One depressing aspect of American politics is the susceptibility of the political and media establishment to charlatans. You might have thought, given past experience, that D.C. insiders would be on their guard against conservatives with grandiose plans. But no: as long as someone on the right claims to have bold new proposals, he’s hailed as an innovative thinker. And nobody checks his arithmetic.

Which brings me to the innovative thinker du jour: Representative Paul Ryan of Wisconsin.

Mr. Ryan has become the Republican Party’s poster child for new ideas thanks to his “Roadmap for America’s Future,” a plan for a major overhaul of federal spending and taxes. News media coverage has been overwhelmingly favorable; on Monday, The Washington Post put a glowing profile of Mr. Ryan on its front page, portraying him as the G.O.P.’s fiscal conscience. He’s often described with phrases like “intellectually audacious.”

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.

Mr. Ryan’s plan calls for steep cuts in both spending and taxes. He’d have you believe that the combined effect would be much lower budget deficits, and, according to that Washington Post report, he speaks about deficits “in apocalyptic terms.” And The Post also tells us that his plan would, indeed, sharply reduce the flow of red ink: “The Congressional Budget Office has estimated that Rep. Paul Ryan’s plan would cut the budget deficit in half by 2020.”