Abstract

This dissertation is about flexibility as a dimension of reality, an objective—independent of mind and language—phenomenon typically referred to as ‘metaphysical modality’. It develops a novel modal account of why reality could be different: that is, why claims like “Possibly, there are talking donkeys,” or “Humphrey could have won the election” are true or false. I contend that primitive dispositional properties called ‘powers’ explain such claims, and do so better than possible-world accounts of modality. The problem with possible-world accounts is that they fail to capture what we mean by modal terms like ‘possibly’, ‘can’, or ‘necessarily’. The phenomenon they capture with possible worlds cannot adequately explain, for instance, that Humphrey regrets not winning the election because: he could have made a difference. Humphrey is told that he could have won the election because some entity represents him as such. But what does some entity’s representing Humphrey have to do with whether Humphrey could have won the election? Simply calling that entity a ‘possible world’ is no help. Powers do better in this regard, preserving a common-sense notion of modality where, because of what a power can do it acts as a cross-roads in history, marking places where reality could have unfolded differently. As such, powers are more clearly modally significant than possible worlds. The conclusion shows how to use powers to underwrite possible-world semantics without possible worlds.