REINHART, Carmen & ROGOFF, Kenneth
This Time is Different
Perhaps more than anything else, failure to recognize the precariousness and fickleness of confidence -especially in cases in which large short-term debts need to be rolled over continuously-is the key factor that gives rise to the this-time-is-different syndrome. Highly indebted governments, banks, or corporations can seem to be merrily rolling along for an extended period, when bang!- confidence collapses, lenders disappear, and a crisis hits.
Economic theory tells us that it is precisely the fickle nature of confidence , including its dependence on the public's expectation of future events, that makes it so difficult to predict the timing of debt crises. High debt levels lead, in many mathematical economics models, to "multiple equilibria" in which the debt level might be sustained - or might not be. Economists do not have a terribly good idea of what kinds of events shift confidence and of how to concretely assess confidence vulnerability. What one does see, again and again, in the history of financial crises is that when an accident is waiting to happen, it eventually does. When countries become too deeply indebted, they are headed for trouble. When debt-fueled asset price explosions seem too good to be true, they probably are. But the exact timing can be very difficult to guess, and a crisis that seems imminent can sometimes take years to ignite.