Thought Experiments in Personal Identity

This paper is primarily about metaphysics; specifically, about a Cartesian view of the self, according to which it is a simple, enduring, non-material entity.I take a critical look at Nida-Rümelin’s novel conceptual arguments for this view and argue that they don’t give us decisive reasons to uphold the Cartesian view. But in Nida-Rümelin’s view, what is at stake in these arguments is not merely theoretical: the truth – and our beliefs about it – has practical consequences as well. In her (...) view, if the Cartesian simple view of the self were false, we would have no reason to love and care for family and friends, and our special interest in our own future would be pointless. In the last section of this paper, I will say something about the sense in which it is right and the sense in which it is wrong to think that the metaphysics of the self has broader relevance for our lives. (shrink)

In her essay, “People and their Bodies,” Judith Thomson writes an evaluation of several formulations of the psychological criterion for personal identity and attempts a strategy of criticizing each formulation of the psychological theory. This is done in order to conclude that a physical theory must be the only remaining viable sufficient candidate for explaining personal identity that is both necessary and sufficient, despite its theoretical weaknesses. This paper seeks to analyze Thomson's critique and explain why her chosen formulations of (...) psychological criterion are inadequate and easy to refine against some of her rather hasty objections. In addition, counterarguments in favor of an 'impure' psychological criterion for personal identity are presented in the hopes of clarifying the philosophical discourse. (shrink)

The following seems to be a truism in modern day philosophy: No agent can have had other parents (IDENTITY). IDENTITY shows up in discussions of moral luck, parenting, gene editing, and population ethics. In this paper, I challenge IDENTITY. I do so by showing that the most plausible arguments that can be made in favor of IDENTITY do not withstand critical scrutiny. The paper is divided into four sections. In the first, I document the prevalence of IDENTITY. In the second, (...) I examine a defense of IDENTITY on the basis of genetic considerations. In the third, I examine a defense of IDENTITY that I call gamete essentialism. In the fourth, I return to genetic considerations to wrap up the paper. (shrink)

In the industrial era, advanced science and technology make immortality-obsessed human beings constantly develop, modify, and reshape their bodies and consciousness, to overcome the fragility and transience of their bodies and approach the dream of immortality. The transformation of the body, in turn, drives society to confront the co-existence of cyborg, transhuman, information subject, nomadic posthuman and other life forms. Focusing on Chinese-American writer Ken Liu’s science fiction the Future Trilogy, Arc, and The Waves, this paper attempts to explore the (...) metamorphosis of the body and the ethical choices in the tension between death and immortality, embodiment and disembodiment. Immortality is not a Utopian paradise but causes many ethical problems and loss of continuity of time, space, history, and identity. Liu’s works suggest that the solution to the problem of posthuman disembodiment involves embracing embodiment and recognizing the importance of memory and social interaction in the formation of one’s identity, affirming that memory and the interaction with others are necessary conditions for the formation of the subject’s identity. Blending genesis myths and technological immortality, Liu explores the possibility of creating new life different from human beings. The posthumans depicted are always in the status of becoming, eager to discover the new world, and indicate the author’s expectations for the bright new future. (shrink)

Animalism is prima facie the most plausible view about what we are; it aligns better with science and common sense, and is metaphysically more parsimonious. Thought experiments involving the brain, however, tend to elicit intuitions contrary to animalism. In this paper, I examine two classical thought experiments from the literature, brain transplant and cerebrum transplant, and a new one, cerebrum regeneration. I argue that they are theoretically possible, but that a scientifically informed account of what would actually happen shows that (...) in none of the cases would the person be separated from the animal. Our intuitions in these cases, when adequately informed by neuroscience, do not conflict with animalism – rather, they suggest a correction of the animalist position: the persisting animal should be at least minimally sentient. Sentience animalism is a new formulation of the animalist account of personal identity that allows us to reconcile facts about our biological persistence conditions with the intuition that human persistence should involve some kind of psychological continuity. (shrink)

