin heard a man who speaks their language.
Sexism: check. When a female journalist asks tough questions, she's not being professional, she's being a bitch. And why is she being a bitch? Well, if she wasn't already that way, it must be that time of the month.
Ignorance: check. How will Trump deal with immigration? Simple, he'll build a wall along the Mexican border. How will he deal with Vladimir Putin and China and Isis? Simple, by being an ass. It's the only language foreigners understand.
General vileness: check. John McCain isn't a hero, he's a loser. He went to Vietnam, got shot down, captured, tortured and spent five hellish years as a prisoner of war. Winners like Trump dodged the draft and stayed home getting rich rather than risking their lives for their country. Trump is the candidate the asses of America have been hanging out for. He's the asses' ass.
New Zealanders shouldn't be too smug, since we've had our own mini-Trump in the form of Kim Dotcom. And the American system does encourage Trump-style candidacies: there have been five Presidents who hadn't previously held elective office, the most recent being Dwight Eisenhower. But he was a soldier-statesman who commanded allied forces in Europe during World War II. As opposed to an ass.