Donald J. Trump, like any good reality TV protagonist, does not inspire neutral opinions. He is a savior or a disaster; a bigot or a patriot; a truth-teller or a buffoon; a commanding front-runner or a bubble on the verge of bursting. On one point, at least, there is something like political pundit consensus: that Mr. Trump’s abrasive, celebrity-driven, Don Ricklesian candidacy is unprecedented. And it is unprecedented, if your television-watching is limited to C-Span and CNN. But if you’ve watched reality TV over the past decade or two, you’ve seen it plenty. You’ve seen it in Richard Hatch and...
