Dean Zimmerman

If extended objects were just sums of unextended parts, no satisfactory theory of contact would be possible. So extended objects are not decomposable into sets of simples. The fact that extended things do not possess a single decomposition into a set of smallest, indivisible parts places important constraints upon the analysis of propositions involving mass terms. In particular, it rules out those which construe masses of matter as set-theoretical constructions out of the parts of things. Consequently, any correct "semantics for mass terms" must recognize as individuals in their own right the masses of matter out of which tables, trees, and human bodies are composed. Although ordinary objects are generally regarded as capable of surviving changes in their parts, masses of matter cannot survive such changes. For instance, if the mass of matter now composing a certain statue does not share every part in common with the mass which made up that statue yesterday, then yesterday's mass of matter is numerically distinct from today's. ;These facts lead to the following argument for mereological essentialism: If there were an object that gained or lost a part, then it would be wholly coincident with a distinct thing--namely, the mass of matter then constituting it. Since masses of matter must count as individuals, and not sets of parts of things that are not themselves masses, objects that gain or lose parts would have to be wholly coincident with objects that cannot. But if both mass and statue weigh 100 pounds, and each is a distinct object in its own right, how is it that I can lift "both" without straining my back? One of the two must be more fundamental, more "real" than the other. Since simple coincidence between mass and constituted object is absurd, there are no objects that gain or lose parts. Part-changing objects are either fictions, logical constructions, or, perhaps, "disturbances" occurring to masses of matter. Neither relative identity theories, temporary identity theories, nor the doctrine of temporal parts can provide the resources to block this argument.

Oxford Studies in Metaphysics is the forum for the best new work in this flourishing field. Much of the most interesting work in philosophy today is metaphysical in character: this new series is a much-needed focus for it. OSM offers a broad view of the subject, featuring not only the traditionally central topics such as existence, identity, modality, time, and causation, but also the rich clusters of metaphysical questions in neighbouring fields, such as philosophy of mind and philosophy of science. Besides independent essays, volumes will often contain a critical essay on a recent book, or a symposium that allows participants to respond to one another's criticisms and questions. Anyone who wants to know what's happening in metaphysics can start here.

Physical boundaries and the earliest topologists. Topology has a relatively short history; but its 19th century roots are embedded in philosophical problems about the nature of extended substances and their boundaries which go back to Zeno and Aristotle. Although it seems that there have always been philosophers interested in these matters, questions about the boundaries of three-dimensional objects were closest to center stage during the later medieval and modern periods. Are the boundaries of an object actually existing, less-than-three-dimensional parts of the object—that is, are solids bounded by two-dimensional surfaces, surfaces by one-dimensional “edges” or “physical lines”, edges by dimensionless “simples”? If not, how does a perfectly spherical object manage to touch a perfectly flat object—what part of the sphere is in immediate contact with the plane, if the sphere has no unextended parts? But if such parts be admitted, are we not then saddled with “actual infinities” of simples, lines, and surfaces spread throughout each continuous object—the boundaries of all the object’s internal parts? Does it help to say that these internal boundaries exist only “potentially”?

Oxford Studies in Metaphysics is the forum for the best new work in this flourishing field. Much of the most interesting work in philosophy today is metaphysical in character: this series is a much-needed focus for it. OSM offers a broad view of the subject, featuring not only the traditionally central topics such as existence, identity, modality, time, and causation, but also the rich clusters of metaphysical questions in neighbouring fields, such as philosophy of mind and philosophy of science. Besides independent essays, volumes will often contain a critical essay on a recent book, or a symposium that allows participants to respond to one another's criticisms and questions. This fifth volume is largely focused on the metaphysics of time, with sections on time travel; persistence through time; and time, space, and location. The final section of the volume is devoted to a neglected topic that is starting to attract philosophical attention: the metaphysics of sounds. Anyone who wants to know what's happening in metaphysics can start here.

The Oxford Handbook of Metaphysics offers the most authoritative and compelling guide to this diverse and fertile field of philosophy. Twenty-four of the world's most distinguished specialists provide brand-new essays about 'what there is': what kinds of things there are, and what relations hold among entities falling under various categories. They give the latest word on such topics as identity, modality, time, causation, persons and minds, freedom, and vagueness. The Handbook's unrivaled breadth and depth make it the definitive reference work for students and academics across the philosophical spectrum.

