In any event, by "intuition pump" Dennett means a scenario or "thought experiment" which draws out implications of a philosophical (or even pre-philosopical) view and, for his polemical purpose, ultimately flushes out the illusions about qualia which persist among laymen and philosophers alike. The "experienced beer drinker" intuition pump concerns the change in taste people mention from their first sip of beer to their later days as beer connoisseurs. Dennett focuses on the ambiguity of the term "taste", since, if qualia are real, then either the intrinsic taste of beer alters over time or the drinker's phenomenal consciousness of that unchanging flavor changes over time. The upshot, in Dennett's argument, is that there is no reliable way to determine what changes take place in a drinker's taste for beer--that is, there is no empirical way to make factual claims about qualia (of beer or anything else)--and therefore qualia have no factual basis. If, for instance, beer retains its quale, but a drinker's memory of his reaction to the fluid over the years has altered, from "I disliked it at first" to "I love beer now," then the drinker has no basis, not even on introspective grounds, for knowing the quale of beer apart from his variable memories of it. As such, does beer really have a quale, or is it more of a bundle of remembered associations in our sensorimotor, functional repertoire? On the other hand, if the drinker's memories are reliable and the quale of beer has in fact changed over time, then, well, what of the intrinsic, supraphysical 'ineffable purity' of qualia?
I think Dennett's argument here--and I should mention that the beer-drinker scenario is but an instance of his central argument against qualia, which deals primarily with two Maxwell House Coffee taste-testers consciously suffering from a change in tastes--is really quite bad, for two reasons. First, who said there is only a single quale for "beer as such"? The central point about qualia is that they are subjective realities, not objective physical features of the world. The factors impinging on our response to "a sip of beer" (or tea or anything) are so complex that, in a sense, every sip is qualitatively unique, so that much of Dennett's argument we can grant without compromising a realist sense of qualia. Indeed, our memories of a previous jolly night with, say, Pabst Blue Ribbon (!) may bias our reaction to it on subsequent night… until we start to notice that "it just doesn't taste the same." These two distinct qualia, complicated and confused though they may be by 'intervening' memories, are still qualia in their own right. General mood, what we have previously eaten, those with whom we're communing, etc., considerably affect how things taste and feel. But precisely in this perceptual variability lies the subjective vitality of qualia as such. If qualia never altered at all, they would ipso facto be objective factors, but since they vary with every experience--indeed, they are the dynamic 'pulse' of experience itself--they are manifestly subjective realities, and therefore Dennett's argument against them actually tries to refute the qualia by complicating some qualia with other qualia (i.e. some phenomenal experiences of beer with other phenomenal experiences of beer). Qualia just are 'the way the world seems to an observer at a specific time in a specific state of affairs'. As such, citing their multiplicity and complexity––even in the conscious domain of a single observer over time––only underscores their nature as immediately perceived realities.
The problem is that Dennett wants to find empirical, scientific means by which to pinpoint and verify qualia, but that fallacy (viz. metabasis eis allo genos, or "category mistake") simply begs the question, since the debate hinges on whether empirical science can accomodate qualia, or if they are irreducibly subjective realities and thus indicators of the limitations of physical reduction. In this way, Dennett, like all scientismatics, is like a man asking for a metaphysical proof of how heavy his car is, or for a chromatic analysis of how his piano sounds, or for a molecular analysis of atoms, and so on. It doesn't matter whether my experience of Pabst Blue Ribbon is not verifiably the same at time t1 as my experience of it at time t2, since that of which I am phenomenally conscious at t2 is precisely that of which I am phenomenally conscious! Dennett wants to convince the reader, in his winsome but insidious way, "What you're feeling now, well, that's just a cognitive illusion." If so, the reader has every right to ask, "What do you mean by 'what I'm feeling right now'? If you say that my feeling of experience is a cognitive illusion then at the very least I have the feeling of this cognitive illusion." And that feeling is 'qualish' if nothing else. So, even apart from this methodological gaffe, Dennett is still invoking qualia in the very act of complexifying them, which leads me to my second objection to his line of reasoning as a self-professed "eliminative materialist."
