Talk: Christopher Menzel (Texas A&M University)

Title:

Modalism and Possible World Semantics

Abstract:

Among the many practical and theoretical applications of possible world semantics for modal logic, one of the most important within philosophy arises when the standard modal operators are taken to express metaphysical necessity/possibility. So taken, “intended” possible world models of interpreted modal languages are typically understood to provide an explicit characterization of the nature of modal reality, of what there is in virtue of which our assertions in those languages are true or false — in a word, a characterization of the grounds of metaphysical modality. Two modal metaphysical paradigms have dominated: modal reductionism, according to which modal notions are reducible to non-modal notions, and modal primitivism, or modalism, according to which modal notions are fundamental and irreducible. Both, however, typically appeal to possible worlds of some ilk. In this talk, I will focus on modalist conceptions of worlds and argue that such worlds, though perhaps useful for other philosophical ends (so long as well-known logical perils are avoided), do not seem able to play any sort of substantive grounding role. I will argue in particular that the modalist needn’t invoke any conception of possible world at all and that they can, nonetheless, still have a robust conception of an intended model for an interpreted modal language. This account assumes a necessitist (a.k.a., as I’ve argued recently, possibilist) metaphysics of the individuals constituting the domains of intended models. Time permitting, generalizing some ideas developed by Leitgeb and Ladyman, I will sketch a sort of structuralist middle-ground between necessitism and contingentism that, I think, does justice to both positions while avoiding their more significant liabilities.