Last week House Republicans voted for the 40th time to repeal Obamacare. Like the previous 39 votes, this action will have no effect whatsoever. But it was a stand-in for what Republicans really want to do: repeal reality, and the laws of arithmetic in particular. The sad truth is that the modern G.O.P. is lost in fantasy, unable to participate in actual governing.

Just to be clear, I’m not talking about policy substance. I may believe that Republicans have their priorities all wrong, but that’s not the issue here. Instead, I’m talking about their apparent inability to accept very basic reality constraints, like the fact that you can’t cut overall spending without cutting spending on particular programs, or the fact that voting to repeal legislation doesn’t change the law when the other party controls the Senate and the White House.

Am I exaggerating? Consider what went down in Congress last week.

First, House leaders had to cancel planned voting on a transportation bill, because not enough representatives were willing to vote for the bill’s steep spending cuts. Now, just a few months ago House Republicans approved an extreme austerity budget, mandating severe overall cuts in federal spending — and each specific bill will have to involve large cuts in order to meet that target. But it turned out that a significant number of representatives, while willing to vote for huge spending cuts as long as there weren’t any specifics, balked at the details. Don’t cut you, don’t cut me, cut that fellow behind the tree.

Then House leaders announced plans to hold a vote cutting spending on food stamps in half — a demand that is likely to sink the already struggling effort to agree with the Senate on a farm bill.

Then they held the pointless vote on Obamacare, apparently just to make themselves feel better. (It’s curious how comforting they find the idea of denying health care to millions of Americans.) And then they went home for recess, even though the end of the fiscal year is looming and hardly any of the legislation needed to run the federal government has passed.

In other words, Republicans, confronted with the responsibilities of governing, essentially threw a tantrum, then ran off to sulk.

How did the G.O.P. get to this point? On budget issues, the proximate source of the party’s troubles lies in the decision to turn the formulation of fiscal policy over to a con man. Representative Paul Ryan, the chairman of the House Budget Committee, has always been a magic-asterisk kind of guy — someone who makes big claims about having a plan to slash deficits but refuses to spell out any of the all-important details. Back in 2011 the Congressional Budget Office, in evaluating one of Mr. Ryan’s plans, came close to open sarcasm; it described the extreme spending cuts Mr. Ryan was assuming, then remarked, tersely, “No proposals were specified that would generate that path.”What’s happening now is that the G.O.P. is trying to convert Mr. Ryan’s big talk into actual legislation — and is finding, unsurprisingly, that it can’t be done. Yet Republicans aren’t willing to face up to that reality. Instead, they’re just running away.

When it comes to fiscal policy, then, Republicans have fallen victim to their own con game. And I would argue that something similar explains how the party lost its way, not just on fiscal policy, but on everything.

Think of it this way: For a long time the Republican establishment got its way by playing a con game with the party’s base. Voters would be mobilized as soldiers in an ideological crusade, fired up by warnings that liberals were going to turn the country over to gay married terrorists, not to mention taking your hard-earned dollars and giving them to Those People. Then, once the election was over, the establishment would get on with its real priorities — deregulation and lower taxes on the wealthy.

At this point, however, the establishment has lost control. Meanwhile, base voters actually believe the stories they were told — for example, that the government is spending vast sums on things that are a complete waste or at any rate don’t do anything for people like them. (Don’t let the government get its hands on Medicare!) And the party establishment can’t get the base to accept fiscal or political reality without, in effect, admitting to those base voters that they were lied to.

The result is what we see now in the House: a party that, as I said, seems unable to participate in even the most basic processes of governing.

What makes this frightening is that Republicans do, in fact, have a majority in the House, so America can’t be governed at all unless a sufficient number of those House Republicans are willing to face reality. And that quorum of reasonable Republicans may not exist.