The notion of multiple location plays an important role in the characterization of endurantism. Several authors have recently offered cases intended to demonstrate the incoherence of multiple location. I argue that these cases do not succeed in making multiple location problematic. Along the way, several crucial issues about multiple location and its use by endurantists are clarified.

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.

In this article, I briefly explain the quantum measurement problem and the Everett interpretation, in a way that is faithful to modern physics and yet accessible to readers without any physics training. I then consider the metaphysical lessons for ontology from quantum mechanics under the Everett interpretation. My conclusions are largely negative: I argue that very little can be said in full generality about the ontology of quantum mechanics, because quantum mechanics, like abstract classical mechanics, is a framework within which (...) we can consider different physical theories which have very little in common at the level of ontology. Along the way I discuss, and criticise, several positive ontological proposals that have been made in the context of the Everett interpretation: ontologies based on the so-called "eigenstate-eigenvalue link", ontologies based on taking the "many-worlds" language seriously at the fundamental level, and ontologies that treat the wavefunction as a complex field on a high-dimensional space. (shrink)

Presents a guide to the basics of quantum mechanics and measurement.

Mereological nihilism says that there do not exist (in the fundamental sense) any objects with proper parts. A reason to accept it is that we can thereby eliminate 'part' from fundamental ideology. Many purported reasons to reject it - based on common sense, perception, and the possibility of gunk, for example - are weak. A more powerful reason is that composite objects seem needed for spacetime physics; but sets suffice instead.

In this book, Lawrence Sklar demonstrates the interdependence of science and philosophy by examining a number of crucial problems on the nature of space and ...

Recently, Cody Gilmore has deployed an ingenious case involving backwards time travel to highlight an apparent conflict between the theory that objects persist by perduring, and the thesis that wholly coincident objects are impossible. However, careful attention to the concepts of location and parthood that Gilmore’s cases involve shows that the perdurantist faces no genuine objection from these cases, and that the perdurantist has a number of plausible and dialectically appropriate ways to avoid the supposed conflict.

Existing puzzles about coinciding objects can be divided into two types, corresponding to the manner in which they bear upon the endurantism v. perdurantism debate. Puzzles of the first type, which involve temporary spatial co-location, can be solved simply by abandoning endurantism in favor of perdurantism, whereas those of the second type, which involve career-long spatial co-location, remain equally puzzling on both views. I show that the possibility of backward time travel would give rise to a new type of puzzle. (...) The new puzzles confront perdurantists and can be solved just by shifting to endurantism. (shrink)

There will be a few themes. One to get us going: expansion versus contraction. About an object, o, and the region, R, of space(time) in which o is exactly located,1 we may ask: i) must there exist expansions of o: objects in filled superregions2 of R? ii) must there exist contractions of o: objects in filled subregions of..

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.

There’s an argument around from so-called “linguistic theories of vagueness”, plus some relatively uncontroversial considerations, to powerful metaphysical conclusions. David Lewis employs this argument to support the mereological principle of unrestricted composition, and Theodore Sider employs a similar argument not just for unrestricted composition but also for the doctrine of temporal parts. This sort of argument could be generalised, to produce a lot of other less palatable metaphysical conclusions. However, arguments to Lewis’s and Sider’s conclusions on the basis of considerations (...) about vagueness are uncompelling, even if we accept the crucial premises about vagueness. And a good thing too, since the generalised form of the argument would prove far too much. (shrink)

I argue that from a very weak recombination principle and plausible assumptions about the nature of parthood and location it follows that it's possible that the mereological structure of the material world and that of spacetime fail to correspond to one another in very radical ways. I defend, moreover, that rejecting the possibility of such failures of correspondence leaves us with a choice of equally radical alternatives. I also discuss a few ways in which their possibility is relevant to various (...) debates in metaphysics. (shrink)

What is the relation between material objects and spacetime regions? Supposing that spacetime regions are one sort of substance, there remains the question of whether or not material objects are a second sort of substance. This is the question of dualistic versus monistic substantivalism. I will defend the monistic view. In particular, I will maintain that material objects should be identified with spacetime regions. There is the spacetime manifold, and the fundamental properties are pinned directly to it.

Identities formed with proper names may be contingent. this claim is made first through an example. the paper then develops a theory of the semantics of concrete things, with contingent identity as a consequence. this general theory lets concrete things be made up canonically from fundamental physical entities. it includes theories of proper names, variables, cross-world identity with respect to a sortal, and modal and dispositional properties. the theory, it is argued, is coherent and superior to its rivals, in that (...) it stems naturally from a systematic picture of the physical world. (shrink)

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)

This chapter argues that from a particularly weak recombination principle and plausible assumptions about the nature of parthood and location, it follows that it is possible that the mereological structure of the material world and that of space-time fail to correspond to one another in very radical ways. The chapter suggests, moreover, that rejecting the possibility of such failures of correspondence leaves us with a choice of no less unappealing alternatives. It also discusses a few ways in which their possibility (...) is relevant to various important debates in metaphysics. (shrink)