Many philosophers have become sceptical of the use of thought experiments in theorising about personal identity. In large part this is due to work in experimental philosophy that appears to confirm long held philosophical suspicions that thought experiments elicit inconsistent judgements about personal identity, and hence judgements that are thought to be the product of cognitive biases. If so, these judgements appear to be useless at informing our theories of personal identity. Using the methods of experimental philosophy, we investigate whether (...) people exhibit inconsistent judgements and, if they do, whether these judgements are likely to be the source of cognitive bias or, instead, sensitivity to some relevant factor. We do not find that people’s judgements are sensitive to any of the factors we investigate (relevant or irrelevant), nor that people have inconsistent judgements across cases. Rather, people’s judgements are best explained by them having a very minimal account of what it takes for a person to survive. Since this pattern of judgements is no reason to think that we are subject to cognitive bias, we see no reason, as things stand, to be sceptical of our judgements. (shrink)

A common interpretation of Philip K. Dick’s texts _Do Androids Dream of Electric Sheep?_ and _We Can Build You_ is that they attempt to answer the question “What does it mean to be human?” -/- Unfortunately, these interpretations fail to deal with the fact that the term “human” has both metaphysical and moral connotations. Metaphysical meanings associated with theories of human nature and moral meanings associated with theories of moral status are thus blurred in the novels and in the literature (...) that discusses them. This is problematic on many levels. The conclusion argued for in this paper is that we should carefully disentangle these meanings. Doing so has many benefits, both for literary criticism and moral philosophy. For literary criticism, disentanglement helps solve some puzzling elements of the texts that are unlikely to be solved if the entanglements are not undone. -/- Furthermore, disentangling the moral and the metaphysical meanings of “human” provides an opportunity to showcase how theories of moral status can be used as an interpretive lens. For moral philosophy, exploring the entanglements of the novels can suggest new ideas about which non-humans—animals, robots, artificial intelligence—are part of the moral community. Finally, disentangling these meanings highlights problems that arise when one assumes that answers to metaphysical questions entail clear moral answers to questions about moral status. (shrink)

This paper presents a new anti-criterialist view, Brutal Personal Identity (BPI). According to BPI, personal identity is a quasi-fundamental fact, which is metaphysically grounded in brute facts about absolutely fundamental personhood. By reversing the order of metaphysical explanation, BPI is not a form of identity mysticism as Dean Zimmerman asserts. Instead, BPI has even the potential to lay a solid foundation for developing an appropriate account of mentality and first-person perspectives. Furthermore, a comparison between BPI and soul theory is provided (...) to show why BPI is better than its main anti-criterialist rival. This provides us a compelling reason for considering BPI in the debate over personal identity. (shrink)

In this chapter, we outline the interdisciplinary contributions that philosophy, psychology, and neuroscience have provided in the understanding of the self and identity, focusing on one specific line of burgeoning research: the importance of morality to perceptions of self and identity. Of course, this rather limited focus will exclude much of what psychologists and neuroscientists take to be important to the study of self and identity (that plethora of self-hyphenated terms seen in psychology and neuroscience: self-regulation, self-esteem, self-knowledge, self-concept, self-perception, (...) and more). We will likewise not engage with many canonical philosophical treatments of self and identity. But we will lay out a body of research that brings together classic themes in philosophy, psychology, and neuroscience to raise empirically tractable philosophical questions, and philosophically rigorous empirical questions about self and identity. More specifically, in section 4.2, we will review some recent research that has treated traditional philosophical questions about self and identity as empirical questions. Within this body of work, we will be primarily concerned with the finding that morality (more so than memory) is perceived to be at the core of self and identity. Then, in section 4.3, we raise and respond to a variety of questions and criticisms: first, about the operationalization of identity concepts in the empirical literature; second, about the generalizability of the moral self effect; third, about the direction of change; fourth, about connections with recent work in neuroscience; and fifth, about the target of evaluation. Finally, in section 4.4, we consider a variety of implications and applications of this work on the moral self. Throughout, we aim to highlight connections between classical themes in philosophy, psychology, and neuroscience, while also suggesting new directions for interdisciplinary collaboration. (shrink)

Suppose that it was possible to teletransport. The teletransporter would destroy your old brain and body and construct an identical brain and body at a new location. Would you survive teletransportation? Many people think that teletransportation would kill you. On their view, the person that emerges from the teletransporter would be a replica of you, but it wouldn't be you. In contrast, I argue that there's no relevant difference between teletransportation and ordinary survival. So, if you survive ordinary life, then (...) you survive teletransportation. Yet my argument may also show that we have little prudential reason to care about our survival in general. (shrink)

