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More than 70 million people tuned in to the presidential debate Tuesday night, and the political commentators among them found the event appalling, even excremental. “That was a shitshow,” CNN’s Dana Bash declared. “We’re on cable—we can say it. Apologies for being crude. But that is really the phrase I’m getting from people on both sides of the aisle on text, and the only phrase I can think of to describe it.”

During the debate, Donald Trump had relentlessly interrupted and talked over Joe Biden and the moderator, Chris Wallace. In media coverage, a consensus quickly formed. Yesterday’s episode of the podcast The Daily came with the warning “This episode contains strong language.” The host, Michael Barbaro, reported that his own mother—“not someone who curses in text messages”—had texted to say, “This is a shitshow.” A teaser for a BuzzFeed News story read, “DEBATE NIGHT: THE GREAT AMERICAN SHITSHOW.”

All of that revulsion fueled calls to cancel the two remaining presidential debates. “Tonight was the first presidential debate of the 2020 election, and if there is any sense or mercy left in this nation, it will be the last too,” David A. Graham wrote in The Atlantic. James Fallows said the chaos “calls into question the value of having any ‘debates’ of this sort ever again.”

Yesterday afternoon, the Commission on Presidential Debates said it would soon announce changes in the structure of the remaining debates, to “ensure a more orderly discussion of the issues.” But canceling future debates would be a mistake. They serve a purpose in American elections that nothing else does and reach citizens whom nothing else in political news can. And if 70 million people came away from the cacophony thinking that American politics is a shit show, were they wrong? Anyone who tuned in expecting a Lincoln-Douglas debate, or an elegant contest between dueling ideologies, was sure to be disappointed.

Still, most of the people watching haven’t been following the race as closely as CNN commentators or podcast hosts do, and they don’t have as committed a partisan or ideological identity. They still have space to learn something new. And when nearly every other part of the political-media complex has been optimized for polarization, debates are one of the few forces pushing in the opposite direction.

Think back to what the media universe was like before Twitter, before Fox News, before Facebook memes. The day’s political updates were funneled through just a few major news organizations: the three broadcast-TV networks, major national or regional newspapers, and wire services. Each outlet had its flaws, but each generally tried to present the latest news through a down-the-middle lens. And these outlets, especially the network-TV newscasts, reached massive audiences. If you watched television at the dinner hour, you had little choice but to watch Walter Cronkite, David Brinkley, or their local equivalents.

On an average evening in 1968, the ratings company Nielsen found, 60 percent of American households had the television on. Of those, about three-quarters were watching a national network newscast. As the political scientist J. Austin Ranney put it in 1983: “When the local and national newscasts mix some political stories in with the others, as they usually do, the passive and not-very-political viewers in the inadvertent audience do not bother to switch channels … So the viewers absorb some political information even when they do not seek it.”

An example: The major networks all aired extensive coverage of the Democratic and Republican nominating conventions every four years. In 1956, those conventions were watched by an astonishing 93 percent of U.S. households with TVs, and for an average aggregate time of more than 16 hours. According to Nielsen data, 4 million homes were still watching at 2:30 a.m. on one night of the Democratic convention, as delegates debated a civil-rights plank in the party’s platform.

Those news shows on ABC, CBS, and NBC—and the fact that people who wanted to watch TV had few other choices at certain hours—had an effect on the Americans who watched them. And the impact was greatest on those who were less educated and who were less interested in politics.

Before TV, political news was available in newspapers. But if you weren’t a political junkie, those articles were easy to skip. “People can learn a lot more about politics from newspapers than from television news—but only if they read the articles,” Princeton’s Markus Prior wrote in his book Post-Broadcast Democracy. “Those who do not buy or borrow a paper do not learn.”

Television news attracted a much broader audience, and less-educated Americans were more likely to watch it than more-educated ones. Prior examined survey data dating back to 1948 and found that for people with an eighth-grade education, the establishment of multiple TV stations in their city led to a roughly 12 percent increase in their political knowledge. Their interest in politics also increased, by about 22 percent. (The impact on both political knowledge and interest was minimal for those who had more than a high-school education—people who were likely already reading political news in newspapers.)

The gap between how likely more- and less-educated Americans were to vote in an election shrank substantially once they had a few options on their VHF dial. And the increases in overall voter turnout were largest in U.S. counties with the lowest levels of education.

That had a major impact on American politics too. Bringing those less engaged citizens into the electorate also tended to support a less polarized, more moderate politics. Prior’s research found that these new voters were less likely to be dedicated partisans or ideologues than the political junkies standing ahead of them in the voting line.

What does all of this have to do with the debate Tuesday night? The old three-network universe is long gone. Anyone with a data plan now has infinite access to political news. But that’s led to whole new sets of divides.

