ABSTRACT
Although the notions of necessity and possibility (the so-called ‘modal notions’) seem indispensable in metaphysics, empiricists have traditionally challenged the appeal to these notions. Developments in the semantics of modal logic have, however, given philosophers reason to believe that the empiricist challenge can be met. At the core of modal semantics is the idea of a plurality of possible worlds. Metaphysicians have argued that this idea is perfectly respectable, indeed, that it is implicit in our prephilosophical thinking about modal matters; and they have claimed that it provides the tools for clarifying not only the concept of de dicto modality (the notion of necessity or possibility as ascribed to a proposition), but also the notion of de re modality (the notion of a thing’s exemplifying a property necessarily or contingently).
