Leibniz’s Law (or as it sometimes called, ‘the Indiscerniblity of Identicals’) is a widely accepted principle governing the notion of numerical identity. The principle states that if a is identical to b, then any property had by a is also had by b. Leibniz’s Law may seem like a trivial principle, but its apparent consequences are far from trivial. The law has been utilised in a wide range of arguments in metaphysics, many leading to substantive and controversial conclusions. This article (...) discusses the applications of Leibniz’s Law to arguments in metaphysics. It begins by presenting a variety of central arguments in metaphysics which appeal to the law. The article then proceeds to discuss a range of strategies that can be drawn upon in resisting an argument by Leibniz’s Law. These strategies divide into three categories: (i) denying Leibniz’s Law; (ii) denying that the argument in question involves a genuine application of the law; and (iii) denying that the argument’s premises are true. Strategies falling under each of these three categories are discussed in turn. (shrink)

The advantages and risks of a number of new genome modifying procedures seeking to create healthy or enhanced individuals, such as Maternal Spindle Transfer, Pronuclear Transfer, Cytoplasmic Transfer and Genome Editing, are currently being assessed from an ethical perspective, by national and international policy organizations. One important aspect being examined concerns the effects of these procedures on different kinds of identity. In other words, whether or not a procedure only modifies the qualities or properties of an existing human being, meaning (...) that merely the qualitative identity of this single individual is affected, or whether a procedure results in the creation of a new individual, meaning that a numerically distinct human being would have come into existence. In this article, the different identity arguments proposed, so far, are presented with respect to these novel reproductive procedures. An alternative view is then developed using the Origin Essentialism argument to indicate that any cha... (shrink)

Plausible assumptions from Cosmology and Statistical Mechanics entail that it is overwhelmingly likely that there will be exact duplicates of us in the distant future long after our deaths. Call such persons “Boltzmann duplicates,” after the great pioneer of Statistical Mechanics. In this paper, I argue that if survival of death is possible at all, then we almost surely will survive our deaths because there almost surely will be Boltzmann duplicates of us in the distant future that stand in appropriate (...) relations to us to guarantee our survival. (shrink)

The central argument for animalism is the thinking animal problem : if you are not an animal, there are two thinkers within the region you occupy, i.e., you and your animal body. This is absurd. So you are an animal. The main objection to this argument is the thinking brain problem : animalism faces a problem that is structurally analogous to TAP. Specifically, if animalism is true, you and your brain both think. This is absurd. So animalism is false. The (...) purpose of this paper is to propose strategies animalists can endorse to solve TBP. I first show that animalists can solve TBP by arguing that it is not sound. This solution to TBP raises questions about personal identity over time and the mereological relation between the person and the brain. I argue that animalists can answer the personal identity question by endorsing non-biological persistence conditions as well as biological ones. For the mereological question, I first show that animalism is incompatible with four-dimensionalism and eliminativism. I then argue that animalists should endorse the dominant sortal account to answer the mereological question. (shrink)

It is widely assumed in psychology, philosophy, and linguistics that we count by identity. For example, to count the dogs by identity, we correlate each dog that isn't identical to the rest with a natural number, starting with one and assigning each successive dog the successive natural number. When we run out of distinct dogs, we've yielded a correct count. I argue that this model of counting is incorrect. We do not count by identity.

David Lewis argues that centered worlds give us a way to capture de se, or self-locating, contents in philosophy of language and philosophy of mind. In recent years, centered worlds have also gained other uses in areas ranging widely from metaphysics to ethics. In this paper, I raise a problem for centered worlds and discuss the costs and benefits of different solutions. My investigation into the nature of centered worlds brings out potentially problematic implicit commitments of the theories that employ (...) them. In addition, my investigation shows that the conception of centered worlds widely attributed to David Lewis is not only problematic, but in fact not his. (shrink)

Everettian accounts of quantum mechanics entail that people branch; every possible result of a measurement actually occurs, and I have one successor for each result. Is there room for probability in such an account? The prima facie answer is no; there are no ontic chances here, and no ignorance about what will happen. But since any adequate quantum mechanical theory must make probabilistic predictions, much recent philosophical labor has gone into trying to construct an account of probability for branching selves. (...) One popular strategy involves arguing that branching selves introduce a new kind of subjective uncertainty. I argue here that the variants of this strategy in the literature all fail, either because the uncertainty is spurious, or because it is in the wrong place to yield probabilistic predictions. I conclude that uncertainty cannot be the ground for probability in Everettian quantum mechanics. (shrink)

In a recent article, Caterina Moruzzi (2018) develops and defends her musical stage theory. This discussion response supposes that Moruzzi's development and def.

