By that standard, but only by that standard, the governor of Alaska did well. But Ms. Palin never really got beyond her talking points in 90 minutes, mostly repeating clichés and tired attack lines and energetically refusing to answer far too many questions.

Senator Biden did well, avoiding one of his own infamous gaffes, while showing a clear grasp of the big picture and the details. He left Ms. Palin way behind on most issues, especially foreign policy and national security, where she just seemed lost. It was in those moments that her lack of experience — two terms as mayor of a tiny Anchorage suburb and less than two years as governor — was most painfully evident.

Asked about Israel, Ms. Palin reeled off her support for “a two-state solution, building our embassy also in Jerusalem, those things that we look forward to being able to accomplish with this peace-seeking nation.” Asked about the possible use of nuclear weapons, she declared “nuclear weaponry, of course, would be the be-all, end-all of just too many people and too many parts of our planet.” On Iraq, all she had to offer was the false accusation that Barack Obama wants to surrender.

Mr. Biden directly challenged Ms. Palin’s debate prep on Afghanistan — pointing out that the commander there had disagreed with Mr. McCain’s call for an Iraq-style “surge” in Afghanistan. Ms. Palin tried to contradict him, but the most memorable part of her answer was that she got the general’s name wrong.

One can argue (and her supporters will) that Ms. Palin is a newcomer and can’t be expected to know all of the wonkish details, that what matters is the image she projects. Except, anyone who is running for vice president in these very dangerous times needs to have detailed knowledge.

When it came to domestic issues, Ms. Palin mainly relied on enthusiasm and humor, talking about hockey moms, soccer moms and Joe Sixpack almost as often as she used the word “maverick” to describe Mr. McCain or herself.

But she offered virtually no detail — beyond the Republican mantra of tax cuts — for how she and Mr. McCain would address the financial crisis or help Americans avoid foreclosure or what programs they would cut because of the country’s disastrous fiscal problems.

Ms. Palin’s primary tactic was simply to repeat the same thing over and over: John McCain is a maverick. So is she. To stay on that course, she had to indulge in some wildly circular logic: America does not want another Washington insider. They want Mr. McCain (who has been in Congress for nearly 26 years). Ms. Palin condemned Wall Street greed and said she and Mr. McCain would “demand” strict oversight. In virtually the next breath, she said government should “get out of the way” of American business.

There were occasional, disturbing flashes of the old, pre-campaign Sarah Palin. Asked about the causes of global warming, Ms. Palin suggested that man had some role — but she wasn’t saying how much.

In the end, the debate did not change the essential truth of Ms. Palin’s candidacy: Mr. McCain made a wildly irresponsible choice that shattered the image he created for himself as the honest, seasoned, experienced man of principle and judgment. It was either an act of incredible cynicism or appallingly bad judgment.