(Reuters) - If the federal government fails to pay its bills and the interest on its borrowing by the middle of the month, it is the overwhelming verdict of the nation's smartest economists that financial mayhem will ensue.

Until this week, no one on either side doubted that. In fact, it was implicit in the Republican case for using the debt ceiling as a lever to cut public spending. Only with the threat of Armageddon in the markets and the prospect of a return to the Crash of 2008 did the Republican bartering make any sense.

Now the looser cannons on the GOP deck have changed their tune. At last count, seven House members and six senators have suggested the government can remain shut down in perpetuity and America can fail to make interest payments on its borrowing and nothing much will happen.

Hard-right Republicans' rejection of basic economics is just the latest example of how they have abandoned rational thought and refuse to accept established scientific facts. Consider their arguments against evolution.

Not long ago, Republicans were hardheaded realists who derided the woolly pipe dreams of their Democratic rivals. Now they appear to have lost all touch with reality, embracing notions that used to be the preserve of paranoid eccentrics who write rambling letters in green ink.

While we live in the Age of Obama, they are living in the Age of Unreason.

For Senator Rand Paul (R-Ky.), the threat of America not paying its debts is not so much about economics as semantics. "It really is irresponsible of the president to try to scare the markets," he said. "If you don't raise your debt ceiling, all you're saying is, ‘We're going to be balancing the budget.' … the American public will say that sounds like a pretty reasonable idea."

An ophthalmologist by trade, Paul should forget grappling with economics and tend to his own shortsightedness.

The flat denial — even in the face of the fact that freezing the federal economy is already causing profound business uncertainty — that blowing past the debt ceiling could lead to a steep stock market slide and will provoke skyrocketing interest rates that could ricochet around the world and set the scene for another Great Recession is part of a pattern. These same Republicans were indifferent to the consequences of the sequester — a mindless, deep slashing at entitlements and defense spending they insist is doing no harm. If they looked around them they would see how the sequester is unfairly causing misery.

Economics has long been an act of faith rather than a rational scientific study for some conservatives and libertarians. The pretense that a successful modern economy could do without a strong central government or that a government should somehow not influence economic policy by intervening is fanciful. There is a reason we are living under the all-pervading influence of John Maynard Keynes rather than the Austrian economists who challenged him, Ludwig von Mises and Friedrich Hayek.

Keynes won the argument 80 years ago and transformed our understanding of economics. There is no putting that toothpaste back in the tube. Some deluded conservatives and libertarians may wish to live in an alternative reality where history never happened, but Keynes won and the Austrians lost. The right should get over it.

Ignorance about business, finance and economics is new to the GOP, which was once the proud party of big business and Wall Street. Now driven by the Tea Party, angry at bankers and Wall Street types who were saved by the government from bankruptcy in 2008 and 2009, the congressional GOP is being pushed around by a radical sect willing to risk the collapse of the world economy rather than accept that the Affordable Care Act is the law of the land.

Little wonder that Wall Street donors are pondering whether they should continue feeding dogs that bite them. It makes you wonder, too, whether the sons and daughters of the anarchists and communists who plotted the overthrow of capitalism have infiltrated the GOP to get the job done. The Party of Lincoln has become the Party of Lenin.

Ignorance about economics is just one example of how a resistance to facts has become an electoral asset for a Republican seeking a candidacy from a mob of ignoramuses. Nowhere is this clearer than in the evolution debate, where a fondness for creationism upends science in the name of piety.

Charles Darwin's contention that we are all descended from common ancestors caused uproar when he first floated it in the 1830s. No one likes being made a monkey. But educated people cannot doubt the wealth of evidence that Darwin was right. All, that is, except the GOP holdouts.

The dodgy science underpinning the prejudices of those who ignore scientific facts became evident in the last general election. For example, GOP Senate candidate Richard Mourdock said, "I believe God controls the universe. I don't believe biology works in an uncontrolled fashion."

Wishful thinking only got him so far. Mourdock convinced Republican primary voters he should be their Senate candidate — then he lost the general election.

This denial of knowledge, or just plain ignorance, is widespread. Recall the absurdity of GOP Senate candidate Todd Akin. "From what I understand from doctors," Akin said, "If it's a legitimate rape, the female body has ways to try to shut that whole thing down."

Akin, a married man with two daughters and four sons — all home-schooled, which may explain a lot — is plainly not paying attention to what goes on under his roof. Before pronouncing on women's health, he should have spent less time talking to "doctors" and more time asking his wife and daughters about the birds and the bees. Despite wearing a dunce's cap, Akin won the primary — but then lost the election.

The fostering of ignorance has also altered the climate change debate. Once it was universally acknowledged that global warming existed, though the reasons for it were less certain. Then came a well-funded campaign to cast doubt on the science behind climate change and disparage the distinguished researchers who provided hard evidence that the globe is getting warmer.

Though the muddying of the science was paid for by the big oil brothers Charles and David Koch, whose interest in keeping the world burning fossil fuels is not in doubt, climate change denial found a ready audience among contrarians, curmudgeons and doubters who welcomed the new "evidence." It proved their conspiracy theory that all this science was a put-up job. These cranks and kooks even deny they are in denial.

Conservatism has always represented a stand against the tide of history. Progress is an anathema to many who wish the world would stop spinning while they catch up.

But elevating ignorance over scholarship should have no place in conservatism. The role of political leadership is to gently persuade people to face the world as it is, the better to change it. The Age of Unreason that insists that Hayek won, that Darwin lost, that hot is cold, and that babies are found under gooseberry bushes brings all rational debate to a halt.

Who can reason with those who, to gain popularity with the foolish and the shallow, rail against the real world?

America may have reached a crossroads. That is what the president suggests by drawing a red line over the debt ceiling. He has decided it is time for a showdown between the realists and the fantasists. Tea Party Housemembers, who appear to have kidnapped Speaker John Boehner, wish to ignore the facts. They regret passage of Obamacare — though it sprang from an idea from the conservative Heritage Foundation. They deny it is truly the law, they deny the Supreme Court found it constitutional and they deny that the straight up and down vote over Obamacare last November re-elected the president with a plurality of votes.

Which part of democracy do they not understand? They lost. The president won. They should stop pretending that the last five years never happened.

A small but significant number, however, are insisting that unless Obamacare is defunded, delayed or repealed now they will not pass a budget nor a debt ceiling increase. They assert that the economic consequences — which all those with knowledge of finance, business and economics say will be disastrous — may even be good for America. These deniers have reduced the public discourse to a farce by declaring that up is down and vice versa.

There is a term in psychology known as the Dunning-Kruger effect. "People tend to be blissfully unaware of their own incompetence," David Dunning and Justin Kruger wrote. "Their lack of skill deprives them not only of the ability to produce correct responses, but also of the expertise necessary to surmise that they are not producing them."

In other words, some people are too stupid to know how stupid they are.

(Nicholas Wapshott is a Reuters columnist. The opinions expressed are his own.)