Existence, ontological commitment, and fictional entities

Abstract

Modal notions like necessity and possibility are central to philosophical inquiry, yet their ontological status remains a subject of significant debate. Reductive theories of modality attempt to define these notions using non-modal terms to satisfy requirements of parsimony and epistemic transparency. The most prominent reductive strategy utilizes the framework of possible worlds. Linguistic and combinatorial versions of abstractionism identify worlds with sets of sentences or states of affairs, but these often fail to achieve genuine reduction by relying on modal primitives to define world consistency or the representation of truth. David Lewis’s modal realism offers a non-circular alternative by positing a multiverse of concrete, spatiotemporally isolated entities. While Lewis’s theory provides a systematic framework for both de dicto and de re modality through counterpart theory, it faces challenges regarding its ontological profligacy and the conceptual limits of spatiotemporal world-individuation. Alternative reductive paths, such as conventionalism, historically identified necessity with analyticity or linguistic rule-following. Although classic conventionalism is undermined by the collapse of the “truth by convention” doctrine and the recognition of synthetic necessary truths, a modified approach may still succeed by characterizing necessity as a conventional label for specific truth classes, such as logic or mathematics. Evaluation of these theories reveals that the fundamental obstacle to reduction remains the difficulty of providing a materially adequate account that avoids implicit circularity. – AI-generated abstract.