Nel nostro universo, qualunque cosa, dalla più piccola particella alla più smisurata galassia, esiste in un qualche tempo e in un qualche luogo. Ma cosa significa esistere in un qualche tempo? Il fenomeno dell’esistenza temporale gioca un ruolo fondamentale nella comprensione dell’universo e di noi stessi quali creature temporali. Eppure è un fenomeno profondamente misterioso. L’esistenza temporale è da intendersi come una relazione? Che legami ha con l’esistenza dell’ontologia? L’esistenza temporale e la localizzazione spaziale sono due fenomeni essenzialmente differenti o (...) due istanze di un’unica relazione? Tutto ciò che esiste nel tempo esiste nel tempo nello stesso modo? Tutto ciò che è nel tempo è anche nello spazio? (shrink)

The Principal Principle (PP) says that, for any proposition A, given any admissible evidence and the proposition that the chance of A is x%, one's conditional credence in A should be x%. Humean Supervenience (HS) claims that, among possible worlds like ours, no two differ without differing in the spacetime-point-by-spacetime-point arrangement of local properties. David Lewis (1986b, 1994a) has argued that PP contradicts HS, and the validity of his argument has been endorsed by Bigelow et al. (1993), Thau (1994), Hall (...) (1994), Strevens (1995), Ismael (1996), Hoefer (1997), and Black (1998). Against this consensus, I argue that PP might not contradict HS: Lewis's argument is invalid, and every attempt – within a broad class of attempts – to amend the argument fails. (shrink)

I consider whether the self-ascription theory can succeed in providing a tenseless (B-theoretic) account of tensed belief and timely action. I evaluate an argument given by William Lane Craig for the conclusion that the self-ascription account of tensed belief entails a tensed theory (A-theory) of time. I claim that how one formulates the selfascription account of tensed belief depends upon whether one takes the subject of selfascription to be a momentary person-stage or an enduring person. I provide two different formulations (...) of the self-ascription account of tensed belief, one that is compatible with a perdurantist account of persons and the other that is compatible with an endurantist account of persons. I argue that a self-ascription account of tensed beliefs for enduring subjects most plausibly involves the self-ascription of relations rather than properties. I argue that whether one takes the subject of self-ascription to be a momentary personstage or an enduring person, the self-ascription theory provides a plausible B-theoretic account of how tensed belief and timely action are possible. (shrink)

Some essence facts have metaphysical explanations. Some metaphysical explanations for essence facts consist in nonessential facts.

The existence and importance of supervenience principles for identity across times and worlds have been noted, but insufficient attention has been paid to their precise nature. Such attention is repaid with philosophical dividends. The issues in the formulation of the supervenience principles are two. The first involves the relevant variety of supervenience: that variety is global, but there are in fact two versions of global supervenience that must be distinguished. The second involves the subject matter: the names “identity over time” (...) and “identity across worlds” are misnomers, for in neither case is identity at issue. The philosophical dividends then follow. Nathan Salmon’s argument that identity over time needs no “grounds” in matters of qualitative fact can be answered, as can an argument offered by many, that coincident objects would require objectionably ungrounded differences in identities across times and worlds. (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)

Eternalist tensism is the thesis that tense is an objective feature of reality as it is in itself and that all times, whether past, present, or future, are equally real. I develop an argument from qualitative change in favor of tensism and defend eternalism from an argument from fatalism.

One of the central debates in contemporary metaphysics has been the debate between endurantism and perdurantism about persistence. In this paper I argue that much of this debate has been misconstrued: most of the arguments in the debate crucially rely on theses which are strictly orthogonal to the endurantism/perdurantism debate. To show this, I note that the arguments in the endurantism/perdurantism debate typically take the following form: one presents a challenge that endurantists allegedly have some trouble addressing, and to which (...) perdurantism apparently has a straightforward response. I argue, however, that in each case, there are versions of endurantism that can offer precisely the same response to the challenge, and thus the ability to provide this particular solution does not directly tell in favour of one the two views. In §1, I elaborate two views which will be particularly prominent in the discussion: liberal endurantism and restrictive perdurantism. In §2–6 I discuss in turn the central pro-perdurantism arguments: the argument from anthropocentricism, the argument from vagueness, the argument from recombination, the argument from temporary intrinsics, and the argument from coincidence. In §7–8, I discuss the main pro-endurantism arguments: the arguments from motion, and the argument from permanent coincidence. Finally, in §9, I discuss what conclusion can be drawn from this discussion. (shrink)

In his excellent book, Four-Dimensionalism: An Ontology of Persistence and Time (Sider, 2001), Theodore Sider defends a version of four-dimensionalism which he calls the ‘stage-theory’. This paper focuses on Sider's argument from vagueness and argues that, due to the problematic nature of the argument from vagueness, Sider’s case in favor of four-dimensionalism is in the end not successful.

I claim that, if persisting objects have temporal parts, then there are non-supervenient relations between those temporal parts. These are relations which are not determined by intrinsic properties of the temporal parts. I use the Kripke-Armstrong 'rotating homogeneous disc' argument in order to establish this claim, and in doing so I defend and develop that argument. This involves a discussion of instantaneous velocity, and of the causes and effects of rotation. Finally, I compare alternative responses to the rotating disc argument, (...) and consider the implications of my arguments for the doctrines of Humean Supervenience and unrestricted mereology. (shrink)

Persistence in Time No person ever steps into the same river twice—or so goes the Heraclitean maxim. Obscure as it is, the maxim is often taken to express two ideas. The first is that everything always changes, and nothing remains perfectly similar to how it was just one instant before. The second is that nothing … Continue reading Persistence in Time →.

