Fair enough. At least you admit you don't know. The only place I've heard a hard cap like that is the Reinhart-Rogoff studies. They found that when debt exceeds 90 percent of GDP, economic growth tends to be slower. I don't think they made a specific prediction of a currency crisis for the U.S.
I don't predict the future either. We can only understand the mechanisms by which things might occur, not whether they will occur. I do think though, that there's at least as much chance of a crisis occurring as a result of the GOP not raising the debt limit, as there is from the U.S. debt level itself. If you read the text of S&P's 2011 downgrade of the U.S., you'll see that the main factor they cited was political dysfunction in Congress. So I'm not quite sure that I understand the logic of creating a crisis to avoid a crisis, but whatever.
Overall though, I do agree that the Democrats should agree to the type of entitlement reform that you want.
Edit: What scares me a lot more than the debt to GDP ratio is the U.S.
net international investment position of -$4 trillion. In the event of a capital flight, this is going to be the number that matters more.