I attempt to rebut Dean Zimmerman's novel argument (2010), which he presents in support of substance dualism, for the conclusion that, in spite of its popularity, the combination of property dualism with substance materialism represents a precarious position in the philosophy of mind. I take issue with Zimmerman's contention that the vagueness of 'garden variety' material objects such as brains or bodies makes them unsuitable candidates for the possession of phenomenal properties. I also argue that the 'speculative materialism' that is available to a substance materialist property dualist who abandons the identification of persons with such garden variety objects is significantly more attractive than Zimmerman allows. Although I do not attempt to refute its substance dualist rival, I conclude that the combination of property dualism with substance materialism can withstand Zimmerman's objections

Lynne Rudder Baker and many others think that paradigmatic instances of one object constituting another—a piece of marble constituting a statue, or an aggregate of particles constituting a living body—involve two distinct objects in the same place at the same time. Some who say this believe in the doctrine of temporal parts; but others, like Baker, reject this doctrine. Such philosophers, whom one might call “coincidentalists”, cannot say that these objects manage to share space in virtue of sharing a temporal part confined to just that place and time. But what can or should coincidentalists say about the nature of constitution? Many have analyzed the relation as one of sharing, “at some level”, all and only the same parts. Most have agreed that such massive part-sharing is at least a central component of and necessary condition for constitution. The heart of Baker’s Persons and Bodies, and its most significant contribution to the development of coincidentalism, is a theory of constitution that makes no appeal to mereology. The leading idea in Baker’s account is, instead, a modal one: objects belonging to constituted kinds are the necessary result of putting objects belonging to appropriate constituting kinds in the right circumstances, circumstances which the constituting objects need not have been in. So putting a piece of man-shaped marble in the right circumstances necessarily results in the existence of a second object, a statue, constituted by the marble; but the piece of marble need not have fallen into these circumstances or any others in which it would constitute a statue.

Mark Johnston’s book, Saving God (Princeton University Press, 2010) has two main goals, one negative and the other positive: (1) to eliminate the gods of the major Western monotheisms (Judaism, Christianity, and Islam) as candidates for the role of “the Highest One”; (2) to introduce the real Highest One, a panentheistic deity worthy of devotion and capable of extending to us the grace needed to transform us from inwardly-turned sinners to practitioners of agape. In this review, we argue that Johnston’s attack on traditional forms of monotheism has less force than his criticism of the “undergraduate atheists” (e.g., Hitchens, Harris, Dawkins); and that his candidate for Highest One is not the greatest possible being, and so could not play the role Johnston casts for it.

Physical boundaries and the earliest topologists. Topology has a relatively short history; but its 19th century roots are embedded in philosophical problems about the nature of extended substances and their boundaries which go back to Zeno and Aristotle. Although it seems that there have always been philosophers interested in these matters, questions about the boundaries of three-dimensional objects were closest to center stage during the later medieval and modern periods. Are the boundaries of an object actually existing, less-than-three-dimensional parts of the object—that is, are solids bounded by two-dimensional surfaces, surfaces by one-dimensional “edges” or “physical lines”, edges by dimensionless “simples”? If not, how does a perfectly spherical object manage to touch a perfectly flat object—what part of the sphere is in immediate contact with the plane, if the sphere has no unextended parts? But if such parts be admitted, are we not then saddled with “actual infinities” of simples, lines, and surfaces spread throughout each continuous object—the boundaries of all the object’s internal parts? Does it help to say that these internal boundaries exist only “potentially”?

This book addresses two basic questions: What is the proper philosophical analysis of the concept of substance? and What kinds of compound substances are there? The second question is mainly addressed by asking what relations among objects are necessary and sufficient for their coming to compose a larger whole. The first 72 pages of the book contain a short history of attempts to answer the first question, and a brief presentation of the analysis the authors defend at length in their earlier book, Substance Among Other Categories. In the remaining 119 pages, the authors take up the second question. This order of presentation makes sense; but it may help to create a false impression in those who only glance at the first few pages—that this book is just a simplified version of the earlier one, with a little bit of history thrown in. It would be quite unfortunate, however, if very many potential readers get this impression; for it might discourage them from looking closely at the bulk of the book, which is new. The issues discussed in the later chapters are at the center of one of the most lively debates in contemporary metaphysics; and the position Hoffman and Rosenkrantz stake out is appealing and carefully articulated. Their views deserve careful attention from philosophers working on the metaphysics of persistence through time, personal identity, artifact identity, and mereology.

My comments have two parts. I begin by laying out the argument that seems to me to be at the core of Olson’s thinking about human persons; and I suggest a problem with his reasons for accepting one of its premises. The premise is warranted by its platitudinous or commonsensical status; but Olson’s arguments lead him to conclusions that undermine the family of platitudes to which it belongs. Then I’ll raise a question about how Olson should construe the vagueness that would seem to infect the boundaries of human animals.