Thomas Sattig

Perdurance is a mode of persistence. The heart of perdurance is a space-time analogy: a perduring object is extended in time in a way that is analogous to how a composite object is extended in space. This paper is a discussion of perdurance in light of the distinction between mereologically structured and unstructured objects. I show that while the standard formulation of perdurance captures the space-time analogy for unstructured objects, it fails to capture the space-time analogy for temporally and spatially structured objects. I conclude that there are substantially different ways for an object to be space-like temporally extended.

This Element is a survey of central topics in the metaphysics of material objects. The topics are grouped into four problem spaces. The first concerns how an object's parts are related to the object's existence and to the object's nature, or essence. The second concerns how an object persists through time, how an object is located in spacetime, and how an object changes. The third concerns paradoxes about objects, including paradoxes of coincidence, paradoxes of fission, and the problem of the many. The fourth concerns views with radical consequences regarding the existence of composite material objects, including mereological nihilism, ontological anti-realism, and deflationism.

As a preliminary, I shall follow MartyMarty, Anton and many others by adopting the common view that short episodes of change through time, such as the movement of a falling leaf or the frequency shift of a tone over the period of a second or less, can be experienced ‘immediately’. In order to motivate this view, compare looking at a falling leaf and looking at a wilting leaf. It seems that in the case of the falling leaf we can see the leaf’s movement just by looking at it, whereas we cannot just see the wilting leaf’s change in shape and colour.

Our perceptual experiences as of change over time seem to be accompanied by the sense that time flows. The sense of flow is widely regarded as one of the most elusive aspects of temporal experience. In this paper, I develop a novel account of its nature. I give an initial characterization of the sense of flow as the sense that the present changes—in short, as the sense of replacement. Further, I specify the type of account of the sense of replacement to be developed: since the sense that the present changes will be assumed to be grounded in the perceptual representation that the present changes, my focus will be to explain the perceptual representation that the present changes. I develop an account of the synchronic perceptual representation of the present. Finally, I develop an account of the diachronic perceptual representation of the present as changing.

Slot mereology reduces parthood to slot-filling: a material object is structured by a certain arrangement of slots; and the fillers of these slots are the object's proper parts. My aim in this essay is to go further and reduce slot-filling to essence and grounding. In combination, the reduction of parthood to slot-filling and the reduction of slot-filling to essence and grounding yields the reduction of parthood to essence and grounding. If this overarching reduction succeeds, it promises new metaphysical foundations for neo-Aristotelian mereology.

We seem to experience time as flowing. Yet according to the leading metaphysical picture of time, the block-universe theory, time in fact does not flow. Block-lovers typically react to this apparent tension by unhitching the sense of flow in our temporal experience from temporal reality, holding that temporal experience is systematically illusory. I shall develop a new block-friendly account of the sense of flow, which preserves a match of temporal experience and temporal reality. According to this account, the sense of flow arises from higher-order temporal experience.

The vast majority of philosophers of personal identity since John Locke have been convinced that the persistence of persons is not grounded in bodily continuity. Why? As numerous ‘textbooks’ on personal identity attest, their conviction rests, to a large extent, on an objection to the bodily approach, which concerns episodic memory. The objection invites us to a thought experiment in which we meet a person who experientially remembers events from the past of a person with a different body. The nature of such first-personal memory-links is viewed as strongly suggesting that the rememberer is identical with the remembered, and hence, given the possibility of such a case, as suggesting that a person can transgress its bodily limits. The memory objection is as influential as it gets in the metaphysics of personal identity. Textbooks often portray it as the starting point of the contemporary debate about personal identity. And it has been widely perceived as a success. As everyone who has taught an introductory course on personal identity knows, the recognition of episodic-memory links in body-switching cases has the power to turn any group of novice students against bodily criteria of personal identity. In this essay, I shall specify and undermine the memory objection. I shall attempt to establish two theses. The first thesis is that the memory objection is only viable if construed as resting on the view that episodic memory contains a sense of personal identity, which teaches us about the reality of personal identity. The second thesis is that there is no such sense of personal identity, that episodic memory teaches us nothing at all about personal identity.

