It was death by a thousand smiles: the first presidential debate, on Wednesday night, was perhaps the most genial exchange of enmity in memory. President Obama and Mitt Romney did not just spar over tax policy and deficit reduction, they fought to see who could keep a look of amused, there-you-go-again contempt for the longest number of minutes.

Wary of split screens on CNN and other networks, Mr. Romney managed, despite a dry throat and some rapid blinking, to keep a choirboy smile pasted on his face while Mr. Obama spoke; Mr. Obama was quicker to drop his bonhomie and adopt the look of a long-suffering headmaster enduring the excuses of a bright student he is going to expel.

Theirs was a glaringly public confrontation that looked oddly intimate and personal. And that may help explain why tens of million of people tune in — there is nothing else like it on television. It’s not a gladiator fight, or a boxing match or the Super Bowl; it’s not a quiz show, a singing competition, a beauty pageant or a finale of “Survivor.” If anything, these confrontations look more like a dispute in couples therapy: neither partner can really win, but either one could get rattled and blurt out something unforgivable.