Are Social Kinds Vague and Does It Matter?

Vagueness is pervasive in social reality yet neglected in social ontology. This neglect stems from a widespread assumption: social kinds have mind-dependent membership conditions fixed by collective attitudes, entailing epistemic transparency—infallible access to the nature and extension of social kinds. I argue that epistemic transparency is incompatible with any interpretation of vagueness, and consequently that anti-realist frameworks cannot accommodate vague social kinds. Realists, however, are better equipped to handle vagueness by relying on theories of kinds as clusters. Anti-realists must drop mind-dependent membership conditions and epistemic transparency entirely, a deeply unsatisfactory solution for a priori projects in social ontology.