Conventionalists hold that the sorts of events that one survives—such as teletransportation, or a brain transplant—is at least partly determined by our attitudes. But if Conventionalism is true, whose attitudes directly determine whether one survives? Do the individual's attitudes do all the work as Private Conventionalists hold, or do the community's attitudes also factor in as Public Conventionalists hold? There has recently been a greater push towards Private Conventionalism, while explicit arguments for Public Conventionalism are difficult to come by. In (...) this paper, I attempt to rectify the situation by presenting my case for Public Conventionalism. (shrink)

Good physical experiments conform to the basic methodological standards of experimental design: they are objective, reliable, and valid. But is this also true of thought experiments? Especially problems of personal identity have engendered hypothetical scenarios that are very distant from the actual world. These imagined situations have been conspicuously ineffective at resolving conflicting intuitions and deciding between the different accounts of personal identity. Using prominent examples from the literature, I argue that this is due to many of these thought experiments (...) not adhering to the methodological standards that guide experimental design in nearly all other disciplines. I also show how empirically unwarranted background assumptions about human physiology render some of the hypothetical scenarios that are employed in the debate about personal identity highly misleading. (shrink)

African perspectives on personhood and personal identity and their relation to those of the West have become far more central in mainstream Western discussion than they once were. Not only are African traditional views with their emphasis on the importance of community and social relations more widely discussed, but that emphasis has also received much wider acceptance and gained more influence among Western philosophers. Despite this convergence, there is at least one striking way in which the discussions remain apart and (...) that is on a point of method. The Western discussion makes widespread use of thought experiments. In the African discussion, they are almost entirely absent. In this article, we put forward a possible explanation for the method of thought experiment being avoided that is based on considerations stemming from John Mbiti’s account of the traditional African view of time. These considerations find an echo in criticism offered of the method in the Western debate. We consider whether a response to both trains of thought can be found that can further bring the Western and African philosophical traditions into fruitful dialogue. (shrink)

Ordinary judgments about personal identity are complicated by the fact that phrases like “same person” and “different person” have multiple uses in ordinary English. This complication calls into question the significance of recent experimental work on this topic. For example, Tobia (2015) found that judgments of personal identity were significantly affected by whether the moral change described in a vignette was for the better or for the worse, while Strohminger and Nichols (2014) found that loss of moral conscience had more (...) of an effect on identity judgments than loss of biographical memory. In each case, however, there are grounds for questioning whether the judgments elicited in these experiments engaged a concept of numerical personal identity at all (cf. Berniūnas and Dranseika 2016; Dranseika 2017; Starmans and Bloom 2018). In two pre-registered studies we validate this criticism while also showing a way to address it: instead of attempting to engage the concept of numerical identity through specialized language or the terms of an imaginary philosophical debate, we should consider instead how the identity of a person is described through the connected use of proper names, definite descriptions, and the personal pronouns “I”, “you”, “he”, and “she”. When the experiments above are revisited in this way, there is no evidence that the differences in question had an effect on ordinary identity judgments. (shrink)

En este ensayo, evaluaremos el problema de la identidad personal en el contexto del transhumanismo. En primer lugar, en contra de la tesis de que el transhumanismo representa una amenaza a la persistencia de la identidad personal argumentaremos lo siguiente: los individuos humanos que son personas no tienen características esenciales. En segundo lugar, con la ayuda del primer episodio de la segunda temporada de la serie de ciencia ficción Black Mirror, defenderemos la tesis de que hay propiedades que realmente importan (...) en el problema de la identidad personal: las propiedades relacionales(esta tesis tiene como consecuencia que nuestros seres queridos son irremplazables, incluso por duplicados exactos). Finalmente, concluiremos que el uso de las tecnologías de mejoramiento humano no representa una amenaza a la identidad personal de un individuo en tanto que no altera sus propiedades relacionales importantes. (shrink)

Derek Parfit’s argument against the platitude that identity is what matters in survival does not work given his intended reading of the platitude, namely, that what matters in survival to some future time is being identical with someone who is alive at that time. I develop Parfit’s argument so that it works against the platitude on this intended reading.