As I discussed in an earlier post, the real strength of an argument like Frank Jackson's argument about Mary's new knowledge (hereafter AK) is that it exposes the entire edifice of phenomenal consciousness which undergirds debates in the philosophy of mind. As I wrote, "physicalist arguments against qualia are parasitic on consciousness as a given. ... Physicalists draw upon qualic consciousness all the time, even in their refutation of AK, since they already grant [Mary] has visual consciousness of black and white, light and dark, etc," as well as tactile and aural consciousness of the rest of her world. And to cite Howard Robinson again about Jackson's turn from KA to physicalism:
What the argument really brings out is that only experience of the appropriate kind can reveal the qualitative, as opposed to purely formal and structural, features of the world. The kind of thing that Mary did not know, generalized from color vision to all the other sensible qualities, is essential to any contentful conception of the world, and physicalism without it would lack any empirical content. (The Case for Qualia, MIT Press, p. 240)
Quite so. These two defects are manifest in Dennett's polemic against irreducibly phenomenal consciousness. First, as I noted above, he downplays the intrinsically subjective character of experience, taking it as proof against qualia that they are radically tailored to an agent's concrete situation. Second, though, and more fundamentally, Dennett shows the same unparsimonious bias against consciousness simpliciter in his argument against Jackson's KA. I perused the pertinent pages yesterday in Dennett's Consciousness Explained (pp. 398–401). The gist of his rebuttal of KA is that if, ex hypothesi, Mary truly had total knowledge of all physical facts about the world, rather than just "a whole lot more scientific knowledge than we can currently fathom," then she would not be surprised by what "seeing red" is like. Her perfect scientific knowledge of the world would allow her to predict, to extrapolate, just how it does feel to see a chromatic world.
As far as I can tell, Dennett does not use the following metaphor in this section of Consciousness Explained, but he uses it in "Quining Qualia," and it seems pertinent enough to add here. Dennett asks us to consider (as another intuition pump) his hearing an osprey cry for the first time. His ornithological reading informs him that the osprey cry will have such-and-such a pattern, such-and-such a pitch, perhaps even such-and-such an 'emotive' tone, and so on. Thus, Dennett at least has a good idea of what not to listen for. "The verbal description," he writes, "gives me a partial confinement of the logical space of possible bird cries" (p. 404). This is a reasonable analogy, but it fails for two reasons. This sounds reasonable, since, as he notes about Mary in Consciousness Explained,
By noting some salient and specific reaction[s] that her brain would have only for yellow or only for red[, Mary could figure out the neuorphysiological effects of specific colors ‘from the inside']. But if you allow her even a little entry into her color space in this way, you should conclude that she can leverage her way to complete advanced knowledge, because she doesn't just know the salient reactions, she knows them all" (pp. 400, 401).
As I wrote in my earlier post, Jackson's scenario already grants too much to the physicalist, since Mary's existence already enjoys a plethora of phenomenal consciousness in the modes of touch, taste, hearing, smell, and non-chromatic vision. Beyond this, though, did you notice Dennett's phenomenological sleight of hand about both Mary and the osprey cry? In one breath he denies there are phenomenally distinct contents of consciousness (qualia), but then in the next breath proposes scenarios that invoke exactly such contents, namely, how personally seeing an imagined color would feel and how the specific tone of a bird cry would sound, respectively. It's already granted that Mary can predict the neurophysiological reactions her brain would have, but the point at issue is whether she could predict the feeling of seeing red, green, blue, and all the rest. Now it may be argued that her prediction of the feeling of seeing such colors just coalesces with her 'internal' grasp of how her chromatically limited but familiar neurophysiological reactions feel, but this only grants the point at issue, namely, that experience of the physical world includes intrinic, internalized feelings. Unless we grant that it is coherent to say that Mary, like all sentient observers, already has the capacity for feeling the visual contents of her consciousness––and allegedly such an "ineffable feeling of experience" is verboten in Dennett's materialism––, then it is formally illicit to allow Mary to leverage her way from non-phenomenal experience to phenomenal inferences.
Even if we let slide his illict reference to an emotive 'tone' or specific pitch, the second flaw in Dennett's analogy is that, as Robinson suggested earlier, the formal features of a bird call--its rhythm, pattern, and duration, for example--crucially differ from its phenomenal features. This objection does not beg the question in favor of qualia anymore than noting that a knowledge of the meter and total number of notes in Beethoven's 9th Symphony is radically different from an actual knowledge of that symphony itself as a musical event begs the question. Knowing how many steps I am about to fall down and of what the stairs are made does not give me a knowledge of "what it's really like" to fall down that staircase, stair after stair, appendage upon appendage.
Interestingly, though, the formally objective precision of, say, an osprey's cry as an object of ornithological study, or of Beethoven's 9th as an object of musicology, does give us a kind of basis for 'verifying' the experience of hearing either. If we gradually lose our sense of "just how Beethoven's 9th sounds," we can buy tickets to hear a live performance of it or play a CD of it. Indeed, if we were musically adept enough, we could even glance at the musical notation itself and remind ourselves of the music note by note. (This latter scenario suffices to remind us once again that while qualia are not in the physical objects of perception––I don't think a B-sharp note represented on a sheet of music really sounds like anything––, yet they are undeniably present in consciousness as an irreducible 'field' of awareness.) We can further 'tune' our qualia by keeping track of the auditorium in which Beethoven's 9th is played, the specific instruments used in a performance, and so on. Even so, none of these formal features deliver the music itself, since it was precisely by first hearing his music "in his head" that Beethoven was able to generate the formal composition for posterity.