 The Threat from Abstractionism: Fictionalists seem to need fictions, in the sense of stories or story-like entities. Some realists about possible worlds treat possible worlds themselves as representational entities of the same general sort that fictions seem to be: these theorists are “abstractionists” in the terminology of van Inwagen 1986, or “ersatzers” in the terminology of Lewis 1986. Abstractionists may take worlds to be constructions out of sentences, or perhaps more commonly identify worlds with maximal propositions or with constructions out of propositions (e.g. sets of propositions). Once we have representations that are rich enough to represent every possibility, fictionalists need to explain why they prefer to be be fictionalists rather than identifying possible worlds with the appropriate representations.