Multilocation and Minimal Mereology do not mix well. It has been pointed out that Three-Dimensionalism, which can be construed as multilocation-friendly, runs into trouble with Weak Supplementation. But in fact, regardless of one’s theory of persistence, if someone posits the possibility of any one of several kinds of multilocation, he or she will not be able to maintain the necessity of any of the three axioms of Minimal Mereology: the Transitivity of Proper Parthood, the Asymmetry of Proper Parthood, and Weak (...) Supplementation. In fact, positing even the mere conceivability of cases involving multilocation will require the denial of the analyticity of Minimal Mereology. In response to this, some have claimed that we ought to relativise parthood, either to one region or to two. Unfortunately, if we replace the axioms of Minimal Mereology with region-relativised counterparts, we will not be able to capture the intuitions that supported the original axioms. The only adequate solution, I maintain, is to restrict multilocation to a domain outside the scope of the rules we intuitively take to govern the parthood relation. For those who take Minimal Mereology to be necessary and universal, that will mean relinquishing the possibility of multilocation. (shrink)

There is a general form of an argument which I call the ‘argument from vagueness’ which attempts to show that objects persist by perduring, via the claim that vagueness is never ontological in nature and thus that composition is unrestricted. I argue that even if we grant that vagueness is always the result of semantic indeterminacy rather than ontological vagueness, and thus also grant that composition is unrestricted, it does not follow that objects persist by perduring. Unrestricted mereological composition lacks (...) the power to ensure that there exist instantaneous objects that wholly overlap persisting objects at times, and thus lacks the power to ensure that there exists anything that could be called a temporal part. Even if we grant that such instantaneous objects exist, however, I argue that it does not follow that objects perdure. To show this I briefly outline a coherent version of three dimensionalism that grants just such an assumption. Thus considerations pertaining to the nature of vagueness need not lead us inevitably to accept perdurantism. (shrink)

I argue that extended simples are possible. The argument given here parallels an argument given elsewhere for the claim that the shape properties of material objects are extrinsic, not intrinsic as is commonly supposed. In the final section of the paper, I show that if the shape properties of material objects are extrinsic, the most popular argument against extended simples fails.

I offer a new criticism of the argument from vagueness to four-dimensionalism [Sider 2001. The argument is modelled after an older argument for mereological universalism [Lewis 1986 and may be looked upon as a tightened-up and extended version of the latter. While I agree with other critics [Koslicki 2003; Markosian 2004 that the argument from vagueness fails precisely because of this affinity, my recipe for dealing with it is different. I reject the assumption, shared by Sider with his opponents, that (...) synchronic composition and ‘minimal diachronic fusion’ are sufficiently similar to use considerations inspired by the analysis of the former to bear on the latter. My objection to a crucial premise of the argument from vagueness turns on the relevant aspect of dissimilarity between these two cases. (shrink)

Simon Saunders and David Wallace have proposed an attractive semantics for interpreting linguistic communities embedded in an Everettian multiverse. It provides a charitable interpretation of our ordinary talk about the future, and allows us to retain a principle of bivalence for propositions and to retain the law of excluded middle in the logic of propositions about the future. But difficulties arise when it comes to providing an appropriate account of the metaphysics of macroscopic objects and events. I evaluate various metaphysical (...) frameworks which might be combined with the Saunders–Wallace semantics. I conclude that the most appropriate metaphysics to underwrite the semantics renders Everettian quantum mechanics a theory of non-overlapping worlds. (shrink)

Bohmian mechanics, which is also called the de Broglie-Bohm theory, the pilot-wave model, and the causal interpretation of quantum mechanics, is a version of quantum theory discovered by Louis de Broglie in 1927 and rediscovered by David Bohm in 1952. It is the simplest example of what is often called a hidden variables interpretation of quantum mechanics. In Bohmian mechanics a system of particles is described in part by its wave function, evolving, as usual, according to Schrödinger's equation. However, the (...) wave function provides only a partial description of the system. This description is completed by the specification of the actual positions of the particles. The latter evolve according to the.. (shrink)

We have two aims in this paper. The first is to provide the reader with a critical guide to recent work on relativity and persistence by Balashov, Gilmore and others. Much of this work investigates whether endurantism can be sustained in the context of relativity. Several arguments have been advanced that aim to show that it cannot. We find these unpersuasive, and will add our own criticisms to those we review. Our second aim, which complements the first, is to demarcate (...) the most defensible form of relativistic endurantism. A recurring theme of this paper is that even those philosophers who do worry about relativity have not taken it seriously enough. (shrink)

I argue that the fundamental space of a quantum mechanical world is the wavefunction's space. I argue for this using some very general principles that guide our inferences to the fundamental nature of a world, for any fundamental physical theory. I suggest that ordinary three-dimensional space exists in such a world, but is non-fundamental; it emerges from the fundamental space of the wavefunction.

I explicate and defend the claim that, fundamentally speaking, there are no numbers, sets, properties or relations. The clarification consists in some remarks on the relevant sense of ‘fundamentally speaking’ and the contrasting sense of ‘superficially speaking’. The defence consists in an attempt to rebut two arguments for the existence of such entities. The first is a version of the indispensability argument, which purports to show that certain mathematical entities are required for good scientific explanations. The second is a speculative (...) reconstruction of Armstrong's version of the One Over Many argument, which purports to show that properties and relations are required for good philosophical explanations, e.g. of what it is for one thing to be a duplicate of another. (shrink)

It is widely believed that shapes are intrinsic properties. But this claim is hard to defend. I survey all known theories of shape properties, and argue that each theory is either incompatible with the claim that shapes are intrinsic, or can be shown to be false.