Possible Worlds

To propose the idea of a possible world that differs in some possible way from our "actual" world, for example, a world where the grass is red or where no people exist, can help us to analyze and understand a range of philosophical concepts, such as counterfactuals, properties, modality, and of course, the notions of "possibility" and "necessity". This introduction to the subject of possible worlds surveys the range of current thinking, examining the ideas of Kripke, Lewis, Armstrong, Stalnaker and others. Beginning with a discussion of "possible for" and "possible that", and imagination and fiction, the author moves on to discuss Kripke's many logics for possibility and Lewis' counterpart worlds. Epistemic possibility, computation and possible worlds, physically possible worlds, impossible worlds, and real possibility, are then discussed in turn in separate chapters. How the idea of a possible world can be put to use in different areas of philosophy is examined, and the problems it may arise, and the benefits that can be gained, are investigated.