Many analysts concluded years ago that the answers to both questions were no. Predatory lending was largely carried out by smaller, non-Wall Street institutions like Countrywide Financial; the crisis itself was centered not on big banks but on “shadow banks” like Lehman Brothers that weren’t necessarily that big. And the financial reform that President Obama signed in 2010 made a real effort to address these problems. It could and should be made stronger, but pounding the table about big banks misses the point.

Yet going on about big banks is pretty much all Mr. Sanders has done. On the rare occasions on which he was asked for more detail, he didn’t seem to have anything more to offer. And this absence of substance beyond the slogans seems to be true of his positions across the board.

You could argue that policy details are unimportant as long as a politician has the right values and character. As it happens, I don’t agree. For one thing, a politician’s policy specifics are often a very important clue to his or her true character — I warned about George W. Bush’s mendacity back when most journalists were still portraying him as a bluff, honest fellow, because I actually looked at his tax proposals. For another, I consider a commitment to facing hard choices as opposed to taking the easy way out an important value in itself.

But in any case, the way Mr. Sanders is now campaigning raises serious character and values issues.

It’s one thing for the Sanders campaign to point to Hillary Clinton’s Wall Street connections, which are real, although the question should be whether they have distorted her positions, a case the campaign has never even tried to make. But recent attacks on Mrs. Clinton as a tool of the fossil fuel industry are just plain dishonest, and speak of a campaign that has lost its ethical moorings.

And then there was Wednesday’s rant about how Mrs. Clinton is not “qualified” to be president.

What probably set that off was a recent interview of Mr. Sanders by The Daily News, in which he repeatedly seemed unable to respond when pressed to go beyond his usual slogans. Mrs. Clinton, asked about that interview, was careful in her choice of words, suggesting that “he hadn’t done his homework.”