This article and video from Real Clear Politics has to be seen to be believed:
Former Chairman of the Federal Reserve Alan Greenspan explains how the United States can pay down the debt. By printing money.
David Gregory, moderator of "Meet The Press" on NBC: "Are U.S. treasury bonds still safe to invest in?"
Alan Greenspan, Former Chairman of the Federal Reserve: "Very much so. This is not an issue of credit rating, the United States can pay any debt it has because we can always print money to do that. So, there is zero probability of default."
Greenspan says the S&P downgrade was just meant to hit a "nerve" and hurt the "self-esteem of the United States."