But it’s the audacity of dopes. Mr. Ryan isn’t offering fresh food for thought; he’s serving up leftovers from the 1990s, drenched in flimflam sauce.

But this means that the supposed budget savings from the Ryan plan are a sham.

So why have so many in Washington, especially in the news media, been taken in by this flimflam? It’s not just inability to do the math, although that’s part of it. There’s also the unwillingness of self-styled centrists to face up to the realities of the modern Republican Party; they want to pretend, in the teeth of overwhelming evidence, that there are still people in the G.O.P. making sense. And last but not least, there’s deference to power — the G.O.P. is a resurgent political force, so one mustn’t point out that its intellectual heroes have no clothes.

But they don’t. The Ryan plan is a fraud that makes no useful contribution to the debate over America’s fiscal future.