Within leading views of properties, various options are available for developing a metaphysics of haecceities. For example, in an effort to assimilate haecceities into a class nominalist ontology where properties are identified with sets, Lewis (1986: 225) characterizes haecceities as follows: “So we get properties that are in no way qualitatively delineated, and some of these are haecceities of this- and other-worldly individuals. A unit set of an individual is one especially stringent haecceity. Also, for any individual and any counterpart relation, there is the set of that individual together with all its counterparts, and this is a less strict sort of haecceity.” The resulting view takes our talk of haecceities to slide between talk of properties distinctive to each worldbound individual and talk of properties shared by individuals unified by a common counterpart relation. (On the broader conception, haecceities are non-qualitative in nature, while, on the narrower conception, haecceities end up being qualitative, provided there are no qualitatively indiscernible worlds.) In contrast to this Lewisian view, other views attribute a more significant metaphysical role to haecceities, taking haecceities to individuate or determine the identity of entities and therefore figure into a metaphysical explanation of facts about identity and individuation.