Nicholas Rescher surveys and analyzes the different kinds of unreal possibilities and nonexistent objects, tying together all the diverse ways in which this area has been approached by philosophers. As he surveys the field and clarifies the kinds of unreality, he also makes a sustained argument against the philosophical fashion for dealing with nonexistent possible world as though they were authentic objects.
The author holds that, while we may discuss possibilities, we ought not to accord them ontological status. The possibility of existence of a certain sort of world is not the existence of possible world of a certain sort. While we may reasonable discuss possibilities at the generic level, such as a world where dogs have horns, this does not require a commitment to a possible world where they do. The work that theorists of logic and language want to accomplish with possible worlds and individuals can be managed with propositional manifolds, stories or scenarios, while the modalities of necessity and possibility that modal logicians want to analyze in terms of realization in possible worlds can be handled by turning instead to figuring in stories or scenarios.