As a scholar not a partisan, I have been trying to think if any president in American history has behaved in a less presidential way than Donald Trump.

Andrew Jackson was a frontier ruffian in some respects, a loud populist, and during his inauguration March 4, 1829, his rural supporters trashed the White House.

Theodore Roosevelt called his enemies colorful names (he said McKinley had the backbone of a chocolate éclair, and he called William Jennings Bryan a human trombone). His roughhousing with his rambunctious children in the White House raised the eyebrows of the Victorian stuff shirts of his time. As president, Roosevelt rattled the nerves of Charles Elliot, the president of Harvard, when he showed up at his old alma mater packing a loaded pistol. When one of his old pals from the Dakota Bad Lands fretted that he might not be admitted into the White House through the usual doors, TR urged him next time just to shoot out one of the windows. Probably he was joking.

Bill Clinton famously spoke with foreign diplomats while receiving oral ministrations in the Oval Office from Monica Lewinski and fiddling creatively with cigars. He was not the only president to have opportunistic sex in the White House, of course, but his sexual style always felt a little like it belonged in a trailer park. JFK is said to have taken LSD in the White House with one of his girlfriends, in the middle of the workday. One hopes it was a relatively quiet day during the nuclear-tipped Cold War.

Most presidents either have or adopt proper Presidential deportment. Think of Ronald Reagan (a conservative populist) or George Bush senior (a patrician) insisting on always wearing a coat and tie in the Oval Office, never propping their feet on the famous Resolute desk, and invariably speaking, at least in public, with decorum, a careful and heightened diction and a demeanor that reflects an awareness that they were the prime representative of one the most powerful and important nations in history — the republic of Washington, Jefferson, Lincoln, Wilson, FDR, Kennedy, Reagan, and elegant Obama.

No. 45, Donald Trump, behaves like a rich frat boy, your crazy unfiltered uncle at the Thanksgiving table, the loudmouth at the end of the bar at 11 p.m. on a Tuesday night, the golfer who wraps his 7-iron around a tree when he misses an easy shot. Trump behaves like a psychologically damaged 70-year-old man trapped in the persona of a spoiled 13-year-old adolescent, a reality TV star who got paid millions to be brash, rude, demeaning, and narcissistic.

And here’s the astonishing thing. For about 35 percent of the American people, it works! In fact, some significant percentage of the electorate thinks this is precisely what American most needs. When you mock a disabled person by waving your arms in what you think is a spastic parody, declare that your wealth and celebrity allow you to grab women by their sexual parts with impunity, when you call Mexicans “hombres,” shove the prime minister of Montenegro out of the way during a photo op or call terrorists who just blew up the bodies of several dozen British young people “losers, a bunch of losers, OK,” you would seem to prove yourself unfit for the presidency of the United States. Who really wants to defend such behavior? And yet, this man who has never tried to hide his core persona was elected president of the United States in 2016.

I have close personal friends, decent, morally mature and sensitive men and women, who defend Donald Trump’s antics and hijinks and say that he is the victim of “fake news” and a liberal national media that is indeed the “enemy of the American people.”

This phenomenon is simply mystifying. Trump’s behavior gets denounced every day, almost every hour of every day now, but I’m much more interested in trying to understand it, or more particularly trying to understand why there is about a third of the population that defends such loutish and unpresidential behavior or even fist pumps it.

If your preacher talked this way, would you defend it? If a high school English teacher talked this way, would you defend it? If Obama had talked this way, would you have defended it? If your best friend talked this way, would you defend it?

I heard a commentator named Dylan Byers on one of the talk shows last week say that we will never recover our national social and political equilibrium until we figure out why about half the nation is so pissed off, so utterly disillusioned with America’s path, so profoundly fed up, cynical and eager to say not much more than “up yours” to the rest of us, that they routinely, even invariably defend the least presidential character in American history.

I suppose you could argue that even Thomas Jefferson had his moments. He deliberately ruffled the feathers of British ambassador Anthony Merry with his pell mell dinner protocols. Occasionally, for effect, or in philosophical absent-mindedness, he greeted White House visitors in his slippers. He blustered about Spain’s colonial presence in the western hemisphere and rattled the saber towards Madrid and Mexico City from time to time, knowing that it was highly unlikely that Spain would take the bait and actually wage war against the United States. Weary of the opposition press of his time, Jefferson eventually suggested that we divide newspapers into four sections: truth, probabilities, possibilities, and bald lies.

That’s the sum total of Jefferson’s rudenesses. Probably no president in our history had more elegance, and a finer sense of etiquette than Thomas Jefferson.

Jefferson’s world was essentially no different from a Jane Austen novel: “Pride and Prejudice,” “Sense and Sensibility,” “Emma.” Everyone is polite, euphemistic, civil, and nonconfrontational. Whatever gets resolved — and, of course, they faced the same problems all humans always face — has to be resolved by indirection, strained politeness and nuance. It’s hard to know when someone is enraged in Jane Austen’s world because they always unburden themselves using their “inside voices” and employing complete sentences. Or they faint.

Thomas Jefferson was an exquisitely civilized man. He did not Tweet or hold impromptu news conferences or mouth platitudes with tedious repetition of every phrase. “We’re going to be great again. I tell you great again. I mean great folks. Really great. So great.”

Jefferson sat down in front of a plain sheet of expensive paper and the best writing instruments of his time. He thought through just what he wanted to express before he touched pen to paper, paused to regroup between sentences, tried hard to phrase his views in a way that would find harmony in the letter’s recipient.

When he disagreed strongly with someone, Jefferson invariably attempted to lighten the tension by saying, “If we disagree, let us disagree as rational friends.” This was a personal application of the famous utterance from his First Inaugural Address: “Every difference of opinion is not a difference of principle. We have called by different names brethren of the same principle. We are all Republicans. We are all Federalists.”

Much later, Jefferson wrote one of his most beautiful letters to a man named Charles Thompson. The letter epitomizes the soul of the kind of individual you want to be president of the United Sates.

“It is a singular anxiety which some people have,” Jefferson wrote, “that we should all think alike. Would the world be more beautiful were all our faces alike, were our tempers, our talents, our tastes, our forms, our wishes, aversions and pursuits cast exactly in the same mould? If no varieties existed in the animal, vegetable or mineral creation, but all moved strictly uniform, catholic and orthodox, what a world of physical and moral monotony would it be!”

Well, I guess you cannot Tweet that.

I’m Clay Jenkinson.