Section 4.3 You Can’t Step into the Same River Twice Self as Process McGraw-Hill © 2013 McGraw-Hill Companies. All Rights Reserved.

4.3-2 Thought Experiment: Shoemaker’s Brain Transplant  Suppose that it’s possible to perform brain transplants.  Suppose further that the brains of Brown and Robinson are switched so that Brown’s brain is in Robinson’s body and vice versa.  Wouldn’t the body with Brown’s brain be Brown?

4.3-3 The Brain Theory  Identical persons are those who are psychologically continuous with one another and whose psychology is caused by and realized in the same brain.

4.3-4 Thought Probe: Body Transplants  Suppose that one day it becomes technically possible to transplant a brain from one body to another.  Do you believe that your identity will go where your brain goes? Why or why not?

4.3-5 Split Brains  In patients who have undergone “split-brain surgery,” there seems to be two centers of consciousness; “two wills in one cranial vault.”  So perhaps just as our entire body in not essential to us, neither is our entire brain.

4.3-6 Thought Probe: Who Is Behind the Hand?  In the case of alien hand syndrome, one hand “seems to perform meaningful acts without being guided by the patient.”  Could the agent behind an alien hand be a person? How could we tell?

4.3-7 Thought Experiment: Parfit’s Division  Suppose that Parfit’s brain hemispheres have the same psychology and that Parfit is one of three identical triplets.  Now suppose that his body is injured as well as the brains of his two identical brothers and that each half of his brain is transplanted into the body of one of his brothers.  Which of the brothers is Parfit?

4.3-8 Closest Continuer Theories  Personal identity cannot consist in psychological or physical continuity because identity is a relation that can hold only between a thing and itself.  To avoid the reduplication problem, it seems that a theory of personal identity must either rule out any sort of splitting, or it must have some means of determining which branch is identical to the original.

4.3-9 Non-branching Theory  Identical persons are those who are psychologically continuous with one another and whose causal connection has not branched.  In this view, neither of the surviving triplets would be Parfit.

Closest Continuer Theory  Identical persons are those who are closest continuers of one another.  In this view, neither of the surviving triplets would be identical to Parfit because they are both equally close.

The Only X and Y Principle  Whether one thing, x, is identical to another thing, y, can depend only on facts about x and y.  Both the non-branching theory and the closest continuer theory reject this principle.

Thought Probe: Branch Lines  Should we reject the only x and y principle?  If someone were to murder one of the two surviving triplets, the closest continuer theory would have us believe that the lone surviving triplet is now identical to Parfit.  Is that plausible?

Identity and What Matters in Survival  In order to survive the death of our bodies, must we be numerically identical to someone who exists after our body dies?  According to Parfit, all that is needed for survival is psychological continuity.

Identity and What Matters in Responsibility  In order to be held responsible for performing an action, must we be numerically identical to the person who performed it?  According to Parfit, all that is needed for responsibility is psychological continuity.

Thought Experiment: Parfit’s Reformed Nobelist  “Suppose that a man aged ninety, one of the few rightful holders of the Nobel Peace Prize, confesses that it was he who, at the age of twenty, injured a policeman in a drunken brawl.”  Should we now punish him for that crime?

Explaining the Self  Why have we been unable to find a set of necessary and sufficient conditions for personal identity?  Perhaps the best explanation is that the self is not a thing but a process.

Thought Probe: Robert and Frank  Suppose that a criminal named Frank changes his name to Robert and changes his personality, beliefs, attitudes and desires.  Should Robert be punished for what Frank did?

Moral Agents and Persons  Only those persons who have the concepts of rights and wrong can be held responsible for what they do.  These people are known as “moral agents.”  For example, the very young, the mentally incapacitated, and the insane may not be moral agents.

Narratives and Personhood  Psychological narrativity thesis: human beings experience their lives as a narrative.  Ethical narrativity thesis: experiencing one’s life as a narrative is necessary for living a good life.  Strawson’s objection: the process of recalling a memory and placing it in a narrative changes it, and living a lie is not a good thing.  Christman’s objection: A unified life doesn’t require a consistent narrative, just self-reflection that yields a consistent character.

Thought Probe: Being Clive Warring  Clive Warring is unable to form new memories or access old ones.  But his intelligence, character, musical talent, love for his wife, and so on all remain constant.  Is there one continuous person living in Clive Waring’s body, or does his body house a succession of persons, each of which exists for only a few minutes?