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.

This article provides a new context for an established metaphysical debate regarding the problem of persistence. I contend that perdurance, a popular view about persistence which maintains that objects persist by having temporal parts, can be formulated in quantum mechanics due to the existence of a formal analogy between temporal and spatial location. However, this analogy fails due to a ‘no-go’ result which demonstrates that quantum systems cannot be said to have temporal parts in the same way that they have (...) spatial parts. Therefore, if quantum mechanics describes persisting physical objects then those objects cannot be said to perdure. (shrink)

This paper is about the metaphysical debate whether objects persist over time by the selfsame object existing at different times (nowadays called “endurance” by metaphysicians), or by different temporal parts, or stages, existing at different times (called “perdurance”). I aim to illuminate the debate by using some elementary kinematics and real analysis: resources which metaphysicians have, surprisingly, not availed themselves of. There are two main results, which are of interest to both endurantists and perdurantists. (1) I describe a precise formal (...) equivalence between the way that the two metaphysical positions represent the motion of the objects of classical mechanics (both point-particles and continua). (2) I make precise, and prove a result about, the idea that the persistence of objects moving in a void is to be analysed in terms of tracking the continuous curves in spacetime that connect points occupied by matter. The result is entirely elementary: it is a corollary of the Heine–Borel theorem. (shrink)

This article discusses recent work in metaphysics on temporal parts. After a short introduction introducing the notion of a temporal part, we examine several well‐known arguments for the view that ordinary material objects such as tables, trees, and persons have temporal parts: (1) positing temporal parts makes it possible to solve puzzles of coincidence (e.g., the statue/lump puzzle); (2) positing temporal parts makes it possible to solve the problem of intrinsic change over time; and (3) the existence of temporal parts (...) can be demonstrated based on considerations about vagueness in composition. We conclude by examining briefly a recent argument that the dispute over whether there are temporal parts is merely verbal. (shrink)

Kant's distinction between things in themselves and things as they appear, or appearances, is commonly attacked on the ground that it delivers a radical and incoherent ‘two world’ picture of what there is. I attempt to deflect this attack by questioning these terms of dismissal. Distinctions of the kind Kant draws on are in fact legion, and they make perfectly good sense. The way to make sense of them, however, is not by buying into a profligate ontology but by using (...) some rather different tools – surprisingly enough, tools first developed in the area of aesthetics. Once this is done, much of what Kant says begins to look perfectly coherent. In the final part of the paper, I point out that none the less all is not well. Kant's Critical doctrines make it hard for us to accept Kant's own version of this otherwise coherent distinction. (shrink)

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)

I discuss three connections between Dummett's writings about time and philosophical aspects of physics. The first connection arises from remarks of Dummett's about the different relations of observation to time and to space. The main point is uncontroversial and applies equally to classical and quantum physics. It concerns the fact that perceptual processing is so rapid, compared with the typical time-scale on which macroscopic objects change their observable properties, that it engenders the idea of a `common now', spread across space. (...) The other two connections are specific to quantum theory, as interpreted along the lines of Everett. So for these two connections, the physics side is controversial, just as the philosophical side is. In Section 3, I connect the subjective uncertainty before an Everettian `splitting' of the multiverse to Dummett's suggestion, inspired by McTaggart, that a complete, i.e. indexical-free description of a temporal reality is impossible. And in Section 4, I connect Barbour's denial that time is real---a denial along the lines of Everett, rather than McTaggart---to Dummett's suggestion that statements about the past are not determinately true or false, because they are not effectively decidable. (shrink)

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)