David Lewis’ contemplations regarding divine foreknowledge and free will, along with some of his other more substantial work on modal realism and his counterpart theory can serve as a springboard to a novel solution to the foreknowledge and metaphysical freedom puzzle, namely a proposal that genuine metaphysical freedom is compatible with determinism, which is quite different from the usual compatibilist focus on the compatibility between determinism and moral responsibility. This paper argues that while Lewis opens the doors to such a (...) possibility, in order to fully elucidate a genuinely metaphysical compatibilist account, Lewis’ own counterpart theory must be abandoned in favour of an account of trans-world identity that is theoretically framed by a modified version of Robert Nozick’s closest continuer theory. (shrink)

Advocates of occasional identity have two ways of interpreting putative cases of fission and fusion. One way—we call it the Creative view—takes fission to involve an object really dividing (or being replicated), thereby creating objects which would not otherwise have existed. The more ontologically parsimonious way takes fission to involve merely the ‘separation’ of objects that were identical before: strictly speaking, no object actually divides or is replicated, no new objects are created. In this paper we recommend the Creative approach (...) as the best way of dealing with certain problem cases involving teletransportation. Our considerations yield novel takes on psychological-continuity theories of personal identity and survival, and on the puzzle of Theseus' ship. (shrink)

Jim Stone argues that one cannot combine three-dimensionalism with counterpart theory. This paper argues to the contrary.

David Lewis's cohabitation theory suffered damaging criticism from Derek Parfit. Though many have defended versions of Lewis's theory Parfit's criticism has not been answered. This paper shows how to defend the cohabitation theory against Parfit's criticism.

The cohabitation theory is a popular solution to the problem of personal fission. It affirms that all the people who result from fission were there cohabiting the pre-fission body all along. Adopting this solution is an uncontroversial move for four-dimensionalists, but is it open to three-dimensionalists too? Some have thought so, but Katherine Hawley, Mark Johnston, and Eric Olson have argued to the contrary. They claim three-dimensionalists simply cannot be cohabitation theorists. In this paper, I explain how they can.

On a plenitudinous ontology, in every filled region of spacetime, there is at least one object that’s ‘exactly then and there’; one per each modal profile that the matter in the region satisfies. One of the strongest arguments for plenitude, the “argument from anthropocentrism”, puts pressure on us to accept that members of different communities correctly self-identify under different subject concepts. I explore this consequence and offer an account of selves on which self-determination is both socially and individually variant; we (...) determine our spatiotemporal boundaries, our de re modal properties, and the kind of being that we are. We do this by determining which of many candidate beings has the property of being a self. (shrink)

Personites are like continuant people but shorter-lived. Johnston argues that personites do not exist since otherwise personites would have the same moral status as persons, which is untenable. I argue that Johnston’s arguments fail. To do that I propose an alternative way to understand intrinsicness and I clarify the meaning of reductionism about persons. I also argue that a plausible ethical theory is possible even if personites have the same moral status as persons. My arguments draw on Johnston’s earlier debate (...) with Parfit about personal identity and the place of ordinary concerns in a naturalistic world. I also describe an important but metaphysics-free problem that arises from Johnston’s discussion. (shrink)

The Problem of Overlappers is a puzzle about what makes it the case, and how we can know, that we have the parts we intuitively think we have. In this paper, I develop and motivate an overlooked solution to this puzzle. According to what I call the self-making view it is within our power to decide what we refer to with the personal pronoun ‘I’, so the truth of most of our beliefs about our parts is ensured by the very (...) mechanism of self-reference. Other than providing an elegant solution to the Problem of Overlappers, the view can be motivated on independent grounds. It also has wide-ranging consequences for how we should be thinking about persons. Among other things, it can help undermine an influential line of argument against the permissibility of elective amputation. After a detailed discussion and defence of the self-making view, I consider some objections to it. I conclude that none of these objections is persuasive and we should at the very least take seriously the idea that we are to some extent self-made. (shrink)

