Concept

Personal identity

Overview

Personal identity is the unique identity of a person over time. Discussions regarding personal identity typically aim to determine the necessary and sufficient conditions under which a person at one time and a person at another time can be said to be the same person, persisting through time.

In philosophy, the problem of personal identity is concerned with how one is able to identify a single person over a time interval, dealing with such questions as, "What makes it true that a person at one time is the same thing as a person at another time?" or "What kinds of things are persons?"

In contemporary metaphysics, the matter of personal identity is referred to as the diachronic problem of personal identity. The synchronic problem concerns the question of what features and traits characterize a person at a given time. Analytic philosophy and continental philosophy both inquire about the nature of identity. Continental philosophy deals with conceptually maintaining identity when confronted by different philosophical propositions, postulates, and presuppositions about the world and its nature.

Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).

In the original texts

Passages from public-domain books where Personal identity is discussed.

As a memory alone acquaints us with the continuance and extent of this succession of perceptions, it is to be considered, upon that account chiefly, as the source of personal identity. Had we no memory, we never should have any notion of causation, nor consequently of that chain of causes and effects, which constitute our self or person.
David Hume, A Treatise of Human Nature
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20. Persons, not Substances, the Objects of Reward and Punishment. In this personal identity is founded all the right and justice of reward and punishment; happiness and misery being that for which every one is concerned for HIMSELF, and not mattering what becomes of any SUBSTANCE, not joined to, or affected with that consciousness. For, as it is evident in the instance I gave but now, if the consciousness went…
John Locke, An Essay Concerning Humane Understanding, Volume 1
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The whole of this doctrine leads us to a conclusion, which is of great importance in the present affair, viz. that all the nice and subtile questions concerning personal identity can never possibly be decided, and are to be regarded rather as grammatical than as philosophical difficulties. Identity depends on the relations of ideas; and these relations produce identity, by means of that easy transition they…
David Hume, Philosophical Works, v. 1
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... In this personal identity is founded all the right and justice of reward and punishment. It may be reasonable to think, no one shall be made to answer for what he knows nothing of, but shall receive his doom, his consciousness accusing or excusing.
William James, Pragmatism
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This description of personal identity will be recognized by the instructed reader as the ordinary doctrine professed by the empirical school. Associationists in England and France, Herbartians in Germany, all describe the Self as an aggregate of which each part, as to its _being_, is a separate fact. So far so good, then; thus much is true whatever farther things may be true; and it is to the imperishable glory of…
William James, The Principles of Psychology, Volume 1
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Personal identity

Overview

In the original texts

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