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.

This is a book that no one but Weyl could have written--and, indeed, no one has written anything quite like it since.

In the course of the discussion, Professor Quine pinpoints the difficulties involved in translation, brings to light the anomalies and conflicts implicit in our ...

[Peter Simons] Commonsense ontology contains both continuants and occurrents, but are continuants necessary? I argue that they are neither occurrents nor easily replaceable by them. The worst problem for continuants is the question in virtue of what a given continuant exists at a given time. For such truthmakers we must have recourse to occurrents, those vital to the continuant at that time. Continuants are, like abstract objects, invariants under equivalences over occurrents. But they are not abstract, and their being invariants (...) enables us to infer both their lack of temporal parts and that non-invariant predications about them must be relativized to times. \\\ [Joseph Melia] In this paper I try to eliminate occurrents from our ontology. I argue against Simons' position that occurrents are needed to supply truthmakers for existential claims about continuants. Nevertheless, those who would eliminate occurrents still need some account of our willingness to assert sentences that logically entail their existence. Though it turns out to be impossible to paraphrase away our reference to occurrents, I show that the truthmakers for such sentences are facts that involve only continuants. This is enough to allow us to regard our ordinary talk about occurrents as fictional. Finally, I argue that a proper conception of the underlying temporal facts about continuants can both avoid the problematic tensed theory of time and the problem of temporary intrinsics. (shrink)

Commonsense ontology contains both continuants and occurrents, but are continuants necessary? I argue that they are neither occurrents nor easily replaceable by them. The worst problem for continuants is the question in virtue of what a given continuant exists at a given time. For such truthmakers we must have recourse to occurrents, those vital to the continuant at that time. Continuants are, like abstract objects, invariants under equivalences over occurrents. But they are not abstract, and their being invariants enables us (...) to infer both their lack of temporal parts and that non-invariant predications about them must be relativized to times. \\\ [Joseph Melia] In this paper I try to eliminate occurrents from our ontology. I argue against Simons' position that occurrents are needed to supply truthmakers for existential claims about continuants. Nevertheless, those who would eliminate occurrents still need some account of our willingness to assert sentences that logically entail their existence. Though it turns out to be impossible to paraphrase away our reference to occurrents, I show that the truthmakers for such sentences are facts that involve only continuants. This is enough to allow us to regard our ordinary talk about occurrents as fictional. Finally, I argue that a proper conception of the underlying temporal facts about continuants can both avoid the problematic tensed theory of time and the problem of temporary intrinsics. (shrink)

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)

Mark Hinchliff concludes a recent paper, "The Puzzle of Change," with a section entitled "Is the Presentist Refuted by the Special Theory of Relativity?" His answer is "no." I respond by arguing that presentists face great difficulties in merely stating their position in Minkowski spacetime. I round up some likely candidates for the job and exhibit their deficiencies.

But this picture of a ‘block universe’, composed of a timeless web of ‘world-lines’ in a four-dimensional space, however strongly suggested by the theory of relativity, is a piece of gratuitous metaphysics. Since the concept of change, of something happening, is an inseparable component of the common-sense concept of time and a necessary component of the scientist's view of reality, it is quite out of the question that theoretical physics should require us to hold the Eleatic view that nothing happens (...) in ‘the objective world’. Here, as so often in the philosophy of science, a useful limitation in the form of representation is mistaken for a deficiency of the universe. (shrink)

In debate about the nature of persistence over time, the view that material objects endure has played the role of "champion" and the view that they perdure has played the role of the "challenger." It has fallen to the perdurantists rather than the endurantists to motivate their view, to provide reasons for accepting it that override whatever initial presumption there is against it. Perdurantists have sought to discharge their burden in several ways. For example, perdurantism has been recommend on the (...) grounds that: (i) it solves several of the puzzles that raise the problem of material constitution; (ii) it is (at least) suggested by the special theory of relativity (hereafter "SR"); (iii) it is the only view that makes sense out of the possibility of intrinsic change; (iv) it is the only view consistent with the doctrine of Humean supervenience; and (v) it makes better sense than its competitor out of the possibility of fission. There are primary and most powerful claims that have been made on behalf of perdurantism. They are individually persuasive and together they constitute a formidable assault upon the hegemony of endurantism. Endurantists of course, have not been without reply. However, since endurantists typically respond to these claims one at a time and in different ways, it is easy to get the impression that perdurantism offers a single, neat solution to a host of problems whereas endurantism requires a patchwork of different strategies. But this impression is an illusion. In Rea 1995, I argued that though perdurantism does solve some of the puzzles that raise the problem of material constitution, it does not solve the problem of material constitution itself. Thus, the problem of material constitution really has no bearing on the debate between endurantists and perdurantists. In his paper, I will show that the same is true with respect to SR, the problem of intrinsic change, the doctrine of Humean supervenience, and the possibility of fission. In short, I will argue that none of (ii-v) is true and that therefore the doctrine of temporal parts stands unmotivated. (shrink)

