Before World War II, most decisions involving the introduction of new technologies were made primarily by individuals or corporations, with only minimal interference from government, usually in the form of regulations. Since the war, however, the increased complexity of modern technologies and their impact on society as a whole have tended to force the focus of decision making toward the federal government, although this power is still usually exercised in the form of regulation rather than outright control. Given the huge social consequences of many such decisions, it seems proper that the decision-making process be moved further into the public arena. Yet one may wonder whether the society has the resources and mechanisms for dealing with these issues. Thus, the nature of such controversies, and the possible means for their resolution, has itself become an object of intense interest. One may approach this subject from at least as many directions as there are academic specialties. Many approaches are primarily empirical in that they attempt to determine the social and political mechanisms that are currently operative in the generation and resolution of controversies over new technologies (Nelkin 1979). Such studies usually do not attempt to determine whether the social mechanisms actually operating are effective mechanisms in the sense that they tend to produce decisions that in fact result in the originally desired out comes. The approach of this chapter is much more theoretical. It begins with a standard model of decision making and then analyzes the nature of technological decisions in terms of the postulated model. The advantage of such an approach is that it provides a clear and simple framework for both analyzing a controversy and judging its outcome. The disadvantage is that it tells us little about the actual social and political processes in the decision. Eventually we would like an account that incorporates both theoretical and empirical viewpoints. Regarding the proposed model, there are several ingredients in any decision. This chapter concentrates on one of these ingredients: scientific knowledge, particularly statistical knowledge of the type associated with studies of low-level environmental hazards. There is no presumption, however, that statistical knowledge, or scientific knowledge generally, is the most important ingredient in any decision.