Extant research argues that public opinion on modern political issues is a by-product of evolved moral intuitions. However, the structure of modern political debates seems to clash with the input conditions of our moral inference systems. Especially, while we evolved to pass moral judgments on specific and well-known individuals, modern politics is about formulating general laws, applying to whole categories of anonymous strangers. Hence, it is argued that in order to produce opinion on political issues, moral heuristics are required to recruit cognitive systems designed for category-based inference. It is predicted and empirically demonstrated, first, that this interplay is conditioned by the extent to which an individual's stored category-level information (i.e., stereotypes) fit the input conditions of evolved heuristics. Second, that the category-oriented inferences are regulated by a scope syntax, which deactivates their role in public opinion formation to the extent the individual is faced with specific and ecologically valid information. Implications for understanding public opinion on modern political issues are discussed.