Persistence through time is like extension through space. A road has spatial parts in the subregions of the region of space it occupies; likewise, an object that exists in time has temporal parts in the various subregions of the total region of time it occupies. This view — known variously as four dimensionalism, the doctrine of temporal parts, and the theory that objects “perdure” — is opposed to “three dimensionalism”, the doctrine that things “endure”, or are “wholly present”.1 I will (...) attempt to resolve this dispute in favor of four dimensionalism by means of a novel argument based on considerations of vagueness. But before argument in this area can be productive, I believe we must become much clearer than is customary about exactly what the dispute is, for the usual ways of formulating the dispute are flawed, especially where three dimensionalism is concerned. (shrink)

Precis of my book by this title, for a symposium.

Katherine Hawley 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, she concludes by advocating stage theory.

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. (shrink)

Hud Hudson presents an innovative view of the metaphysics of human persons according to which human persons are material objects but not human organisms. In developing his account, he formulates and defends a unique collection of positions on parthood, persistence, vagueness, composition, identity, and various puzzles of material constitution. The author also applies his materialist metaphysics to issues in ethics and in the philosophy of religion. He examines the implications for ethics of his metaphysical views for standard arguments addressing the (...) moral permissibility of our treatment of human persons and their parts, fetuses and infants, the irreversibly comatose, and corpses. He argues that his metaphysics provides the best foundation in the philosophy of religion for the Christian doctrine of the resurrection of the body. Hudson addresses a broad range of metaphysical issues, but among his most strikingly original contributions are his defense of the "Partist" view and his argument for the compatibility of Christianity with a materialistic theory of human persons. (shrink)

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)

Region R Question: How many objects — entities, things — are contained in R? Ignore the empty space. Our question might better be put, 'How many material objects does R contain?' Let's stipulate that A, B and C are metaphysical atoms: absolutely simple entities with no parts whatsoever besides themselves. So you don't have to worry about counting a particle's top half and bottom half as different objects. Perhaps they are 'point-particles', with no length, width or breadth. Perhaps they are (...) extended in space without possessing spatial parts (if that is possible). Never mind. We stipulate that A, B and C are perfectly simple. We also stipulate that they are connected as follows. A and B are stuck together in such a way that when a force is applied to one of them, they move together 'as a unit'. Moreover, the two of them together exhibit behavior that neither would exhibit on its own — Perhaps they emit a certain sound, or glow in the dark — whereas C is.. (shrink)

Occasions of Identity is an exploration of timeless philosophical issues about persistence, change, time, and sameness. Andre Gallois offers a critical survey of various rival views about the nature of identity and change, and puts forward his own original theory. He supports the idea of occasional identities, arguing that it is coherent and helpful to suppose that things can be identical at one time but distinct at another. Gallois defends this view, demonstrating how it can solve puzzles about persistence dating (...) back to the Ancient Greeks, and investigates the metaphysical consequences of rejecting the necessity and eternity of identities. (shrink)

Terence Parsons presents a lively and controversial study of philosophical questions about identity. Because many puzzles about identity remain unsolved, some people believe that they are questions that have no answers and that there is a problem with the language used to formulate them. Parsons explores a different possibility: that such puzzles lack answers because of the way the world is (or because of the way the world is not). He claims that there is genuine indeterminacy of identity in the (...) world. He articulates such a view in detail and defends it from a host of criticisms. (shrink)

The following quotation, from Frank Jackson, is the beginning of a typical exposition of the debate between those metaphysicians who believe in temporal parts, and those who do not: The dispute between three-dimensionalism and four-dimensionalism, or more precisely, that part of the dispute we will be concerned with, concerns what persistence, and correllatively, what change, comes to. Three-dimensionalism holds that an object exists at a time by being wholly present at that time, and, accordingly, that it persists if it is (...) wholly present at more than one time. For short, it persists by enduring. Four-dimensionalism holds that an object exists at a time by having a temporal part at that time, and it persists if it has distinct temporal parts at more than one time. For short, it persists by perduring. In the light of these comments, some readers will perhaps find the question that forms the title of this paper a little puzzling. They may have learned to use the terms ‘fourdimensionalism’ ‘perdurantism’ and ‘belief in temporal parts’ interchangeably; or perhaps even to define one in terms of the other. Such a usage, however, is inapposite. We might imagine a Flatland-like world of two spatial dimensions and one temporal, whose philosophers are divided between a theory of persistence on which they persist by having temporal parts, and a theory on which they persist by being wholly located in each of several times. This is just the same issue we face, but at least the label ‘four-dimensionalism’ seems inapposite: the four-dimensionalist Flatlanders believe in only three dimensions! (shrink)