Endurantism is not inconsistent with the theory of special relativity, or so I shall argue. Endurantism is not committed to presentism, and thus not committed to a metaphysics that is at least prima facie inconsistent with special relativity. Nor is special relativity inconsistent with the idea that objects are wholly present at a time just if all of their parts co-exist at that time. For the endurantist notion of co-existence in terms of which “wholly present” is defined, is not, I (...) will argue, a notion according to which co-existence is transitive. Although an absence of absolute simultaneity presents some problems for the endurantist claim that objects are wholly present whenever they exist, there are a number of ways that the endurantist can respond to this difficulty. Thus, I conclude, considerations pertaining to the theory of special relativity certainly do not rule out endurantism as a metaphysics of persistence. (shrink)

There are two main theories about the persistence of objects through time: endurantism and perdurantism. Endurantists hold that objects are three-dimensional, have only spatial parts, and wholly exist at each moment of their existence. Perdurantists hold that objects are four-dimensional, have temporal parts, and only partly exist at each moment of their existence. In this paper we argue that endurantism is poorly suited to describe the persistence of objects in a world governed by Special Relativity, and can accommodate a relativistic (...) world only at a high price, one that we argue is not worth paying. Perdurantism, on the other hand, fits beautifully with our current scientific understanding of the world. Furthermore, we make this argument from implications of the Lorentz transformations, without appeals to geometrical interpretations, dimensional analogies, or auxillary premises like temporal eternalism. (shrink)

I formulate a theory of persistence in the endurantist family and pose a problem for the conjunction of this theory with orthodox versions of special or general relativity. The problem centers around the question: Where are things?

Yuri Balashov has argued that endurantism isuntenable in the context of Minkowskispacetime. Balashov's argument runs through twomain theses concerning the relation ofcoexistence, or temporal co-location. (1)Coexistence must turn out to be an absolute or objective matter; and inMinkowski spacetime coexistence must begrounded in the relation of spacelikeseparation. (2) If endurantism is true, then(1) leads to absurd conclusions; but ifperdurantism is true, then (1) is harmless. Iobject to both theses. Against (1), I arguethat coexistence is better construed as beingrelative to a (...) hyperplane of simultaneity.Against (2), I argue that the consequences of(1) given endurantism are no worse than theconsequences of (1) given perdurantism. (shrink)

In two earlier works (Balashov, 2000a: Philosophical Studies 99, 129–166; 2000b: Philosophy of Science 67 (Suppl), S549–S562), I have argued that considerations based on special relativity and the notion of coexistence favor the perdurance view of persistence over its endurance rival. Cody Gilmore (2002: Philosophical Studies 109, 241–263) has subjected my argument to an insightful three fold critique. In the first part of this paper I respond briefly to Gilmore’s first two objections. I then grant his observation that anyone who (...) can resist the first objection is liable to succumb to the third one. This, however, opens a way to other closely related relativistic arguments against endurantism that are immune to all three objections and, in addition, throw new light on a number of important issues in the ontology of persistence. I develop two such novel arguments in the second half of the paper. (shrink)

I offer an argument in defense of four-dimensionalism, the view that objects are temporally, as well as spatially extended. The argument is of the inference-to-the-best-explanation variety and is based on relativistic considerations. It deals with the situation in which one and the same object has different three-dimensional shapes at the same time and proceeds by asking what sort of thing it must be in order to present itself in such different ways in various "perspectives" (associated with moving reference frames) without (...) being different from itself. I argue that the best answer is that the object must be four-dimensional. It will then have differing 3D shapes in different perspectives because such shapes are intrinsic properties of its 3D parts. (shrink)

The nature of persistence of physical objects over time has been intensely debated in contemporary metaphysics. The two opposite views are widely known as "endurantism" (or "three-dimensionalism") and "perdurantism" ("four-dimensionalism"). According to the former, objects are extended in three spatial dimensions and persist through time by being wholly present at any moment at which they exist. On the rival account, objects are extended both in space and time and persist by having "temporal parts," no part being present at more than (...) one time. Relativistic considerations seem highly relevant to this debate. But they have played little role in it so far. This paper seeks to remedy that situation. I argue that considerations based on the special theory of relativity and the notion of coexistence favor perdurantism over endurantism. (shrink)

