(SOUNDBITE OF 1988 VICE PRESIDENTIAL DEBATE)
LLOYD BENTSEN: I served with Jack Kennedy. I knew Jack Kennedy. Jack Kennedy was a friend of mine. Senator, you're no Jack Kennedy.
(SOUNDBITE OF 2000 PRESIDENTIAL DEBATE)
GEORGE W BUSH: Man's practicing fuzzy math again. There's differences.
(SOUNDBITE OF 2012 PRESIDENTIAL DEBATE)
MITT ROMNEY: I went to a number of women's groups and said, can you help us find folks? And they brought us whole binders full of women.
MICHEL MARTIN, HOST:
Recognize any of those lines from past debates? That's Lloyd Bentsen in 1988, Bush and Gore in 2000 and Mitt Romney four years ago. We've been talking about tomorrow's matchup between Hillary Clinton and Donald Trump, and we wanted to talk a little bit more about the point of a debate. And we were also wondering how do you win one? To figure that out, we called Allan Lichtman. He's a distinguished professor of history at American University in Washington, D.C.
ALLAN LICHTMAN: Different people are going to have different views of who won a debate. And the referee in the debate really is the American people as expressed through the polls.
MARTIN: Winning a debate does not necessarily ensure winning in November. But sometimes there are meaningful exchanges that can make a difference.
LICHTMAN: The debate that may have had the most to do with winners or losers - but even there it's hard to say - is the second debate in 1984. Reagan, sitting president, had kind of stumbled through the first debate. There was talk that maybe he was too old. And in one line in the second debate he dispelled all those ideas.
(SOUNDBITE OF 1984 PRESIDENTIAL DEBATE)
RONALD REAGAN: I will not make age an issue of this campaign. I am not going to exploit for political purposes my opponent's youth and inexperience.
MARTIN: Well, if they don't make that much difference, why even have them? We asked Larry Sabato, director of the University of Virginia Center for Politics. We spoke to him via Skype.
LARRY SABATO: In a sense, debates are catch-up time. It's an opportunity for voters to learn a lot about each candidate. The candidates may be repeating things they've said many times before. But millions of people haven't heard them many times before, maybe not at all.
MARTIN: But this year could be different because, as everybody knows, this election has been unconventional. Here's American University's Allan Lichtman.
LICHTMAN: I think this is the one year because the election is so different because of Donald Trump that the debates may matter. People are going to look at Donald Trump and, you know, take a hard look at him as to whether or not he really is fit to be commander in chief and chief executive of the United States. Transcript provided by NPR, Copyright NPR.