Personal Identity

A Quick Introduction

Key Concepts and Distinctions

Qualitative vs. numerical identity

Self

Survival

Qualitative vs. Numerical Identity

Two things are qualitatively identical if they are exactly similar, that is, if they share properties in common sufficient to make them indistinguishable from each other in most cases.

Two things are numerically identical if they are one and the same thing.

Confused?

Consider that identical twins are qualitatively identical but numerically distinct.

In the same way, Superman and Clark Kent are qualitatively distinct, but numerically identical.

What is the self?

Some possible answers:The self is a conception one forms upon

reflection about their own experiences.The self is a socially constructed set of

labels imposed on a person.The self is a story one tells to others

about who one is.

None of the Above

Psychoanalytical, social, and narrative senses of ‘self’ are interesting, but not at issue in this discussion.

All of these senses of self trade on qualitative identity, not numerical identity.

The Main Question

What it is for one and the same person to persist through time, numerical identity

intact?

i.e. How is survival possible?

Survival

Some person, ‘A’, survives, just in case:

1. There is some future person ‘B’ who is numerically identical with ‘A’.

2. ‘A’ and ‘B’ are connected such that ‘A’ may legitimately anticipate ‘B’s experiences, and ‘B’ may correctly be said to remember ‘A’s experiences.

Three Main Positions

Body Theory

Psychological Continuity Theory

Soul Theory

“Non-Self” Theory

Body Theory

A survives if and only if A’s body (or some really important part of it, e.g. A’s brain, or DNA, etc.) is numerically identical with (the same part of) B’s body.

Psychological Continuity Theory

A survives if and only if A is psychologically continuous with B.

Psychological continuity is a matter of B’s psychological states being historically continuous with A’s, like, perhaps, frames in a single strip of film.

The Soul Theory

A survives if and only if A’s soul is identical with B’s soul.

This view is nearly always associated with the position of mind-body dualism: the view that minds are non-physical substances, and bodies are a physical substances that interact with minds.

The “No Self” Theory

There is nothing that can ground the numerical identity of A and B. A and B may well be qualitatively identical, but there is nothing that can establish their numerical identity over time.

This is the Buddhist view! It is also the view of the 18th Century Scottish

philosopher, David Hume.

Does Survival Matter?

At least one philosopher says “No”.

Derek Parfit argues that is not our numerical identity with future “selves” but the fact of our being connected in a particular way to some (non-numerically-identical, but perhaps qualitatively identical) future person.