As TV news approaches more moments of truth (and untruth) in the coming presidential debates.

Hillary Clinton and Donald Trump appeared for the first time on the same stage (though not at the same time) Wednesday night during an NBC-hosted forum moderated by longtime Today Show co-anchor Matt Lauer. Lauer neglected to call out Trump on his factual inaccuracies, including the false claim that he opposed the Iraq War (Trump initially supported it), but did repeatedly interrupt Hillary Clinton.

Lauer’s unimpressive performance makes Todd Gitlin’s new post on the moderators’ role in the presidential debates all the more relevant. In it, Gitlin writes: “Toward the goal of helping viewers and listeners evaluate the abilities of the candidates, one principle should be simple: It’s better for the moderator to dispute one false claim than none; better two than one; better three than two.”

Chris Wallace wants be seen as a self-effacing fellow. “I see myself as a conduit,” he told Howard Kurtz, Rupert Murdoch’s idea of a house media critic.

Both men were celebrating Wallace being chosen as moderator of the third presidential debate on Oct. 19, the first time a Fox News figure has been picked to moderate a general election debate. Wallace was emphatic about his mission: “I do not believe that it’s my job to be a truth squad.” Kurtz, who winced visibly at the laughable thought that anyone could think that Fox News was a right-wing network, asked: “Does this help dispel that perception?” Wallace, no fool, pulled back from the invitation to read the minds of the audience, but crowed that he had been designated (along with the other moderators) by a “blue-ribbon” Commission on Presidential Debates headed by Democratic and Republican bigwigs, who, it’s fair to say, value the debates’ reputation for “nonpartisanship” more than their fidelity to truth.

Wallace was clear on what his task was not: “I do not believe that it’s my job to be a truth squad. It’s up to the other person to catch them on that” — i.e., to correct falsehoods. In his conception, a moderator is a talk-show or dinner-party host or a traffic cop who operates under Three Commandments.

Rule 1: Keep the conversation flowing. (“If one of them is filibustering, I’m going to try to break in respectfully and give the other person a chance to talk….[E]ngage the two [candidates] in conversation.”)

Rule 2: Be unobtrusive. (“I view it as kind of being a referee in a heavyweight championship fight. If it succeeds, when it’s over people will say, ‘You did a great job. I don’t even remember you on the stage.’”) If the candidate is down, make sure the opponent moves to a neutral corner. Of course, if I’m not mistaken, it’s also the referee’s job to call out punches beneath the belt, but never mind.

Rule 3 might be especially interesting: “Ask smart questions.” But what’s the test of smartness? Is it enough to ask a question that ranks A on the great report card in the sky? In the end, is it such a smart question if a candidate succeeds in dodging it or dissembling? In that case, doesn’t a smart question demand one or more smart follow-up questions? Doesn’t a certain kind of smart question invite the candidates to reveal something of their ideas about government, their commitments, values, knowledge and moral seriousness? Isn’t another kind of smart question one that demands of the candidates a grown-up recognition that all policies produce both winners and losers?

We’ll see how well Wallace does.

The chief criterion for a good debate is not simply whether it flows or whether it appears “fair and balanced.” That criterion must be whether it illuminates what is at stake in the election; how the candidates approach issues; how they arrive at judgments; and how they address conflict, which is, after all, the mother’s milk of politics. Toward the goal of helping viewers and listeners evaluate the abilities of the candidates, one principle should be simple: It’s better for the moderator to dispute one false claim than none; better two than one; better three than two.

To be fair and balanced, the problem is not solely Chris Wallace’s idea about moderator decorum. The “blue-ribbon” Commission on Public Debates shares the blame. Here is their announced job description:

The CPD uses three criteria to select its moderators: a) familiarity with the candidates and the major issues of the presidential campaign; b) extensive experience in live television broadcast news; and c) an understanding that the debate should focus maximum time and attention on the candidates and their views.

They all have that noncontroversial ring, or thud, familiar to viewers of TV news, but the third is the worthiest of attention. What does it mean to “focus maximum time and attention on the candidates and their views”? If the moderator nods as the candidate distorts the truth, this does not qualify as attention worth paying attention to. This qualifies as a certificate of successful evasion. Suppose the candidate issues two falsehoods, and her opponent corrects only one. Wouldn’t the audience benefit from a correction of the other?

If the moderator lets falsehoods go undisputed — say, how much violent crime is committed by immigrants, and whether a budget deficit is dangerous — said moderator has not in fact demonstrated “familiarity with the candidates and the major issues of the presidential campaign.” If the candidates share a consensus on what is in fact a highly disputable claim — say, that bad trade deals are major reasons for job shrinkage and low wages — then the moderator has left intact a debatable proposition and no one is left the wiser. Unlike the referee, the moderator has a responsibility to the audience. It’s them, ourselves, the citizens, not the knockout king, that’s either the winner or the loser.

If a candidate evades a question and the opponent wants to make a point of her own, is it not a public service for the moderator to say, “You didn’t answer the question”? To return to Wallace’s metaphor, if the boxer comes out of his corner with his glove dripping with some unknown substance, is it not the job of the referee to interfere?

When one of the debaters is Donald Trump, let us grant that the moderator is faced with a practical problem. In the case of Trump, Politifact judged that, in sum, for 2015-16, if we look at all of Donald Trump’s statements of fact, 4 percent were true, 11 percent mostly true, 15 percent half-true, 17 percent mostly false, 35 percent false and 18 percent “pants on fire.” On one occasion in March, The Huffington Post had reporters examine the transcript of a Trump town hall the night before. They found “71 separate instances in which Trump made a claim that was inaccurate, misleading or deeply questionable” — more than one a minute. At that pace, Trump’s tropism toward untruth poses a serious challenge to any moderator — or opponent or fact-checker, for that matter — especially when everyone is limited to short statements. It is not too much to ask all the moderators — Lester Holt, Elaine Quijano (for Tim Kaine and Mike Pence), Martha Raddatz and Anderson Cooper, as well as Chris Wallace — to expose blatant untruths and correct the most egregious ones.

Over the course of the same period, Politifact claims a grand total 15 falsehoods committed by Hillary Clinton. Others may count differently, but the reader might survey Politifact’s list and see if they rise to the gravity of the Trump list. My judgment is that they do not, that most of Clinton’s falsehoods are errors of hype rather than errors of rank ignorance and deception. If the moderators have a different view, fine, let them demonstrate her errors as well. But do not let Trump’s sheer gushing bounty of lies, half-truths and quarter-truths become an excuse for letting him flow on uninterrupted to muddy the republic.

Todd Gitlin is a professor of journalism and sociology and chair of the Ph.D. program in communications at Columbia University. He is the author of 16 books, including several on journalism and politics. His next book is a novel, The Opposition. Follow him on Twitter:@toddgitlin.