Why would the much-married Donald Trump, billionaire, self-promoter, real-estate developer, and leading figure in the world of flashy entertainment, a man who until recently apparently accepted the views of his class on hot-button political and social issues, suddenly become the leading contender for the Republican presidential nomination?

The man’s been successful in a variety of very competitive pursuits, so he’s no dummy. He’s put together large projects in New York City, so he knows something about practical politics and dealing effectively with complex situations in ways that bring difficult people together. And he obviously knows how to get and use publicity, a crucial skill in an age in which spin and image swamp achievement and reputation.

But all that is not enough to explain his sudden rise. The missing piece of the puzzle is the artificiality of public life in the United States. In a land of chain stores, internet memes, pop-culture formulas, and endless consultants, Trump has his own highly charged way of communicating. Whatever the topic, he attracts notice when he speaks.

He’s a successful entrepreneur with a brand he’s created for himself without the aid of pollsters, focus groups, or handlers. As such, his words and actions are of course designed for effect—he’s a pro-wrestling version of a politician rather than an...