Katherine Hawley

(1971 - 2021)

This chapter explores the connections between David Lewis's perdurance theory and his Humean supervenience, arguing that his influential argument about temporary intrinsics is best seen in this light. It presents domestic dispute within the anti‐endurantist camp and analyzes the following questions: why does Lewis identify ordinary objects with world‐bound parts of transworld objects, but not with time‐bound parts of transtemporal objects? Given that Lewis is a counterpart theorist about modality, why isn't he a stage theorist about persistence? Humean supervenience in isolation does not entail perdurance theory, even for the actual world. Lewis's treatment of temporary intrinsics in On the Plurality of Worlds forms part of a discussion of both persistence and its modal analogue, for which there is no neutral term. Perdurance theory is challenged by the stage theory of persistence, which identifies ordinary objects with brief stages instead of transtemporal sums of those stages.

I claim that, if persisting objects have temporal parts, then there are non-supervenient relations between those temporal parts. These are relations which are not determined by intrinsic properties of the temporal parts. I use the Kripke-Armstrong 'rotating homogeneous disc' argument in order to establish this claim, and in doing so I defend and develop that argument. This involves a discussion of instantaneous velocity, and of the causes and effects of rotation. Finally, I compare alternative responses to the rotating disc argument, and consider the implications of my arguments for the doctrines of Humean Supervenience and unrestricted mereology.

‘Fusion’ is a philosophical term of art, with a variety of uses. First, it is often a synonym for ‘sum’. In this sense, a is a fusion of b, c and d iff b, c and d are parts of a, and every part of a shares a part with b, c or d. So a cat is a fusion of the cells which compose it, and the same cat is a fusion of the molecules which compose it. Relatedly, ‘fusion’ can refer to the occurrence of such composition: philosophers disagree about whether fusion is widespread, about whether it can be a vague matter, and so on.