According to three-dimensionalism, objects persist in time by being wholly present at each time they exist; on the contrary, four-dimensionalism asserts that objects persist by having different temporal parts at different times or that they are instantaneous temporal parts of four-dimensional aggregates. Le Poidevin has argued that four-dimensionalism better accommodates two common assumptions concerning persistence and continuity; namely, that time itself is continuous and that objects persist in time in a continuous way. To this purpose, he has offered two independent (...) arguments, each of which moves from a different understanding of continuity. In this paper, both of Le Poidevin’s arguments will be discussed and rejected. (shrink)

I argue that time travel to the past is impossible, given a certain metaphysical theory, namely, The Dynamic Theory of Time. I first spell out my particular way of capturing the difference between The Dynamic Theory of Time and its rival, The Static Theory of Time. Next I offer four different arguments for the conclusion that The Dynamic Theory is inconsistent with the possibility of time travel to the past. Then I argue that, even if I am wrong about this, (...) it will still be true that The Dynamic Theory entails that you should not want to travel back to the past. Finally, I conclude by considering a puzzle that arises for those who believe that time travel to the past is metaphysically impossible: What exactly are we thinking about when we seem to be thinking about traveling back in time? For it certainly does not feel like we are thinking about something that is metaphysically impossible. (shrink)

There is a popular theory in the metaphysics of time according to which time is one of four similar dimensions that make up a single manifold that is appropriately called spacetime. One consequence of this thesis is that changing an object’s orientation in the manifold does not change its intrinsic features. In this paper I offer a new argument against this popular theory. I claim that an especially good performance of a particularly beautiful piece of music, when oriented within the (...) manifold in the normal way, adds to the intrinsic value of the world, but that if the same performance is turned sideways within the manifold, so that it involves a number of different notes spread out in space and all occurring at the same time, then it does not add the same intrinsic value to the world. (shrink)

According to The Static Theory of Time, time is like space in various ways, and there is no such thing as the passage of time. According to The Dynamic Theory of Time, on the other hand, time is very different from space, and the passage of time is an all-too-real phenomenon. This paper first offers some suggestions about how we should understand these two theories, and then introduces five new arguments for The Dynamic Theory of Time.

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)

One way of understanding the reduplicative formula "Christ is, ’qua’ God, omniscient, but ’qua’ man, limited in knowledge" is to take the occurrences of the ‘qua‘ locution as picking out different parts of Christ: a divine part and a human part. But this view of Christ as a composite being runs into paradox when combined with the orthodox understanding of the Incarnation, according to which Christ is identical to the second person of the Trinity. In response, we have to choose (...) between modifying the orthodox understanding, adopting a philosophically and theologically contentious perdurantist account of persistence through time, or rejecting altogether the idea of the composite Christ. (shrink)

One way of understanding the reduplicative formula ‘Christ is, qua God, omniscient, but qua man, limited in knowledge’ is to take the occurrences of the ‘ qua ’ locution as picking out different parts of Christ: a divine part and a human part. But this view of Christ as a composite being runs into paradox when combined with the orthodox understanding of the Incarnation, according to which Christ is identical to the second person of the Trinity. In response, we have (...) to choose between modifying the orthodox understanding, adopting a philosophically and theologically contentious perdurantist account of persistence through time, or rejecting altogether the idea of the composite Christ. (shrink)

The literature suggests two main answers to the question of what it is for a material object to be located at a region of spacetime. Both have a number of virtues. However, both suffer from well-known problems. According to one answer, location is a primitive relation with no informative metaphysical analysis. But this makes a number of necessary truths seem mysterious and leaves them unexplained. According to the other answer, to be located at a region is just to be identical (...) to that region. But this is inconsistent with a number of independently plausible theses about material objects and their locations. In this paper, I explore a new theory of location and argue that it has the virtues of these familiar theories but not their vices. I then explore some further connections the new theory has with some contemporary issues in metaphysics. (shrink)

