Theodore Sider has recently produced an argument which he takes to show that three-dimensionalism is incompatible with the possibility of time travel. I wish to argue that there is indeed a problem for the three-dimensionalist who wishes to countenance time travel, but that Sider has misdiagnosed it. I show why his putative challenge fails, and furthermore that if it were to succeed this would be as problematic for a wide class of four-dimensionalist positions, including Sider’s own, as it would be (...) for three-dimensionalism. Finally, I present the problem that the possibility of time travel genuinely poses for the three-dimensionalist. (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)

It is possible to wholly exist at multiple spatial locations at the same time. At least, if time travel is possible and objects endure, then such must be the case. To accommodate this possibility requires the introduction of a spatial analog of either relativising properties to times—relativising properties to spatial locations—or of relativising the manner of instantiation to times—relativising the manner of instantiation to spatial locations. It has been suggested, however, that introducing irreducibly spatially relativised or spatially adverbialised properties presents (...) some difficulties for the endurantist. I will consider an objection according to which embracing such spatially relativised properties could lead us to reject mereology altogether in favour of a metaphysics according to which objects are wholly present at every space-time point at which they exist. I argue that although such a view is coherent, there are some good reasons to reject it. Moreover, I argue that the endurantist can introduce spatially relativised or adverbialised properties without conceding that objects lack spatial parts. Such a strategy has the additional advantage that it allows the endurantist not only to explain time travel, but also to reconcile our competing intuitions about cases of fission. (shrink)

It is possible to wholly exist at multiple spatial locations at the same time. At least, if time travel is possible and objects endure, then such must be the case. To accommodate this possibility requires the introduction of a spatial analog of either relativising properties to times—relativising properties to spatial locations—or of relativising the manner of instantiation to times—relativising the manner of instantiation to spatial locations. It has been suggested, however, that introducing irreducibly spatially relativised or spatially adverbialised properties presents (...) some difficulties for the endurantist. I will consider an objection according to which embracing such spatially relativised properties could lead us to reject mereology altogether in favour of a metaphysics according to which objects are wholly present at every space-time point at which they exist. I argue that although such a view is coherent, there are some good reasons to reject it. Moreover, I argue that the endurantist can introduce spatially relativised or adverbialised properties without conceding that objects lack spatial parts. Such a strategy has the additional advantage that it allows the endurantist not only to explain time travel, but also to reconcile our competing intuitions about cases of fission. (shrink)

Theodore Sider’s Four-Dimensionalism is a well-organized and clearly written book that is chock-full of important arguments. Both friends and foes of the views defended by Sider will benefit enormously from careful study of the book. I am going to focus on just two of Sider’s many arguments for Four-Dimensionalism: his argument from vagueness, which I take to be the most important and powerful argument in the book, and his argument from time travel, which I find to be the funnest to (...) think about. (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)

Memory theories of personal identity are subject to the difficulty that distinct simultaneous person stages may both stand in the memory relation to an earlier person stage. Apparently, Such theories entail that these two duplicate person stages are stages of the same person, A claim argued to be "obviously false". In this paper, I argue that the characteristics of these duplication cases usually cited to support this claim do not provide adequate evidence to make it cogent.

The prominent place 0f corpuscularizm mechanism in L0ckc`s Essay is nowadays universally acknowledged} Certainly, L0ckc’s discussions 0f the primary/secondary quality distinction and 0f real essences cannot be understood without reference to the corpuscularizm science 0f his day, which held that all macroscopic bodily phenomena should bc explained in terms 0f the motions and impacts 0f submicroscopic particles, 0r corpuscles, each of which can bc fully characterized in terms of 21 strictly limited range 0f (primary) properties: size, shape, motion (or mobility), (...) and, perhaps, solidity 0r impcnctrability.2 Indeed, L0ckc’s lists 0f primary quali-. (shrink)

The article presents a new interpretation of Hume’s treatment of personal identity, and his later rejection of it in the “Appendix” to the Treatise. Hume’s project, on this interpretation, is to explain beliefs about persons that arise primarily within philosophical projects, not in everyday life. The belief in the identity and simplicity of the mind as a bundle of perceptions is an abstruse belief, not one held by the “vulgar” who rarely turn their minds on themselves so as to think (...) of their perceptions. The author suggests that it is this philosophical observation of the mind that creates the problems that Hume finally acknowledges in the “Appendix.” He is unable to explain why we believe that the perceptions by means of which we observe our minds while philosophizing are themselves part of our minds. This suggestion is then tested against seven criteria that any interpretation of the “Appendix” must meet. (shrink)

The article presents a new interpretation of Hume's treatment of personal identity, and his later rejection of it in the “Appendix” to the Treatise. Hume's project, on this interpretation, is to explain beliefs about persons that arise primarily within philosophical projects, not in everyday life. the belief in the identity and simplicity of the mind as a bundle of perceptions is an abstruse belief, not one held by the “vulgar” who rarely turn their minds on themselves so as to think (...) of their perceptions. the author suggests that it is this philosophical observation of the mind that creates the problems that Hume finally acknowledges in the “Appendix.” He is unable to explain why we believe that the perceptions by means of which we observe our minds while philosophizing are themselves part of our minds. This suggestion is then tested against seven criteria that any interpretation of the “Appendix” must meet. (shrink)

Locke’s theory of consciousness is often appropriated as a forerunner of present-day Higher-Order Perception (HOP) theories, but not much is said about it beyond that. We offer an interpretation of Locke’s account of consciousness that portrays it as crucially different from current-day HOP theory, both in detail and in spirit. In this paper, it is argued that there are good historical and philosophical reasons to attribute to Locke the view not that conscious states are accompanied by higher-order perceptions, but rather (...) that conscious states constitute perceptions of themselves. (shrink)

Locke has been accused of failing to have a coherent understanding of consciousness, since it can be identical neither to reflection nor to ordinary perception without contradicting other important commitments. I argue that the account of consciousness is coherent once we see that, for Locke, perceptions of ideas are complex mental acts and that consciousness can be seen as a special kind of self-referential mental state internal to any perception of an idea.