In der Diskussion um personale Identität nehmen die einflussreichen Arbeiten Derek Parfits eine Sonderstellung ein, insofern Parfit nicht bestrebt ist, eines der gängigen Identitätskriterien zu verteidigen, sondern vielmehr behauptet, dass unsere alltäglichen wie philosophischen Vorstellungen von personaler Identität unrettbar inkohärent sind und deshalb aufgegeben werden sollten. In seinem Beitrag beleuchtet Sascha Settegast die verschiedenen Argumente, die Parfit für diese provokante These vorbringt, und unternimmt insbesondere den Versuch einer systematischen Dekonstruktion der wichtigsten Gedankenexperimente Parfits, die zeigen soll, dass sich diese Gedankenexperimente (...) auf eine Weise auflösen lassen, die unsere alltäglichen Intuitionen über personale Identität intakt belässt. Settegast entwickelt dabei die Grundzüge einer Konzeption personaler Identität, die sich einerseits von den gängigen neo-lockeanischen und animalistischen Ansätzen abgrenzt und andererseits bewusst an den zeitgenössischen Neo-Aristotelismus in der Ethik anknüpft, wie er etwa bei Philippa Foot und Michael Thomp-son anzutreffen ist. Die diachrone numerische Identität menschlicher Personen gründet nach Settegasts Auffassung darin, dass der Verlauf ihres Lebens eine zeitliche Einheit aufweist, die dadurch bedingt ist, dass ihre Lebensführung die menschliche Lebensform auf eine individuell charakteristische Weise exemplifiziert. Insofern dies aber nur durch Kultivierung der Tugen-den zu erreichen ist, handelt es sich laut Settegast bei personaler Identität letztlich nicht um eine Tatsache, die einfach vorliegt oder nicht, sondern um eine Aufgabe, die uns als Menschen gegeben ist und wesentlich darin besteht, in bewusster Orientierung auf das gute Leben hin ein stabiles, sich zeitlich durchhaltendes Selbst allererst auszubilden. (shrink)

Many philosophers hypothesize that our concept of personal identity is partly constituted by the one-person-one-place rule, which states that a person can only be in one place at a time. This hypothesis has been assumed by the most influential contemporary work on personal identity. In this paper, we report a series of studies testing whether the hypothesis is true. In these studies, people consistently judged that the same person existed in two different places at the same time. This result undermines (...) some widely held philosophical assumptions, supports others, and fits well with recent discoveries on identity judgments about inanimate objects and non-human animals. (shrink)

David Lewis defends the following "non-circular definition of personhood": "something is a continuant person if and only if it is a maximal R-interrelated aggregate of person-stages. That is: if and only if it is an aggregate of person-stages, each of which is R-related to all the rest (and to itself), and it is a proper part of no other such aggregate." I give a counterexample, involving a person who is a part of another, much larger person, with a separate mental (...) life. I then offer an easy repair, which preserves the virtues of Lewis's definition without introducing any new vices. (shrink)

Theories of personal identity face a paradox, which traces back to Bernard Williams: some scenarios obviously show that mental continuity is what solely matters in survival; others, on the contrary, show with equal obviousness that it is bodily continuity. Different authors have produced diverging and partly conflicting answers in response to that problem. Based on recent research concerning the structure of philosophical thought experiment, this paper reevaluates and, for the first time, neatly classifies those answers. What is more, several existing (...) approaches of how to answer the paradox are developed further, and two new answers are introduced. (shrink)

The paper begins with a characterization of thought experiments, followed by a general outline of contemporary debates in the field. The discussion reveals that the most significant controversy involved is the dispute over the epistemic status of thought experiments between empiricists, Platonists, and the proponents of mental models. After a critical analysis of these approaches, a new theoretical framework proposed by Paul Bartha is introduced. It is suggested that Bartha’s approach, which appeals to a theory of analogy, offers new insights (...) into the structure of thought experiments. The paper concludes with general remarks on the state of the art in the field. (shrink)

Nils-Frederic Wagner takes issue with my argument that influential critics of “transplant” thought experiments make two cardinal mistakes. He responds that the mistakes I identify are not mistakes at all. The mistakes are rather on my part, in that I have not taken into account the conceptual genesis of personhood, that my view of thought experiments is idiosyncratic and possibly self-defeating, and in that I have ignored important empirical evidence about the relationship between brains and minds. I argue that my (...) case still stands and that transplant thought experiments can do damage to rivals of a psychological continuity theory of personal identity like Marya Schechtman’s Person Life View. (shrink)

