Debt is not valid if it's essentially imposed by force. The Third World debt is odious debt. That's even been recognized by the U.S. representative at the IMF, Karen Lissaker, an international economist, who pointed out a couple of years ago that if we were to apply the principles of odious debt, most of the Third World debt would disappear.
For example, if somebody comes into your office from the university biology department and says, You're going to be a subject in an experiment. I'm going to stick electrodes into your brain and measure this, that, and the other thing, you're permitted to say, I'm sorry, I don't want to be a subject. They are not allowed to come back to you and say, You have to be, unless you can provide scientific evidence that this is going to harm you. But the U.S. is insisting on exactly that internationally.
The international economic arrangements, the so-called free trade agreements, are basically designed to maintain that. They undergird what's called a "flexible labor market," meaning that people have no security. The growing worker insecurity that Alan Greenspan once said was one of the major factors in the fairy-tale economy. If people are afraid, they don't have job security, they're just not going to ask for better conditions.
(thanks, Toby!)