By any normal standard, Hillary Clinton crushed Donald Trump in the first presidential debate.

Trump was erratic, inconsistent and incoherent. He did not make a memorable case on any issue except perhaps his call for law and order.

His justification for refusing to release his taxes, his claim that “my strongest asset by far is my temperament,” his defense of his bankruptcies, his use of debt and his failure to pay creditors, his support for reducing taxes on the wealthy, and his failure to document such broad claims as “we have the greatest mess you have even seen” all rang weak.

This same pattern became obvious as Trump tried to claim he actually did Obama a favor by pushing for the release of his birth certificate and failed to explain why he continued to make birther claims for years afterward.

Trump’s weaknesses were compounded by confused syntax, irritating intrusiveness and disregard for the efforts of Lester Holt, the moderator, to move the debate along.

Clinton, in contrast, was coherent and fact-based, making her arguments in a fashion that the audience could easily understand.

At one point, Trump described Clinton as “all talk, no action,” but the comment was more applicable to his failure to substantiate his expansive assertions.

On a crucial issue, especially for Clinton, Trump appeared unprepared with anything approaching a plan to deal with matters from ISIS to nuclear weapons to cybersecurity, while Clinton was loaded for bear.

I asked some political aficionados for their thoughts.

Norman Ornstein, a scholar at the American Enterprise Institute, emailed me back. Trump, he said, “was angry, rambling, fidgety and often simply incoherent. His bar was to look even modestly like a president, in carriage and temperament, plus a very, very low bar on fundamental knowledge. He failed on them all.”

Arthur Lupia, a political scientist at the University of Michigan wrote: “Her raising of numerous hypotheses about why Trump was not releasing his tax returns was brilliant stagecraft. By raising the ideas as questions, rather than making assertions, the presentation can set the stage for days of questioning about the topic.”

Alan Abramowitz, a political scientist at Emory, wrote that Trump’s “performance would not persuade anyone who was on the fence.”

The theme of Trump’s struggle to express himself versus Clinton’s forceful presentation built to a crescendo throughout the 90 minutes, culminating in the final minutes when Clinton became the clear aggressor.

“This is a man who has called women pigs, slobs and dogs,” she declared. As Trump looked on in frustration, Clinton reminded the audience that Trump had once referred to a young Latina Miss Universe, Alicia Machado, as “Miss Piggy” and “Miss Housekeeping.”

Trump was so disconcerted that as the debate went on, he got more rattled, telling the audience that he had thought about making some extremely “rough” attacks on Clinton and her family. But, he added, “I said to myself, I just can’t do it.” Ultimately, he was reduced to whining about Clinton’s television commercials: “It’s not a nice thing she has done.”

Thomas B. Edsall is a contributing opinion writer.