Psychologically based accounts of personal identity over time start from a view of persons as experiencing subjects. Derek Parfit argues that if such an account is to justify the importance we attach to identity it will need to provide a deep unity of consciousness throughout the life of a person, and no such unity is possible. In response, many philosophers have switched to a view of persons as essentially agents, arguing that the importance of identity depends upon agential unity rather than unity of consciousness. While this shift contributes significantly to the discussion, it does not offer a fully satisfying alternative. Unity of consciousness still seems required if identity is to be as important as we think it is. Views of identity based on agential unity do, however, point to a new understanding of unity of consciousness which meets Parfit's challenge, yielding an integrated view of identity which sees persons as both subjects and agents.

According to the Constitution View of persons, a human person is wholly constituted by (but not identical to) a human organism. This view does justice both to our similarities to other animals and to our uniqueness. As a proponent of the Constitution View, I defend the thesis that the coming-into-existence of a human person is not simply a matter of the coming-into-existence of an organism, even if that organism ultimately comes to constitute a person. Marshalling some support from developmental psychology, I give a broadly materialistic account of the coming-into-existence of a human person. I argue for the metaphysical superiority of the Constitution View to Biological Animalism, Thomistic Animalism, and other forms of Substance Dualism. I conclude by discussing the single implication of the Constitution View for thinking about abortion.

The constitution view of persons, according to which a person is constituted by a body, has both interesting extensions as well as limitations. Here I shall leave discussion of the limitations for another time and concentrate on several extensions. The chief extensions of the constitution view that I shall explore here concern the implications of combining it with ontological pluralism, and applications of it (or something like it) to thinking about various forms of social agency.

To the extent that dualism is even taken to be a serious option in contemporary discussions of personal identity and the philosophy of mind, it is almost exclusively either Cartesian dualism or property dualism that is considered. The more traditional dualism defended by Aristotelians and Thomists, what I call hylemorphic dualism, has only received scattered attention. In this essay I set out the main lines of the hylemorphic dualist position, with particular reference to personal identity. First I argue that overemphasis of the problem of consciousness has had an unhealthy effect on recent debate, claiming instead that we should emphasize the concept of form. Then I bring in the concept of identity by means of the notion of substantial form. I continue by analyzing the relation between form and matter, defending the traditional theses of prime matter and of the unicity of substantial form. I then argue for the immateriality of the substantial form of the human person, viz. the soul, from an account of the human intellect. From this follows the soul's essential independence of matter. Finally, although the soul is the immaterial bearer of personal identity, that identity is still the identity of an essentially embodied being. I explain how these ideas are to be reconciled.

Defenders of the thesis of self-ownership generally focus on the “ownership” part of the thesis and say little about the metaphysics of the self that is said to be self-owned. But not all accounts of the self are consistent with robust self-ownership. Philosophical accounts of the self are typically enshrined in theories of personal identity, and the paper examines various such theories with a view to determining their suitability for grounding a metaphysics of the self consistent with self-ownership. As it happens, only one such theory is suitable: the hylemorphic theory of Aristotle and Aquinas. To adopt such a theory, however, is to see that self-ownership may in some respects have implications different from those many of its defenders take it to have.

Derek Parfit's “reductionist” account of personal identity (including the rejection of anything like a soul) is coupled with the rejection of a commonsensical intuition of essential self-unity, as in his defense of the counter-intuitive claim that “identity does not matter.” His argument for this claim is based on reflection on the possibility of personal fission. To the contrary, Simon Blackburn claims that the “unity reaction” to fission has an absolute grip on practical reasoning. Now David Lewis denied Parfit's claim that reductionism contravenes common sense, so I revisit the debate between Parfit and Lewis, showing why Parfit wins it. Is reductionism about persons then inherently at odds with the unity reaction? Not necessarily; David Velleman presents a reductionist theory according to which fission does not conflict with the unity reaction. Nonetheless, relying on the distinction between person level descriptions of first-person states and the first-person perspective itself, I argue that Velleman's theory does not eliminate fission-based conflict with the unity reaction.

In this essay, I propose a standard of practical rationality and a grounding for the standard that rests on the idea of autonomous agency. This grounding is intended to explain the “normativity” of the standard. The basic idea is this: To be autonomous is to be self-governing. To be rational is at least in part to be self-governing; it is to do well in governing oneself. I argue that a person's values are aspects of her identity—of her “self-esteem identity”—in a way that most of her ends are not, and that it therefore is plausible to view action governed by one's values as self-governed. This is also plausible on independent grounds. Given this, I say, rational agents comply with a standard—the “values standard”—that requires them to serve their values, and to seek what they need in order to continue to be able to serve their values.

