The impulse to question the conventional wisdom about world problems has in recent years reflected the perfectly normal dissatisfaction with the way things were going. The temptation has been great to question the rationality of a system preserved against disastrous collapse only, it seemed, by shared knowledge of how disastrous the consequences of collapse would be. (One is reminded of the young lady at the ball who was asked by her escort what it was that held up her strapless evening gown. When she replied that it was “gravity”, he queried the principle. “Gravity”, he said, “should make it fall down.” Her response perhaps describes the contemporary dilemma: “sOh, I don't mean Newton's gravity, but the gravity of my situation if the darned thing doesn't work.”) The phenomenon is, perhaps, described as “self-preventing prophecy.” The fact that the phenomenon has seemed to work thus far is hardly an adequate response to those who are uneasy about its reliability, as no one can fail to be.