Blindsight,%20Zombies%20

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Blindsight, Zombies ConsciousnessJim
FaheyDepartment of Cognitive ScienceRensselaer
Polytechnic Institute10/4/2007

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Materialism and the Mind

• Standard Materialist View
• The Mind is NOTHING BUT the Brain and its
  workings.

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Problems for the Materialist

• Raw Feels - pain, love, boredom
• Perceptual States - what you see when you look
  in the mirror in the morning
• Intentional States - beliefs, wants, hopes

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Problems for the Materialist (cont.)

• Regarding Raw Feels How can my feeling of love
  be nothing but neurons firing?
• Isnt it possible for me to coherently conceive
  that my neurons might fire in a
  pain-like-pattern and yet I feel no pain?

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Problems for the Materialist (cont)

• Regarding Perceptual States How can my
  perception of myself in the mirror be nothing
  but neurons firing?
• Isnt it possible for me to coherently conceive
  that my neurons might fire in a
  seeing-self-in-mirror way and yet I have no
  perception?

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Problems for the Materialist (cont)

• Regarding Intentional States How can my hope
  that You have all started working on your final
  projects, be nothing but neurons firing?
• Isnt it possible for me to coherently conceive
  that my neurons might fire in a
  hope-against-procrastination way and yet I have
  no hope?

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Problems for the Materialist (cont) The Zombie
Possibility

• More generally, consider the possibility of
  Zombies
• Zombies are like me in that they have brains and
  the neurons of those brains
• Fire in pain-like-patterns
• Fire in seeing-self-in-mirror patterns
• Fire in hope-against-procrastination patterns

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What Zombies Lack

• But while Zombies have brains that are
  neuron-for-neuron identical to ours, Zombies
• FEEL no pain
• SEE nothing
• Have no HOPE

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Standard Materialist Responses to Zombie
Arguments

• Reductive Materialist Response
• It is appropriate to say that pains, seeings and
  hopes are nothing but neurons firing. We may
  not understand at present how to carry out the
  reduction of mental goings-on to neuronal
  activity but someday we will.
• Conclusion Zombies are impossible, since same
  physical stuff/structure guarantees same mental
  state.

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Standard Materialist Responses to Zombie
Arguments (cont.)

• Eliminative Materialist Response
• It is NOT appropriate to say that our
  folk-psychological notions of pains, seeings
  and hopes are nothing but neurons firing.
• Conclusion We DONT HAVE pains, seeings and
  hopes in the folk-psychological sense and thus
  we ARE the ZOMBIES to which the proponents of
  folk-psychology refer!

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Nicholas Humphreys Darwinian Tale (in his A
History of the Mind)

• Nicholas Humphrey offers a sketch of a possible
  history of the mind that he believes is well
  supported by contemporary evolutionary theory.
• The key to Humphreys account is the distinction
  between the mind as an instrument that reveals
  what is happening to me and the mind as an
  instrument that reveals what is happening out
  there (typically, outside of me).

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Sensation

• Humphrey argues that evolutionary theory supports
  the view that early mind was the progenitor of
  what he calls sensation.
• Consider a patch of sunlight falling on the skin
  of an amoeba-like animal. The light has
  immediate implications for the animals own state
  of bodily health, and for that reason it gets
  represented as a subjective sensation (p. 43)

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Sensation (cont.)

• The surface of the amoeba undergoes a causal
  interaction with the sunlight that falls on it.
  As a result of this impression, the amoeba
  wiggles and thus avoids the sun.
• Humphrey believes that at some point in the
  evolving history of life on earth, counterparts
  of such impression-wiggle reactions become
  full-fledged sensations, sensations that count as
  raw feelings of experience of the inner states of
  the organisms which are soon followed by
  associated behaviors (eg. movements away from the
  light).

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Perception

• Later in evolutionary history we find a very
  different kind of information process that
  develops in more advanced animals. Again,
  speaking of the amoeba-like animal, Humphrey
  says,
• But the light also signifies as we now know
  an objective physical fact, namely the existence
  of the sun. And, although the existence of the
  sun might not matter much to an amoeba, there are
  other animals and other areas of the physical
  world where the ability to take account of what
  exists out there beyond my body could be of
  paramount survival value (p. 43).

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Perception (cont.)

• Humphrey argues that this ability on the part of
  animals was not merely a development of the
  animal capacity for sensation but rather it was
  the development of an entirely new capacity, that
  of perception.

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Two Track ModelSensation Perception
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Humphreys Arguments for theTwo Track Model

• Why hold that perception is a new capacity? Why
  not hold instead that perception grows out of and
  depends on sensation?
• Humphrey begins by arguing that we can
  introspectively separate the feeling aspectsor
  sensations of vision from the perception aspects.

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Humphreys View Amended

• But Humphrey does not mean to suggest that
  sensation necessarily involves any kind of what
  we would call reasoning. Rather, sensations
  are feelings that baldly occur. It is only
  much later in the evolutionary process that
  sensations become bound up with reasoning
  about what exists and we get intentional states
  of a robust sort.

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Milners Goodales Model
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Amended Two Track Model
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Amended Two Track Model Plus
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The Phenomenon of Blindsight

• If the two track model is correct, we might
  expect that damage to one of the tracks that
  leaves the other intact might yield kinds of
  mental states that are atypical.
• Such is the Phenomenon of Blindsight ...

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Blindsight (cont.)

• What is blindsight? Lawrence Weiskrantz, the
  originator of the term says in his recent
  Consciousness Lost and Found (1997) that it is
  the loss of phenomenal seeing in the
  contra-lateral half of the visual field caused by
  damage to the primary visual cortex, but with
  residual capacity still present. What does this
  come to?

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Blindsight (cont.)

• See Humphrey (p. 88)

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Blindsight (cont.)

• The following video, Nova Secrets of the Mind,
  features neuropsychologistV. S. Ramachandran
• Questions you should consider concerning what
  follows1. What is consciousness? What role
  does it play in our mental life?2. Do the
  various psychological syndromes depicted show
  substance dualism to be false? Why or why not?