Prejudice is a bane of humanity. Unjustified aversive beliefs and affect are the primary proximal causes of aversive behavior toward groups. Such beliefs and sentiments cause aversive speech and physical violence. They also serve as justification for denying people rights and opportunities. Prejudice also creates a deadweight loss. For instance,

Part of empirical social science is about finding fundamental truths about people. It is a difficult enterprise partly because scientists only observe data in a particular context. Neither cross-sectional variation nor data that goes back at best by tens of years is often enough to come up with generalizable truths.