This paper develops the Diachronic Self-Making View, the view that we are the non-accidentally best candidate referents of our ‘I’-beliefs. A formulation and defence of DSV is followed by an overview of its treatment of familiar puzzle cases about personal identity. The rest of the paper focuses on a challenge to DSV, the Puzzle of Inconstant ‘I’-beliefs: the view appears to force on us inconsistent verdicts about personal identity in cases that we would naturally describe as changes in one’s de (...) se beliefs. To solve this problem, the paper defends the possibility of overlapping people, and addresses a number of objections to this idea. (shrink)

In his excellent book, Four-Dimensionalism: An Ontology of Persistence and Time (Sider, 2001), Theodore Sider defends a version of four-dimensionalism which he calls the ‘stage-theory’. This paper focuses on Sider's argument from vagueness and argues that, due to the problematic nature of the argument from vagueness, Sider’s case in favor of four-dimensionalism is in the end not successful.

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)

JOHANNES ROESSLER & NAOMI EILAN (Eds.)Oxford: Oxford University Press, 2003ISBN 0199245622 (pbk, 415 pages, $39.95)In The Principles of Psychology, William James presents an interesting case of a ‘...

Many of those working on moral responsibility assume that "once blameworthy, always blameworthy." They believe that blameworthiness is like diamonds: it is forever. We argue that blameworthiness is not forever; rather, it can diminish through time. We begin by showing that the view that blameworthiness is forever is best understood as the claim that personal identity is sufficient for diachronic blameworthiness. We argue that this view should be rejected because it entails that blameworthiness for past action is completely divorced from (...) the distinctive psychological features of the person at the later time. This is because on none of the leading accounts of personal identity does identity require the preservation of any distinctive psychological features, but merely requires some form of continuity. The claim that blameworthiness is forever should therefore be rejected. We then sketch an account of blameworthiness over time, and consider two objections. (shrink)

Moral responsibility seems to presuppose personal identity. However, there are problems with this view, raised by Derek Parfit’s arguments for the view that personal identity isn’t what matters for our practical concerns. While Parfit discusses moral responsibility only in passing, the problems that arise for the connection between moral responsibility and personal identity have recently been sharpened by David Shoemaker. This paper defends the claim that moral responsibility presupposes personal identity against these problems. It argues, first, that only reductionist views (...) about personal identity have problems with the connection between responsibility and identity, which suggests that personal identity is a non-reductionist concept. Second, it argues that while non-reductionism is problematic, there is a novel view—non-representationalism about personal identity, according to which we account for personal identity in terms of a distinctive non-representational function—that is equally well-positioned to rescue the connection as non-reductionism, without suffering from non-reductionism’s problems. (shrink)

ABSTRACTOne argument that has been suggested for conventionalism about personal identity is that it captures that certain disagreements about personal identity seem irresolvable, without being committed to the view that these disagreements are merely verbal. In this paper, I will take the considerations about disagreement used to motivate conventionalism seriously. However, I will use them to motivate a very different, novel, and as yet unexplored view about personal identity. This is the view that personal identity is a non-representational concept, the (...) nature of which isn’t to be accounted for in terms of what entity it represents, but its non-representational role. I highlight that we find structurally very similar concerns about disagreement in another philosophical debate, namely in meta-ethics. But, in meta-ethics, such sorts of considerations are, traditionally, thought to support one distinctive view: meta-ethical expressivism, a non-representational view about normative thought and discourse. This suggests that we should take a similar view seriously for personal identity. I also develop what such an unfamiliar view might look like, using expressivism as a template. On this view, judgements about personal identity are plans that regulate who to hold accountable. (shrink)

Many people believe that the wrongness of killing a person does not depend on factors like her age, condition, or how much she has to lose by dying – a view Jeff McMahan calls the ‘Equal Wrongness Thesis’. This article argues that we should reject the Equal Wrongness Thesis on the basis of the moral equivalence between killing a person and knocking her unconscious.