Background and assumptions. Persistence and philosophy of time ; Atomism and composition ; Scope ; Some matters of methodology -- Persistence, location, and multilocation in spacetime. Endurance, perdurance, exdurance : some pictures ; More pictures ; Temporal modification and the "problem of temporary intrinsics" ; Persistence, location and multilocation in generic spacetime ; An alternative classification -- Classical and relativistic spacetime. Newtonian spacetime ; Neo-Newtonian (Galilean) spacetime ; Reference frames and coordinate systems ; Galilean transformations in spacetime ; Special relativistic (...) spacetime ; Length contraction and time dilation ; Invariant properties of special relativistic spacetime -- Persisting objects in classical spacetime. Enduring, perduring, and exduring objects in Galilean spacetime ; The argument from vagueness ; From minimal D-fusions to temporal parts ; Motivating a sharp cutoff ; Some objections and replies ; Implications -- Persisting objects in Minkowski spacetime. Enduring, perduring, and exduring objects in Minkowski spacetime ; Flat and curved achronal regions in Minkowski spacetime ; Early reflections on persisting objects in Minkowski spacetime : Quine and Smart ; "Profligate ontology"? ; Is achronal universalism tenable in Minkowski spacetime? ; "Crisscrossing" and immanent causation -- Coexistence in spacetime. The notion of coexistence ; Desiderata ; Coexistence in Galilean spacetime ; Coexistence in Minkowski spacetime : CASH ; Alexandrov-Stein present and Alexandrov-Stein coexistence ; AS-Coexistence v. CASH : symmetry, multigrade, and objectivity ; As-coexistence v. CASH : relevance ; The mixed past of coexistence ; No need in the extended now -- Strange coexistence? Coexistence and existence@ ; The asymmetry thesis ; The absurdity thesis ; Collective CASH value of coexistence ; Collective existence@ and coexistence in classical spacetime ; Collective existence@ and coexistence in Minkowski spacetime ; Contextuality ; Chronological incoherence ; Some objections -- Shapes and other arrangements in Minkowski spacetime. How rigid is a granite block? ; Perspectives in space ; Perspectives in spacetime ; Are shapes intrinsic to objects? ; The causal objection ; The micro-reductive objection ; Pegs, boards, and shapes ; Perduring objects exist. (shrink)

Although considerations based on contemporary space-time theories, such as special and general relativity, seem highly relevant to the debate about persistence, their significance has not been duly appreciated. My goal in this paper is twofold: (1) to reformulate the rival positions in the debate (i.e., endurantism [three-dimensionalism] and perdurantism [four-dimensionalism, the doctrine of temporal parts]) in the framework of special relativistic space-time; and (2) to argue that, when so reformulated, perdurantism exhibits explanatory advantages over endurantism. The argument builds on the (...) fact that four-dimensional entities extended in space as well as time are relativistically invariant in a way three-dimensional entities are not. (shrink)

Four-dimensionalism, or perdurantism, the view that temporally extended objects persist through time by having (spatio-)temporal parts or stages, includes two varieties, the worm theory and the stage theory. According to the worm theory, perduring objects are four-dimensional wholes occupying determinate regions of spacetime and having temporal parts, or stages, each of them confined to a particular time. The stage theorist, however, claims, not that perduring objects have stages, but that the fundamental entities of the perdurantist ontology are stages. I argue (...) that considerations of special relativity favor the worm theory over the stage theory. (shrink)

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)

Four- Dimensionalism defends the thesis that the material world is composed of temporal as well as spatial parts. This defense includes a novel account of persistence over time, new arguments in favour of the four-dimensional ontology, and responses to the challenges four- dimensionalism faces." "Theodore Sider pays particular attention to the philosophy of time, including a strong series of arguments against presentism, the thesis that only the present is real. Arguments offered in favour of four- dimensionalism include novel arguments based (...) on time travel, the debate between spacetime substantivalists and relationalists, and vagueness. Also included is a comprehensive discussion of the paradoxes of coinciding material objects, and a novel resolution of those paradoxes based on temporal counterpart theory. In conclusion Sider replies to prominent objections to four- dimensionalism, including discussion of the problem of the rotating homogenous disk. (shrink)

Thomas Sattig develops a comprehensive framework for doing philosophy of time, and offers an original three-dimensionalist picture of the material world. He brings together a variety of different perspectives, linking our ordinary conception of time with the physicist's conception, and linking metaphysical questions about time with questions in the philosophy of language.

In debate about the nature of persistence over time, the view that material objects endure has played the role of “champion” and the view that they perdure has played the role of “challenger.” As in other contests, the champion’s job is merely to defend her title, whereas the challenger’s job is to prove herself worthy. I have no view about how these roles came to be assigned; but the historical fact is that perdurantists have traditionally borne the proverbial burden of (...) proof in this debate. It has fallen to the perdurantists rather than the endurantists to motivate their view, to provide reasons for accepting it that override whatever initial presumption there is against it. (shrink)