On Philosophy

October 27, 2006

Materialism And Qualia

Filed under: Mind — Peter @ 12:55 am

Materialism has made a great deal of progress in explaining the mind in terms of a completely physical process happening in the brain. The first person perspective, intending, representing, these were once all considered things that were unexplainable by materialism, but over time philosophers have shown how these aspects of the mind can be explained be purely physical events (although obviously complete descriptions have to be left to neuroscientists). However, there still remains one major explanatory hurdle for materialism: qualia. I am not one of the philosophers who think that qualia prove that the mind can’t be explained in materialist terms, there are many good reasons to believe that the mind must have such an explanation. But I wouldn’t deny that qualia, and the explanatory gap, are a problem that materialism needs to address.

I don’t think qualia are an in surmountable problem, as some do, because it seems like an open question whether a particular qualia are really some brain process (by open question I mean that it seems rational to ask how or why it is that brain process). All open questions show is that we are ignorant about some of the necessary details, making the truth of the identity seem obscure. For example, our ancestors may have thought that the identification of water with H2O was an open question (is water “really” H2O?), especially since water seems to have properties, such as infinite divisibility, that H2O does not. But eventually such skepticism about identity claims tends to disappear, especially when it can be shown that H2O really can play the role of “water” (it has all the same objective properties, although obviously not the same subjective properties, since at the very least they have different names).

Thus the fact that identifying qualia with some brain process feels like an open question really reveals that we simply haven’t shown that some brain process can play the same role as qualia, not that they are necessarily distinct.* And trying to remedy this problem illuminates some of the real problems that make qualia so hard to address under materialism. Simply attempting to define what a qualia is can be a serious problem. We can roughly describe a qualia as experience as given to us. For example “redness” is a kind of qualia. But this doesn’t actually pin down what qualia are, at least not enough to be able to say if something definitely is a qualia or not, it is simply suggestive. Imagine attempting to define “redness” to someone who has never seen red (without simply avoiding the question by saying “a kind of qualia” or “a kind of sensation”). The only way to convey what “redness” is seems to be by pointing out things that evoke the sensation of “redness” (the color or roses, ect). Or if we are more poetical we might attempt to describe how “redness” makes us feel in terms of associated sensations (it feels “angry” or “dangerous”).

But, if that is the role that the physical process must play, then there seems to be no problem in capturing it in materialist terms. What a specific qualia, like redness, could be, physically, is a combination of two things. One is a specific kind of visual input. We can conceive of the visual input, which is integrated into experience as visual sensation, as an array of numbers (as what is happening physically, not as how it is presented to us; it is presented to us as just a certain color, different from other colors). Redness then would be a distinct number. Additionally this number is combined with associations**, both of other objects that have evoked this particular visual input, and possibly with memories, feelings, ect that the mind has linked to this input for some reason. Many of these associations are unconscious (or at least at the periphery of awareness), but we can assume that when focusing on the specific sensation they are more likely to be brought to our attention. We can assume that thinking about red, instead of experiencing it, is simply a process of imagining red, in which the usual visual input in now being generated by imagination instead of perception. This physical process can play the same role of “redness” as described above. Redness, being some particular kind of visual input, is naturally the kind of thing you can’t explain in words directly, since it is part of your neural activity, and not something that can described directly. Instead we must appeal to the associations, which are generally publicly accessible objects, and by using labels such as “red”, which are really just shorthand for these associations.

Given this definition can we address the problem of Mary the color scientist? (See here for my description of the problem.) I think we can, because part of what defines individual the qualia are a specific kind of sensory input. Even if Mary learns what specific neurons and firing patterns are involved in this qualia she doesn’t possess the concept of red as we do, because when we think of red we generate red in our imaginations (simulating the experience of seeing red). But even learning what “redness” is doesn’t enable Mary to make the right patterns of neurons fire (the neurons that are the “red” visual input); that is just not an ability we have, to go from a description of the way the mind works to making our minds work in that way. So Mary “learns” something new about red when she first sees red, because now she is able to think about it in the same way we are, by imagining it. But she hasn’t learned anything new about the qualia of redness, she has simply acquired a new way of thinking about it.

So does the account given here really explain qualia? I am willing to entertain the possibility that there is something more that qualia do for us, some additional role they play in the mind that is not captured by the description that I have given here. The problem is identifying what that role is, so that we can determine what physical descriptions could play that same role (or if they could play the same role). And to be honest with you I simply can’t see what qualia are supposed to be beyond the description that I have given here. This is not to say that I am unaware of other descriptions of qualia, just that they are so vague that they don’t really inform us as to what properties something must have to be a qualia, and thus of little help in determining whether some physical process really is a qualia.

* Defining what role a specific concept plays is often essential to determining what it is exactly. For example, meaning, knowledge, ect.

** I have discussed in other places how our experience is saturated with concepts, when we see a tree we don’t see simply a visual impression, we see a visual impression as a tree, and this “seeing as” is part of the experience, not something we add to it by reflecting or thinking about it. These associations then should be simply treated as another example of this conceptual saturation.



