In philosophy, the issue of personal identity seeks to determine whether two mental states belong to the same person, whether a person exhibits continuity through time, and whether a person can switch bodies or characteristics and memories with another person and retain his continuous consciousness.

For example, imagine that after your death there is someone, in the next world or in this one, who is a bit like you. How would that being have to relate to you as you are now in order to be you?

There are two schools of thought on personal identity. The first is sychronic: what it means to be a person at one time; and diachronic: what it means to be the same person over time.

David Hume claims that there is no diachronic personal identity, because identity simply is what it states: identical. And since cells are always dying, hair grows and gets cut or falls out, memories are replaced and forgotten, etc., people are not the same person as a person that represented them in the past, or will they be the same as the person who represents them in the future ('the person' in other tenses is intentional to prevent begging the question).

Hume claims that a synchronic self is just a bundle of perceptions/experiences. But he doesn't seem to explain how this bundle is something more as Immanuel Kant does; that the self is the unity of these perceptions.

There have been other thought experiments about personal identity, for example, "swamp man".

Further reading

• Daniel Dennett, Where am I?
• Derek Parfit, Reasons and Persons, part 3.
• Bernard Williams, The Self and the Future, in Philosophical Review 79.
• Ship of Theseus
• Personal life

External link

• Stanford Encyclopedia of Philosophy entry on personal identity