Some tools introduced by Linnebo to show that mathematical entities are thin objects can also be applied to non-mathematical entities, which have been thought to be thin as well for a variety of reasons. In this paper, I discuss some difficulties and opportunities concerning the application of abstraction and interpretational modalities to mereological sums. In particular, I show that on one hand some prima facie attractive candidates for the role of an explanatory plural abstraction principle for mereological sums (in terms (...) of pluralities of summed entities) are not really explanatory; on the other hand, singular abstraction principles (in terms of single summed entities) are materially inadequate. Nonetheless, explanatory criteria of identity and conditions of existence for mereological sums are provided by classical extensional mereology independent of abstraction principles. Thus, given classical extensional mereology, the reasons why, according to Linnebo, mathematical abstracted entities are thin also hold for mereological sums. Finally, I contend that interpretational modalities can be used to characterise the process by which a subject adds sums of previously admitted entities to the domain of quantification. (shrink)

This paper presents a synoptic overview of two key philosophical concepts – self and identity - in Indian tradition. Drawing on both Indian and Western studies on the concept of self-hood and its implications for conceptualising identity, the paper reviews the contemporary scholarship on self-hood and outlines its relation to identity needs to be rethought if ethical possibilities of self-hood are to be given due consideration. This paper asks and addresses the nature and experience of the self in the Indian (...) intellectual tradition, how representative Indian thinkers conceptualised the self, how such a conception of self-hood engages with the overall conception of Western history of self-hood and so on. The paper offers a comparative study of self-hood that not only underscores the significant points of convergence and divergence as theorised in Indian and Western philosophical traditions but also highlights how certain conceptions of self-hood and identity enable the project of the self’s ethical transformation. (shrink)

This paper provides a detailed examination of Kit Fine’s sizeable contribution to the development of a neo‐Aristotelian alternative to standard mereology; I focus especially on the theory of ‘rigid’ and ‘variable embodiments’, as defended in Fine 1999. Section 2 briefly describes the system I call ‘standard mereology’. Section 3 lays out some of the main principles and consequences of Aristotle’s own mereology, in order to be able to compare Fine’s system with its historical precursor. Section 4 gives an exposition of (...) Fine’s theory of embodiments and goes on to isolate a number of potential concerns to which this account gives rise. In particular, I argue that Fine’s theory threatens to proliferate primitive sui generis relations of parthood and composition, whose characteristics must be stipulatively imposed on them, relative to particular domains; given its ‘superabundance’ of objects, Fine’s system far outstrips the already inflated ontological commitments of standard mereology; and there is a legitimate question as to why we should consider Fine’s primitive and sui generis relations of parthood and composition to be genuinely mereological at all, given their formal profile. These three objections lead me to conclude that we ought to explore other avenues that preserve the highly desirable, hylomorphic, features of Fine’s mereology, while avoiding its methodological and ontological excesses. (shrink)

In this paper I propose a novel treatment of generic sentences, which proceeds by means of different levels of analysis. According to this account, all generic sentences (I-generics and D-generics alike) are initially treated in a uniform manner, as involving higher-order predication (following the work of George Boolos, James Higginbotham and Barry Schein on plurals). Their non-uniform character, however, re-emerges at subsequent levels of analysis, when the higher-order predications of the first level are cashed out in terms of quantification over (...) individuals: this last step, I suggest, involves knowledge concerning the lexical meaning of the predicates in question. (shrink)

Whenever an object constitutes, makes up or composes another object, the objects in question share a striking number of properties. This paper is addressed to the question of what might account for the intimate relation and striking similarity between constitutionally related objects. According to my account, the similarities between constitutionally related objects are captured at least in part by means of a principle akin to that of strong supervenience. My paper addresses two main issues. First, I propose independently plausible principles (...) by means of which to delineate, in a non-ad-hoc, non-stipulative and non-circular fashion, those properties which can be expected to be shared among constitutionally related objects in virtue of their being so related from those which in general cannot be expected to be shared, or which are shared for other reasons. Secondly,I spell out in detail the nature of the supervenience-principle at work in this context. My account thus aims at isolating, in a methodologically responsible fashion, the particular sort of restricted indiscernibility principle which is a component of the constitution-relation. (shrink)

