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.

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)

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)

Are concrete objects in some sense made up of the properties they exemplify? A distinguished tradition holds they are. I begin by defending the distinction: there is a real and not just semantic distinction between asserting and denying that concrete objects have their properties as parts. I then argue in favor of the view that concrete objects are not made up of their parts. First, this view has less ontological baggage than its opponent. Next, the supposed advantages of the alternative (...) view—its superiority in understanding persistence, exemplification, or the possibility of diverse duplicates—dissipate under analysis. (shrink)

Revisionary ontologies seem to go against our common sense convictions about which material objects exist. These views face the so-called Problem of Reasonableness: they have to explain why reasonable people don’t seem to accept the true ontology. Most approaches to this problem treat the mismatch between the ontological truth and ordinary belief as superficial or not even real. By contrast, I propose what I call the “uncompromising solution”. First, I argue that our beliefs about material objects were influenced by evolutionary (...) forces that were independent of the ontological truth. Second, I draw an analogy between the Problem of Reasonableness and the New Evil Demon Problem and argue that the revisionary ontologist can always find a positive epistemic status to characterize ordinary people’s beliefs about material objects. Finally, I address the worry that the evolutionary component of my story also threatens to undermine the best arguments for revisionary ontologies. (shrink)

Mereological nihilism is the view that no objects have proper parts. Despite how counter‐intuitive it is, it is taken quite seriously, largely because it solves a number of puzzles in the metaphysics of material objects – or so its proponents claim. In this article, I show that for every puzzle that mereological nihilism solves, there is a similar puzzle that (a) it doesn’t solve, and (b) every other solution to the original puzzle does solve. Since the solutions to the new (...) puzzles apply just as well to the old puzzles, the old puzzles provide no motivation to be a mereological nihilist. (shrink)

What are we? Despite much discussion in historical and contemporary philosophy, we have not yet settled on an answer. A satisfactory personal ontology, an account of our metaphysical nature, will be informed by issues in the metaphysics of material objects. In the dissertation, I target two prominent materialist ontologies: animalism, the view that we are numerically identical to human organisms, and constitutionalism, the view that we are constituted by, but not identical to, human organisms. Because of the problems that arise (...) from endorsing these ontologies, I instead advance immaterialism, the view that we are essentially immaterial. In Chapter 2, I discuss how animalists must respond to a widely-discussed metaphysical puzzle, the problem of the many. This puzzle prompts some to endorse revisionary ontologies of material objects, and I argue that the animalist cannot appeal to these revisionary ontologies to solve the puzzle as it arises for personal ontology. In addition, solutions that don’t involve a commitment to revisionary ontology will be unavailable to the animalist: I argue that if animalists make use of non-revisionary solutions to the problem, they must abandon the most successful argument for their view. Absent their most successful argument, animalists will need to motivate the view in some other way. Some new arguments for animalism have been proposed, and I argue that they fail to give us reason to endorse animalism over competing ontologies. Without a strong argument, we should not prefer animalism over the other, more attractive, views. In Chapter 3, I show how constitutionalists face a different problem: explaining how the person is not the very same thing as the human organism, despite sharing the very same parts and occupying the very same physical space. We think that the person and the organism are different things because they have different modal profiles – the human organism can survive permanent loss of psychological life, but the person, presumably, cannot. Constitutionalists must then explain what grounds the difference in modal profiles, but such an explanation is hard to come by. This is an instance of the grounding problem, which is notoriously intractable. While the grounding problem is a well-known challenge to constitutional accounts of objects, I demonstrate that this puzzle is even more threatening when applied to persons. Some “solutions” to the problem fail to solve it at all, and solutions that might get the right result for ordinary objects require accepting that there are a multitude of persons where we ordinarily take there to be only one. We should not accept a personal ontology that requires a commitment to that multitude. I argue that the threat of the grounding problem is so great that we must reject the constitutionalist personal ontology. We will see from these puzzles in personal ontology that materialist solutions are either unsuccessful or yield unacceptable consequences. This should prompt us toward considering, instead, immaterialism. According to immaterialism, persons are not material objects, and the immaterialist can then provide solutions to the puzzles that threatened materialist ontologies. In Chapter 4, I outline these immaterialist solutions and show that the puzzles cannot be reinstantiated successfully against the immaterialist. I then discuss different available varieties of immaterialism and argue in defense of my preferred version. Ultimately, I argue that we are simple, immaterial entities that come into existence at the proper functioning of the brain. Endorsing this view of personal ontology permits us to adequately respond to metaphysical puzzles and retain judgments about persons that should be most important to us. In particular, the immaterialist has the resources to avoid the problem of too many thinkers and retain the judgment that there is exactly one person in circumstances where we take there to be just one. The immaterialist also has the resources to plausibly analyze thought experiments, such as cerebrum-swap cases, that threaten materialist ontologies. All things considered, it remains to be seen which personal ontology has the most evidence in its favor. In the context of debates that arise from material object metaphysics, however, evidence weighs in favor of immaterialism. Materialist personal ontologies are saddled with unacceptable responses to metaphysical puzzles, and endorsing materialism about persons requires taking on a very high cost: Either there are far more of us than we ordinarily take there to be, or there are no persons – far fewer of us than we ordinarily take there to be. Some might argue that these are the only acceptable options, so cost be damned. But we cannot afford to be so cavalier about our personal ontology. Instead, I advance immaterialist solutions to puzzles in personal ontology and propose that, in the interest of saving ourselves and everyone we love, we should seriously consider accounts according to which we are immaterial entities. (shrink)

It is uncontroversial that artifacts like statues and tables are mind-dependent. What is controversial is whether and how this mind-dependence has implications for the ontology of artifacts. I argue the mind-dependence of artifacts entails that there are no artifacts or artifact joints in the extra-mental world. In support of this claim, I argue that artifacts and artifact joints lack any extra-mental grounding, and so ought not to have a spot in a realist ontology. I conclude that the most plausible story (...) about artifacts is that they are in minds of suitably intelligent creatures, and not the extra-mental world. Artifacts and their joints are merely mental projections onto a world of ‘indifferent materials’. With this established, I show how many cases of object coincidence, the view that more than one material object can be located in the same exact region of space-time, cannot occur. (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.

The problem of change plays a central role in the metaphysics of time and material objects, and whoever does best in solving this problem has a leg up when it comes to choosing a metaphysics of time and material objects. But whether this central role of the problem of change in metaphysics is legitimate is not at all clear. This is so in part since it is not clear what the problem of change is, and why it is a problem (...) in metaphysics. We will investigate what metaphysical problem the problem of change might be, and how it relates to various other problems related to change that are studied in the empirical sciences. The problem of change can thus be a case study of what makes a problem a metaphysical one and how metaphysics relates to other parts of inquiry. We conclude that the central role the problem of change is given in the contemporary metaphysics of time is not justified. (shrink)