Saturday will see Hillary Clinton and Donald Trump face off in the first of three planned televised debates between the presidential candidates.

James Fallows, in a preview of the debates for The Atlantic, argues they are “must-watch TV” because they will see the most extreme contrast of personal, intellectual and political styles in American democratic history: “Right brain versus left brain; gut versus any portion of the brain at all; impulse versus calculation; id versus superego; and of course man versus woman.”

No doubt, with Trump’s penchant for spectacle, the debates will be watched by many — tens, maybe hundreds of millions around the world.

But will they matter?

People hear what they want to hear

Not really, writes Jonathan Bernstein for Bloomberg View.

For all their hype, Bernstein points out that the debates don’t have much of an effect on voter choice:

People hear what they want to hear, so most Hillary Clinton supporters will wind up convinced she did well while most Donald Trump supporters will think he “won.”

Even when the debates appear to produce a temporary shift in the polls — such as four years ago, when Barack Obama didn’t impress in his first confrontation with Mitt Romney — the evidence suggests this is more of a survey effect than anything else:

If a candidate is perceived as doing poorly, his or her supporters are (briefly, while the story is still in the news) less likely to respond to pollsters, thus giving the false impression of a real shift in the electorate.

Is Trump different?

I’m not quite convinced Bernstein’s logic will hold this year. Perhaps seeing Trump struggle with the issues in the debates will — finally — convince center-right voters he is unworthy.

If so, it will be more of a final straw, though, than a sudden realization Trump is ill-prepared for the presidency.

In that sense, Bernstein is probably right and the debates do more to reinforce voters’ existing perceptions of the candidates than they change them.

Which is for the best, because — as he points out — debate skills aren’t really important for a president to have. Formal debates do not resolve foreign-policy crises or disputes with Congress. “Nor is the ability to deliver pre-planned zingers important to the functioning of the presidency.”