When some objects are the parts of another object, they compose that object and that object is composite. This article is intended as an introduction to the central questions about composition and a highly selective overview of various answers to those questions. In §1, we review some formal features of parthood that are important for understanding the nature of composition. In §2, we consider some answers to the question: which pluralities of objects together compose something? As we will see, the (...) dominant answers are all of them and none of them. In §§3-4, we examine one of the main arguments that has driven philosophers to these extreme answers: the argument from vagueness. In §5, we turn to the question of whether composition is unique: is it sometimes the case that some things compose more than one thing? Finally, in §6, we turn from the question of which composites exist to the question of which composites exist fundamentally. (shrink)

Current formulations of Four-Dimensionalism may be objected to on grounds that they are too inflexible: the formulations do not seem to allow for enough variety in the views they are paired with. For instance, Kit Fine has noted that formulations of Four-Dimensionalism in terms of instantaneous parts may be too demanding for Four-Dimensionalists who believe nothing is instantaneous. And Trenton Merricks has argued that one can think something persists four-dimensionionally without taking it to have proper temporal parts, and claims that (...) our formulation of Four-Dimensionalism should be revised to allow for this. I will add my own worries to those of Fine and Merricks. I will note that current formulations of Four-Dimensionalism are not sufficiently neutral with respect to the structure of time, with respect to how liberally objects decompose into parts, and with respect to whether objects and the regions they fill match in mereological structure. I will show that we can formulate Four-Dimensionalism in a sufficiently neutral way, while still producing a view that can do the work we typically require of Four-Dimensionalism. (shrink)

Multilocation and Minimal Mereology do not mix well. It has been pointed out that Three-Dimensionalism, which can be construed as multilocation-friendly, runs into trouble with Weak Supplementation. But in fact, regardless of one’s theory of persistence, if someone posits the possibility of any one of several kinds of multilocation, he or she will not be able to maintain the necessity of any of the three axioms of Minimal Mereology: the Transitivity of Proper Parthood, the Asymmetry of Proper Parthood, and Weak (...) Supplementation. In fact, positing even the mere conceivability of cases involving multilocation will require the denial of the analyticity of Minimal Mereology. In response to this, some have claimed that we ought to relativise parthood, either to one region or to two. Unfortunately, if we replace the axioms of Minimal Mereology with region-relativised counterparts, we will not be able to capture the intuitions that supported the original axioms. The only adequate solution, I maintain, is to restrict multilocation to a domain outside the scope of the rules we intuitively take to govern the parthood relation. For those who take Minimal Mereology to be necessary and universal, that will mean relinquishing the possibility of multilocation. (shrink)

Judith Thomson, David Lewis, and Ted Sider have each formulated different arguments that apparently pose problems for our ordinary claims of diachronic sameness, i.e., claims in which we assert that familiar, concrete objects survive (or persist) through time by enduring as numerically the same entity despite minor changes in their intrinsic or relational properties. In this paper, I show that all three arguments fail in a rather obvious way--they beg the question--and so even though there may be arguments that provide (...) grounds to fuss about whether our ordinary claims of diachronic sameness are defective, Thomson, Lewis, and Sider's arguments are not among them. (shrink)

Sider has argued that four‐dimensionalism can be given a clear and coherent formulation, and has attempted to provide one. He has also argued that three‐dimensionalism resists adequate formulation. I argue that Sider's worries about whether there is an adequate formulation of three‐dimensionalism are misplaced, and suggest a formulation of three‐dimensionalism different from the ones considered and rejected by Sider. I then give a ‘matching’ formulation of four‐dimensionalism, and argue that it captures four‐dimensionalism better than Sider's own formulation of that doctrine.

