Personal Identity

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Personal Identity
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Cognitive Science and Personal Identity

• Imagine building a robot duplicate which thinks.
  It confronts you and you try to convince the
  duplicate that it isnt you. How would you do
  that?
• Persons arent static, momentary entities. They
  endure. So what are their identity conditions?
• Turing was interested in whether machines could
  think. Whether machines can be persons may be a
  distinct question.

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Self at a time vs. Self over time

• What is self at a time?
• unity of consciousness How are all these mental
  states mental states of one thing?
• What is a self over time?
• How are beliefs had one year ago my beliefs?

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Identification vs. Identity

• A criterion for identifying the same person over
  time isnt necessarily a theory of identity over
  time.
• How do you identify persons at conventions?
• By nametags

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Analyses of Personal Identity

• Find necessary (N) and sufficient (S)
  conditions
• Necessary conditions conditions which must be
  fullfilled for identity over time.(If A is the
  same over time, then N)
• Sufficient conditions conditions, which if
  fulfilled, mean that something is identical over
  time. (If S, then A is the same over time.)

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Candidate Conditions

• Well look at the following
• The body
• The soul
• The core body (the brain)
• Continuity of personality
• Memory
• Causal connectedness

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The (shell) Body

• Is it necessary?
• Brain transplants Would you want to be the donor
  or the recipient?
• Sufficient?
• Is a corpse a person?

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The Soul

• Is it necessary?
• What is a soul? How do you know you have the same
  soul over time? (Identity of the soul is more
  mysterious than identity of the person.)
• Is it sufficient?
• Maybe, if we knew what a soul is.

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The Core Body

• Necessary?
• Could you survive as you with an artificial
  brain?
• Sufficient?
• A corpse has a brain too.

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Continuity of Personality

• Necessary?
• Do you have the same personality you had as a
  four year old?
• Sufficient?
• Suppose we built a duplicate of you with your
  personality. Would it be you?

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Memory

• Necessary?
• Suppose you lost your long term memory. Would you
  cease to be the same person?
• Sufficient?
• Could a duplicate have your memories?

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Causal Connectedness

• Necessary
• A future stage of you has to have the right
  causal connection to earlier stages of your self.
• But there are fusion problems.
• Sufficient
• Fission problems

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Where am I?

• Dennett Brain inside body

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First Alteration

• Brain (Yorick) placed in a vat
• Neural connections stretched via radio signals.
  
• Body is named Hamlet.
• Where is Dennett?

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Second Alteration

• Radio contact with Hamlet is lost.
• Where is Dennett?

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Third Alteration

• New body introduced Fortinbras.
• Is this still Dennett? Is he the same person?
• If so, then it shows that sameness of shell body
  is not necessary for personal identity.

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Fourth Alteration

• Tandem brain, Hubert has be in existence since
  the brain was placed in a vat.
• Control can switch from Yorick to Hubert and
  back.
• When Hubert controls Fortinbras? Is it still
  Dennett?

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Final Alteration

• Yorick and Hubert get out of synch.
• This is a case of fission.
• Which one (if any) is Dennett?