Impossible Worlds

... [the authors] think that in order to do full justice to the complexities of meaning, it is not enough to invoke constructions based on possible worlds. An adequate theory must appeal to impossible worlds as well. They defend this view by philosophical arguments, implement it by proposing a metaphysical account of the nature of impossible worlds, deploy it in developing model theoretic treatments of modal logic and other formalisms, and then apply it to a range of philosophical topics that includes information, bounded rationality, fiction, and counterpossible conditionals