Sider has argued that four‐dimensionalism can be given a clear and coherent formulation, and has attempted to provide one. He has also argued that three‐dimensionalism resists adequate formulation. I argue that Sider's worries about whether there is an adequate formulation of three‐dimensionalism are misplaced, and suggest a formulation of three‐dimensionalism different from the ones considered and rejected by Sider. I then give a ‘matching’ formulation of four‐dimensionalism, and argue that it captures four‐dimensionalism better than Sider's own formulation of that doctrine.

Take this banana. It is now yellow, and when I bought it yesterday it was green. How can a single object be both green all over and yellow all over without contradiction? It is, of course, the passage of time which dissolves the contradiction, but how is this possible? How can a banana ripen? These questions raise the problem of change. The problem is sometimes called the problem of temporary intrinsics, but, as I shall explain below, this emphasis on intrinsic (...) properties is misleading. For my more recent thoughts in this area, please see my 'David Lewis on Persistence' (2015). (shrink)

Can institutional objects be identified with physical objects that have been ascribed status functions, as advocated by John Searle in The Construction of Social Reality (1995)? The paper argues that the prospects of this identification hinge on how objects persist – i.e., whether they endure, perdure or exdure through time. This important connection between reductive identification and mode of persistence has been largely ignored in the literature on social ontology thus far.

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)

We have compelling extra-philosophical reasons for caring about identity, parthood, and location. For example, we desire ceteris paribus that nothing every part of which is very near to our location be very near to the location of something dangerous, evil, or otherwise unpleasant. This essay argues that such considerations are relevant to certain first-order metaphysical debates, namely, the debates over immanent universals and tropes and endurantism and perdurantism, respectively. As a consequence, even the non-specialist has a reason to care about (...) the metaphysics of properties and persistence. (shrink)

This critical notice describes some of Thomas Sattig’s book The Double Lives of Objects: An Essay in the Metaphysics of the Ordinary World and raises several critical issues about it.

Hylomorphically complex objects are things that change their parts or matter or that might have, or have had, different parts or matter. Often ontologists analyze such objects in terms of sets (or functions, understood set-theoretically) or other extensional entities such as mereological fusions or quantities of matter. I urge two reasons for being wary of any such analyses. First, being extensional, such things as sets are ill-suited to capture the characteristic modal and temporal flexibility of hylomorphically complex objects. Secondly, sets (...) are often appealed to because they seem to contain their members. But the idea that sets do contain their members, in the ordinary sense of containment, is a substantive metaphysical position that makes analyses that rely on that idea for their plausibility much more metaphysically committing than is generally thought. (shrink)

Four-dimensionalism, the stage theory version in particular, has been defended as the best solution for avoiding vagueness in regards to composition, persistence and identity. Stage theory is highly problematic by itself, and the two views usually packed with it, unrestricted composition and counterpart theory, are a heavy burden. However, dispensing with these two views, four-dimensionalism could avoid vague persistence by issuing a criterion that would establish sharp temporal boundaries for the existence of genuine entities (simples, molecules and living organisms). This (...) would avoid vague existence and vague identity, but in a way that is still compatible with endurantism. Nevertheless, a minimal (substantialist) four-dimensionalism, a worm perdurantist ontology, would fit better with the unique way in which organisms persist: by retaining both identity and intrinsic change. (shrink)

This paper opposes universal mereological composition (UMC). Sider defends it: unless UMC were true, he says, it could be indeterminate how many objects there are in the world. I argue that there is no general connection between how widely composition occurs and how many objects there are in the world. Sider fails to support UMC. I further argue that we should disbelieve in UMC objects. Existing objections against them say that they are radically unlike Aristotelian substances. True, but there is (...) a stronger objection. This is that they are characterized by no properties, and so fail to be like anything – even themselves. (shrink)

This paper opposes universal mereological composition. Sider defends it: unless UMC were true, he says, it could be indeterminate how many objects there are in the world. I argue that there is no general connection between how widely composition occurs and how many objects there are in the world. Sider fails to support UMC. I further argue that we should disbelieve in UMC objects. Existing objections against them say that they are radically unlike Aristotelian substances. True, but there is a (...) stronger objection. This is that they are characterized by no properties, and so fail to be like anything – even themselves. (shrink)

