Don't take it from me--take it from those who know more than either of us:
S&P downgrading the United States is like Consumer Reports downgrading Coca-Cola. Consumer Reports is a great institution. For example, if you want to know how reliable a 2007 Ford Explorer is going to be, they have done more research than anyone to figure out the reliability history of every single vehicle. Those ratings are a real public service, since they add information to the world. But when it comes to Coke and Pepsi, everyone has an opinion already, and no one cares which one, according to Consumer Reports, “really” tastes better. When S&P rated some tranche of a CDO AAA back in 2006, it meant that some poor analyst had run some model fed to her by an investment bank and made sure that the rows and columns added up correctly, and the default probability percentage at the end was below some threshold. It might have been crappy information, but it was new information. When S&P rates long-term Treasuries AA+, it means . . . nothing. And if any serious buy-side investor were tempted to take S&P’s rating into account, she would be deterred by the fact that the analysis that produced the rating included a $2 trillion arithmetic error.
http://baselinescenario.com/2011/08/06/so-what-part-two/#more-9228Meanwhile, the CBO estimates potential real GDP in 2021 at about $18 trillion in 2005 dollars, or around $19 trillion in 2011 dollars.
Put these together, and they say that an extra trillion in borrowing adds something like 0.07% of GDP in future debt service costs. Yes, that zero belongs there. The $4 trillion S&P said it needed to see clocks in at less than 0.3% of GDP.
These are not, to say the least, make or break numbers. So what are we talking about here?
America does have a long-run fiscal problem, driven by the combination of rising health costs, an aging population, and the unwillingness to raise taxes to pay for the programs we already have. If we don’t come to grips with that problem, bad things will happen. But what happens to the deficit in the medium term is almost irrelevant to the question of whether our long-run finances will get under control.
Yet S&P (and others) obsess about those medium-term numbers, without ever explaining why. Maybe they think there’s some critical level of debt — but they don’t know that. Maybe they think that fiscal austerity over the next decade will somehow guarantee good behavior further out — but that didn’t work in the 1990s. Or maybe they’re just pulling stuff out of regions I can’t mention in the Times.
http://krugman.blogs.nytimes.com/2011/08/06/the-arithmetic-of-near-term-deficits-and-debt/