Katherine Hawley

(1971 - 2021)

ABSTRACTThe Ant Trap is a terrific book, which opens up new opportunities to use philosophical methods in the social realm, by drawing on the tools and techniques of contemporary metaphysics. Epstein uses concepts of dependence, constitution, and grounding, of parts and whole, of membership and kindhood, both to clarify existing accounts of social reality and to develop an account of his own. Whilst I admire the general strategy, I take issue with some aspects of Epstein’s implementation, notably his distinction between grounding and anchoring. I recommend that he give up this distinction, which is not crucial to his project.

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.

In his 1991 book, Parts of Classes, David Lewis discusses the idea that composition is identity, alongside the idea that mereological overlap is a form of partial identity. But this notion of partial identity does nothing to help Lewis achieve his goals in that book. So why does he mention it? I explore and resolve this puzzle, by comparing Parts of Classes with Lewis's invocation of partial identity in his 1993 paper ‘Many But Almost One’, where he uses it to address Unger's problem of the many. I raise some concerns about this way of thinking of partial identity, but conclude that, for Lewis, it is an important defence against accusations of ontological profligacy.

‘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.

How do things persist? Are material objects spread out through time just as they are spread out through space? Or is temporal persistence quite different from spatial extension? This key question lies at the heart of any metaphysical exploration of the material world, and it plays a crucial part in debates about personal identity and survival. This book explores and compares three theories of persistence — endurance, perdurance, and stage theories — investigating the ways in which they attempt to account for the world around us. Having provided valuable clarification of its two main rivals, the book concludes by advocating stage theory. Such a basic issue about the nature of the physical world naturally has close ties with other central philosophical problems. This book includes discussions of change and parthood, of how we refer to material objects at different times, of the doctrine of Humean supervenience, and of the modal features of material things. In particular, it contains new accounts of the nature of worldly vagueness, and of what binds material things together over time, distinguishing the career of a natural object from an arbitrary sequence of events. Each chapter concludes with a reflection about the impact of these metaphysical debates upon questions about our personal identity and survival.