Marya Schechtman has raised a series of worries for the Psychological Continuity Theory of personal identity (PCT) stemming out of what Derek Parfit called the ‘Extreme Claim’. This is roughly the claim that theories like it are unable to explain the importance we attach to personal identity. In her recent Staying Alive (2014), she presents further arguments related to this and sets out a new narrative theory, the Person Life View (PLV), which she sees as solving the problems as well (...) as bringing other advantages over the PCT. I look over some of her earlier arguments and responses to them as a way in to the new issues and theory. I argue that the problems for the PCT and advantages that the PLV brings are all merely apparent, and present no reason for giving up the former for the latter. (shrink)

This paper—written for nonspecialist readers—asks whether life after death is in any sense possible given the apparent fact that after we die our remains decay to the point where only randomly scattered atoms remain. The paper argues that this is possible only if our remains are not in fact dispersed in this way, and discusses how that might be the case. -/- 1. Life After Death -- 2. Total Destruction -- 3. The Soul -- 4. Body-Snatching -- 5. Radical Resurrection (...) -- 6. Irreversibility -- 7. Atomic Reassembly -- 8. The Transporter -- 9. Replicas and Originals -- 10. Survival and Causal Connections. (shrink)

Phineas Gage’s story is typically offered as a paradigm example supporting the view that part of what matters for personal identity is a certain magnitude of similarity between earlier and later individuals. Yet, reconsidering a slight variant of Phineas Gage’s story indicates that it is not just magnitude of similarity, but also the direction of change that affects personal identity judgments; in some cases, changes for the worse are more seen as identity-severing than changes for the better of comparable magnitude. (...) Ironically, thinking carefully about Phineas Gage’s story tells against the thesis it is typically taken to support. (shrink)

‘Transplant’ thought-experiments, in which the cerebrum is moved from one body to another, have featured in a number of recent discussions in the personal identity literature. Once taken as offering confirmation of some form of psychological continuity theory of identity, arguments from Marya Schechtman and Kathleen Wilkes have contended that this is not the case. Any such apparent support is due to a lack of detail in their description or a reliance on predictions that we are in no position to (...) make. I argue that the case against them rests on two serious misunderstandings of the operation of thought-experiments, and that even if they do not ultimately support a psychological continuity theory, they do major damage to that theory’s opponents. (shrink)

It seems plausible that (i) how much punishment a person deserves cannot be affected by the mere existence or nonexistence of another person. We might have also thought that (ii) how much punishment is deserved cannot increase merely in virtue of personal division. I argue that (i) and (ii) are inconsistent with the popular belief that, other things being equal, when people culpably do very wrong or bad acts, they ought to be punished for this—even if they have repented, are (...) now virtuous, and punishing them would benefit no one. Insofar as we cannot deny (i), we are either forced to abandon the popular belief in desert, or else allow that personal division could, as I put it, “multiply desert.” Some may not find the latter, considered by itself, troubling. But I argue that the thesis that division multiplies desert faces a potentially serious problem, which arises in the context of personal fusion. It is difficult to see how to maintain a particular family of desert views in light of the cases here presented. (shrink)

In this paper I discuss a set of problems concerning the method of cases as it is used in applied ethics and in the metaphysical debate about personal identity. These problems stem from research in social psychology concerning our access to the data with which the method operates. I argue that the issues facing ethics are more worrying than those facing metaphysics.

Martha Nussbaum has argued in support of the view (supposedly that of Aristotle) that we can, through thought-experiments involving personal identity, find an objective foundation for moral thought without having to appeal to any authority independent of morality. I compare the thought-experiment from Plato’s Philebus that she presents as an example to other thought-experiments involving identity in the literature and argue that this reveals a tension between the sources of authority which Nussbaum invokes for her thought-experiment. I also argue that (...) each of her sources of authority presents further difficulties for her project. Finally, I argue that it is not clear that her thought-experiment is one that actually involves identity in any crucial way. As a result, the case she offers does not offer any satisfactory support for her view on the relation between identity, morality and thought-experiments, but we do gain some insights into what that relation really is along the way. (shrink)