  1. I did a series of posts which argued the same thing, but the reason why it turned into a series rather than a single post was that Clark and Richard kept giving me some really good objections which I was forced to meet. Here are two problems which I see with your post:

    1) If material substances and properties are all publicly available for inspection, then how can a radically subjective and private properties every be fully explained in terms of such? (I take this to point toward a mild form of property dualism.)

    2) Once Mary is released from her colorless world, if she is immediately confronted with a green and red square, would she be able to pick out the red square with confidence? If not, it seems that she would in fact learn something new, something propositional, upon experiencing and identifying red for herself.

    Comment by Jeff G — October 27, 2006 @ 8:31 am

  2. 1) I don’t see the problem of access requiring any kind of dualism. It’s just a fact that our experiences contain different information. Perhaps one day such “private” information could be made public with the right technology, thus I see no fundamental divide, just a divide in the way we currently experience them.

    2) I see this as misleading the reader. Yes she would learn how to have two new concepts. No, she might not know which was which originally. But this is because learning about the qualia red and green haven’t given her the concepts red and green. And without someone informing her as to which was which she wouldn’t be able to tell upon experiencing red that it wasn’t green (assuming they were color patches) means that the knowlegde as to which is which is something that is given by associations, either with objects or with people labeling them, and not something in experience. Thus the physical account has completely explained qulia, as experianced, but not provided the cognitive associations, which is not something we expect it to do.

    Comment by Peter — October 27, 2006 @ 10:16 am

  3. I don’t think I understand your responses at all.

    1) Property dualism does not posit any kind of “mind-stuff” out in the world. Indeed, it is a form of naturalism, maybe even materialism if loosely defined. All property dualism suggests is that there are some properties of material substances which are private and subjective in the sense that they are no observable from any third-person perspective.

    This is what Qualia are, right? Yes, it is a case of different people having different information and some information is simply not available from any but the first person perspective. I have no idea how qualia could ever become public except by way of our first person experiencing of publicly available information. But this isn’t the sharing of the same qualia, but rather is production of what we assume to be the same qualia in two people. The point is, that we could never know whether we are actually sharing qualia or not, since qualia are intrinsically private and subjective.

    2) “But this is because learning about the qualia red and green haven’t given her the concepts red and green.”

    But this is exactly the point in question, for while she has learned a lot about the perception of green and red, she has learned (prior to release) absolutely nothing about about red and green qualia at all. It is precisely for this reason that she would not be able to identify which color was which.

    “She hasn’t learned anything new about the qualia of redness, she has simply acquired a new way of thinking about it.”

    This is the very point at which Jackson would protest, for the reasons I already mentioned. (Of course he is an epiphenomenalist while I certainly am not.)

    Comment by Jeff G — October 27, 2006 @ 4:04 pm

  4. 1) No, property dualism is the belief that there are mental properties that are not realized by physical properties / reducible to physical properties, they are fundamental in their own right. This is not naturalism/materialism in the least. Fundamentally it has nothing to do with access, access can be explained materially. Privacy is not what defines qualia, although it is an aspect of them. All mental activity is in some sense private, but it it isn’t all qualia, and most if it is considered to be unproblematic to explain materially, even though it is “private”.

    2) You are still confusing the concepts with the qualia. I say she knows all about the qualia, the concepts aren’t giving her more information about qualia / experience, they are simply giving her a new way to conceptualize some input. But qualia aren’t the input, they aren’t about the world, they are a label for an aspect of experience. Learning to use the concepts red and green is learning about the world, about how other people label their experiences. Mary already knew from her physical studies that color patches of different colors would feel different, and that is all she can tell from seeing two different color patches for the first time. She is not learning about her own experience. Of course some would object that she is learning the way it feels, but I have already addressed that, it is just a new way of conceptualizing experience. And if we aren’t learning about our own experiances then we can claim that we have already explained the nature of experiance and qualia. And we have no problem explaining concepts materially.

    Example: even if you know all about baseball from reading about it you still learn something new when you first play baseball. But that something new isn’t about baseball. Likewise when you first experiance a qualia you learn something new, but that something new isn’t about the qualia.

    Also a sub-note: Jackson is a materialist, you should read his more recent work, he changed his mind.

    Comment by Peter — October 27, 2006 @ 4:26 pm

  5. I was mostly agreeing with this until, “But she hasn’t learned anything new about the qualia of redness, she has simply acquired a new way of thinking about it.”

    She clearly has learned something new: What it “feels like” when the nerve cells associated with red fire. Before her study, all she knew is that the cells do fire in red experiences. Now, she has experienced those cells firing. To say that this just a new way of thinking about it is to ignore the whole problem of qualia, namely what does it mean for these cells firing to “feel like” anything all?

    Comment by Carl — October 28, 2006 @ 4:02 am

  6. see next posst

    Comment by Peter — October 28, 2006 @ 11:50 am

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