This paper argues that, in light of certain scenarios involving time travel, Sider’s definition of ‘instantaneous temporal part’ cannot be accepted in conjunction with a semantic thesis that perdurantists often assume. I examine a rejoinder from Sider, as well as Thomson’s alternative definition of ‘instantaneous temporal part’, and show how neither helps. Given this, we should give up on the perdurantist semantic thesis. I end by recommending that, once we no longer accept such semantics, we should accept a new set (...) of definitions, which are superior in certain respects to Sider’s original set. (shrink)

This article discusses two arguments in favor of perdurance. The first is Sider’s argument from vagueness, “one of the most powerful” in favor of perdurantism. I make the observation that endurantists have principled grounds to claim that the argument is unsound, at least if endurance is formulated in locative rather than mereological terms. Having made this observation, I use it to emphasize a somewhat neglected difference between endurantists and perdurantists with respect to their views on material objects. These views, in (...) the case of endurantists, lead to a further, less than conclusive but nevertheless interesting argument against endurantism—the anti-fundamentality argument—which I discuss and tentatively endorse. That argument posits that endurantists must take location to be a fundamental relation, and that this has as a consequence the metaphysical possibility of some rather unwelcome scenarios. Perdurantists may avoid this consequence by denying that location is fundamental, perhaps by embracing supersubstantivalism. (shrink)

The notion of multiple location plays an important role in the characterization of endurantism. Several authors have recently offered cases intended to demonstrate the incoherence of multiple location. I argue that these cases do not succeed in making multiple location problematic. Along the way, several crucial issues about multiple location and its use by endurantists are clarified.

Résumé Dans les débats métaphysiques contemporains, « endurer » et « perdurer » désignent deux manières irréductibles de persister dans le temps et de subir le changement. Parce qu’ils mobilisent différemment la forme de représentation « espace-temps », ces schèmes conceptuels révèlent peut-être deux figures ou deux aspects du temps lui-même.

According to the prevalent 'sum view' of stuffs, each portion of stuff is a mereological sum of its subportions. The purpose of this paper is to re-examine the sum view in the light of a modal temporal mereology which distinguishes between different varieties of summation relations. While admitting David Barnett's recent counter-example to the sum view, we show that there is nonetheless an important sense in which all portions of stuff are sums of their subportions. We use our summation relations (...) to develop, as an alternative to the sum view, an analysis of stuffs that distinguisher between the ways in which different sorts of stuffs are sums of their subportions. (shrink)

It is often assumed that indeterminacy in mereological relations—in particular, indeterminacy in which collections of objects have fusions—leads immediately to indeterminacy in what objects there are in the world. This assumption is generally taken as a reason for rejecting mereological vagueness. The purpose of this paper is to examine the link between mereological vagueness and existential vagueness. I hope to show that the connection between the two forms of vagueness is not nearly so clear-cut as has been supposed.

In this paper, I focus on three issues intertwined in current debates between endurantists and perdurantists—(i) the dimension of persisting objects, (ii) whether persisting objects have timeless, or only time-relative, parts, and (iii) whether persisting objects have proper temporal parts. I argue that one standard endurantist position on the first issue is compatible with standard perdurantist positions on parthood and temporal parts. I further argue that different accounts of persistence depend on the claims about objects' dimensions and not on the (...) auxiliary claims about parthood and temporal parts. (shrink)

