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Tuesday, March 17, 2009

Phenomenal Knowledge and The Knowledge Argument

This is the latest in my email correspondence with Professor Torin Alter, who specializes in the philosophy of mind.

Dear Torin,

I'm not going to respond to all of the issues raised in our previous exchanges. I would, for example, like to discuss the issue of operational definitions and your discomfort with my a priori approach to physicalism. But I'll put those topics off for a possible future time. For now, I've decided to construct a new argument about phenomenal knowledge which may help clear a path towards mutual understanding.

I checked out your paper, “Phenomenal Knowledge Without Experience,” as you suggested, and I would like to begin by quoting its opening sentences: “Phenomenal knowledge usually comes from experience. For example, I know what it’s like to see red because I have done so.”

The meaning of the phrase "phenomenal knowledge" is not obvious, which may be one reason why so many papers are written about it. One thing seems clear enough to me: An experience of red does not automatically translate to knowledge about that experience. (We can imagine countless scenarios in which we experience something and later alter our interpretation of that experience, and we can imagine countless scenarios in which our experiences never produce anything we would call "knowledge.") The question is, how do you get from experiencing red to knowing what it is like to see red? Mustn’t you first know that you have seen red?

If phenomenal knowledge (“P”) is about some experience (“X”), we must have some experiences (“Y”) which allow us to regard X as such. X is not sufficient for P, whether or not it is necessary for P. (From your paper, I take it that you are not convinced that X is necessary for P; however, this point does not seem relevant to my concern here.)

What are the conditions for Y here? In other words, what can ground P?

Y cannot be evidence of X, because then we would require some other experience (“Z”) to ground our knowledge of Y. Y must provide a ground for P in some other way, or else we would find ourselves with an infinite regress. Indeed, Y is not supposed to be a justification for ordinary knowledge; rather, Y is supposed to ground "phenomenal knowledge." It would seem the distinction between ordinary knowledge and phenomenal knowledge hinges on the nature of Y.

Consider the case of Mary again. When Mary leaves her black-and-white room, Mary's experiences of color vision do not automatically and immediately translate to phenomenal knowledge. She can see red without knowing that she has seen red. It might even take some time before she can clearly distinguish between various shades of different colors.

At what point does she say, “now I know what it is like to see red?” It must be some time after she has seen red, and after she has learned from some other experience that she had seen red. That is, she needs a Y-experience, and this must involve language. She needs to learn how to use the names of colors in a new way.

Mary could look at a book with colors and their names. Or she could be told the name of the colors. The point is, learning what it is like to see red amounts to learning how to use the word “red” to name various objects of experience. So, when she says, “now I know what it is like to see red,” she means, “now I can use the word 'red' to name objects of my experience.”

Of course, she has new experiences here. She experiences red directly, no longer limited by her monochromatic room. But this does not mean she has learned any facts about color vision.

To see this, imagine a different set of Y-experiences which ground Mary's phenomenal knowledge. Instead of looking up colors in a book or talking to people, Mary has a small device which reads wavelengths of light. (Mary could have been taught to use [or even build] this machine inside her black-and-white room.) Since Mary remembers everything she learned about color vision in her black-and-white room, she will remember how to translate the data from her machine into words, such as “red,” “green,” and “blue.” Thus, she can ground her phenomenal knowledge of color vision by associating her visual experience of color with the data from her machine.

Interestingly, while Mary could ground her phenomenal knowledge in this way, she could also use the machine without grounding any phenomenal knowledge at all. She could use the machine to identify specific colors, relying on her knowledge of wavelengths, but without bothering to notice any correspondence between the machine’s data and her visual experience of color. She could thus name colorful objects using the words “red” and “blue” as any normal person would (perhaps even with greater consistency), but only in response to the machine’s outputs. She does not have to use the machine to learn how to say such things as, “now I know what it is like to see red.”

We can imagine Mary never knowing what it is like to see red, even while accurately reporting instances of redness with her wavelength-detecting device, even though she has color experiences which she would be justified in calling "red," if she were so inclined to learn the rules of the language.

The point here is to emphasize that Mary’s visual experience of colors does not translate into phenomenal knowledge of color vision (if "phenomenal knowledge" is taken to be whatever leads a person to say, "now I know what it is like to see X"), nor does it improve her ability to understand color vision or make predictions about color vision.

Now, what happens if Mary does finally learn to associate her visual experiences with the names of colors? She will learn how to refer to colors without her machine. In this case, she will have learned a new skill: how to refer to the colors of objects without any technological prosthetics; but her knowledge of color vision will not have expanded. She will be able to say, “now I know what it is like to see red,” but that only means that now she does not need a prosthetic color detector to indicate redness. She can do it on her own.

I am tempted to conclude that phenomenal knowledge is the ability to name objects of experience in accordance with the rules of a language. And what Y-experience can ground this ability? It must be the experience of learning a language. More specifically, it is the experience of naming objects of experience.

In sum . . .

There is a parallel here between this scenario and the Lonesome Mary/Mary System scenario I described earlier, though I hadn't until now emphasized the importance of language in this thought experiment.

Everything Mary needs to gain phenomenal knowledge is available to her in the black-and-white room. When she gets out of the room, she gains phenomenal knowledge (whatever is implied by the claim that “I know what it is like to experience X”), but only when she learns how to name things on her own. She does not learn any new facts about what she is naming, nor does she learn any new names.

And we should not fall into the trap of saying that she does learn a new fact about color vision, like the fact that "seeing red is just like this," because what is expressed here is only the fact that Mary has learned to name something "red." That is not a fact about color vision, but a fact about her ability to use the language.

Mary cannot speak any more intelligently or knowledgably about color vision than she had previously been able to do. She therefore does not improve her understanding of color vision, and there is no sense in which she gains propositional knowledge (information) about color vision.

There is no sense in which any information about color vision was not discursively learnable here. If anything is not discursively learnable in Mary’s situation, it is the mechanisms which make language-learning possible. Such mechanisms do not constitute information (propositional knowledge) about color vision, but are those aspects of an organism which make propositional knowledge possible.

Thus, the case of Mary offers no grounds for claiming that scientific (physicalistic) descriptions of color vision are bound to leave out any information which is known to people who have color vision. The most we can say is that such descriptions do not automatically provide a person with phenomenal knowledge, because to gain phenomenal knowledge a person must make the effort to learn a particular use of the language. Phenomenal knowledge of colors is not information (propositional knowledge) about color vision at all. It is the ability to use discursively learnable information about color vision to refer to one’s own color vision.

I'm not sure how much of this new. I certainly hope you find it compelling. In any case, I look forward to your response.