Think about what it takes to be a viable Republican candidate today. You have to denounce Big Government and high taxes without alienating the older voters who were the key to G.O.P. victories last year — and who, even as they declare their hatred of government, will balk at any hint of cuts to Social Security and Medicare (death panels!).

And you also have to denounce President Obama, who enacted a Republican-designed health reform and killed Osama bin Laden, as a radical socialist who is undermining American security.
So what kind of politician can meet these basic G.O.P. requirements? There are only two ways to make the cut: to be totally cynical or totally clueless.

Mitt Romney embodies the first option. He’s not a stupid man; he knows perfectly well, to take a not incidental example, that the Obama health reform is identical in all important respects to the reform he himself introduced in Massachusetts — but that doesn’t stop him from denouncing the Obama plan as a vast government takeover that is nothing like what he did. He presumably knows how to read a budget, which means that he must know that defense spending has continued to rise under the current administration, but this doesn’t stop him from pledging to reverse Mr. Obama’s “massive defense cuts.”

Mr. Romney’s strategy, in short, is to pretend that he shares the ignorance and misconceptions of the Republican base. He isn’t a stupid man — but he seems to play one on TV.

Unfortunately from his point of view, however, his acting skills leave something to be desired, and his insincerity shines through. So the base still hungers for someone who really, truly believes what every candidate for the party’s nomination must pretend to believe. Yet as I said, the only way to actually believe the modern G.O.P. catechism is to be completely clueless.

And that’s why the Republican primary has taken the form it has, in which a candidate nobody likes and nobody trusts has faced a series of clueless challengers, each of whom has briefly soared before imploding under the pressure of his or her own cluelessness. Think in particular of Rick Perry, a conservative true believer who seemingly had everything it took to clinch the nomination — until he opened his mouth.

So will Newt Gingrich suffer the same fate? Not necessarily.
       
Many observers seem surprised that Mr. Gingrich’s, well, colorful personal history isn’t causing him more problems, but they shouldn’t be. If hypocrisy is the tribute vice pays to virtue, conservatives often seem inclined to accept that tribute, voting for candidates who publicly espouse conservative moral principles whatever their personal behavior. Did I mention that David Vitter is still in the Senate?

And Mr. Gingrich has some advantages none of the previous challengers had. He is by no means the deep thinker he imagines himself to be, but he’s a glib speaker, even when he has no idea what he’s talking about. And my sense is that he’s also very good at doublethink — that even when he knows what he’s saying isn’t true, he manages to believe it while he’s saying it. So he may not implode like his predecessors.

The larger point, however, is that whoever finally gets the Republican nomination will be a deeply flawed candidate. And these flaws won’t be an accident, the result of bad luck regarding who chose to make a run this time around; the fact that the party is committed to demonstrably false beliefs means that only fakers or the befuddled can get through the selection process.

Of course, given the terrible economic picture and the tendency of voters to blame whoever holds the White House for bad times, even a deeply flawed G.O.P. nominee might very well win the presidency. But then what?

The Washington Post quotes an unnamed Republican adviser who compared what happened to Mr. Cain, when he suddenly found himself leading in the polls, to the proverbial tale of the dog who had better not catch that car he’s chasing. “Something great and awful happened, the dog caught the car. And of course, dogs don’t know how to drive cars. So he had no idea what to do with it.”

The same metaphor, it seems to me, might apply to the G.O.P. pursuit of the White House next year. If the dog actually catches the car — the actual job of running the U.S. government — it will have no idea what to do, because the realities of government in the 21st century bear no resemblance to the mythology all ambitious Republican politicians must pretend to believe. And what will happen then?