Qualia

Psy391D - Class 4

(This page last updated 21 September, 2004.)

Supplemental Reading The textbook summarizes an article by the philosopher Thomas Nagel entitled "What is it Like to be a Bat?" It is Chapter 24 of the Hofstadter & Dennett book on reserve in the library. You can skip the footnotes, but it is worth reading the Reflections by Hofstadter at the end. You might also be interested in reading an excerpt from Dennett's book Consciousness Explained, pp. 398-406. It is a section entitled "Epiphenomenal" Qualia?

At this point, we have thoroughly surveyed the different solutions that have been proposed to the mind-body problem. Now we will consider those things that are hardest to explain in a materialist theory: Qualia and the nature of our experience.

Nagel: What is it Like to be a Bat?

Here you will see the term physicalism used as a synonym for materialism.

Nagel's message: We cannot ignore our subjective experience, as some materialists do. He defines subjective experience as "what is is like to be", and explores what it will take to be able to understand it. However, it is difficult to see how we can explain our experience in a materialist framework, because we cannot put our subjective experience into the objective terms required by science.

Possible materialist reply: How can you expect to explain something when you cannot describe it? What makes you think subjective experience actually exists?

Mary the Color Scientist

We will also discuss Frank Jackson's argument for qualia based on Mary the color scientist. If you like, you can read Dennett's comments on this argument on pp. 398-406 of his book Consciousness Explained. Dennett believes that qualia are not a problem for a materialist theory of mind, and in this excerpt he explains why Jackson's argument does not convince him.

On p. 401 Dennett refers to Julius and Ethel Rosenberg's Jell-O box. This is a method used by one spy to detect another spy. A piece of a cardbox is torn into two pieces, and each piece is delivered to one of the spies. When they meet, they can put the two together to see if they match. The tear produces two edges with so much information that they are virtually impossible to duplicate.

The argument about Mary the color scientist leads Dennett into a consideration of epiphenomalism. If epiphenomenalism is true, it raises the possibility of zombies: people who behave just like you and me but have no consciousness. As you will see, Dennett thinks that the idea of zombies, and of epiphenomenalism in general, is silly.

Zombies

• Is it possible for someone to act like a human without experiencing what it is like to be a person?
• How would you distinguish a zombie from a person with conscious experience?
• Is there any aspect of our behavior that requires conscious experience?

Behavior Without Awareness

A number of experiments have demonstrated that information can sometimes control behavior without our being aware of it. One clear example comes from patient D.F.

• Brain damage in areas V2, V3, and V4, or "WHAT" pathway
• Unable to recognize objects visually
• Dissociation between perceptual awareness and visuomotor control.
  • Cannot explicitly report orientation of slot, but can orient card to fit through it.
  • Cannot report width of block, but can position fingers to pick it up.
  • Cannot distinguish shapes, but can position figures near center to pick up.
• Visuomotor coordination working without her awareness.

There is additional evidence for a dissociation between awareness and visuomotor control in Blackmore's book. Taken together, these studies demonstrate that we are not always aware of all aspects of our behavior.

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Psych 391D: Consciousness Kyle Cave Psychology Dept. U. Mass.