Impossible Worlds

Impossible worlds constitute an increasingly popular yet controversial topic in logic and metaphysics. The term “impossible worlds” parallels the term “possible worlds” and commonly refers to setups, situations, or totalities (“worlds”) that are inconsistent, incomplete, non-classical, or non-normal in possible-world semantics and metaphysics. These may verify a proposition and its negation, be silent as to the truth value of a proposition, or somehow fail to conform to the (classical) laws of logic. Some authors object to the term “impossible world,” preferring to talk of nonstandard worlds or partial situations instead. While the term “impossible world” is sometimes used to refer to a world that is inaccessible from another relative to some specified accessibility relation, impossible worlds are often conceived of as absolutely impossible in a broadly logical, conceptual, or metaphysical sense. As in the case of possible worlds, modern talk of impossible worlds originates with semantic interpretations of modal and non-classical logics, yet the potential applicability of these worlds to logical, metaphysical, and semantic philosophical puzzles has allowed them to permeate the wider philosophical arena. Arguments for impossible worlds often parallel those for possible worlds (see From Possible Worlds to Impossible Worlds) and focus largely on the proposed applications for such worlds (see Applications). As with possible worlds, there are various metaphysical conceptions of impossible worlds (see the Metaphysics of Impossible Worlds), and objections to such worlds are often theory specific (see Objections to Applications and Objections to Impossible Worlds). This article focuses on modern work on impossible worlds and its critics.