It follows from David Lewis's counterpart-theoretic analysis of modality and his counterfactual theory of causation that causal claims are relativized to a set of counterpart relations. Call this Shlewis's view. I show how Shlewis's view can provide attractively unified solutions to similar modal and causal puzzles. I then argue that Shlewis's view is better motivated, by his own lights, than the view Lewis actually held, and also better motivated than a similar approach which relativizes causal claims to sets of ‘contrast (...) events’. (shrink)

Rebecca Roache’s recent critique of David Lewis’s cohabitation view assumes that a person cannot be properly concerned about something that rules out that she ever exists. In this brief response, I argue against this assumption.

Derek Parfit famously defends a number of surprising views about "fission." One is that, in such a scenario, it is indeterminate whether I have survived or not. Another is that the fission case shows that it does not matter, in itself, whether I survive or not. Most critics of the first view contend that fission makes me cease to exist. Most opponents of the second view contend that fission does not preserve everything that matters in ordinary survival. In this paper (...) I shall provide a critique that does not rely on either of these contentions. There are other, interrelated reasons to reject Parfit's defense of the two theses. In particular, the availability of the following view creates trouble for Parfit: I determinately survive fission, but it is indeterminate which fission product I am. (shrink)

Most versions of the psychological-continuity approach to personal identity (PCA) contain a 'non-branching' requirement. Recently, Robert Francescotti has argued that while such versions of PCA handle Parfit's standard fission case well, they deliver the wrong result in the case of an intact human brain. To solve this problem, he says, PCA-adherents need to add a clause that runs contrary to the spirit of their theory. In this response, I argue that Francescotti's counterexample fails. As a result, the revision he suggests (...) is not needed. (shrink)

The standard view of the value of death is the Deprivation Approach, according to which a person's death is bad for her insofar as she would have been better off without it. On the face of it, the Deprivation Approach sits much better with our normative intuitions about death than does the Epicurean view that death is never bad for the deceased. However, this issue is more complex and nuanced than it might appear.

Scott Campbell has recently defended the psychological approach to personal identity over time by arguing that a person is literally a series of mental events. Rejecting four-dimensionalism about the persistence of physical objects, Campbell regards constitutionalism as the main rival version of the psychological approach. He argues that his "series view" has two clear advantages over constitutionalism: it avoids the "two thinkers" objection and it allows a person to change bodies. In addition, Campbell suggests a reply to the objection, often (...) raised against views such as his, that thoughts must be distinct from their thinker. In this paper, I argue that Campbell's responses to the "two thinkers" and the "thoughts/thinker" objections are unsuccessful. Furthermore, his reply to the latter leads to four-dimensionalism of the kind he wanted to avoid – and this view too allows a person to change bodies. Moreover, I argue that it speaks against the series view that generalised versions of it fare much more poorly than do generalised versions of constitutionalism and four-dimensionalism. (shrink)

According to the cohabitation account, all the persons that result from a fission event cohabit the same body prior to fission. This article concerns a problem for this account. Suppose Manuel and Jimena are suffering from an equally painful migraine. Unlike Jimena, however, Manuel will undergo fission. Assuming you have a spare painkiller, whom should you give it to? Intuitively, you have no more reason to give it to one or the other. The problem is that the cohabitation account suggests (...) otherwise. According to the account, there are two persons cohabiting Manuel’s body, in which case you should arguably give them the pill, since doing so alleviates the pain of more beings. One response argues that the two persons cohabiting Manuel’s body share one pain. Thus, giving them the pill alleviates no more pain than giving it to Jimena, and therefore you have no more reason to do one or the other. The goal of this article is to show that this response fails. (shrink)

I present an internal problem for David Lewis’s genuine modal realism. My aim is to show that his analysis of modality is inconsistent with his metaphysics. I consider several ways of modifying the Lewisian analysis of modality, but argue that none are successful. I argue that the problem also affects theories related to genuine modal realism, including the stage theory of persistence and modal fictionalism.

