A lot of people believe that distinct objects can occupy precisely the same place for the entire time during which they exist. Such people have to provide an answer to the 'grounding problem' – they have to explain how such things, alike in so many ways, nonetheless manage to fall under different sortals, or have different modal properties. I argue in detail that they cannot say that there is anything in virtue of which spatio-temporally coincident things have those properties. However, (...) I also argue that this may not be as bad as it looks, and that there is a way to make sense of the claim that such properties are primitive. (shrink)

Two versions of global supervenience have recently been distinguished from each other. I introduce a third version, which is more likely what people had in mind all along. However, I argue that one of the three versions is equivalent to strong supervenience in every sense that matters, and that neither of the other two versions counts as a genuine determination relation. I conclude that global supervenience has little metaphysically distinctive value.

This book is a defense of modal realism; the thesis that our world is but one of a plurality of worlds, and that the individuals that inhabit our world are only a few out of all the inhabitants of all the worlds. Lewis argues that the philosophical utility of modal realism is a good reason for believing that it is true.

It is my aim in this paper to show that the contemporary assimilation of essence to modality is fundamentally misguided and that, as a consequence, the corresponding conception of metaphysics should be given up. It is not my view that the modal account fails to capture anything which might reasonably be called a concept of essence. My point, rather, is that the notion of essence which is of central importance to the metaphysics of identity is not to be understood in (...) modal terms or even to be regarded as extensionally equivalent to a modal notion. The one notion is, if I am right, a highly refined version of the other; it is like a sieve which performs a similar function but with a much finer mesh. (shrink)

Some theories of personal identity allow some variation in what it takes for a person to survive from context to context; and sometimes this is determined by the desires of person-stages or the practices of communities.This leads to problems for decision making in contexts where what is chosen will affect personal identity.‘Temporal Phase Pluralism’ solves such problems by allowing that there can be a plurality of persons constituted by a sequence of person stages. This illuminates difficult decision making problems when (...) persons have to choose between different life-altering choices. (shrink)

I argue for a property mereology and for mereological bundle theory. I then apply this theory to the one over many problem (universals) and puzzles concerning persistence and material constitution.

I discuss puzzles involving coinciding material objects (such as statues and their constitutive lumps of clay) and propose solutions.

I argue that a solution to puzzles concerning the relationship ofobjects and their properties – a version of the `bundle' theory ofparticulars according to which ordinary objects are mereologicalfusions of monadic and relational tropes – is also a solution topuzzles of material constitution involving the allegedco-location of material objects. Additionally, two argumentsthat have played a prominent role in shaping the current debate,Mark Heller's argument for Four Dimensionalism and Peter vanInwagen's argument against Mereological Universalism, are shownto be unsound given this version (...) of the bundle theory. (shrink)

Are the sculpture and the mass of gold which permanently makes it up one object or two? In this article, we argue that the monist, who answers ‘one object’, cannot accommodate the asymmetry of material constitution. To say ‘the mass of gold materially constitutes the sculpture, whereas the sculpture does not materially constitute the mass of gold’, the monist must treat ‘materially constitutes’ as an Abelardian predicate, whose denotation is sensitive to the linguistic context in which it appears. We motivate (...) this approach in terms of modal analyses of material constitution, but argue that ultimately it fails. The monist must instead accept a deflationary, symmetrical use of ‘materially constitutes’. We argue that this is a serious cost for her approach. (shrink)

There is a well-known argument from Leibniz's Law for the view that coincident material things may be distinct. For given that they differ in their properties, then how can they be the same? However, many philosophers have suggested that this apparent difference in properties is the product of a linguistic illusion; there is just one thing out there, but different sorts or guises under which it may be described. I attempt to show that this ‘opacity’ defence has intolerable consequences for (...) the functioning of our language and that the original argument should therefore be allowed to stand. (shrink)

This provocative book attempts to resolve traditional problems of identity over time. It seeks to answer such questions as 'How is it that an object can survive change?' and 'How much change can an object undergo without being destroyed'? To answer these questions Professor Heller presents a theory about the nature of physical objects and about the relationship between our language and the physical world. According to his theory, the only actually existing physical entities are what the author calls 'hunks', (...) four-dimensional objects extending across time and space. This is a major contribution to ontological debate and will be essential reading for all philosophers concerned with metaphysics. (shrink)

An encyclopedia entry which covers various revisionary conceptions of which macroscopic objects there are, and the puzzles and arguments that motivate these conceptions: sorites arguments, the argument from vagueness, the puzzles of material constitution, arguments against indeterminate identity, arguments from arbitrariness, debunking arguments, the overdetermination argument, and the problem of the many.