The entire 90-minute debate Monday night was a demonstration that Donald Trump doesn‘t have the temperament to be president. 

Hillary Clinton was prepared -- she always is -- and she baited Trump early and often. And Trump got caught each time. He also hooked himself, including in at least two exchanges with moderator Lester Holt (who did an excellent job, allowing both candidates to talk). Here are some examples.

In Clinton’s very first response to Trump, about trade, she managed to work in that the reality television star “started his business with $14 million, borrowed from his father.” Trump could have let that go. Trade is a pretty good issue for him, and one on which he scored one of his few debating points of the night. But he just couldn‘t pass up the challenge to his claim to being a self-made man, and he got diverted into defending himself against her jab.

This one didn’t cost him much momentum. But it established a pattern that continued for the rest of the night. She would bait him about something, and he would defend himself.

Perhaps the most damaging part was on his undisclosed tax returns, which Holt asked him about. Trump gave his standard (nonsense) answer that he couldn‘t release his returns while he was under an IRS audit, and then he finished strong with an attack on Clinton’s emails. The contrast in what happened next was instructive.

Clinton entirely ignored the email question, and immediately launched into several points about what Trump might be hiding in his tax returns. She was prepared, and it showed. In responding, Trump not only never remembered to return to the email question, he also wound up essentially bragging about never paying any taxes.

The Republican nominee also wound up in a long, extended and unflattering argument with Holt about the “birther” issue, another subject he‘s probably better off just deflecting and moving on from.

He also fought with Holt over the question of whether he supported or opposed the Iraq war before it started. Evidence shows he supported it. He could have simply admitted that he wasn’t really engaged on the issue at the time and had been willing at first to trust George W. Bush on the war. Then he could have pointed out that Clinton was in a position to know better and accused her of failing the nation. Instead, for no apparent reason, other than plain old stubbornness, he clearly came ready to argue about audio clips from 2002.

The most revealing display, however, was when he was actually flying off the handle. After Trump bragged about his temperament, Clinton responded with a few real-world examples of why “a man who could be provoked by a tweet shouldn‘t have his fingers anywhere near the nuclear codes.” She mentioned the episode recently when Trump wanted US forces to fire on Iranian boats that had taunted them. He interrupted (as he did quite often), correcting her (or so he thought) that, “No, they were taunting us.”

In other words, Trump was advocating a foreign policy that would let no taunt go unpunished. Even if it led to a few more wars.

As for the other debate action, little of it went well for Trump. As usual, he displayed little or no knowledge of government and public policy. At one point, when asked if the US should adopt a no-first-use doctrine, he clearly had no idea what that was.

Clinton, to my eyes, gave a performance that was about average for her. She fell in love with one unimpressive zinger (calling his economic plans “Trumped-up trickle-down” twice), but overall she showed that she’s a perfectly adequate candidate for anyone looking for one. And she had a few strong moments, absolutely burying Trump when he questioned her stamina near the end of the debate, for example.

Once again, Trump reacted to her devastating shot by trying a do-over, flailing around and making the same pointless attack in a different way when he should have dropped it and moved on. He ended up prolonging the moment, a clear point for her. In sum, it was the story of the night.

By Jonathan Bernstein
Bloomberg

Jonathan Bernstein is a Bloomberg View columnist. – Ed.