PHILOSOPHY 100 Ted Stolze

1
PHILOSOPHY 100 (Ted Stolze)
Notes on James Rachels, Problems Philosophy
2
Chapter Five The Problem of Personal Identity
3
What is a Thought Experiment?

• A thought experiment is an imaginary scenario
  thats used to help concentrate the mind on
  certain key factors in . . . reasoning. The
  basic principles of thought experiments are the
  same as those for actual scientific experiments
  isolate the variables to be tested see how
  individually altering these factors effects the
  result the draw general conclusions about the
  significance of these variables. In contrast
  with scientific experiments, of course, the
  significance of thought experiments in . . .
  philosophy will be philosophical . . . rather
  than physical.
• (From Julian Baggini and Peter S. Fosl, The
  Ethics Toolkit A Compendium of Ethical Concepts
  and Methods Malden, MA Blackwell, 2007, p.
  199.)

4
The Duplicator Thought Experiment
5
Two Aspects of Personhood

• At a Moment
• Over Time

6
Two Theories of Personhood at a Moment

• The Soul Theory
• The Bundle Theory

7
The Soul Theory

• Within each person is a kernel that may be
  called the soul or the ego or the self. It is
  the subject of all the persons experiences. It
  is simple and indivisible. And it is present
  throughout the persons life (p. 57).

8
The Bundle Theory
The parade of mental items is all that
exists, as far as the mind is concerned (p.
57).
9
Split Brains and the Bundle Theory
10
Two Senses of Personhood over Time

• Qualitative
• Numerical

11
Two Theories of Personal Identity over Time

• Same-Body (Same-Brain)
• Same-Memory (Memory-Links)

12
The Same-Body Theory
X, who exists at an earlier time, and Y, who
exists at a later time, are the same person
(numerically) if and only if they have the same
body (p. 61).
13
Objections to the Same-Body Theory

• The Prince and the Cobbler thought experiment
• Variations involving gender, age, species, etc.
• The Ship of Theseus thought experiment

14
The Same-Brain Theory

• X, who exists at an earlier time, and Y, who
  exists at a later time, are the same person
  (numerically) if and only if they have the same
  brain (p. 63).

15
The Memory Theory
X, who lived at an earlier time, is the same
person (numerically) as Y, who lives at a later
time, if and only if Y can remember doing what
X did, feeling what X felt, thinking what X
thought, and so on (p. 60).
16
An Objection to the Memory Theory

• Forgetting and amnesia

17
The Memory-Links Theory

• X, who lived at an earlier time, is the same
  person (numerically) as Y, who lives at a later
  time, if and only if a chain of memories links X
  and Y (p. 60)

18
Memory and Responsibility
19
Another Objection to the Memory (and
Memory-Links) Theory

• Apparent vs. real memories