Marya Schechtman's The Constitution of Selves presented an impressive attempt to persuade those working on personal identity to give up mainstream positions and take on a narrative view instead. More recently, she has presented new arguments with a closely related aim. She attempts to convince us to give up the view of identity as a matter of psychological continuity, using Derek Parfit's story of the “Nineteenth Century Russian” as a central example in making the case against Parfit's own view, and (...) offers a form of narrative theory as a way out of the problem. In this paper I consider this new case, and argue that we should not be persuaded towards the narrative. (shrink)

Wie ist es wohl, eine Fledermaus zu sein? Wäre ein rein physikalisches Duplikat von mir nur ein empfindungsloser Zombie? Muss man sich seinem Schicksal ergeben, wenn man sich unfreiwillig als lebensnotwendige Blutwaschanlage eines weltberühmten Violinisten wieder findet? Kann man sich wünschen, der König von China zu sein? Bin ich vielleicht nur ein Gehirn in einem Tank mit Nährflüssigkeit, das die Welt von einer Computersimulation vorgegaukelt bekommt? Worauf beziehen sich die Menschen auf der Zwillingserde mit ihrem Wort 'Wasser', wenn es bei (...) ihnen gar kein H2O gibt? -/- Diese und weitere seltsame Fragen sind das tägliche Brot vieler professioneller Philosophen. Die abstrusen Umstände, die dabei geschildert werden, nennt man "Gedankenexperimente". -/- Was soll die Erörterung dieser Szenarien, die sich so weit von unserem alltäglichen Leben, z.T. außerhalb der Grenzen unserer Wirklichkeit abspielen? Welche Rolle spielen diese "Gedankenexperimente" in der philosophischen Methodologie? Ist diese Rolle überhaupt berechtigt? -/- Das vorliegende Buch gibt Antworten auf diese Fragen. Es stellt sich heraus, dass diese seltsamen Gedankenexperimente nicht nur berechtigte, sondern überaus wichtige Instrumente philosophischen Forschens darstellen. (shrink)

Eric Olson argues in The Human Animal that thought-experiments involving body-swapping do not in the end offer any support to psychological continuity theories, nor do they pose any threat to his Biological View. I argue that he is mistaken in at least the second claim.

Recent work in personal identity has emphasized the importance of various conventions, or ‘person-directed practices’ in the determination of personal identity. An interesting question arises as to whether we should think that there are any entities that have, in some interesting sense, conventional identity conditions. We think that the best way to understand such work about practices and conventions is the strongest and most radical. If these considerations are correct, persons are, on our view, conventional constructs: they are in part (...) constituted by certain conventions. A person exists only if the relevant conventions exist. A person will be a conscious being of a certain kind combined with a set of conventions. Some of those conventions are encoded in the being itself, so requiring the conventions to exist is requiring the conscious being to be organized in a particular way. In most cases the conventions in question are settled. There is no dispute about what the conventions are, and thus no dispute about which events a person can survive. These are cases where we take the conventions so much for granted, that it is easy to forget that they are there, and that they are necessary constituents of persons. Sometimes though, conventions are not settled. Sometimes there is a dispute about what the conventions should be, and thus a dispute about what events a person can survive. These are the traditional puzzle cases of personal identity. That it appears that conventions play a part in determining persons’ persistence conditions only in these puzzle cases is explained by the fact that only in these cases are the conventions unsettled. Settled or not though, conventions are necessary constituents of persons. (shrink)

This paper is a defence of a psychological view of personal identity against the attack Peter Unger launches against it in his Identity, Consciousness and Value. Unger attempts to undermine the traditional support which a psychological criterion of identity has drawn from thought-experiments, and to show that such a criterion has totally unacceptable implications -- in particular, that it allows that persons can go out of and come back into existence. I respond to both aspects of this criticism, arguing that (...) the relevant thought-experiments (and the support they appear to offer) survive Unger's attack intact, and that he does not establish his case against intermittent existence. (shrink)

This is a critical review of Raymond Martin's 'Self-Concern' (1998), focusing especially on his criticism of Parfit's use of fission thought-experiments and his own 'fission rejuvenation' thought-experiment.

This is a critical review of Raymond Martin's 'Self-Concern'(1998).

