And it’s not just taxes, it’s everything. For example, Republicans have been promising to offer an alternative to Obamacare ever since the Affordable Care Act passed in 2010, but have yet to produce anything resembling an actual health plan.

Yet most of the news media, and most pundits, still worship at the church of “balance.” They are committed to portraying the two big parties as equally reasonable. This creates a powerful demand for serious, honest Republicans who can be held up as proof that the party does too include reasonable people making useful proposals. As Slate’s William Saletan, who enthusiastically touted Mr. Ryan but eventually became disillusioned, wrote: “I was looking for Mr. Right — a fact-based, sensible fiscal conservative.”

And Paul Ryan played and in many ways still plays that role, but only on TV, not in real life. The truth is that his budget proposals have always been a ludicrous mess of magic asterisks: assertions that trillions will be saved through spending cuts to be specified later, that trillions more will be raised by closing unnamed tax loopholes. Or as the nonpartisan Tax Policy Center put it, they’re full of “mystery meat.”

But Mr. Ryan has been very good at gaming the system, at producing glossy documents that look sophisticated if you don’t understand the issues, at creating the false impression that his plans have been vetted by budget experts. This has been enough to convince political writers who don’t know much about policy, but do know what they want to see, that he’s the real deal. (A number of reporters are deeply impressed by the fact that he uses PowerPoint.) He is to fiscal policy what Carly Fiorina was to corporate management: brilliant at self-promotion, hopeless at actually doing the job. But his act has been good enough for media work.

His position within the party, in turn, rests mainly on this outside perception. Mr. Ryan is certainly a hard-line, Ayn Rand-loving and progressive-tax-hating conservative, but no more so than many of his colleagues. If you look at what the people who see him as a savior are saying, they aren’t talking about his following within the party, which isn’t especially passionate. They’re talking, instead, about his perceived outside credibility, his status as someone who can stand up to smarty-pants liberals — someone who won’t, says MSNBC’s Joe Scarborough, be intimidated by “negative articles in The New York Times opinions page.” (Who knew we had such power?)