Republican presidential nominee Donald Trump after the final presidential debate, in Las Vegas on Oct. 19. (Robyn Beck/Agence France-Presse via Getty Images)
Opinion writer

It is the nature of extreme partisanship to turn honest disagreements into alternative realities. The representatives of our own ideological team must always be good and beautiful, strong and surging. Admission of facts inconsistent with this premise is taken as disloyalty.

The third presidential debate was a perfect test of this tendency. Republicans who contend that Donald Trump was the winner are on their fourth Kool-Aid martini. For the first half-hour, Trump — appearing alternately sedate and sedated — managed (briefly) to sound like a Republican by asserting basic conservative policies and principles. It was jarring to be reminded that Hillary Clinton strongly supports the legality of late-term abortions, a real streak of extremism. It was useful to be reminded that gun control in Chicago has hardly been a smashing success.

But the 30-minute mark was the limit of Trump’s strategy, patience, knowledge, responsibility and stability. The remainder was a rout. Clinton’s debate performance was a reminder that she must have been a formidable lawyer while in practice. She built her anti-Trump case calmly and systematically, using Trump’s own words and views as jabs before tough punches of accusation. Vladi­mir Putin would “rather have a puppet as president of the United States.” And: “There’s only one of us on this stage who’s actually shipped jobs to Mexico.” And: “Donald thinks belittling women makes him bigger.

The most ironic moment of the evening was when Trump said, “This has been such an incredible education for me.” As far as I can tell, Trump displays no growth in skills or knowledge compared with early GOP primary debates. His responses to attacks — “No puppet! No puppet! You’re the puppet!” — are still of schoolyard quality. His judgment of others is still shaped by a bottomless neediness. When the topic of Putin was raised, Trump’s initial reaction was not to criticize Russia’s external aggression or internal oppression. It was: “He said nice things about me.” Justice Ruth Bader Ginsburg did not say such nice things, making her the enemy.

At this late stage, it is worth stating bluntly: When it comes to the issues any American president would face, Trump is a shockingly ignorant man. He can state a position on the Second Amendment or Obamacare, but he is unprepared to make actual arguments. He bluffs through questions on campaign finance and foreign policy (“Mosul is so sad”) as though the dog really did eat his homework. What explains his pervasive shallowness? Laziness? Lack of curiosity? Who knows? But I have honestly met precocious high school students with more civic and policy knowledge than Trump displayed during the final presidential debate. The justification that he is not a career politician does not excuse an inability to learn.

Factual or not? Here's a look at the top claims from the third and final Clinton-Trump presidential debate. (Jenny Starrs/The Washington Post)

The Las Vegas debate sharpened an important distinction — the gap between disagreement and disqualification. I disagree strongly with Clinton on tax policy and Iran policy. But it is disqualifying for a presidential nominee to brag about his techniques of sexual assault, and then have several credible victims describe how he allegedly carried these methods into practice. Trump dismissed these accusations as “largely debunked,” but saying it doesn’t make it so.

It is disqualifying to dismiss or play down Russian espionage directed toward influencing a presidential election, especially when you are the one it is designed to help. How in the world did Trump’s revival of American nationalism become a common cause with Russian hackers and WikiLeaks’s Julian Assange?

And it is disqualifying for a presidential candidate to encourage distrust of our electoral system as an electoral strategy, while refusing to pledge acceptance of a democratic verdict. Trump’s joke on this topic — “I’ll keep you in suspense” — is symbolic of his superficiality. Belief in the fairness of our electoral system was hard-won, through a long history of strife and courage. But Trump cannot feel the weight of a history he does not seem to know.

With the final debate over, two points are particularly evident. First, a serious GOP candidate would probably be winning this election, which was forfeited the moment Trump became the nominee. And second, an authoritarian populist with serious abilities might have a disturbingly large audience in 21st-century America. Imagine a Trump-like figure with the political skills of Bill Clinton or Tony Blair, feeding and riding the backlash against rapid economic and social change. It is the first time in my political lifetime that I have seen fragility at the heart of American democracy. And that glimpse should shock us back to a more civil and responsible politics.

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