This chapter develops a three-dimensionalist account of temporal supervenience — the temporal-regions account — and argues that the latter shares the main virtues and avoids the main drawbacks of its four-dimensionalist rival. The three-dimensionalist account asserts and explains the theses that the facts of persistence logically supervene on facts about the spatiotemporal location of objects, and that the facts of temporal instantiation logically supervene on the atemporal instantiation of properties by temporally unextended spacetime regions occupied by objects. Structural similarities of the temporal-regions account and the temporal-parts account are pointed out, and the temporal-regions account is shown to avoid the problems that threaten the temporal-parts account. The remainder of the chapter deals with various consequences and apparent difficulties of three-dimensionalist supervenience.

This chapter serves as an introduction to the themes of the book. The thesis of temporal supervenience is that all facts about ordinary time, all facts shaped by our ordinary temporal discourse, logically supervene on facts about spacetime; what goes on in spacetime fully determines what goes on in ordinary time. Temporal supervenience has many aspects, corresponding to various kinds of supervenient temporal phenomena. Among the most basic phenomena are persistence and change through ordinary time. The problem of temporal supervenience with respect to these phenomena has two components. The first component is to specify the spatiotemporal supervenience base of persistence and change. How do objects occupy spacetime? And how are properties instantiated across occupied spacetime? The second component is to build an explanatory bridge from the supervenience base to the supervenient phenomena. Such a bridge requires an ‘analysis’ of temporal existence and temporal instantiation, that is, a semantic account of ordinary temporal predications such as ‘a was F’. The problem of temporal supervenience thus connects the metaphysics of time with the semantics of temporal discourse. Before the supervenience of ordinary temporal facts on spacetime facts can be explained, the shape of ordinary time needs to be clarified. This is a further task of Chapter 1. Tenserism and A-time are criticized in the context of temporal supervenience with the aim of promoting detenserism as the correct account of tense and B-time as the true shape of ordinary time.

Part of the problem of temporal supervenience is the problem of spatiotemporal location: how are objects located in spacetime? This chapter provides a detailed statement of various answers to this problem. The main answers are three-dimensionalism and four-dimensionalism. The three-dimensionalist holds that an object occupies many temporally unextended regions of spacetime, whereas the four-dimensionalist holds that an object occupies only a single temporally extended region of spacetime. Subsequently to stating these accounts of spatiotemporal location, the chapter discusses the relationship of three-dimensionalism and four-dimensionalism to other theses and theories, including the theory of temporal parts, endurantism, perdurantism, eternalism, and presentism.

The problem of the many poses the task of explaining mereological indeterminacy of ordinary objects in a way that sustains our familiar practice of counting these objects. The aim of this essay is to develop a solution to the problem of the many that is based on an account of mereological indeterminacy as having its source in how ordinary objects are, independently of how we represent them. At the center of the account stands a quasi-hylomorphic ontology of ordinary objects as material objects with multiple individual forms.

What happens to a person in a case of fission? Does it survive? Does it go out of existence? Or is the outcome indeterminate? Since each description of fission based on the persistence conditions associated with our ordinary concept of a person seems to clash with one or more platitudes of common sense about the spatiotemporal profile of macroscopic objects, fission threatens the common-sense conception of persons with inconsistency. Standard responses to this paradox agree that the common-sense conception of persons is unstable, differing over which part of the conception requires revision. I will show that this entrenched view of fission is not compulsory. I will develop a solution to the paradox that maintains the consistency of the common-sense conception of persons on the basis of an ontology of persons and other ordinary objects as double-layered compounds. Each of various descriptions of the outcome of personal fission is compatible with principles about the spatiotemporal profile of persons, because the descriptions and the principles manifest different perspectives on persons and are made true or false by different ontological components of the latter. What holds for the fission of persons, holds for the fission of other kinds of objects

If ordinary objects have temporal parts, then temporal predications have the following truth conditions: necessarily, ( a is F) at t iff a has a temporal part that is located at t and that is F. If ordinary objects have temporal counterparts, then, necessarily, ( a is F) at t iff a has a temporal counterpart that is located at t and that is F. The temporal-parts account allows temporal predication to be closed under the parthood relation: since all that is required to be F at t is to have a temporal part, a t , that is located at t and that is F, every object that has a t as a temporal part is F at t . Similarly for the temporal-counterparts account. Both closure under parthood and closure under counterparthood are shown to have unacceptable consequences. Then strategies for avoiding closure are considered and rejected.

