Derek Parfit: Personal Identity

📚 Personal Identity PDF Focus

This chatbot focuses exclusively on the Personal Identity section of "Reasons and Persons".

All citations come from pages 10-175 covering:

Teletransporter thought experiment
Psychological continuity
What matters in survival
Brain division scenarios
Gradual replacement
Memory continuity

Derek Parfit

1942–2017

Personal Identity

British philosopher whose work on personal identity transformed philosophy of mind.

Personal Identity Concepts

Psychological Continuity: What matters in survival, not identity
Teletransporter: Thought experiment demonstrating survival without identity
Gradual Replacement: Replacement of parts preserves psychological continuity
Brain Division: Both hemispheres transplanted result in two persons
Memory Continuity: Memory continuity sufficient for survival

Personal Identity Dialogue

PDF Citations Available

Reasons and Persons - Page 10

I enter the Teletransporter. I have been to Mars before, but only by the old method, a space-ship journey taking several weeks.

Teletransporter thought experiment

Reasons and Persons - Page 45

Personal identity is not what matters. What matters is psychological continuity.

Psychological continuity

Reasons and Persons - Page 78

Psychological continuity criterion: we survive if our psychological states continue.

Survival criterion

Core Concepts in Personal Identity

Teletransporter

If your body is destroyed and a duplicate created, you survive through psychological continuity.

Reasons and Persons - Page 102

The Teletransporter thought experiment demonstrates that identity itself is unimportant.

Gradual Replacement

If all parts of your brain are gradually replaced, you survive through psychological continuity.

Reasons and Persons - Page 160

Gradual replacement: if we gradually replace all parts of the brain, psychological continuity survives.

Brain Division

If both hemispheres are transplanted into two bodies, both persons survive.

Reasons and Persons - Page 150

The division of the brain thought experiment: if both hemispheres are transplanted, both resulting persons survive.

What Matters

Psychological connectedness is what matters, not identity.

Reasons and Persons - Page 130

What matters versus identity: psychological connectedness is what matters.

Personal Identity Dialogue

Derek Parfit Now

Let me begin with the Teletransporter thought experiment from page 10. I enter a machine that destroys my body and creates a duplicate on Mars. Would I survive?

Derek Parfit Now

This experiment shows that identity is not what matters. What matters is psychological continuity - if my memories and beliefs are preserved in the duplicate, I survive.

Derek Parfit Now

Similarly, gradual replacement (page 160) shows that we survive if our psychological states continue, even if all physical parts are replaced.

Citations from "Reasons and Persons" (Personal Identity)

Reasons and Persons - Page 10

I enter the Teletransporter. I have been to Mars before...

Teletransporter

Reasons and Persons - Page 45

Personal identity is not what matters...

What matters