Traditionally, this puzzle has been solved in various ways. Aristotle, for example, distinguished between “accidental” and “essential” changes. Accidental changes are ones that don't result in a change in an objects' identity after the change, such as when a house is painted, or one's hair turns gray, etc. Aristotle thought of these as changes in the accidental properties of a thing. Essential changes, by contrast, are those which don't preserve the identity of the object when it changes, such as when (...) a house burns to the ground and becomes ashes, or when someone dies. Armed with these distinctions, Aristotle would then say that, in the case of accidental changes, (1) and (2) are both false—a changing thing can really change one of its “accidental properties” and yet literally remain one and the same thing before and after the change. (shrink)

Material objects extend through space by having different spatial parts in different places. But how do they persist through time? According to some philosophers, things have temporal parts as well as spatial parts: accepting this is supposed to help us solve a whole bunch of metaphysical problems, and keep our philosophy in line with modern physics. Other philosophers disagree, arguing that neither metaphysics nor physics give us good reason to believe in temporal parts.

An introduction to the theories of endurantism and perdurantism, and persistence more broadly.

This is a copy of my DPhil thesis, the abstract for which is as follows: The first third of this thesis argues for a B-theoretic conception of time according to which all times exist equally and the present is in no way privileged. I distinguish "ontological" A-theories from "non-ontological" ones, arguing that the latter are experientially unmotivated and barely coherent. With regard to the former, I focus mainly on presentism. After some remarks on how to formulate this (and eternalism) non-trivially, (...) I review the non-relativistic case against presentism. I then consider the impact of Special Relativity on the debate, and attempt to deepen this impact by supplying a modal variation on the standard arguments. The middle third of the thesis investigates persistence, contending that both endurance and perdurance are consonant with the eternalism already endorsed. After introducing these theories of persistence, and discussing in particular how best to formulate an eternalist endurance, I proceed to defend the coherence of this combination. The Problem of Change is addressed here. I then respond in some detail to recent allegations of relativistic threats to endurance. The final third of the thesis questions the validity of the endurantist-perdurantist dispute. I criticize two recently proposed translation schemes that aim to show this dispute to be non-substantive. However, the second scheme suggests a doctrine of "Ontological Equivalence" which I develop and consider. I then address the Rotating Discs Argument, using this to launch a discussion of identity, genidentity, and the relationship between them. (shrink)

In this paper I consider an objection that friends of the Metaphysic of Temporal Parts (MTP) press against other solutions to the problem of temporary intrinsics and turn it against the MTP itself. I do not argue that the MTP must be false, nor do I argue that there are no arguments in favor of the MTP. Rather, the conclusion I draw is conditional: if the MTP provides an adequate response to the problem of temporary intrinsics, then the MTP provides (...) no reason to reject our commonsense view of the nature of material objects. (shrink)

Some recent philosophical debate about persistence has focussed on an argument against perdurantism that discusses rotating perfectly homogeneous discs. The argument has been mostly discussed by metaphysicians, though it appeals to ideas from classical mechanics, especially about rotation. In contrast, I assess the RDA from the perspective of the philosophy of physics. After introducing the argument and emphasizing the relevance of physics, I review some metaphysicians' replies to the argument, especially those by Callender, Lewis, Robinson and Sider. Thereafter, I argue (...) for three main conclusions. They all arise from the fact, emphasized in Section 2, that classical mechanics is both more subtle, and more problematic, than philosophers generally realize. The first conclusion is that the RDA can be formulated more strongly than is usually recognized: it is not necessary to ``imagine away'' the dynamical effects of rotation. The second is that in general relativity, the RDA fails because of frame-dragging. The third is that even setting aside general relativity, the strong formulation of the RDA can after all be defeated. Namely, by the perdurantist taking objects in classical mechanics to have only temporally extended, i.e. non-instantaneous, temporal parts: which immediately blocks the RDA. Admittedly, this version of perdurantism defines persistence in a weaker sense of `definition' than pointilliste versions that aim to define persistence assuming only instantaneous temporal parts. But I argue that temporally extended temporal parts: can do the jobs within the endurantism- perdurantism debate that the perdurantist wants temporal parts to do; and are supported by both classical and quantum mechanics. (shrink)

If temporal parts are bona fide parts, then it is fitting to clarify and extend that notion (and related ones) using the resources of a theory of parts. But it often seems that those engaged in the 3D/4D debate appear to take for granted that, aside from introducing a welcome measure of rigor to the discussion, issues regarding theories of parthood can be allowed to recede into the background. What follows challenges that assumption — I demonstrate that the nature of (...) the fundamental mereological relation1 can decisively influence the outcome of the debate over persistence. In short, I show that if the fundamental mereological relation is proper parthood-at-atime then four-dimensionalism is false.2 Recognizing this does at least two things for us. First, it supplies a framework in which three-dimensionalists can clarify two things they have tended to say all along, namely that persisting things are ‘wholly present’ throughout their careers and that they do not have temporal parts. Second, it re-focuses the debate on a narrower and perhaps more tractable question: “What is the nature of the fundamental mereological relation?”. (shrink)