By PAUL KRUGMAN

On Saturday, Senator John Barrasso of Wyoming delivered the weekly Republican address. He ignored Syria, presumably because his party is deeply conflicted on the issue. (For the record, so am I.) Instead, he demanded repeal of the Affordable Care Act. “The health care law,” he declared, “has proven to be unpopular, unworkable and unaffordable,” and he predicted “sticker shock” in the months ahead.

So, another week, another denunciation of Obamacare. Who cares? But Mr. Barrasso’s remarks were actually interesting, although not in the way he intended. You see, all the recent news on health costs has been good. So Mr. Barrasso is predicting sticker shock precisely when serious fears of such a shock are fading fast. Why would he do that?

Well, one likely answer is that he hasn’t heard any of the good news. Think about it: Who would tell him?

My guess, in other words, was that Mr. Barrasso was inadvertently illustrating the widening “wonk gap” — the G.O.P.’s near-complete lack of expertise on anything substantive. Health care is the most prominent example, but the dumbing down extends across the spectrum, from budget issues to national security to poll analysis. Remember, Mitt Romney and much of his party went into Election Day expecting victory.

About health reform: Mr. Barrasso was wrong about everything, even the “unpopular” bit, as I’ll explain in a minute. Mainly, however, he was completely missing the story on affordability.

For the truth is that the good news on costs just keeps coming in. There has been a striking slowdown in overall health costs since the Affordable Care Act was enacted, with many experts giving the law at least partial credit. And we now have a good idea what insurance premiums will be once the law goes fully into effect; a comprehensive survey by the Kaiser Family Foundation finds that on average premiums will be significantly lower than those predicted by the Congressional Budget Office when the law was passed.

But do Republican politicians know any of this? Not if they’re listening to conservative “experts,” who have been offering a steady stream of misinformation. All those claims about sticker shock, for example, come from obviously misleading comparisons. For example, supposed experts compare average insurance rates under the new system, which will cover everyone, with the rates currently paid by a handful of young, healthy people for bare-bones insurance. And they conveniently ignore the subsidies many Americans will receive.

At the same time, in an echo of the Romney camp’s polling fantasies, other conservative “experts” are creating false impressions about public opinion. Just after Kaiser released a poll showing a strong majority — 57 percent — opposed to the idea of defunding health reform, the Heritage Foundation put out a poster claiming that 57 percent of Americans want reform defunded. Did the experts at Heritage simply read the numbers upside down? No, they claimed, they were referring to some other poll. Whatever really happened, the practical effect was to delude the right-wing faithful.

And the point is that episodes like this have become the rule, not the exception, on the right. How many Republicans know, for example, that government employment has declined, not risen, under President Obama? Certainly Senator Rand Paul was incredulous when I pointed this out to him on TV last fall. On the contrary, he insisted, “the size of growth of government is enormous under President Obama” — which was completely untrue but was presumably what his sources had told him, knowing that it was what he wanted to hear.

For that, surely, is what the wonk gap is all about. Political conservatism and serious policy analysis can coexist, and there was a time when they did. Back in the 1980s, after all, health experts at Heritage made a good-faith effort to devise a plan for universal health coverage — and what they came up with was the system now known as Obamacare.

But that was then. Modern conservatism has become a sort of cult, very much given to conspiracy theorizing when confronted with inconvenient facts. Liberal policies were supposed to cause hyperinflation, so low measured inflation must reflect statistical fraud; the threat of climate change implies the need for public action, so global warming must be a gigantic scientific hoax. Oh, and Mitt Romney would have won if only he had been a real conservative.

It’s all kind of funny, in a way. Unfortunately, however, this runaway cult controls the House, which gives it immense destructive power — the power, for example, to wreak havoc on the economy by refusing to raise the debt ceiling. And it’s disturbing to realize that this power rests in the hands of men who, thanks to the wonk gap, quite literally have no idea what they’re doing.