Eric T. Olson (2002; substantive revision 30 June 2023), “Personal Identity”, Stanford Encyclopedia of Philosophy, ed. Edward N. Zalta and Uri Nodelman — https://plato.stanford.edu/entries/identity-personal/.
On the citation. The brief gave the author and title, which are right,
and asked for the current revision. The entry was first published on 20
August 2002 and last substantively revised on 30 June 2023, so
published: is the first date, following how the record files SEP entries
(LIT-160, LIT-130). The archive page names the Winter 2024 Edition as the
fixed citable copy of this text (plato.stanford.edu/archives/win2024/).
Key takeaways
- There is no single problem of personal identity. The entry separates seven questions: characterization (what makes me the person I am, in the “identity crisis” sense, which it credits to Schechtman’s term), personhood, persistence, evidence, population (how many of us there are now), personal ontology (what we are made of, what kind of thing we are) and what matters in survival. It says discussions often leave unclear which one is at stake.
- “Self” is set aside. The word “is often used without any clear meaning and will be avoided here”. The entry is about persons and their persistence, not about the self as later work in this batch uses the word.
- The persistence question is about numerical identity, not about “remaining the same person”, which presupposes numerical identity and concerns character. And it should not be framed as “a person at one time and a person at another”, which assumes person essentialism and so rules out by fiat that you were once an embryo.
- Three answers. Psychological-continuity views (most philosophers since the early twentieth century) replace Locke’s memory criterion with chains of causally dependent psychological states. Brute-physical views tie us to the body or the organism (Olson, Snowdon, van Inwagen, Williams). Anticriterialism (Merricks) denies there are informative persistence conditions at all.
- Fission (each hemisphere transplanted into a different head) forces psychological views either into “multiple occupancy” (two people were there all along, Lewis and Perry) or into a non-branching clause, on which fission is death and so identity is not what matters (Parfit, Shoemaker).
- The too-many-thinkers objection. If we persist by psychological continuity we are not organisms; but the organism also thinks, so there are two thinkers in your chair and you cannot know which you are. The replies (organisms do not think; “I” refers only to the person) are “easy to say” and “hard to defend”, by the entry’s account.
- Animalism is not an account of personhood. Its main cost is the transplant intuition (you would stay behind with an empty head), which the entry argues is weaker than it looks.
- Temporal parts make many overlapping candidates think your thoughts, so “I” may refer indeterminately, and it may be indeterminate what we are and when we began.
Standing in the record
Filed on 2026-10-02 at the owner’s request to fill out the record’s coverage of identity, personhood and selfhood, as the general map of the analytic persistence debate. It is the companion survey to Dufner’s “Personal Identity and Ethics” (LIT-130), which surveys how the same contested positions bear on ethics and points to Olson 1997 and Schechtman 1996 as primary sources. Those two books are filed beside this entry (LIT-448, LIT-468). No anthology topic holds it, it carries no instruction for machine-learning practice, and the anthology does not hold it.
NOTE-374 is the reading, and it placed the work: Active. It is the standard reference and is current to 2023. It argues: §§6–8 make the animalist’s case and leave the psychological theorist’s replies looking weak, which is the author’s own position (Olson 1997 is the animalist book). Read it as the best map of persistence and population, and read LIT-130 and the narrative literature for the questions it puts aside.
Where it bears on what the record holds:
- Dennett’s two essays. “Where Am I?” (LIT-405) is a brain-in-a-vat and duplication case. The entry’s §4 asks whether brain-state transfer is the right kind of causal dependence, and its §6 duplicating machine raises the same “which one am I?” question. The entry does not cite Dennett. Its population question (can one organism house two thinking beings, as Wilkes and Rovane hold for multiple personality?) is where “The Self as a Center of Narrative Gravity” (LIT-442) counts two selves in one body by interpretation.
- The extended self (LIT-097). “Where do our spatial boundaries lie … Do we extend all the way out to our skin?” is listed under personal ontology, and the entry does not answer it. Clark and Chalmers’s one-paragraph inference that the self extends is an answer to that question, not to the persistence question.
- Machines. Personhood is asked of “a chimpanzee or a Martian or a computer”. Animalism is consistent with “intelligent robots” being people. On whether there could be machine persons the entry takes no side. The fission and copying cases are the tools LIT-206 needs for per-conversation instances, as NOTE-166 already said of LIT-130.
The classical sources this entry reports (Locke, Hume, Parfit’s fission and “what matters”, Williams, Lewis on survival) are being filed in parallel, and this entry is the map they sit on.