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.

Mr. Trump, famously, is a “birther” — someone who has questioned whether President Obama was born in the United States. But is that any worse than Scott Walker’s declaration that he isn’t sure whether the president is a Christian?

Mr. Trump’s declared intention to deport all illegal immigrants is definitely extreme, and would require deep violations of civil liberties. But are there any defenders of civil liberties in the modern G.O.P.? Notice how eagerly Rand Paul, self-described libertarian, has joined in the witch hunt against Planned Parenthood.

And while Mr. Trump is definitely appealing to know-nothingism, Marco Rubio, climate change denier, has made “I’m not a scientist” his signature line. (Memo to Mr. Rubio: Presidents don’t have to be experts on everything, but they do need to listen to experts, and decide which ones to believe.)

The point is that while media puff pieces have portrayed Mr. Trump’s rivals as serious men — Jeb the moderate, Rand the original thinker, Marco the face of a new generation — their supposed seriousness is all surface. Judge them by positions as opposed to image, and what you have is a lineup of cranks. And as I said, this is no accident.

It has long been obvious that the conventions of political reporting and political commentary make it almost impossible to say the obvious — namely, that one of our two major parties has gone off the deep end. Or as the political analysts Thomas Mann and Norman Ornstein put it in their book “It’s Even Worse Than It Looks,” the G.O.P. has become an “insurgent outlier … unpersuaded by conventional understanding of facts, evidence, and science.” It’s a party that has no room for rational positions on many major issues.

Or to put it another way, modern Republican politicians can’t be serious — not if they want to win primaries and have any future within the party. Crank economics, crank science, crank foreign policy are all necessary parts of a candidate’s resume.

Until now, however, leading Republicans have generally tried to preserve a facade of respectability, helping the news media to maintain the pretense that it was dealing with a normal political party. What distinguishes Mr. Trump is not so much his positions as it is his lack of interest in maintaining appearances. And it turns out that the party’s base, which demands extremist positions, also prefers those positions delivered straight. Why is anyone surprised?

Remember how Mr. Trump was supposed to implode after his attack on John McCain? Mr. McCain epitomizes the strategy of sounding moderate while taking extreme positions, and is much loved by the press corps, which puts him on TV all the time. But Republican voters, it turns out, couldn’t care less about him.

Can Mr. Trump actually win the nomination? I have no idea. But even if he is eventually pushed aside, pay no attention to all the analyses you will read declaring a return to normal politics. That’s not going to happen; normal politics left the G.O.P. a long time ago. At most, we’ll see a return to normal hypocrisy, the kind that cloaks radical policies and contempt for evidence in conventional-sounding rhetoric. And that won’t be an improvement.