One of those centers around interest. People who love politics can now see minute-by-minute outrages on Twitter, read a dozen political email newsletters each morning, and broadcast the latest Trump or Biden video to their like-minded friends. But for those who aren’t so interested in politics, checking out of it entirely is easier than ever. They can fill their Instagram feed with celebrities and influencers. They can while away an empty hour playing Candy Crush instead of flipping through a magazine. Research has shown that having more media options increases the gap between those who follow politics and those who couldn’t care less.

The other divide centers around partisanship. You don’t have to spend much time online to notice an enormous boom in ideologically driven media—conservative sites, liberal sites, Trumpist sites, Never Trumper sites. A three-network America had no room for a Breitbart, but partisan news becomes more popular in a world of infinite choice. Each day’s list of the most-shared links on Facebook is chock-full of red-meat posts for one political side or the other. (The conservative side, most often.)

In this world of partisan media and curated feeds, the presidential debates are just about the only relic of the old mass-media world. They’re the rare moment of political news that isn’t designed for one psychographic slice of the population or another. A debate is just the candidates, the moderator, and 90 minutes. Fierce partisans who live in different political universes are watching the same images and hearing the same words. And people who haven’t been paying attention to the race—people who have no idea who Chuck Todd is—watch in big numbers.

In 2016, 84 million people tuned in to the first debate between Trump and Hillary Clinton—and that’s not counting everyone who saw it at a watch party, in a bar, or via streaming video. How many American TV programs have had a bigger audience than that? The M*A*S*H finale and Super Bowls—that’s it. In the Trump-Clinton debate, more people heard the Republican nominee say that Mexico would pay for the wall than learned who shot J.R. or watched the finales of Cheers, Seinfeld, or Friends. The top-rated show on American television in 2016, NBC’s Sunday Night Football, averaged 20.3 million viewers; this had four times that. The Oscars had 34.3 million viewers that year.

Viewership remained huge for the two other presidential debates in 2016, with 66.5 million and 71.6 million tuning in. Given that 136.7 million people voted that November, the debates likely reached a majority of all voters. And most people who watch stick around for the whole thing. In 2012, Nielsen found that 60 percent of debate viewers did not tune out until the final handshake.

No other campaign event comes close. The peak audience at this year’s party conventions—during Trump and Biden’s acceptance speeches—topped out at 23.8 million for Republicans and 24.6 million for Democrats. (These viewers are much more likely to have their mind made up; the audience for each party’s convention is disproportionately composed of its own supporters.) State of the Union audiences can be large—under Trump and Barack Obama, viewership each year has come in between 31 million and 52 million—but those aren’t happening a few weeks before the most consequential votes Americans make.

Not much strong evidence suggests that presidential debates consistently help one party or the other, or convert many viewers from one candidate to the other. But in election cycles since 1992, about 10 percent of voters have said they made up their mind on who to vote for during or just after the presidential debates.

Debates offer the sorts of interactions that don’t happen in other campaign contexts. Candidates spend months giving stump speeches in front of friendly audiences; on the debate stage, they pitch to something closer to the median American voter. And while there are plenty of venues in which politicians’ lies or exaggerations get fact-checked, there’s rarely an opportunity for immediate pushback, from an opponent or a moderator, live and in real time.

Many people who comment on politics for a living were quick to say that the noise overpowered the signal Tuesday—that the public had nothing to learn from watching Trump and Biden. Yet the debate could, in fact, change the audience’s opinions of the contest and the two candidates in it.

For some viewers, what they saw might dispel misinformation peddled by one party about another. Other viewers might not previously have paid much attention. People lead busy lives, as they deal with work and remote schooling and all the other stressors of day-to-day life in 2020. Politics makes them anxious or depressed; they don’t view it as entertainment or distraction. But they’ll put in 90 minutes to watch a presidential debate. And the information they get from it doesn’t have to be about policy. They’re seeing how candidates react under stress, and how much concern each one shows about people like them.

Viewers of Tuesday’s debate may not have learned a lot about the candidates’ health-care plans. But they did learn about the two men on stage. Just look at the reactions of voters who watched, whether undecided or already committed. If you’re describing someone you were considering voting for as “unhinged,” “chaotic,” a “bully,” or “un-American,” it means the debate had an impact.

By all means, find ways to improve the debates that still remain on the calendar. But the problem with the shit show had much less to do with the concept of a presidential debate and much more to do with Donald Trump and his decision to be … Donald Trump. If he had suddenly acted “presidential”—never interrupting, primly addressing Biden as “the gentleman from Delaware,” saying please and thank you—the debate would have been much more pleasant to watch. But it also would have presented a false picture of who he is. This is a deeply, profoundly ugly time in American politics—it shouldn’t be surprising that it produced such an ugly debate.

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