Debate: What makes you the same person over time?

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.

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.

Defended by

John Locke, Derek Parfit, Sydney Shoemaker

Animalism

You are a human animal. You are the same as the child because you are one continuing living organism.

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.

Defended by

Eric Olson, Aristotle

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.

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.

Defended by

David Hume, Derek Parfit, Siddhartha Gautama (the Buddha)

Where you stand

What makes you the same person over time?

Choose one to see how people answer.

For the full background, variations and open questions, read the entry: Are you the same person you were at eight?.