While ersatzist views identify possible worlds with abstract entities, Lewisian modal realism identifies possible worlds with maximal sums of (analogically) spatiotemporally interrelated entities. According to Lewisian modal realism, for any way things could have been, there is some possible world that represents that possibility. Moreover, these possible worlds are no less “real” or concrete than our actual world. (Lewis characterizes these possible worlds as “concrete” only with reservation, given competing, non-equivalent conceptions of the abstract-concrete distinction.)