Harry Frankfurt, an eminent moral philosopher and former professor at Princeton, wrote a brilliant essay in 1986 called “ On Bullshit .” ( Frankfurt himself wrote about Trump in this vein, as have Jeet Heer and Eldar Sarajlic .) In the essay, Frankfurt distinguishes crucially between lies and B.S.: “Telling a lie is an act with a sharp focus. It is designed to insert a particular falsehood at a specific point. . . . In order to invent a lie at all, [the teller of a lie] must think he knows what is true.”

But someone engaging in B.S., Frankfurt says, “is neither on the side of the true nor on the side of the false. His eye is not on the facts at all . . . except insofar as they may be pertinent to his interest in getting away with what he says.” Frankfurt writes that the B.S.-er’s “focus is panoramic rather than particular” and that he has “more spacious opportunities for improvisation, color, and imaginative play. This is less a matter of craft than of art. Hence the familiar notion of the ‘bullshit artist.’ ”

This has been Trump’s mode all his life. He boasts — and boasts and boasts — about his business, his buildings, his books, his wives. Much of it is a concoction of hyperbole and falsehoods. And when he’s found out, he’s like that guy we have all met at a bar who makes wild claims but when confronted with the truth, quickly responds, “I knew that!”