This paper examines three proposals on the difference between the complex and the simple view about personal identity: Parfit’s original introduction of the distinction, Gasser and Stefan’s definition, and Noonan’s recent proposal. I argue that the first two classify the paradigm cases of simplicity as complex, while Noonan’s proposal makes simplicity and complexity turn on features whose relevance for the distinction is questionable. Given these difficulties, I examine why we should be interested in whether a position is complex or simple. (...) I describe two purposes of having a distinction, and show that extant accounts of the complex versus simple distinction fail to serve these. I argue that unless we find a satisfying account of the difference between complex and simple positions, we should not frame discourses on personal identity in these terms. (shrink)

This paper examines three proposals on the difference between the complex and the simple view about personal identity: Parfit’s original introduction of the distinction, Gasser and Stefan’s definition, and Noonan’s recent proposal. I argue that the first two classify the paradigm cases of simplicity as complex, while Noonan’s proposal makes simplicity and complexity turn on features whose relevance for the distinction is questionable. Given these difficulties, I examine why we should be interested in whether a position is complex or simple. (...) I describe two purposes of having a distinction, and show that extant accounts of the complex versus simple distinction fail to serve these. I argue that unless we find a satisfying account of the difference between complex and simple positions, we should not frame discourses on personal identity in these terms. (shrink)

We argue that animalism is the only materialist account of personal identity that can account for the autonomy that we typically think of ourselves as possessing. All the rival materialist theories suffer from a moral version of the problem of too many thinkers when they posit a human person that overlaps a numerically distinct human animal. The different persistence conditions of overlapping thinkers will lead them to have interests that conflict, which in many cases prevents them both from autonomously forming (...) and acting on the same intentions. These problems are exacerbated by problems of self-reference plaguing the overlapping thinkers. We contend that the impossibility of simultaneous autonomous action by animals and persons provides a reason to favor animalism over Neo-Lockeanism, Four-Dimensionalism, Constitution theory, and brain-size views of the person. We anticipate and reject arguments that the autonomy of the person and the animal can be shown to be compatible by relying upon either the Parfitian thesis that identity isn’t what matters or claiming that animals acquire the interests of the person they constitute. (shrink)

In multiple parts of the Critique of Pure Reason, Kant describes how time is dependent on space – which is the fundament of his distinction between inner and outer sense. However, he does not provide us with an argument for this dependency. In this article, two reasons for this dependency thesis are introduced. The first one aims at providing a conceptual link between time and space but runs into conflict with the Transcendental Aesthetic. The second one shifts our focus from (...) the conceptual level to a priori possible objects of experience: Time cannot provide such objects, which are different from our subjective states due to its one-dimensionality. Only space makes such objects possible. (shrink)

The defensibility of the extended mind thesis (EMT) is often thought to hinge on the possibility of extended selves. I argue that the self cannot extend and consider the ramifications of this finding, especially for EMT. After an overview of EMT and the supposed cruciality of the extended self to the defensibility of the former thesis, I outline several lines of argument in support of the possibility of extended selves. Each line of argument appeals to a different account of diachronic (...) personal identity. I argue that no such argument for extended selves succeeds, as no account of diachronic personal identity is both plausible and supports the view that the self can extend. Next, I consider three objections that, if successful, would undercut the preceding argument that the self cannot extend. I conclude by reflecting on the implications of the conclusion that the self cannot extend, including the prospects for EMT. (shrink)

There have been many objections to the possibility oftime travel. But all the truly interesting ones concern the possibility of reversecausation. What is objectionable about reverse causation? I diagnose that the trulyinteresting objections are to a further possibility: that of causal loops. I raisedoubts about whether there must be causal loops if reverse causation obtains; but devote themajority of the paper to describing, and dispelling concerns about, various kinds ofcausal loop. In short, I argue that they are neither logically nor (...) physically impossible.The only possibly objectionable feature that all causal loops share is that coincidenceis required to explain them. Just how coincidental a loop will be varies: some arereally quite ordinary, and some are incredibly unlikely. I end by speculating thatthe tendency amongst physicists to avoid discussion of causal loops involving intentionalaction may have been unfortunate, since intentional action is an excellent way tonon-mysteriously bring about what otherwise would have been an unlikely coincidence. Hencecausal loops may be more likely in a world with beings like us, than in one without. (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.

Three arguments for the conclusion that objects cannot endure in B-time even if they remain intrinsically unchanged are examined: Carter and Hestevolds enduring-objects-as-universals argument (American Philosophical Quarterly 31(4):269-283, 1994) and Barker and Dowe's paradox 1 and paradox 2 (Analysis 63(2):106-114, 2003, Analysis 65(1):69-74, 2005). All three are shown to fail.