Possible Worlds and Explanation of Modality

Abstract

Contemporary semantics explains modal notions in terms of possible worlds. “It is possible that p” means that there is a possible world in which p is true. Logical and mathematical results of the possible world theory are exceptional but the concept of a possible world is problematic. Basic requirements of classical philosophical analysis are presented. In the older logical tradition possible worlds were maximal models. Diametrically opposed to this concept is a theory of possible worlds as concrete entities defended by David Lewis. His theory achieves the goal of reductive analysis of modal concepts but the explanatory value of the ontologically extravagant apparatus is dubious. In the final section an alternative, functional conception of possible world is sketched. I also defend modalism – according to this doctrine modal notions are irreducible.