An account of temporal supervenience requires an account of temporal predication: a semantic account of the language in which facts about ordinary time are stated. For the detenser, the problem of temporal predication is essentially the task of giving an account of the semantic function of the modifier ‘at t’ in ‘a is F at t’. In the project of explaining temporal supervenience, an account of temporal predication functions as an analysis of ordinary temporal facts, which is required to build an explanatory bridge from these temporal facts to their spatiotemporal supervenience base. This chapter discusses various accounts of temporal predication that share the common feature that temporal supervenience cannot be explained on the basis of them, because these accounts allow no plausible explanatory link between the facts of persistence and change and any facts about spacetime.

Gareth Evans adduces a case in which a proper name apparently undergoes a change in referent. ‘Madagascar’ was originally the name of a part of Africa. Marco Polo, erroneously thinking he was following native usage, applied the name to an island off the African coast. Today ‘Madagascar’ is the name of that island. Evans argues that this kind of case threatens Kripke ’s picture of naming as developed in Naming and Necessity. According to this picture, the name, as used by Marco Polo, referred to a part of the African mainland, since he was connected to the latter by a historical chain of communication. Since we are historically connected to Marco Polo, the name, as it is used today, still refers to the African mainland. But it doesn’t. The aim of the present paper is to give a conclusive account of the phenomenon adduced by Evans, which is compatible with Kripke ’s picture

Gareth Evans (1973) adduces a case in which a proper name apparently undergoes a change in referent. ‘Madagascar’ was originally the name of a part of Africa. Marco Polo, erroneously thinking he was following native usage, applied the name to an island off the African coast. Today ‘Madagascar’ is the name of that island. Evans argues that this kind of case threatens Kripke’s picture of naming as developed in Naming and Necessity. According to this picture, the name, as used by Marco Polo, referred to a part of the African mainland, since he was connected to the latter by a historical chain of communication. Since we are historically connected to Marco Polo, the name, as it is used today, still refers to the African mainland. But it doesn’t. The aim of the present paper is to give a conclusive account of the phenomenon adduced by Evans, which is compatible with Kripke’s picture.

It seems to be a platitude of common sense that distinct ordinary objects cannot coincide, that they cannot fit into the same place or be composed of the same parts at the same time. The paradoxes of coincidence are instances of a breakdown of this platitude in light of counterexamples that are licensed by innocuous assumptions about particular kinds of ordinary object. Since both the anticoincidence principle and the assumptions driving the counterexamples flow from the folk conception of ordinary objects, the paradoxes threaten this conception with inconsistency. Typical approaches to the paradoxes reject the anticoincidence principle or some portion of the assumptions driving the counterexamples, thereby partially revising our common conception of the world around us. This essay offers a compatibilist solution to the paradoxes that sustains the folk conception of ordinary objects in its entirety. According to this solution, the various cases of distinct coincidents do not clash with the anticoincidence principle since the cases and the principle manifest different yet compatible perspectives on the world

This chapter presents a new account of temporal predication — the representational account — combined with four-dimensionalism to yield the temporal-parts account of temporal supervenience. This elegant account asserts and explains the theses that the facts of persistence logically supervene on facts about the spatiotemporal location of temporal parts of objects, and that the facts of temporal instantiation logically supervene on facts about the atemporal instantiation of properties by temporal parts of objects. It is further shown that the questions of temporal supervenience as well as the four-dimensionalist answers to these questions have interesting spatial and modal analogues. Despite its success in explaining the supervenience of facts of persistence and change, the temporal-parts account has objectionable consequences. Three problems are raised, the most serious of which is the problem of predicational overkill. Each of these problems concerns the account’s failure to capture certain ordinary temporal facts.