Do Presidential Debates Matter? Probably Sooner Than Later

By most accounts, Monday’s first presidential debate brings Americans a strange mixture of joy and despair. On one hand, this interminable campaign is finally entering its homestretch. On the other hand, an evening of hand-to-hand mudslinging will dominate our televisions and our discussions even more than usual.

Each season, the first head-to-head debate seems to mark the unofficial beginning of the campaign’s end. And while the buildup is always dramatic, the country seems especially on edge this time around. Not only have the polls been tightening of late, but there has also been unusually high variance in the results, adding extra uncertainty. Throw in two candidates who most Americans don’t like, and it’s no surprise that analysts are predicting Monday evening’s debate could be the most watched in history.

This got me wondering how much of a difference these election debates actually make. Do presidential debates matter really? Is all the commotion remotely justified? What do the hard data say?

I dug into the research.

As it turns out, the answer academics have come up with is a go-to favorite among ivory-tower types. Do the debates make a difference? It depends.  

First of all, general election debates seem to matter less than everyone thinks. Surveying the literature, Professor John Sides at George Washington University concludes that presidential debates usually have little to no effect on general election outcomes. One study he cites, by political scientists Robert Erikson and Christopher Wlezien, examined a big set of elections from 1952 to 2008. Their finding? “The best prediction from the debates is the initial verdict before the debates.”

So the general election debates hardly ever yield earth-shattering inflection points. But the data can still help us guess what might happen Monday night. In 2012, Nate Silver looked back at the historical record and found that the first debate usually helps the candidate whose party is out of power. Interestingly, he published his piece just a few days before Mitt Romney turned in an enormously successful performance in his first debate with President Obama. Romney’s big night won him a real bump in the polls (as per Silver’s analysis), but it soon faded away, and the underlying fundamentals of the race returned to the fore (as per Erikson’s and Wlezien’s hypothesis).

But this contrasts sharply with the research on primary debates, which seem to matter a lot. One 2013 study found that after primary debates, a whopping 35 percent of viewers said they changed their candidate preference. After the general election debates, only 3.5 percent of viewers said the same. People’s minds are seemingly only 1/10th as open during the general debates as during the primary debates. Why? I’ll make a few guesses.

For one thing, the primaries usually feature candidates with similar views. If voters can hardly distinguish between their options on policy substance, it makes sense that stylistic differences would exert a larger impact. What’s more, we hear a lot from primary voters that they are actually value debating skills pretty highly as an important trait that they’re looking for. (“I want someone who can really take the case to the other guy on national TV in October!”)

In sum, we are left with a bit of a paradox. While many primary voters seem to care a lot about rhetorical skills when they’re choosing who will represent their “team” in the general election, very few general election voters seem to be swayed permanently by those prime-time performances. As a result, debates matter a lot in the primaries but only a little in October.

Try dropping that factoid into the conversation at your debate watch party. It might be the most substantive talking point people hear all night.