Many theorize that cultural similarities in moral judgments arise from a specialized cognitive system devoted to morality. We claim, in contrast, that people make moral judgments using a general-purpose, value-based decision-making process. We present a computational cognitive model to predict response time and response choice to moral dilemmas using valuations as input. Cultural similarities in moral judgment are explained by a culturally stable set of valuations that drives choices that aid survival. Corresponding cultural differences are explained by changes in a decisional bias parameter that accounts for differences in the perceived costs of making various kinds of decisional errors. The model accurately predicts the timed choices of both U.K. and Chinese respondents from values collected from U.S. respondents.