QuestionsVIII
Are you the same person you were at eight?
Almost every cell, belief and memory has changed. Something makes that child you. The question is what.
- Reading time
- 4 min
- Difficulty
- Introductory
- Branch
- Identity
- First posed
- John Locke, An Essay Concerning Human Understanding, 1694 edition
The question
Find a photo of yourself at eight. That child had different handwriting, a different voice, different fears and favourite foods. Most of the molecules in that child's body have since been replaced. They could not have imagined most of what you now know, and you have forgotten most of what they experienced.
And yet you say, without hesitation, 'That's me.' The question of personal identity over time asks what makes this true. What is it about a person at one time and a person at a later time that makes them one person, rather than two similar people in a sequence?
Philosophers distinguish two kinds of sameness. Qualitative sameness is being exactly alike, as two identical coins are. Numerical sameness is being one and the same thing. You and the child are obviously not qualitatively the same. The claim is that you are numerically the same, despite the changes. What grounds that claim?
“As far as this consciousness can be extended backwards to any past action or thought, so far reaches the identity of that person.”
John Locke, An Essay Concerning Human Understanding (1694)
Why it matters
Identity carries moral weight. We punish people for crimes committed years ago, hold them to promises they made long before, and plan for our own futures because the future person will be us. If identity over time is weaker than we think, these practices need rethinking.
It also matters for medicine. A patient with advanced dementia may have no memories of their earlier life. Should decisions be guided by the wishes they recorded years ago, or by what they want now? The answer depends on whether they are still the same person in the sense that matters.
Key terms
- Personal identityWhat makes a person at one time the same person as someone at another time.
- Numerical identityBeing one and the same thing, as opposed to being exactly alike. Twins may be qualitatively identical; only you are numerically identical to you.
- Qualitative identityBeing exactly alike in every property, without necessarily being one and the same thing.
- Psychological continuityOverlapping chains of memories, intentions, beliefs and character linking a person at different times. Many theories of personal identity are built on it.
- AnimalismThe view that each of us is a human animal, so that personal identity over time is the persistence of a biological organism, not of memories or psychology.
The positions
Psychological continuity
You are the same person as the child because a chain of memories, intentions and character links you, each stage connected to the next.
Animalism
You are a human animal. You are the same as the child because you are one continuing living organism.
No persisting self
There is no single enduring self that stays the same. 'You' are a series of connected experiences, and identity over time is a useful fiction.
Arguments and objections
Psychological continuity
- Best argument
- Consider John Locke's case of a prince whose memories and personality are transferred into a cobbler's body. Most people say the prince now wakes up in the cobbler's body: the person goes where the mind goes. You need not remember being eight directly; it is enough that you remember being twelve, who remembered being ten, and so on in overlapping links.
- Strongest objection
- Psychological connections can branch. If your mind were copied into two new bodies, both would be psychologically continuous with you, but they cannot both be you, since they are not each other. A relation that can branch cannot be identity, which is always one-to-one.
- The reply
- Derek Parfit accepts the problem and draws a radical conclusion: identity is not what matters. What matters is psychological continuity itself, and in the branching case you would survive twice over, even though neither copy is strictly you.
Animalism
- Best argument
- Eric Olson asks a simple question: who is reading this sentence? There is a human animal sitting where you are, using its brain to think. If you were something other than that animal, there would be two thinkers in your chair. The simplest answer is that you are the animal. And the animal clearly persisted from age eight, as a single life, through all its changes.
- Strongest objection
- Animalism says that if your cerebrum were transplanted into another body, you would stay behind as a mindless body on life support. Most people's intuition is that you would go with your brain.
- The reply
- Animalists accept the cost and argue that our intuitions here are tracking what we care about, not what we are. You might care about the transplant recipient as you care about yourself without being identical to it.
No persisting self
- Best argument
- When David Hume looked inward for a self, he found only particular perceptions, never a perceiver beneath them. Buddhist philosophy reached a similar conclusion centuries earlier with the doctrine of anattā, or no-self. Parfit argues that once you see that facts about identity reduce to facts about connections, you lose nothing real by giving up the idea of a deep further fact. See the no-self view.
- Strongest objection
- It seems impossible to live by. Planning, promising and caring about your future all presuppose someone who will be there. If no one persists, why save for retirement?
- The reply
- Parfit reported finding the view liberating: the walls between himself and others seemed to dissolve, and he cared less about his own death. One can care about future experiences connected to present ones without a metaphysical self binding them.
Who argued what
- Psychological continuity John Locke, Derek Parfit, Sydney Shoemaker
- Animalism Eric Olson, Aristotle
- No persisting self David Hume, Derek Parfit, Siddhartha Gautama (the Buddha)
Where you stand
What makes you the same person over time?
In surveys
Choose one to see how people answer.
Variations
The brave officer
Thomas Reid objected to Locke with a story. A boy is flogged for stealing apples. As a young officer, he remembers the flogging. As an old general, he remembers being the officer but has forgotten the flogging. By Locke's memory test, the general is the officer and the officer is the boy, but the general is not the boy. That breaks the logic of identity, which is transitive. Overlapping chains of memory were introduced to fix exactly this.
Gradual dementia
If psychological continuity is what makes you you, then severe dementia may gradually end a person while the body lives on. Many carers find this description both apt and unbearable, which shows how much rides on the theory.
Go deeper
Is identity a matter of degree?
Identity in logic is all or nothing: a thing is either itself or not. But the relations that seem to underpin personal identity, like psychological connectedness, come in degrees. You are strongly connected to yourself last week and weakly connected to yourself at eight. Parfit suggested that our attitudes should follow the degrees: it may make sense to feel less responsible for what you did decades ago, and to care somewhat less about a far future self.
Related ideas
Further reading and sources
- EncyclopediaStanford Encyclopedia of Philosophy: Personal Identity
- WikipediaPersonal identity
- SurveyPhilPapers Survey, 2020 · question: Personal identity; about 1,785 professional philosophers; accept or lean toward
- BookReasons and Persons, Derek Parfit
- BookPersonal Identity, John Perry (editor)
- BookA Dialogue on Personal Identity and Immortality, John Perry
Open questions
- If every one of your memories were replaced, would you still be you?
- Should a promise made by your twelve-year-old self bind you now?
- Does it matter whether you survive, or only whether someone very like you does?