Would anyone cast a vote for political office, from president down to dogcatcher, because a candidate was nice? Perhaps not. Yet in last year’s presidential election, many Americans voted against Donald Trump less because of his policies than because they thought him a braggart, a bully, a buffoon—all things a nice guy isn’t. Had Mr. Trump been less bumptious, had he attempted to establish himself as a more sympathetic figure, would he be beginning his second term as president? Hard to know, but exhibiting a touch or two of niceness surely wouldn’t have hurt his chances.

How many of our recent presidents or presidential candidates qualified as nice? Ronald Reagan was less nice than charming, which isn’t the same; charm is about outer attractiveness, niceness about inner thoughtfulness. George H.W. Bush, who tried to sell himself as a Texan, never lost the East Coast WASP in himself that came off as more dignified than nice. Bill Clinton’s claims to niceness were squashed by reports of his sexual predations. Barack Obama came off as nice; he seemed a good father and devoted husband. But he could also be acerbic when challenged. Hillary Clinton might have lost the presidency by too clearly establishing her lack of niceness. How many votes, one wonders, did she lose by calling Mr. Trump’s supporters “deplorables”?