We are not having a debt crisis.

It’s important to make this point, because I keep seeing articles about the “fiscal cliff” that do, in fact, describe it — often in the headline — as a debt crisis. But it isn’t. The U.S. government is having no trouble borrowing to cover its deficit. In fact, its borrowing costs are near historic lows. And even the confrontation over the debt ceiling that looms a few months from now if we do somehow manage to avoid going over the fiscal cliff isn’t really about debt.

No, what we’re having is a political crisis, born of the fact that one of our two great political parties has reached the end of a 30-year road. The modern Republican Party’s grand, radical agenda lies in ruins — but the party doesn’t know how to deal with that failure, and it retains enough power to do immense damage as it strikes out in frustration.

Before I talk about that reality, a word about the current state of budget “negotiations.”

Why the scare quotes? Because these aren’t normal negotiations in which each side presents specific proposals, and horse-trading proceeds until the two sides converge. By all accounts, Republicans have, so far, offered almost no specifics. They claim that they’re willing to raise $800 billion in revenue by closing loopholes, but they refuse to specify which loopholes they would close; they are demanding large cuts in spending, but the specific cuts they have been willing to lay out wouldn’t come close to delivering the savings they demand.

It’s a very peculiar situation. In effect, Republicans are saying to President Obama, “Come up with something that will make us happy.” He is, understandably, not willing to play that game. And so the talks are stuck.

Why won’t the Republicans get specific? Because they don’t know how. The truth is that, when it comes to spending, they’ve been faking it all along — not just in this election, but for decades. Which brings me to the nature of the current G.O.P. crisis.

Since the 1970s, the Republican Party has fallen increasingly under the influence of radical ideologues, whose goal is nothing less than the elimination of the welfare state — that is, the whole legacy of the New Deal and the Great Society. From the beginning, however, these ideologues have had a big problem: The programs they want to kill are very popular. Americans may nod their heads when you attack big government in the abstract, but they strongly support Social Security, Medicare, and even Medicaid. So what’s a radical to do?

The answer, for a long time, has involved two strategies. One is “starve the beast,” the idea of using tax cuts to reduce government revenue, then using the resulting lack of funds to force cuts in popular social programs. Whenever you see some Republican politician piously denouncing federal red ink, always remember that, for decades, the G.O.P. has seen budget deficits as a feature, not a bug.

Arguably more important in conservative thinking, however, was the notion that the G.O.P. could exploit other sources of strength — white resentment, working-class dislike of social change, tough talk on national security — to build overwhelming political dominance, at which point the dismantling of the welfare state could proceed freely. Just eight years ago, Grover Norquist, the antitax activist, looked forward cheerfully to the days when Democrats would be politically neutered: “Any farmer will tell you that certain animals run around and are unpleasant, but when they’ve been fixed, then they are happy and sedate.”

O.K., you see the problem: Democrats didn’t go along with the program, and refused to give up. Worse, from the Republican point of view, all of their party’s sources of strength have turned into weaknesses. Democratic dominance among Hispanics has overshadowed Republican dominance among southern whites; women’s rights have trumped the politics of abortion and antigay sentiment; and guess who finally did get Osama bin Laden.

And look at where we are now in terms of the welfare state: far from killing it, Republicans now have to watch as Mr. Obama implements the biggest expansion of social insurance since the creation of Medicare.

So Republicans have suffered more than an election defeat, they’ve seen the collapse of a decades-long project. And with their grandiose goals now out of reach, they literally have no idea what they want — hence their inability to make specific demands.

It’s a dangerous situation. The G.O.P. is lost and rudderless, bitter and angry, but it still controls the House and, therefore, retains the ability to do a lot of harm, as it lashes out in the death throes of the conservative dream.

Our best hope is that business interests will use their influence to limit the damage. But the odds are that the next few years will be very, very ugly.