Philosophers struggle to explain why human beings with deep cognitive impairments have a higher moral status than certain non-human animals. Modal personism promises to solve this problem. It claims that humans who lack the capacities of “personhood” and the potential to develop them nonetheless could have been persons. I argue that modal personism has poor prospects because it's hard to see how we could offer a plausible account of modal personhood. I search for an adequate understanding of modal personhood by (...) considering existing accounts and sketching new ones. But each account fails, either because it objectionably excludes some deeply cognitively impaired humans from the class of modal persons or because it makes modal personhood doubtfully relevant to moral status. And the modal personist cannot solve this problem by appealing to the misfortune suffered by modal persons. (shrink)

In this commentary paper, we are taking one step further in questioning the central assumptions in the bioethical debates about reproductive technologies. We argue that the very distinction between “person affecting” and “identity affecting” interventions is based on a questionable form of material-origin essentialism. Questioning of this form of essentialist approach to human identity allows treating genome editing and genetic selection as more similar than they are taken to be in the standard approaches. It would also challenge the idea that (...) normative reasons we have in these two types of cases markedly differ in strength. (shrink)

The consensus among spacetime substantivalists is to respond to Leibniz's classic shift arguments, and their contemporary incarnation in the form of the hole argument, by pruning the allegedly problematic metaphysical possibilities that generate these arguments. Some substantivalists do so by directly appealing to a modal doctrine akin to anti-haecceitism. Other substantivalists do so by appealing to an underlying hyperintensional doctrine that implies some such modal doctrine. My first aim in this paper is to pose a challenge for all extant forms (...) of this consensus position. My second aim is to show what form substantivalism must take in order to uphold the consensus while addressing this challenge. The result is a novel "plenitudinous" substantivalist view, which predicts that certain modal facts about spacetime are vague or indeterminate. I then argue against this view on independent grounds, concluding that substantivalists should reject the consensus position. The paper also discusses the way forward for substantivalists in light of this conclusion. (shrink)

This paper considers two objections based in axiological considerations against the position that whether a given outcome, or possible future or world, is morally worse than a second world may depend in part on what is going on at a third world. Such a wide-angled approach to determining worseness is critical to the solution I have previously proposed in connection with the nonidentity problem. I argue that both objections fail.

ABSTRACT I motivate ‘Origin Conventionalism’—the view that which facts about one’s origins are essential to one’s existence depends partly on our person-directed attitudes. One important upshot is that the view offers a novel and attractive solution to the Nonidentity Problem. That problem typically assumes that the sperm-egg pair from which a person originates is essential to that person’s existence; in which case, for many future persons that come into existence under adverse conditions, had those conditions not been realized, the individuals (...) wouldn’t have existed. This is problematic because it delivers the counter-intuitive conclusion that it’s not wrong to bring about such adverse conditions since they don’t harm anyone. Origin Conventionalism, in contrast, holds that whether a person’s sperm-egg origin is essential to their existence depends on their person-directed attitudes. I argue that this provides a unique and attractive way of preserving the intuition that the actions in the ‘nonidentity cases’ are morally wrong because of the potential harm done to the individuals in question. (shrink)

The idea of “material plenitude” has been gaining traction in recent discussions of the metaphysics of material objects. My main goal here is to show that this idea may have important dialectical implications for the metaphysics of properties – more specifically, that it provides nominalists with new resources in their attempt to reject an ontology of universals. I will recapitulate one of the main arguments against nominalism – due to David Armstrong – and show how plenitude helps the nominalist overcome (...) the argument. (shrink)

A number of prominent metaphysicians have recently defended a set of ideas which I will call ‘essentialist plenitude.’ Very roughly, and to a first approximation, essentialist plenitude says that wherever there is an object with properties P1, …, Pn there is in fact a plenitude of coincident objects that differ only in the distribution of essentiality and accidentality across P1, …, Pn (§1). The main purpose of this paper is to arouse the suspicion that essentialist plenitude may have far-reaching consequences (...) for the semantics of proper names. More specifically, I will argue that neither descriptivist nor causal theories of proper names work in a plenitude setting (§2). I will close by suggesting that our use of proper names may be thoroughly infected by semantic indecision about which among many coincident objects is referred to (§3). (shrink)

A number of prominent metaphysicians have recently defended the idea of material plenitude: wherever there is one material object, there is in fact a great multitude of them, all coincident and sharing many properties, but differing in which of these properties they have essentially and which accidentally. The main goal of this paper is to put on the agenda an important theoretical decision that plenitudinists face, regarding whether their plenitude is egalitarian or elitist, depending on whether or not they take (...) all objects that coincide at a certain location to be in some sense ontologically on a par. Many current proponents of plenitude tend toward egalitarianism. But current proponents often also point to an Aristotelian tradition they claim to carry on; indeed, the view is sometimes referred to as “neo-Aristotelian plenitude.” By examining some of the historical protagonists of Aristotelian plenitude, however, I show that they defended rather an elitist form of plenitude, wherein a single coincident is ontologically privileged in every occupied region. In the final section of the paper, I also try to articulate the basic motivation for each outlook, by way of initiating discussion of which view plenitudinists should believe. (shrink)

According to material plenitude, every material object coincides with an abundance of other material objects that differ in the properties they have essentially and accidentally. Although this kind of plenitude is becoming increasingly popular, it isn't clear how to make sense of the view beyond its slogan form. As I argue, it turns out to be extraordinarily difficult to do so: straightforward attempts are either inconsistent or fail to capture the target idea. Making progress requires us to engage in more (...) delicate metaphysics than we might have expected and, along the way, reveals substantive constraints on the material world. In this article, I argue that any attempt to develop a coherent version of plenitude is subject to two under-appreciated challenges, and I develop a version of plenitude (global plenitude) capable of overcoming both. (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.

The subject of this paper is the epistemology of identity: a general theory of knowledge, evidence and justification for the claim that one thing is identical to another. Although identity figures significantly in our epistemic lives, this is a topic that, to the best of my knowledge, has gone entirely unexplored. Initial attempts to integrate such an epistemology into existing theories of evidence---many of which are tailor-made for contingent propositions---are confounded by the necessity of identity. I defend a restricted form (...) of skepticism according to which the only knowable identity claims are trivial. (shrink)