Many Americans, sensitized by the media to the dangers of cigarette smoking, have been appalled to discover on their visits to the Far East that most adult Chinese smoke. The Chinese, on the other hand, consume little alcohol and have expressed bewilderment about the hazardous and excessive drinking in the West. Differences in risk acceptance, however, are not merely cross cultural. Within a given country, some persons are scuba divers, hang gliders, or motorcyclists, and some are not; there are obvious discrepancies in attitudes toward individual risk. At the level of societal risk—for example, from nuclear power, toxic dumps, and liquefied natural gas facilities—different persons also exhibit analogous disparities in their hazard evaluations. In this chapter I shall argue that two of the major accounts of societal risk acceptance are highly questionable. Both err because of fundamental flaws in their conception of knowledge. This means that to understand the contemporary controversy over societal risk, we need to accomplish a philosophical task, that is, to uncover the epistemologies assumed by various participants in the conflict. Proponents of both positions err, in part, because they are reductionistic and because they view as irrational the judgments of citizens who are risk averse. After showing why both views are built on highly doubtful philosophical presuppositions, I shall argue in favor of a middle position that I call scientific proceduralism. An outgrowth of Karl Popper's views, this account is based on the notion that objectivity in hazard assessment requires that risk judgments be able to withstand criticism by scientists and lay people affected by the risks. Hence the position is sympathetic to many populist attitudes toward involuntary and public hazards. Although scientific proceduralism is not the only reasonable view that one might take regarding risk, I argue that it is at least a rational one. And if so, then rational behavior should not be defined purely in terms of the assessments of either the cultural relativists or the naive positivists. Most importantly, risk experts should not "write off" the common person. Because hazard assessment is dominated by these two questionable positions, it is reasonable to ask whether criticizing them threatens the value of quantified risk analysis (QRA). Indeed, many of those allegedly speaking "for the people," as I claim to be doing, are opposed to scientific and analytic methods of assessing environmental dangers.