I offer a clear conception of a temporal part that does not make the existence of temporal parts implausible. This can be done if (and only if) we think of physical objects as four dimensional, The fourth dimension being time. Unless we are willing to deny the existence of most spatial parts, Or willing to accept the possibility of coincident entities, Or accept something even more implausible, We should accept the existence of temporal parts.

I examine the issue of persistence over time in thecontext of the special theory of relativity (SR). Thefour-dimensional ontology of perduring objects isclearly favored by SR. But it is a different questionif and to what extent this ontology is required, andthe rival endurantist ontology ruled out, by thistheory. In addressing this question, I take theessential idea of endurantism, that objects are whollypresent at single moments of time, and argue that itcommits one to unacceptable conclusions regardingcoexistence, in the context of SR. (...) I then propose anddiscuss a plausible account of coexistence forperduring objects, which is free of these defects. This leaves the endurantist room for some maneuvers. I consider them and show that they do not really helpthe endurantist out. She can accommodate the notionof coexistence in the relativistic framework only atthe cost of renouncing central endurantist intuitions. (shrink)

In no possible world does a time traveler succeed in killing herearlier self before she ever enters a time machine. So if many,many time travelers went back in time trying to kill theirunprotected former selves, the time travelers would fail inmany strange, coincidental ways, slipping on bananapeels, killing the wrong victim, and so on. Such cases producedoubts about time travel. How could ``coincidences'' beguaranteed to happen? And wouldn't the certainty of coincidentalfailure imply that time travelers are not free to killtheir (...) earlier selves? But if so, what would inhibit theirfreedom? Despite initial appearances, these and other doubtsmay be answered: the possibility of time travel survives yetanother challenge. (shrink)

An introduction to temporal parts theory. Most of us believe in spatial parts: hands are spatial parts of people, an electron is a spatial part of a hydrogen atom, the earth is a spatial part of the solar system. Why are these parts "spatial" parts? Because they are spatially smaller: the hand is spatially smaller than the person, the electron is spatially smaller than the atom, the earth is spatially smaller than the solar system. Temporal parts, then, are parts that (...) are temporally smaller. My current temporal part, "me-today", we might call it, is temporally smaller than me, since it exists today and only today. Temporal parts theory says that objects are made up of temporal as well as spatial parts. (shrink)

In his interesting article 'Constitution is not Identity' (1992), Mark Johnston argues that (in a sense soon to be explained) constitution is distinct from identity. In what follows, I dispute Johnston's contention.

This is an expansion of the author's 1991 work which investigates the implications of Gödel's writings on Einstein's theory of relativity as they relate to the fundamental questions of the nature of time and the possibilities for time travel.

This is a defense of endurantism against an alleged paradox.

Immanent universals, being wholly present wherever they are instantiated, are capable of both multi-location and co-location. As a result, they can become involved in some bizarre situations, situations whose contradictory appearance cannot be dispelled by any of the relativizing maneuvers familiar to metaphysicials as solutions to the problem of change. Douglas Ehring takes this to be a fatal problem for immanent universals, but I do not. Although the old relativizing maneuvers don't solve the problem, I propose a new one that (...) does. I spend half the paper defending the proposed solution against objections, and in the course of this task I touch upon such topics as backward time travel and the distinction between universals and particulars. I close by putting forward -- merely as an option -- a new way to draw the distinction in question. (shrink)

