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.

Let’s begin with a simple example. Consider two quarks: one near the tip of your nose, the other near the center of Alpha Centauri. Here is a question about these two subatomic particles: Is there an object that has these two quarks as its parts and that has no other parts? According to one view of the matter (a view that is surprisingly endorsed by a great many contemporary philosophers), the answer to this question is Yes. But I think it (...) is fair to say that according to common sense, the answer to this question is really No, there is no object that has as its only two parts a quark near the tip of your nose and another quark near the center of Alpha Centauri. (shrink)

According to standard, pre-philosophical intuitions, there are many composite objects in the physical universe. There is, for example, my bicycle, which is composed of various parts - wheels, handlebars, molecules, atoms, etc. Recently, a growing body of philosophical literature has concerned itself with questions about the nature of composition.1 The main question that has been raised about composition is, roughly, this: Under what circumstances do some things compose, or add up to, or form, a single object? It turns out that (...) it is surprisingly difficult to give a satisfactory answer to this question that accords with standard, pre-philosophical intuitions about the universe's composite objects. In fact, the three rival views in response to this question that have received the most support in the literature are (i) that there are no objects composed of two or more parts (which means that there are no stars, chairs, humans, or bicycles);2 (ii) that the only objects composed of two or more parts are living organisms (which still means no stars. (shrink)

This paper defends Mereological Universalism(the thesis that, for any set S of disjoint objects, there is an object that the members of S compose. Universalism is unpalatable to many philosophers because it entails that if there are such things as my left tennis shoe, W. V. Quine, and the Taj Mahal, then there is another object that those three things compose. This paper presents and criticizes Peter van Inwagen's argument against Universalism and then presents a new argument in favor of (...) Universalism. It turns out that the most reasonable way to resist the argument for Universalism is to deny the existence of artifacts; thus, if we believe in artifacts, we have no real choice other than to embrace Universalism. (shrink)

This is a short response to a paper by Trenton Merricks in which he argues against the following doctrine: Microphysical Supervenience (MS) Necessarily, if atoms A1 through An compose an object that exemplifies intrinsic qualitative properties Q1 through Qn, then atoms like A1 through An (in all their respective intrinsic qualitative properties), related to one another by all the same restricted atom-to-atom relations as A1 through An, compose an object that exemplifies Q1 through Qn.

This is a defense of endurantism against an alleged paradox.

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..

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.

There is widespread disagreement as to what the facts are concerning just when a collection of objects composes some further object; but there is widespread agreement that, whatever those facts are, they are necessary. I am unhappy to simply assume this, and in this paper I ask whether there is reason to think that the facts concerning composition hold necessarily. I consider various reasons to think so, but find fault with each of them. I examine the theory of composition as (...) identity, but argue that the version of this doctrine that entails universalism is implausible. I consider the claim that the a priority of such facts leads to their necessity, but give a defence of substantial contingent a priori truths. I ask whether the contingency of such facts would lead to unwelcome possibilities, but argue that the worrying looking possibilities can be blocked if it is desired. Next, I argue against the thought that the Lewis-Sider argument against restricted composition might give us reason to accept the necessity of universalism. Lastly, I respond to two objections from the 2006 BSPC. I conclude in favour of the contingency of the facts concerning when some things compose some thing. (shrink)

The aim of the paper is to discuss some recent variants of familiar puzzles concerning the relations of parts to wholes put forward by Trenton Merricks and Eric Olson. The argument is put forward that so long as the familiar distinction between 'loose and popular' and 'strict and philosophical' senses of identity claims is accepted the paradoxical conclusions at which Merricks and Olson arrive can be resisted. It is not denied that accepting the distinction between 'loose and popular' and 'strict (...) and philosophical' senses of identity claims is itself a departure from common-sense, but it is argued that it is the smallest such departure available to us. (shrink)

I argue that composition as identity is incompatible with the possibility of emergent properties (as characterized in the paper) and so should be rejected.

The doctrine of Microphysical Supervenience (MS) states that: Necessarily, if atoms A1 through An compose an object that exemplified intrinsic qualitative properties Q1 through Qn, then atoms like A1 through An (in all their respective intrinsic qualitative properties), related to one another by all the same restricted atom-to-atom relations as A1 through An, compose an object that exemplifies Q1 through Qn. I show that MS entails a contradiction and so must be rejected. And my argument against MS provides the resources (...) to show that Global Microphysical Supervenience (GMS) is false. GMS states that possible worlds qualitatively exactly alike at the microphysical level are qualitatively exactly alike at the macrophysical level. (shrink)