Philosophy Personal Identity
Eric Olson
  • LAST REVIEWED: 13 December 2022
  • LAST MODIFIED: 28 February 2017
  • DOI: 10.1093/obo/9780195396577-0086


The term “personal identity” means different things to different people. Psychologists use it to refer to a person’s self-image—to one’s beliefs about the sort of person one is and how one differs from others. In philosophy the term normally refers to philosophical questions about ourselves that arise by virtue of our being people, questions that may otherwise have little in common. Some philosophers use the term more loosely and include such topics as the nature of self-knowledge, self-deception, rationality, and the will. This article covers personal identity in the stricter sense.

General Overviews

Penelhum 1967 and Perry 2008 are good but a bit dated. The others are reliable guides to current debates. The Garrett 1998 and Olson 2015 encyclopedia articles survey the field; DeGrazia 2005 approaches the subject from an ethicist’s perspective.

  • DeGrazia, David. Human Identity and Bioethics. Cambridge, UK: Cambridge University Press, 2005.

    DOI: 10.1017/CBO9780511614484

    Chapter 2 is a lengthy but highly readable survey with lots of examples, focusing mainly on identity over time and its practical importance. Sympathetic toward animalism.

  • Garrett, Brian. “Personal Identity.” In Routledge Encyclopaedia of Philosophy. Vol. 7. Edited by Edward Craig, 305–314. London: Routledge, 1998.

    A brief but useful introduction and an excellent place to start. The online version (2004, subscription required) is more up to date.

  • Olson, Eric T. “Personal Identity.” In The Stanford Encyclopedia of Philosophy. Edited by Edward N. Zalta. Stanford, CA: Stanford University Press, 2015.

    Usefully distinguishes seven separate problems of personal identity, then focuses on identity over time, with particular attention to different versions of the question.

  • Penelhum, T. “Personal Identity.” In Encyclopedia of Philosophy. Vol. 6. Edited by Paul Edwards, 95–107. New York: Macmillan, 1967.

    A sophisticated discussion of Locke, Hume, and the debates of their day about evidential criteria of personal identity over time.

  • Perry, John. “The Problem of Personal Identity.” In Personal Identity. 2d ed. Edited by John Perry, 3–30. Berkeley: University of California Press, 2008.

    A lively and accessible introduction to traditional debates on personal identity over time. Originally published in 1975.

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