This was, according to many commentators, going to be the election cycle Republicans got to show off their “deep bench.” The race for the nomination would include experienced governors like Jeb Bush and Scott Walker, fresh thinkers like Rand Paul, and attractive new players like Marco Rubio. Instead, however, Donald Trump leads the field by a wide margin. What happened?

The answer, according to many of those who didn’t see it coming, is gullibility: People can’t tell the difference between someone who sounds as if he knows what he’s talking about and someone who is actually serious about the issues. And for sure there’s a lot of gullibility out there. But if you ask me, the pundits have been at least as gullible as the public, and still are.

For while it’s true that Mr. Trump is, fundamentally, an absurd figure, so are his rivals. If you pay attention to what any one of them is actually saying, as opposed to how he says it, you discover incoherence and extremism every bit as bad as anything Mr. Trump has to offer. And that’s not an accident: Talking nonsense is what you have to do to get anywhere in today’s Republican Party.

For example, Mr. Trump’s economic views, a sort of mishmash of standard conservative talking points and protectionism, are definitely confused. But is that any worse than Jeb Bush’s deep voodoo, his claim that he could double the underlying growth rate of the American economy? And Mr. Bush’s credibility isn’t helped by his evidence for that claim: the relatively rapid growth Florida experienced during the immense housing bubble that coincided with his time as governor.