Once upon a time the Republican Party included a few widely-respected leaders who valued reason and flexibility — names like Eisenhower, Javitz, Weicker and a few others come to mind. Hell, Nixon was a paragon of sanity compared to some of the loons running the GOP asylum now. if this sounds overstated, read Richard Cohen’s Sunday WaPo column “A Grand Old Cult,” in which he explains:

To become a Republican, one has to take a pledge. It is not enough to support the party or mouth banalities about Ronald Reagan; one has to promise not to give the government another nickel. This is called the “Taxpayer Protection Pledge,” issued by Americans for Tax Reform, an organization headed by the chirpy Grover Norquist. He once labeled the argument that an estate tax would affect only the very rich “the morality of the Holocaust.” Anyone can see how singling out the filthy rich and the immensely powerful and asking them to ante up is pretty much the same as Auschwitz and that sort of thing.
…Almost all the GOP’s presidential candidates have taken this oath, swearing before God and Grover Norquist to cease thinking on their own, never to exercise independent judgment and, if necessary, to destroy the credit of the United States, raise the cost of borrowing and put the government deeper into the hole.

Cohen notes the role of revisionist history and denial in the Republicans’ increasingly unhinged worldview:

…The hallmark of a cult is to replace reason with feverish belief. This the GOP has done when it comes to the government’s ability to stimulate the economy. History proves this works — it’s how the Great Depression ended — but Republicans will not acknowledge it.
The Depression in fact deepened in 1937 when Franklin D. Roosevelt tried to balance the budget and was ended entirely by World War II, which, besides being a noble cause, was also a huge stimulus program. Here, though, is Sen. Richard Shelby mouthing GOP dogma: Stimulus programs “did not bring us out of the Depression,” he recently told ABC’s Christiane Amanpour, but “the war did.” In other words, a really huge stimulus program hugely worked. Might not a more modest one succeed modestly? Shelby ought to follow his own logic.

‘Logic’ may not be the best word to describe GOP thinking in the second decade of the 21st century. Cohen notes a similar pattern of denial with respect to Republican policies on abortion and global warning, and adds,

…Independent thinkers, stop right here! If you believe in global warming, revenue enhancement, stimulus programs, the occasional need for abortion or even the fabulist theories of the late Charles Darwin, then either stay home — or lie.
This intellectual rigidity has produced a GOP presidential field that’s a virtual political Jonestown. The Grand Old Party, so named when it really did evoke America, has so narrowed its base that it has become a political cult. It is a redoubt of certainty over reason and in itself significantly responsible for the government deficit that matters most: leadership. That we can’t borrow from China.

The problem for Democrats is that, when Republicans become irrational proponents of discredited ideas and failed polices, there is not much incentive for Dems to up their game. Dems are not being challenged to respond to good arguments so much as tantrums by intellectually-constipated ideologues. The public gets cheated out of an enlightening debate and everybody loses.
What puzzles is why all of the Republicans have guzzled the Koolaid. Why hasn’t it dawned on the party’s brighter bulbs, perhaps Senator Lugar or, maybe Scott Brown or Huntsman that “Hmm, I could really separate myself from the pack of idjits by taking things to a more rational level”? All indications are that the public would like to see a little more flexibility from Republicans.
There may well come a point when the Republicans’ impressive party discipline starts to look like pointless obstructionism to swing voters. The public can see that, so far only one party is compromising. If sanity prevails, the Republicans’ unspoken meme that “we’re 100 percent right, and they’re 100 percent wrong, so we won’t give an inch” can’t play much longer without diminishing returns.