As 20 Democratic contenders face off this week, here's a look at some stories from our archives that offer insight into the format.

(Photos: Drew Angerer, Nicholas Kamm, Emmanuel Dunand & Win McNamee/Getty Images; Illustration: Ian Hurley/Pacific Standard)

With the 2020 election still more than a year away, there is plenty of time for the people of the United States to shape and reshape their opinions of the 24 candidates currently vying for the Democratic nomination. This week, 20 of those candidates will attempt to shift opinions in their favor during the first official Democratic debate, which will be split into two events, taking place on Wednesday and Thursday evenings.

But will these debates actually change how voters feel about the candidates? And who will win? Here's a look at some stories from our archives that offer insight.

People Like to Learn About Candidates Through Debates

Research has shown that people are more knowledgeable about where candidates stand on issues after debates, Francie Diep wrote in 2017—and, according to one survey, debates are the way American voters prefer to learn about their choices:

Americans of all ages said debates were their favorite election information source, outranking "watching broadcast interviews or seeing the candidates in person," "published positions on key issues," and "news coverage of presidential campaigns."

Debates Can Be Helpful—but Don't Ask Who Won

According to Seth Masket, debates serve a number of functions:

They can allow us to watch the candidates think and respond in real time, going beyond their stump speeches. They can force candidates to make commitments to audiences, commitments which they would later work to meet once in office. They can be useful for airing disagreements within a party. They can help convey a party's or candidate's messages to a larger audience.

But, Masket argues, they're not sporting events with winners and losers, and making such a determination would not be useful anyway: Winning a debate would not likely make a candidate more likely to win the nomination.

Or Maybe Everyone Wins?

While making a serious blunder in a debate can hurt a candidate, debates tend to equalize the participants, according to a study published in The International Journal of Press/Politics. As political scientist Andrea M.L. Perrella of Ontario's Wilfrid Laurier University told Tom Jacobs:

Generally, everybody comes out of a debate better off.... As we have learned from Hollywood, any publicity is good publicity. As long as we're talking about the candidates, we're thinking about the candidates, and that thinking process may elevate the evaluations. The less we know, the more we are prone to render a negative evaluation.

But If You Still Want to Win in This Crowded Field…

In a 10-person debate—as Seth Masket explained before the first Republican debate for the last presidential election—your opponent isn't really the other nine participants: