On the Prospects of Modal Fictionalism

Possible world discourse has two important aims. First, it offers a promising approach to modal semantics. Quantifying across possible worlds enables us to reduce modal sentences to non-modal sentences. This reduction enables us to replace the poorly understood modal terms 'possibly' and 'necessarily' with truth-functional quantifiers. In this way, a powerful and elegant modal logic, developed by Kripke (1963) and others, provides us with a theory of formal validity which can also be brought to bear on philosophical issues involving, for example, counterfactuals, contingency, essence, supervenience and theological evil. Accounts of possible worlds also aim to explain which facts about reality make modal propositions true. Because modalities are alternatives to reality, it is difficult to see how a modal proposition can be true in virtue of some fact about the actual world. Hence, it seems promising to suppose that possible worlds offer the ontological grounding for m...