The problem is, those pivotal moments weren’t pivotal, after all. In fact, political science research shows that presidential debates rarely, if ever, decide a presidential election. Most people have their minds up about the presidential race by the time the debates roll around. The reason they watch, then, is not to decide who to vote for, but to cheer on their team. As political scientist Jody Baumgartner puts it: “Rather than swaying voters' minds, presidential debates tend to reinforce voters' preexisting views.”
It’s true, you may see a post-debate bump (or dip) for one of the candidates. But that doesn’t mean voters are changing their minds, necessarily. For example, after then-President Barack Obama’s faceplant in the first debate of 2012 — which even Democrats conceded he had “lost” — Republican challenger Mitt Romney seemed to close the gap in national polls. But a later analysis by political scientists John Sides and Lynn Vavreck showed that Romney had not actually won over Obama voters; rather, these gains mostly represented wavering Republicans “coming home” to support Romney, as they probably would have done eventually, anyway.
In the same way, Trump, for example, might gain in the polls following a better than expected debate performance against Biden. But if so, will this be because he has persuaded independents or Democrats to support him? Or because wavering Republicans — perhaps alienated by Trump’s pandemic response or personal conduct — seize on this excuse to return to the party fold?
By all means, watch the debate on Tuesday. I’ll be joining you. But, like me, you shouldn’t expect it to decide the 2020 election.
Christopher J. Devine is an assistant professor of political science at the University of Dayton.