Identity of Persons

General problems about identity had been discussed long before the early modern period, but the problem of personal identity in the form in which it is so widely discussed today has its origin in John Locke's (1632–1704) chapter "Of Identity and Diversity," which he added to the second edition of his Essay Concerning Human Understanding (1694). Indeed, most early twenty-first-century views on the issue were anticipated in the seventeenth and eighteenth centuries.

Seventeenth Century

A standard topic in medieval philosophy was the search for a principle of individuation—that is, the question about what it is that makes an individual (object or person) the individual it is and distinguishes it from all other individuals of the same kind. Indeed, the medieval disputes formed a major part of the background for the early modern discussions about the issue. But from about the middle of the seventeenth century onward most philosophers (for example, Thomas Hobbes, Robert Boyle, Locke) neglected the issue of individuation and focused on identity over time instead—that is, on the question about the requirements for an individual's remaining the same over time, although that individual may have undergone some change. Also, there was a marked shift in the discussions away from a primarily ontological to a more subjective treatment of the topic. Our concepts of those things whose identity is in question came to be regarded as crucial for dealing with problems of individuation and identity. In Locke this move is connected to his view that we cannot know the real essences of substances. For Locke the question of how much a thing can change without losing its identity can be answered only with respect to "nominal essences"—that is, with respect to our abstract or "sortal" ideas of those beings whose identity is under consideration.

Early modern philosophers considered the issue of the identity of persons over time to be of special importance, as it is central to theological issues such as the doctrine of life after death and related moral questions. But for most of those thinkers (such as René Descartes) who believed that the soul is an immaterial substance, there was no real problem of personal identity at all. They argued that personal identity consists in the identity of a mental substance or soul and that the identity of the mental substance is a direct consequence of its immaterial nature; it is because of its immateriality that the mind is not subject to change and remains the same through time.

Locke's account marked a decisive break with both the Cartesian and Scholastic positions, which identified either the soul or the man (or human being) with the person as a res whose individuality and identity is constituted independently of and prior to consciousness. Locke treated the special problem of personal identity in accordance with his general theory of identity. Therefore, he argued that we need to be clear about the concept of person in order to be able to determine what constitutes the identity of persons. And to be clear about the concept of person, we have to distinguish it from those of thinking substance or spirit, and of man or human being because each of these concepts carries with it different identity-criteria. The identity of the self as man (or human being) consists in the identity of the same organic body. As we do not know the real nature of the soul as substance, personal identity is accounted for in terms of what we know about the self through inner experience or consciousness uniting thoughts and actions. To consider the self as a person is to consider the self with regard to all those thoughts and actions of which it is conscious. Through consciousness we link present with past thoughts and actions, thereby constituting our personal identity. Only with respect to our personal identity are we morally and legally responsible for past actions. This is why Locke said that "person" is a "forensic" term.

Locke's theory aroused controversy soon after its first publication and inspired critics and defenders throughout the eighteenth century. One standard objection was the charge of circularity, urging that consciousness presupposes personal identity and therefore cannot constitute personal identity (John Sergeant, Joseph Butler). However, this charge presupposes the very thing Locke challenged, namely that the person is an object, thing, or substance to which consciousness relates as to an already individuated being. Another standard objection was that Locke's theory is inconsistent with the transitivity of identity because consciousness is not transitive (George Berkeley, Thomas Reid). In Germany, Locke's most important contemporary critic, Gottfried Wilhelm Leibniz (1646–1716), distinguished between the metaphysical identity of the self (as immaterial substance), which is secured a priori by its intrinsic nature or "complete notion," and the moral identity of the self (as person), which is constituted by consciousness (Nouveaux Essais, 1704). However, while Locke argued for keeping personal and substantial identity separate, Leibniz maintained that the (personal) identity required for morality could be preserved only by the metaphysical identity of the self as immaterial soul. Through Christian von Wolff (1679–1754), Leibnizian theory dominated philosophy at German universities until about the middle of the eighteenth century.

