First-person concern may resist reduction
Even if identity facts reduce to continuity, people may reasonably care whether one numerically identical subject survives.
Contemporary philosophy · 1942–2017
Parfit
Parfit argues that personal identity may matter less than the psychological relations that connect lives across time.
Derek Parfit was a British philosopher whose work transformed debates about personal identity, future generations, reasons and moral theory. Through tightly constructed thought experiments, he argued that identity is not always determinate and that morality must take seriously people whose existence depends on our choices.
MindEthicsAgencyJustice
The question he enters
The question Parfit enters
If your psychology divided perfectly between two future people, what would be lost when neither was strictly identical with you?
The central move
Separate survival from strict identity
Parfit treats persons as constituted by physical and psychological continuities rather than by a further indivisible self. In branching cases, identity may fail to be one-to-one while memory, intention and character continue. This suggests that what prudentially matters can survive even when the question 'which future person is me?' has no single answer.
Key ideas
Terms that carry the argument.
- Psychological continuity
- Overlapping chains of memory, intention, belief and character that connect stages of a life.
- Reductionism about persons
- The view that facts about personal identity consist in more basic physical and psychological relations, with no further ego fact.
- Relation R
- Psychological connectedness and continuity with the right kind of cause, which Parfit argues is what matters in survival.
- Non-identity problem
- The difficulty of explaining how choices wrong future people when different choices would have caused different people to exist.
Where the view strains
Objections and limits.
Population ethics produces severe paradoxes
Impartial aggregation can lead towards the repugnant conclusion or other choices that conflict with strong intuitions about lives and equality.
Sources and routes
Read the work. Follow the argument.
Primary texts
Where to meet the position.
- Oxford AcademicReasons and PersonsWebPersonal identity, rationality, future generations and population ethics.Oxford University Press online edition; print ISBN 9780198249085. · Publisher record with online chapter access subject to purchase or subscription. Checked Aug 2026.
- Open LibraryOn What MattersWebA large-scale attempt to connect consequentialist, Kantian and contractualist moral reasoning.Work-level library catalogue record for On what matters; select a listed edition on the record. · Bibliographic record with edition, library-location, borrowing or preview links where available; this row is bibliographic or sample-only unless the selected edition states otherwise. Checked Aug 2026.
- JSTORPersonal IdentityWebAn influential paper developing reductionism and psychological-continuity cases.The Philosophical Review, volume 80, number 1, January 1971, pages 3-27. · Stable journal record with institutional full-text access where available; bibliographic or preview-only otherwise. Checked Aug 2026.
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