Throughout the Western world, people’s policy views are correlated across domains in a strikingly similar fashion. This paper proposes that what partly explains the structure of ideology is moral universalism: the extent to which people exhibit the same level of altruism and trust towards strangers as towards in-group members. In new large-scale multinational surveys, heterogeneity in universalism descriptively explains why some people support redistribution, health care, environmental protection, affirmative action and foreign aid, while others advocate for spending on the military, law enforcement and border protection. Universalism is a substantially stronger predictor of policy views and ideological constraint than variables such as income, wealth, education, religiosity, or beliefs about government efficiency. Consistent with the idea that universalism shapes policy views, we further document that the left-right divide on redistribution, environmental protection or foreign aid strongly attenuates or even reverses when people evaluate less universalist implementations of these policies.