The phrase ‘in virtue of’ is a mainstay of metaphysical discourse. In recent years, many philosophers have argued that we should understand this phrase, as metaphysicians use it, in terms of a concept of metaphysical dependence called ‘grounding’.This dissertation explores a range of central issues in the theory of grounding. Chapter 1 introduces the intuitive concept of grounding and discusses some compulsory questions in the theory of grounding. Chapter 2 focusses on scepticism on grounding, according to which the recent philosophical (...) interest in the topic is misguided. In chapter 3 I discuss grounding’s explanatory roles. Chapter 4 focusses on the claim that if an entity is grounded then it is an ontological free lunch. Chapter 5 discusses and rejects the claim that groundingis a relation between facts. This conclusion raises a problem: if grounding is not a relation between facts it becomes difficult to specify the connections between grounding and explanation and grounding and necessity. But not only is it desirable to specify these relations, it is essential for establishing that grounding is able to play the explanatory roles that are discussed in chapter 3. Chapter 6 responds to this problem by outlining an approach to grounding based on David Lewis’s (2003) theory of truthmaking. Against this backdrop I discuss, in chapter 7, some issues in the logic of grounding. (shrink)

Many believe that Perdurantism entails unrestricted composition. I try to explore one Perdurantist schema that accommodates restricted composition. That being said, I intend to show, that the Endurantism/Perdurantism debate is independent from the debate about material composition.

Vision has dominated philosophical thinking about perceptual experience and the nature of its objects. Color has long been the focus of debates about the metaphysics of sensible qualities, and philosophers have struggled to articulate the conditions on the visual experience of mind-independent objects. With few notable exceptions, "visuocentrism" has shaped our understanding of the nature and functions of perception, and of our conception of its objects. The predominant line of thought from the early modern era to the present is that, (...) in the philosophically interesting respects, as things are with vision, so they are with hearing, touch, olfaction, and the rest. A closely related line of thought has been particularly strong in the case of the secondary qualities. (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 →.

Mereological essentialists argue that mereological summations cannot change their parts. Mereological inessentialists argue that mereological summations can change some or all of their parts. In this paper I articulate and defend a position called Moderate Mereological Inessentialism, according to which certain mereological summations can change some, but not all, of their parts. Persistent mereological summations occur when the functional parts of mereological summations persist through alterations to its spatial parts.

Composition as Identity is the view that an object is identical to its parts taken collectively. I elaborate and defend a theory based on this idea: composition is a kind of identity. Since this claim is best presented within a plural logic, I develop a formal system of plural logic. The principles of this system differ from the standard views on plural logic because one of my central claims is that identity is a relation which comes in a variety of (...) forms and only one of them obeys substitution unrestrictedly. I justify this departure from orthodoxy by showing some problems which result from attempts to avoid inconsistencies within plural logic by means of postulating other non-singular terms besides plural terms. Thereby, some of the main criticisms raised against Composition as Identity can be addressed. Further, I argue that the way objects are arranged is relevant with respect to the question which object they compose, i.e. to which object they are identical to. This helps to meet a second group of arguments against Composition as Identity. These arguments aim to show that identifying composite objects on the basis of the identity of their parts entails, contrary to our common sense view, that rearranging the parts of a composite object does not leave us with a different object. Moreover, it allows us to carve out the intensional aspects of Composition as Identity and to defend mereological universalism, the claim that any objects compose some object. Much of the pressure put on the latter view can be avoided by distinguishing the question whether some objects compose an object from the question what object they compose. Eventually, I conclude that Composition as Identity is a coherent and plausible position, as long as we take identity to be a more complex relation than commonly assumed. (shrink)

An overview of contemporary part-whole theories, with reference to both their axiomatic developments and their philosophical underpinnings.

Discussions of the nature of time, and of various issues related to time, have always featured prominently in philosophy, but they have been especially important since the beginning of the 20th Century. This article contains a brief overview of some of the main topics in the philosophy of time — Fatalism; Reductionism and Platonism with respect to time; the topology of time; McTaggart's arguments; The A Theory and The B Theory; Presentism, Eternalism, and The Growing Universe Theory; time travel; and (...) the 3D/4D controversy — together with some suggestions for further reading on each topic, and a bibliography. (shrink)

An encyclopedia entry which covers various revisionary conceptions of which macroscopic objects there are, and the puzzles and arguments that motivate these conceptions: sorites arguments, the argument from vagueness, the puzzles of material constitution, arguments against indeterminate identity, arguments from arbitrariness, debunking arguments, the overdetermination argument, and the problem of the many.

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.