In the textbooks, public policy analysis is a rational process in which policies are formulated to address social problems perceived by the public to be unacceptable. Effectiveness is one of the major criteria of policy evaluation. Consensus on effectiveness is difficult to achieve because underdetermined causes are the occasion for conflicting beliefs about the causes and solutions of problems, which Kahan (2016) calls "fact polarization." Fact polarization can be explained by political ideologies, which are expressions of cultural worldviews. These worldviews are based on incompatible beliefs about how society should be organized. Using gun violence as an example, this article shows how beliefs about the causes of gun violence, associated values, and policy solutions vary among liberals, libertarians and economic conservatives, and social conservatives. If policy is ideologically determined, the textbook presentation of policy analysis as a rational process that will help policymakers make better decisions may be wishful thinking.