Life is full of uncertainties. Most of us have learned to live comfortably with day-to-day uncertainties and to make choices and decisions in their presence. We have evolved cognitive heuristics and developed strategies, technologies, and institutions such as weather reports, pocket-sized raincoats, and insurance to accommodate or compensate for the effects of uncertainty. Looked at with care, these heuristics and strategies do not always perform as well as we would like (Dawes, 1988). When our cognitive processes for dealing with uncertainty introduce error or bias into our judgments we are often unable to detect the fact. When things go seriously wrong we may not be around to learn the lesson – or we may still be unable to detect that the problem came from faulty processing of uncertain information. Thus, we muddle through – often doing quite well, occasionally getting into serious trouble.

Of course, uncertainty is not limited to our private lives. It also occurs in larger and more public situations. Frequently in public discussion, policy analysis, regulatory decision making and other contexts, we proceed as if we understand and can predict the world precisely. While a moment's reflection is sufficient to persuade anyone that this is not true, a number of political, behavioral, and analytical factors combine to promote the continuation of this practice.