Skip to 3:00 for an instant classic of the last-days-of-the-republic genre, as a Nobel prize winner scolds a comedian for not taking the idea of a magical coin seriously enough. I joked last week after Colbert’s bit on the coin that if Stewart ended up goofing on it too, that’d be the coup de grace for liberal/media opinion. Lefty pundits seemed to sense that as well: Krugman wasn’t the only commentator to post something grouchy on Friday about Stewart having misunderstood what the coin was supposed to do. Is that right, that he didn’t understand it? Or was he just trying to steer them away from a political disaster in the making a la saner liberals like Ezra Klein?

Minting the coin would interrupt that process, uniting Republicans — and many voters and business groups — against what they would see as an unsettling, illegal and inflationary power grab from the executive. And if you think the press spreads blame too equally over the debt ceiling, wait till you see the coverage if the White House decides to respond by creating a trillion-dollar coin out of nothing. You can explain the basic logic of fiat currency until you’re blue in the face, but it’s not going to matter. That coin would drive our country’s increasingly deranged politics, which are really at the heart of this crisis, to the edge.

I think that minting the coin could go quite badly, while the debt-ceiling fight would likely end quite well, with Republicans finally admitting they’re not willing to allow default. And forcing the Republican Party to accept a more normal approach to politics is, in the end, the main objective. That doesn’t mean Washington will enter an Edenic period of cooperation and compromise. Republicans would probably just content themselves with threatening more ordinary government shutdowns. But that itself would be a real advance.

Stewart’s core brand, remember, is “sanity,” so this was a heavy lift for coin fans twice over. You can’t wave an idea this goofy in front of a comic sensibility, even a lefty one, and not expect it to bite. It literally doesn’t pass the laugh test.