Eighteenth Century

In eighteenth-century Britain, the most important treatment of the topic is by David Hume (1711–1776) in a famous section of his Treatise of Human Nature (1739). Hume rejects the traditional Cartesian view, arguing that through inner experience one can identify only a variety (a "bundle") of distinct perceptions; there is no experiential evidence of a soul that remains the same through time. Hume recognizes, however, that we nevertheless have a "natural propension" to ascribe unity and identity to the self. He argues that the idea of a unitary and identical mind is to the result of the imagination's connecting successive ideas in such a way as to create the belief that there is an identical self to which all these ideas belong. In the appendix to the Treatise Hume reflects critically on his own discussion of personal identity, relating the problem to his earlier explanation of "the principle of connexion" that "makes us attribute" identity to the mind. But Hume still holds that inner experience and observation reveal only collections or "bundles" of perceptions and that we nevertheless have a "natural propension" to ascribe identity to the self. Hume has mostly been read as reducing the self to its experiences or perceptions and as denying the existence of an essential self beyond the perceptions; but this reading has been criticized in recent commentary. While most eighteenth-century materialist thinkers simply adopted the Lockean view about personal identity, some (Michael Hissmann, Thomas Cooper) started from a Humean position but explicitly argued, unlike Hume, that there is no such a thing as personal identity at all.

Immanuel Kant's (1724–1804) approach, however, is different in kind from previous theories, as he was not concerned with empirical personal identity. Although Kant commented on empirical questions in some places, he did so in the light of his important distinction between empirical and what he calls "pure" or "transcendental" self-consciousness, or apperception, in the Critique of Pure Reason (1781). Unity and identity of self-consciousness are required for any thought to be possible at all. The identity of transcendental self-consciousness is "original" because it "precedes a priori all my determinate thought." Empirical consciousness, by contrast, "is in itself diverse and without relation to the identity of the subject." Kant makes use of this distinction in his critique of traditional rationalist metaphysics of the self or soul, known as "rational psychology." Its aim, according to Kant, is to show by way of a priori reasoning that (among other things) the self is a simple substance or soul and numerically identical at different points of time. But he argues that even the substantiality of the soul could not be inferred from the consciousness that I am the subject of all my thoughts. For knowledge of objects, including knowledge of the self as object, requires experience. In his moral philosophy Kant distinguished moral personality from both the empirical and the transcendental self and attempted to show that the idea of moral-practical freedom of the self has objective reality. In German idealism, too, the issue of empirical personal identity through time was not a major concern. However, both Kantian and empiricist examinations of consciousness and identity continued to appear simultaneously with the speculations of the idealists.

Twentieth and Twenty-First Centuries

In the twentieth and early twenty-first centuries the issue of personal identity has continued to be a major theme especially in Anglo-American analytical philosophy. The debate is mainly between those who favor bodily continuity and those who favor psychological continuity as constituting personal identity. There is, however, considerable variety within the two main positions. Thus, some proponents of the psychological continuity view assign special importance to some rather than other psychological relations (such as memory). Since the 1970s the debate has focused on a revival of reductionist accounts of personal identity according to which selves are nothing over and above people's bodies and their mental lives. For Derek Parfit the common-sense view that regards personal identity as significant is mistaken. Rather, what matters are psychological relations that are normally but not necessarily connected with the personal identity relation. By arguing that personal identity is not "what matters" Parfit undermines notions, such as responsibility, that presuppose personal identity. The debate about Parfit's reductionism has also sparked off a revival of Kantian arguments about identity. It is argued that the subject should be regarded primarily as an agent and not as a mere locus of experience, and that this emphasis on the concept of agency leads to nonreductionist conclusions about personal identity: the identity of the self as agent is a necessity of practical reason. Another important feature of recent debates in the reductionist context is the introduction of a four-dimensional view of persons. On this view, which goes back to Willard van Orman Quine (1953), persons (as well as physical objects) are extended not only in space but also in time and thus can be said to have temporal parts. That is to say, at one point of time only part of me exists, in the same way in which the parts of my body exist only in their respective spatial regions. The four-dimensionalist view has been criticized from within the analytical tradition as conceptually incoherent and as inconsistent with our common-sense way of talking and thinking about things and persons.

Feminist philosophers have argued that analytical philosophers' reliance on a distinction between psychological and bodily continuity is in effect "marginalizing the body," and they promote instead a view according to which selves are embodied, discontinuous, malleable, and socially constructed beings (James, pp. 31–32). The most influential account of personal identity in Continental philosophy has been developed by Paul Ricoeur in terms of the notion of narrativity. According to this account, our personal identity is not given to us or constituted metaphysically prior to or independently of our activity of making sense of our own self by telling ourselves a story about our own lives. Only this narrative links actions into one and the same person. The view according to which a person creates his or her identity by forming an autobiographical narrative has recently been taken up in analytical discussions.

See also Identity: Personal and Social Identity ; Responsibility ; Society .

bibliography

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Udo Thiel