The thought-experiment presented by Bernard Williams in 'The self and the future' continues to draw the attention of writers in the debate about personal identity. While few of them agree on what implications it has for the debate, almost all agree that those implications are significant ones. Some have even claimed that it has consequences not only for personal identity, but also concerning the viability of thought-experiment as a method. This paper surveys what these consequences might be at both levels (...) - as a substantive contribution to the debate on identity, and as to what it shows about the usefulness of thought-experiments. It argues ultimately that thought-experiments like Williams's do provide a useful philosophical tool as long as we temper our expectations of them, and that it offers some support to a view of personal identity but one which is at odds with Williams's own view. (shrink)

Imagine that you and a duplicate of yourself are lying unconscious, next to each other, about to undergo a complete step-by-step exchange of bits of your bodies. It certainly seems that at no stage in this exchange of bits will you have thereby switched places with your duplicate. Yet it also seems that the end-result, with all the bits exchanged, will be essentially that of the two of you having switched places. Where will you awaken? I claim that one and (...) the same person possesses both bodies, occupies both places and will experience both awakenings, just as a person whose brain has been bisected must at once experience both of the unconnected fields of awareness, even though each of these will falsely appear to him as the entirety of his experience. I also claim that the more usual apparent boundaries of persons are as illusory as those in brain bisection; personal identity remains unchanged through any variation or multiplication of body or mind. In all conscious life there is only one person - I - whose existence depends merely on the presence of a quality that is inherent in all experience - its quality of being mine, the simple immediacy of it for whatever is having experience. One powerful argument for this is statistical: on the ordinary view of personhood it is an incredible coincidence for you (though not for others) that out of 200,000,000 sperm cells the very one required on each occasion for your future existence was first to the egg in each of the begettings of yourself and all your ancestors. The only view that does not make your existence incredible, and that is not therefore (from your perspective) an incredible view, is that any conscious being would necessarily have been you anyway. It is a consequence that self-interest should extend to all conscious organisms. (shrink)

The paper takes a close look at Derek Parfit’s example of the Nineteenth Century Russian in 'Reasons and Persons'. Parfit presents it as an example which illustrates the moral consequences of adopting his reductionist view of personal identity in a positive light. I argue that things turn out to be more complex than he envisages, and that it might be far more difficult to live in his world than he allows.

This paper could be thought of as divided into two parts. In the first I show through a series of thought experiments that it is a mistake to think of one’s individual experience as necessarily belonging to only one particular place, time and organism. In repetitions across a universe large enough to host them, the particular experience that one finds oneself in, which can be individuated only by the detailed type that is the entirety of its momentary subjective content, would (...) exist equally in every occurrence of that type, much as a moment in the plot of a novel would exist equally in every copy of that novel. Each distinguishable subjective moment of experience is thus a ‘moment universal’. In the second part of the paper I draw from this the conclusion that there could not be any proper possessors of lines of experience - that there are no proper persons - no continuing subjects of consciousness and self-interest. About five years after writing this paper I came to see that the particular identity of an experience could not be confined by types of momentary subjective detail any more than it could be confined by particular places, times or organisms. All experience is equally here, now and mine and all conscious organisms are equally I. My argument for this crucial further development is presented in ‘One Self – The Logic of Experience’, Inquiry 33 (1991): pp. 39-68. (shrink)

Much mischief concerning the concept of a human body is generated by the failure of philosophers to distinguish various important senses of the term 'body.' I discuss three of those senses and illustrate the issues they can generate by discussing the concept of a Lockean exchange of bodies as well as the brain-body switch.

This is an extension of my earlier work, How in the World Are There Many Worlds and it's a lot more interesting! This paper explores personal identity and persistence through time in the many-worlds framework, governed by the Many Worlds Interpretation (MWI) of quantum mechanics (QM). First, I will motivate our consideration of the MWI in this context. Second, I will introduce endurantism, which is one answer to the puzzle concerning persistence through time. Third, I will explain the foundational physics (...) underlying the MWI that lends itself to branching worlds. In turn, I will explain what exactly a world amounts to in this picture. Then, I will present three views on personal identity and persistence through time: the bye-bye Betty view, the every-branch view, and the privileged branch view. I will argue that the privileged branch view is the most attractive of the bunch for determining the best candidate among close continuers. Finally, I will discuss knowledge, attitudes, and moral responsibility within the privileged branch view. (shrink)