Readings

• [Required] Jackson, Frank (1982) "Epiphenomenal Qualia" in Philosophical Quarterly 32, pp. 127-36. Also HERE.
• [Required] Tye (forthcoming) "Knowing What It Is Like: the Ability Hypothesis and the Knowledge Argument"
• Tye (1999) "Phenomenal Consciousness: the Explanatory Gap as Cognitive Illusion" Mind 108, pp. 705-725.
• James Pryor's notes (see the section on Jackson's argument): HERE.
• Churchland P. (1985) "Reduction, qualia, and the direct introspection of brain states" Journal of Philosophy 82, pp.8-28.
• Van Gulick (1993) "Understanding the phenomenal mind : are we all just armadillos?" in Davies and Humphreys Consciousness : Psychological and Philosophical Essays Blackwell.

Jackson's knowledge argument

• Fred is supposed to be able see two different shades of red when we can only see one.
• Mary the scientist has only seen black and white. But she is supposed to know all the physical facts there are. She is supposed not to know what it is like for others to see colours.

1. While still in the room, Mary knows all the physical facts there are about other people and their experiences.
2. When Mary leaves the room and sees something red for the first time, she acquires new knowledge about the experiences of other people.
3. So when she was still in the room, there was some fact about other people's experiences that Mary did not know.
4. This new fact about other people's experiences that Mary was ignorant of was not captured by the physical information about those other people. It is a non-physical fact.

Discussion and replies

Against 1

• The argument assumes that all physical facts can be learnt in the black-and-white environment.

Against 2

• The claim that Mary does not know everything there is to know about the colour experiences of other people is an intuition that has no justification.
• It is hard to imagine what it is like to really know all the physical facts about other people's experiences. It is just as sensible to say that Mary would not learn anything new. (Dennett)

Against 3

• (Lewis) Agree : Knowing what an experience is like requires having had the experience. Physical knowledge is not enough to give you the experience.
• Disagree : Coming to know what an experience is like is not a matter of learning new information, or learning a new fact.
• Justification : Acquiring information, including non-physical information, is not enough to enable Mary to know what it is like to see red.
• Proposal : Knowing what an experience is like is knowing-how - having the ability to imagine, remember, recognize the experience.
• Implication : Although Mary learns something new, she acquires new abilities but not any new information.

Against 4

• Mary does learn a new fact, but it is just an old fact under a new "mode of presentation". There are no non-physical objects or properties involved. (Churchland)
• The H₂O analogy : One can know that rivers contain water without knowing that rivers contain (liquid) H₂O. Under a fine-grained notion of fact, the fact that rivers contain water is distinct from the fact that rivers contain H₂O. So knowing a new fact does not imply knowing about some new object or property.
• Problem with the H₂O analogy - to know that rivers contain water but not that rivers contain H₂O is to lack certain physical knowledge, e.g. water molecules are constituted by hydrogen and oxygen. If one knows everything physical there is to know about water, one would know that water is H₂O.
• But the analogy shows that even though fact X &ne fact Y, X and Y need not be about different objects or properties. So even if Mary does learn something new, it does not follow that what she learns is about something that is not physical.
• But to make this more plausible, we should come up with an explanation of the differences between these two facts.

Further issues to think about

• What do we mean by "physical"?