What does a person really want when he asks for an apology? Why do people so often find it difficult to give an apology? Repentance is relevant to personal identity because the unrepentant soul has his own theory of personal identity. The unrepentant person believes he is his preference, and that he is entitled to the behavior that flows from those preferences. This fact can explain why people are so often reluctant to admit wrongdoing, why people place so much importance upon receiving an apology and other behaviors that would be otherwise inexplicable. The unrepentant person uses something akin to a naive economic theory of human behavior. The naive version of homo economicus, or economic man, can never truly be sorry for anything, and as a result, will be almost impossible to live with. A person who identifies himself too closely with his preferences will bring misery to himself and those around him.

The so-called “problem of personal identity” can be viewed as either a metaphysical or an epistemological issue. Metaphysicians want to know what it is for one individual to be the same person as another. Epistemologists want to know how to decide if an individual is the same person as someone else. These two problems converge around evidence from mediumship and apparent reincarnation cases, suggesting personal survival of bodily death and dissolution. These cases make us wonder how it might be possible for a person to survive death and either temporarily or permanently animate another body. And they make us wonder how we could decide if such postmortem survival has actually occurred. In this essay I argue, first, that metaphysical worries about postmortem survival are less important than many have supposed. Next, I'll consider briefly why cases suggesting postmortem survival can be so intriguing and compelling, and I'll survey our principal explanatory options and challenges. Then, I'll consider why we need to be circumspect in our appraisal of evidence for mind-body correlations. And finally, I'll try to draw a few tentative and provocative conclusions.

The four kinds of explanation identified by Aquinas at the beginning of his commentary on Aristotle's Ethics are deployed to show that the identity of the human person is sui generis and mysterious, even though each of its elements is more or less readily accessible to our understanding. The essay attends particularly to the explorations by Aquinas and, with different techniques, by Shakespeare of the experience and understanding of (a) one's lasting presence to oneself as one and the same bodily and mental self, and (b) one's self-shaping by one's free choices, especially of commitments. Shakespeare further explores these, quite deliberately, through displays of mistaken identity and humiliating deflations of the personas one constructs for life in society.

In the first part of this article, I argue that even those entities that in their own right and for their own sake give us reason not to destroy them and to help them are sometimes substitutable for the good of other entities. In so arguing, I consider the idea of being valuable as an end in virtue of intrinsic and extrinsic properties. I also conclude that entities that have claims to things and against others are especially nonsubstitutable. In the second part, I argue that cloning poses no threat to the nonsubstitutability of these entities (and in this sense, to the dignity of persons). I also consider the relation between cloning and (what I called) holistic identity, and between the latter and genetic identity. In the concluding part of the article, I try to distinguish cases where identity over time and so-called person-affecting acts have and do not have greater moral significance than nonidentity over time and nonperson-affecting acts. I try to apply my results to cases involving embryos, future generations, and to the so-called Non-Identity Problem.

Technologies are being developed for significantly altering the traits of existing persons (or fetuses or embryos) and of future persons via germ line modification. The availability of such technologies may affect our philosophical, legal, and everyday understandings of several important concepts, including that of personal identity. I consider whether the idea of personal identity requires reconstruction, revision or abandonment in the face of such possibilities of technological intervention into the nature and form of an individual's attributes. This requires an account of the work done by the concept of personal identity, and an explanation of what “conceptual impacts of technology” and “conceptual reconstruction” might mean.

Our existing notions of personal identity and related ideas such as personhood and autonomy may seem unable to comfortably accommodate the possibilities of technologically directed trait formation and development. This is a matter of moral and legal importance because the idea of personal identity embeds major values and reflects value-laden beliefs and attitudes. The assumed endurance of identity underlies interpersonal relationships, the assignment of rewards and punishments, and the very idea of what constitutes an autonomous person. Perhaps radical restructuring or even abandonment of concepts are sometimes called for when the world changes drastically, but I suggest that conceptual modification is not “compelled” for personal identity except under extreme circumstances—the remote possibility of rapid human “shape shifting” where physical and mentational attributes can be transformed quickly and continuously.

Efforts to enhance human traits, including merit attributes and other resource-attractive characteristics (e.g., intellectual and athletic aptitudes, physical size and appearance), may generate legal problems wherever the persistence of identity is presupposed. Some advance speculation is thus warranted on how trait change generally will be managed within our legal and socioeconomic systems, and more particularly on rights of access to trait-altering technologies. I mention the possible distributive effects of enhancing highly-resource attractive traits, including the strengthening individual powers to acquire still more increments in such traits in a self-reinforcing cycle. A brief review of some constitutional issues bearing on trait change completes the discussion.

I conclude that existing and projected technologies do not impel the abandonment or remodeling of the idea of personal identity. We may, however, have to reconsider some uses of this concept in different settings, to rethink our understandings of ideas of merit and desert, and to deal with the distribution of resources that may enlarge and entrench the “distances” between social and economic groups.