The Fundamental Theorem of World Theory


Christopher Menzel and Edward N. Zalta


Journal of Philosophical Logic, 43/2 (2014): 333–363.


The fundamental principle of the theory of possible worlds is that a proposition p is possible if and only there is a possible world at which p is true. In this paper we present a valid derivation of this principle from a more general theory in which possible worlds are defined rather than taken as primitive. The general theory uses a primitive modality and axiomatizes abstract objects, properties, and propositions. We then show that this general theory has very small models and hence that its ontological commitments – and, therefore, those of the fundamental principle of world theory – are minimal.

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