On Monday, Donald Trump held a rally in Manchester, New Hampshire, where he merrily repeated a woman in the crowd who called Ted Cruz a pussy. Twenty-four hours later, Donald Trump won the New Hampshire primary in a landslide.

I'm not here to clutch my pearls over Trump's vulgarity; what was telling, rather, was the immaturity of the moment, the glee Trump took in his "she said it, I didn't" game. The media, which has grown used to covering Trump as a sideshow, delighted in the moment along with him — it was funny, and it meant clicks, takes, traffic. But it was more than that. It was the frontrunner for the Republican nomination for president showing off the demagogue's instinct for amplifying the angriest voice in the mob.

It is undeniably enjoyable to watch Trump. He's red-faced, discursive, funny, angry, strange, unpredictable, and real. He speaks without filter and tweets with reckless abandon. The Donald Trump phenomenon is a riotous union of candidate ego and voter id. America's most skilled political entertainer is putting on the greatest show we've ever seen.

It's so fun to watch that it's easy to lose sight of how terrifying it really is.

Trump is the most dangerous major candidate for president in memory. He pairs terrible ideas with an alarming temperament; he's a racist, a sexist, and a demagogue, but he's also a narcissist, a bully, and a dilettante. He lies so constantly and so fluently that it's hard to know if he even realizes he's lying. He delights in schoolyard taunts and luxuriates in backlash.

Trump is in serious contention to win the Republican presidential nomination. His triumph in a general election is unlikely, but it is far from impossible. He's not a joke and he's not a clown. He's a man who could soon be making decisions of war and peace, who would decide which regulations are enforced and which are lifted, who would be responsible for nominating Supreme Court justices and representing America in the community of nations. This is not political entertainment. This is politics.

Trump's path to power has been unnerving. His business is licensing out his own name as a symbol of opulence. He has endured bankruptcies and scandal by bragging his way out of them. He rose to prominence in the Republican Party as a leader of the birther movement. He climbed to the top of the polls in this election by calling Mexicans rapists and killers. He defended a poor debate performance by accusing Megyn Kelly of being on her period. He responded to rival Ted Cruz's surge by calling for a travel ban on Muslims. When two of his supporters attacked a homeless man and said they did it because "Donald Trump was right, all these illegals need to be deported," he brushed off complaints that he's inspiring violence by saying his supporters are "very passionate."

Behind Trump's success is an unerring instinct for harnessing anger, resentment, and fear. His view of the economy is entirely zero-sum — for Americans to win, others must lose. "We're going to make America great again," he said in his New Hampshire victory speech, "but we're going to do it the old-fashioned way. We're going to beat China, Japan, beat Mexico at trade. We're going to beat all of these countries that are taking so much of our money away from us on a daily basis. It's not going to happen anymore."

Trump answers America's rage with more rage. As the journalist Molly Ball observed, "All the other candidates say 'Americans are angry, and I understand.' Trump says, 'I’M angry.'" Trump doesn't offer solutions so much as he offers villains. His message isn't so much that he'll help you as he'll hurt them.

Trump's other gift — the one that gets less attention but is perhaps more important — is his complete lack of shame. It's easy to underestimate how important shame is in American politics. But shame is our most powerful restraint on politicians who would find success through demagoguery. Most people feel shame when they're exposed as liars, when they're seen as uninformed, when their behavior is thought cruel, when respected figures in their party condemn their actions, when experts dismiss their proposals, when they are mocked and booed and protested.

Trump doesn't. He has the reality television star's ability to operate entirely without shame, and that permits him to operate entirely without restraint. It is the single scariest facet of his personality. It is the one that allows him to go where others won't, to say what others can't, to do what others wouldn't.

Trump lives by the reality television trope that he's not here to make friends. But the reason reality television villains always say they're not there to make friends is because it sets them apart, makes them unpredictable and fun to watch. "I'm not here to make friends" is another way of saying, "I'm not bound by the social conventions of normal people." The rest of us are here to make friends, and it makes us boring, gentle, kind.

This, more than his ideology, is why Trump genuinely scares me. There are places where I think his instincts are an improvement on the Republican field. He seems more dovish than neoconservatives like Marco Rubio, and less dismissive of the social safety net than libertarians like Rand Paul. But those candidates are checked by institutions and incentives that hold no sway over Trump; his temperament is so immature, his narcissism so clear, his political base so unique, his reactions so strange, that I honestly have no idea what he would do — or what he wouldn't do.

When MSNBC's Joe Scarborough asked Trump about his affection for Vladimir Putin, who "kills journalists, political opponents and invades countries," Trump replied, "He's running his country, and at least he's a leader, unlike what we have in this country." Later, he clarified that he doesn't actually condone killing journalists, but, he warned the crowd, "I do hate them."

It's a lie that if you put a frog into a pot of water and slowly turn up the heat the frog will simply boil, but it's a fact that if you put the American political system in a room with Trump for long enough we slowly lose track of how noxious he is, or we at least run out of ways to keep repeating it.

But tonight is a night to repeat it. There is something scary in Donald Trump. We should fear his rise.

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