I think one of the things we learned from the physicists and also the theoretical biologists is the idea that when you're dealing with very complex s… - Kenneth Arrow

From the point of view of seeking a consensus of the moral imperative of individuals, such consensus being assumed to exist, the problem of choosing an electoral or other choice mechanism, or, more broadly, of choosing a social structure, assumes an entirely different form from that discussed in the greater part of this study.

The meaning of information is precisely a reduction in uncertainty. From the viewpoint of economics or decision theory, uncertainty is relevant because it concerns the consequences of decisions. An individual making a decision may be supposed to be choosing one among a set of feasible alternatives. In general, these alternatives are themselves plans extending in time, and he will want to choose the one that yields the most satisfying consequences. These may be profits in successive periods for a business firm, or they may be other satisfactions, such as consumption, power, bequests, or interesting challenges. It can be assumed that the individual compares the entire set of consequences deriving from each alternative in his decision set with those of the others and chooses the preferred one.

In fact, is is not a mere empirical accident that not all the contingent markets needed for efficiency exist but a necessary fact with deep implications for the workings and structure of economic institutions. Roughly speaking, information about particular events, even after they have occurred, is not spread evenly throughout the population. Two people cannot enter into a contract contingent on the occurrence of a certain event or state if only one of them in fact will know that the event has occurred. A particular example of this is sometimes known as “moral hazard” in the insurance and economic literature. The very existence of insurance will change individual behavior in the direction of less care in avoiding risks.