Tuesday, April 27, 2010

What does Mary learn when she sees red?

In Frank Jackson's famous argument, Mary has grown up without ever seeing anything red or reddish, but she has learned complete and correct scientific accounts of the world, including of optical and perceptual phenomena. One day, Mary sees a red tomato. In so doing, she finds out something: she finds out what it was like for other people who were seeing red all along. But she knew all the science of subjective experience, but without seeing red (or having an apparent memory of seeing red?) she couldn't know this, so there must be a scientifically inaccessible component to subjective experience that she learned.

I think the argument may well fail. Start with an argument that even before she sees a tomato, Mary could have known what it is like for other people to see red, simply by having enough naturalistically accessible information about her future. For she could know that at t1 she would see a tomato, that a tomato is red, and that there is a common core to people's experiences of red. Thus, she could know that:

  1. Other people's experiences of red are like that experience.

Now, you might object: But that's not what it is to know what it is like to see red. But this isn't clear. Suppose she is now seeing a tomato. Then what does she know? What she knows is simply:

  1. Other people's experiences of red are like this experience.

But observe that there is reason to think that (1) and (2) express the same proposition. When the sunset is present, I would say I know:

  1. This is a sunset
but afterwards I would say:
  1. That was a sunset.
If (3) and (4) express different propositions, then our ability to engage in diachronic conversations is endangered: the propositions communicated can no longer be grasped, it seems.

If this is right, we have good reason to think (1) and (2) express the same proposition. But perhaps you dispute this (I am not sure of it myself). Maybe the different ways that a present-tense "this" and a non-present-tense "that" point give rise to different proposition. If so, then it may very well be the case that before she sees the tomato, Mary cannot know (2). But a this/that difference does not challenge materialism. After all, we all think materialism holds about the moon. But by exactly the same token as (1) and (2) express different propositions, so do:

  1. That is the crater Clavius
as spoken while looking from earth through a telescope, and:
  1. This is the crater Clavius
as spoken while sitting blindfolded in the middle of it. If (6) expresses a different proposition than (5), then when the astronomer is blindfolded and transported to Clavius, she has learned a new proposition. But she has not learned anything non-trivial, in the way that Mary's learning is supposed to be. Certainly, she has not gained any knowledge that would challenge the claim that the moon is physicalistically understandable.

Now, it could be that Mary's gain in knowledge is in some way deeper than that of the astronomer who is put blindfolded in Clavius. But that needs an argument. On its face, Mary has simply gained a new way to refer to her experience of red: beforehand, she would call it "that future experience", and when faced with it, she would call it "this present experience". And that does not seem enough to ground an argument against materialism, dearly as I love arguments against materialism.


hatsoff said...

Well, one of the problems with Mary's room is that it is often left much too vague. If we say that Mary has learned everything about organisms experiencing red short of experiencing red herself, then what exactly do we mean?

Suppose Mary knows so much about the brain that she can create a false memory of having seen red. If minds really are just features of brain structures, then certainly this is possible, since brains are physical machines which can be pushed and prodded like any other. If she creates such a false memory, then has she learned something new when she actually sees red for the first time?

Maybe we wish to prevent her from tinkering with her own brain, except through everyday learning experiences such as reading or thinking---and this is tantamount to a restriction on learning. But if we restrict her learning while in the room, then is it really any surprise that she learns something new when she finally exits that room?

Having such a memory seems to be the difference between "this experience" and "that experience." As long as she is referring to others' memories, she does not really know everything about the relationship between red light and organisms.

There are some other objections, too, which I think hold promise. For example, a human being cannot appreciate at once the full structure of a brain which has experienced red, and so she cannot really learn everything about such brains. Another possible objection is drawing a distinction between actual experiences and models of those experiences, where we insist that learning is the same as constructing such models. That is an idealist's objection, and perhaps the most promising of all.

Anyway, those are just some thoughts. I've gotta run.

Marc said...

Dr. Pruss:

I think I'd want to resist the proposal that (1) and (2) express the same proposition, or at least suggest that the materialist may require something more.

In those propositions, it seems that the word "like" is sufficiently flexible so as to represent both the "common core to people's experiences of red" as well as the phenomenal distinctiveness of each person's experience. Put differently, "like" allows for and captures difference. Upon experiencing red for the first time, Mary might announce, "Yes, my experience of red is indeed like that experience, but not exactly or even primarily like that." Mary also might report that the similarity between other people's experiences of red and her own experience of red doesn't extend beyond the fact that they and she were appeared to redly. (1) and (2) seem imprecise enough to express something quite similar, but not precise enough for materialism.

Propositions (3) and (4), however, seem considerably more precise. If they express the same proposition, the subject of experience and the object of experience are necessarily identical. Their diachronic integrity depends on this.

So, it may be the case that the "this/that difference" is innocuous with respect to materialism in some instances but deleterious in others. Perhaps (3) - (6) are an instance of the former, whereas (1) and (2) are an instance of the latter.