The outright falsehoods, you won’t be surprised to learn, tend to be politically motivated. In those 1996 data, Republicans were much more likely than Democrats to hold false views about the deficit, and the same must surely be true today. After all, Republicans made a lot of political hay over a supposedly runaway deficit early in the Obama administration, and they have maintained the same rhetoric even as the deficit has plunged. Thus Eric Cantor, the second-ranking Republican in the House, declared on Fox News that we have a “growing deficit,” while Senator Rand Paul told Bloomberg Businessweek that we’re running “a trillion-dollar deficit every year.”

Do people like Mr. Cantor or Mr. Paul know that what they’re saying isn’t true? Do they care? Probably not. In Stephen Colbert’s famous formulation, claims about runaway deficits may not be true, but they have truthiness, and that’s all that matters.

Still, aren’t there umpires for this sort of thing — trusted, nonpartisan authorities who can and will call out purveyors of falsehood? Once upon a time, I think, there were. But these days the partisan divide runs very deep, and even those who try to play umpire seem afraid to call out falsehood. Incredibly, the fact-checking site PolitiFact rated Mr. Cantor’s flatly false statement as “half true.”

Now, Washington still does have some “wise men,” people who are treated with special deference by the news media. But when it comes to the issue of the deficit, the supposed wise men turn out to be part of the problem. People like Alan Simpson and Erskine Bowles, the co-chairmen of President Obama’s deficit commission, did a lot to feed public anxiety about the deficit when it was high. Their report was ominously titled “The Moment of Truth.” So have they changed their tune as the deficit has come down? No — so it’s no surprise that the narrative of runaway deficits remains even though the budget reality has completely changed.

Put it all together, and it’s a discouraging picture. We have an ill-informed or misinformed electorate, politicians who gleefully add to the misinformation and watchdogs who are afraid to bark. And to the extent that there are widely respected, not-too-partisan players, they seem to be fostering, not fixing, the public’s false impressions.

So what should we be doing? Keep pounding away at the truth, I guess, and hope it breaks through. But it’s hard not to wonder how this system is supposed to work.