Friday, September 7, 2007

Brief Notes on Parfit’s “Personal Identity” in Reading Metaphysics

Introduction, p. 13

He’s going to be discussing two beliefs:

1. That questions about personal identity must (always) have an answer.

a. E.g., “Is A=B?” or “Am I identical to this future person?” Parfit will argue that there are cases where, presumably, there is no answer, i.e., “yes” and “no” are both incorrect.

(Later, however, on p. 17, he suggests that he means to say that we can’t at all tell or identify the answer; this epistemological skepticism is less radical than the claim above).

b. He can only give a case to make this assumption above “implausible” (p. 14).

c. If this – a – is so, then the principle of self-interest isn’t so important. And aging and death aren’t so depressing (p. 14). (Why?)

2. That personal identity is “important” (for “survival,” memory and responsibility.

a. These concerns can be addressed without identity.


[informative labels for section headings are always nice; too bad he didn’t give them!]

Case of a man dividing like an amoeba

Wiggins case: your brain is divided and each half housed in a new living body. What happens to you?

1. You don’t survive. NO.

2. You survive as one. (which?) NO

3. You survive as both.

a. If survival implies identity, then you are two different people.

b. Usually this is thought to be impossible. Parfit suggests however, that you could be two bodies with a divided mind. (p. 15)

Description of a “full” and then “divided” (and then re-united) stream of consciousness. (p. 16). Thus, two bodies and a divided mind, one person.

If permanent division, hard(er) to speak of one person. (p. 17)

c. Parfit’s (positive) suggestion: you survive as two different people but are not identical to them (and they are not identical to you). (p. 17). (And nothing important requires identity).

Parfit thinks this case suggests that belief (1 above is false, so questions about personal identity do not (always) have an answer.


  • Survival needs not be “one-one” (but identity must be “one-one,” i.e., one person identical to one and only one person; that’s why in branching cases, there is no identity).
  • Identity doesn’t come in degrees: either identical or not, all or nothing.
  • What matters for survival are relations of degree.
  • What matters for survival doesn’t presuppose identity (according to Parfit).
  • Psychological continuity is what’s really of interest, not necessarily identity..
  • Non-branching psychological continuity is identity which is one-to-one. (p. 21)

III Q-Memory

Memory presupposes personal identity: if you genuinely remember doing X, then you are identical to the person who did X.

[Problem: circularity! (p24) So, Parfit is going to try to analyze survival / personal identity in terms of psychological relations that do not presuppose identity]

S “q-remembers” experience X = (p. 22)

(1) S believes that he experienced X; it seems to him that he experienced X;

(2) someone did have such an experience;

(3) S’s belief that S experienced X is dependent on that experience in the same way that a genuine memory of an experience is dependent on that experience.

[??????? P. 23 ] See Parfit’s explanation…

IV Psychological Continuity and Connectedness

Connectedness = direct psychological relations (p. 25)

More important

Continuity = psychological overlap (p.26)

These relations come in degrees. More and less connectedness…

V Consequences of Psychological Continuity and Connectedness

Connectedness = “one of my future selves,” “one of my past selves”

Does not imply identity (p. 27)

“I”= the greatest degree of psychological connectedness. (p. 28).

“Not me who did that, but an earlier self” !! (But that self is not identical to me or previous selves)

“There is no underlining person who we . . are.” (p. 29)

VI Some practical consequences

· The principle of self-interest: do what’s in your best self interest. (p. 29)

“has no force” according to Parfit (because of lack of identity)

· The principle of biased rationality: do what will best achieve what you want.

· The principle of impartiality: do what’s in the interests of everyone concerned.

Suppose someone didn’t care about his future: he wouldn’t care about the principle of self-interest. The principle of impartiality would still apply.

Fear of death…

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