The thesis is concerned with the outline of an ontology which admits only particulars and with the persistence of particulars through time. In Chapter 1 it is argued that a neglected class of particulars--the cases--have to be employed in order to solve the problem of universals, i.e., to give a satisfactory account of properties and kinds. In Chapter 2, two ways in which particulars could persist though time are distinguished. Difficulties are raised for the view that everything perdures through time, (...) i.e., the view that each persisting thing is a sum of continuous and dependent temporal parts. Objections to the view that people perdure are presented in Chapter 3, objections to the effect that such a view cannot capture salient truths about the nature of experience and wrongly implies that our special concern for ourselves, our friends and our familiars is irrational. An alternative account of persisting particulars is provided in Chapter 4 by way of given a theory of substances. Finally, in Chapter 5, this alternative account is applied to the issue of personal identity and to the issue of the identity over time of living things in general. A Hylomorphic View of living things is sketched and briefly defended. ;Throughout, certain themes recur: essentialism is taken to be relatively unproblematic, various connections between time and modality are exploited, reductionism is regarded as bearing the onus of proof, characterless entities such as prime matter, substrata, bare particulars and haecceities are rejected and the differences between the animate and the inanimate are emphasized. (shrink)

This is a critical notice of Theodore Sider's book, _Four-Dimensionalism_.

The so-called paradoxes of time travel have played a significant role in both the physics and philosophy literatures - but how much force do these alleged paradoxes really have?

It has been suggested by several philosophers that many of the so-called paradoxes of backward time travel can be resolved if we conceive of the backward time traveller as having a zig-zag or N-shaped world line in spacetime. In this I am in general agreement. But there is still a problem in conceiving of backward time travel this way. In this note I will show how we can solve this problem by conceiving of backward time travel in terms of the (...) closed time-like world lines in certain general relativistic space-times. Indeed, it has often been claimed that such world models as Godei spacetime show that backward time travel is conceivable. Our discussion will help to make clear just why this claim is correct. (shrink)

I thank my commentators for their kind words, and for their close reading and challenging criticisms of my book. I have chosen selective and substantive replies. Those criticisms I ignore, I ignore because I have little more to say, not because they are unworthy of discussion.

My dissertation divides into four parts, each of which consists of two chapters. ;Part I sets up the issues to be dealt with in the remainder of the dissertation. Chapter One introduces the central presuppositions and primitive notions upon which I rely thereafter. Chapter Two offers a new taxonomy of views about persistence. Whereas the traditional taxonomy recognizes just one distinction---namely, the 3D v. 4D distinction---my new taxonomy recognizes two quite separate distinctions: the distinction between objects that persist by being (...) temporally extended and objects that persist without being temporally extended , and the distinction between objects that persist by having temporal parts and objects that persist without having temporal parts . ;Part II is concerned with extended simples---extended material objects that have no proper parts. Chapter Three criticizes a series of existing considerations for and against the possibility of such objects and concludes that this possibility has been neither established nor refuted. Chapter Four presents a new problem for the possibility of extended simples. ;Part III deals with some issues arising from the possibility of co-location , multi-location and time travel. Chapter Five proposes a solution to a newly uncovered problem for any type of entity that is capable of both multi-location and co-location. Chapter Six raises a new, time travel-based problem for worms. ;Part IV deals with questions about persistence and composition in the relativistic context of Minkowski spacetime. Chapter Seven criticizes a recent argument for the conclusion that only the 4D or worm view is tenable in Minkowski spacetime. Chapter Eight poses a new problem for the conjunction of the following views: there are composite material objects, persisting material objects are saints, not worms, and spacetime is Minkowskian. (shrink)

In this essay for a PPR book symposium on Theodore Sider's _Four-Dimensionalism<D>, I focus on two of Sider's arguments for four-dimensionalism: (i) his argument from vagueness, and (ii) his argument from time travel. Concerning (i), I first show that Sider's argument commits him to certain strange consequences that many four-dimensionalists may not endorse, and then I discuss an objection that involves appealing to 'brutal composition', the view that there is no informative answer to Peter van Inwagen's 'special composition question'. Concerning (...) (ii), I argue that the three-dimensionalist can account for time travel scenarios in a way that is analogous to Sider's four-dimensionalist account of such scenarios. (shrink)