 Social entities as products of the individual mind: Locke’s theory of “nominal essence” is important for a number of contemporary approaches to social ontology, even though Locke does not himself associate nominal essences with the social world in particular. A nominal essence is a definition of a species or sort of thing, which people assemble in their minds out of ideas. Individuals generate these definitions when they observe things in the world and classify them according to their apparent similarities. Nominal essences, in Locke’s approach, are generated mentalistically: they are formed from the association of ideas in the mind. Moreover, they are generated individualistically: a nominal essence defined by any given person is fully defined by that person’s own mental states.