The idea of a possible world that differs in some way from our "actual" world - a world where, for example, the grass is red or no people exist - can help us analyse and understand a wide range of philosophical concepts, such as counterfactuals, properties, modality, and the notions of possibility and necessity. In Possible Worlds Rod Girle surveys current thinking about possible worlds by Kripke, Lewis, Armstrong, Stalnaker, and others.

Beginning with a discussion of "possible for" and "possible that," and imagination and fiction, Girle moves on to analyse Kripke's many logics for possibility and Lewis's counterpart worlds. Epistemic possibility, computation and possible worlds, physically possible worlds, impossible worlds, and real possibility are discussed in separate chapters. How the idea of a possible world can be put to use in different areas of philosophy is examined, as are problems that may arise and the benefits that can be gained.