Reading � Dennett, �Quining qualia�

Greg Detre

Friday, 15 March, 2002

1. Corralling the Quicksilver

qualia =

the way things seem to us

"properties of conscious experience"

"raw feels" or "phenomenal properties" or "subjective and intrinsic properties" or "the qualitative character" of experience

"to quine" = "To deny resolutely the existence or importance of something real or significant." (The Philosophical Lexicon (Dennett 1978c, 8th edn., 1987))

�Everything real has properties, and since I don't deny the reality of conscious experience, I grant that conscious experience has properties. I grant moreover that each person's states of consciousness have properties in virtue of which those states have the experiential content that they do. That is to say, whenever someone experiences something as being one way rather than another, this is true in virtue of some property of something happening in them at the time, but these properties are so unlike the properties traditionally imputed to consciousness that it would be grossly misleading to call any of them the long-sought qualia. � My claim � which can only come into focus as we proceed � is that conscious experience has no properties that are special in any of the ways qualia have been supposed to be special.�

�I want to shift the burden of proof, so that anyone who wants to appeal to private, subjective properties has to prove first that in so doing they are not making a mistake.�

qualia deserve the same status as an �elan vital�

what are qualia?

�If you got to ask, you ain't never gonna get to know.� � Louis Armstrong on jazz (Block, 1978, p.281) � �only half in jest�

�Rigorous arguments only work on well-defined materials, and since my goal is to destroy our faith in the pretheoretical or "intuitive" concept, the right tools for my task are intuition pumps, not formal arguments.�

2. The Special Properties of Qualia

Intuition pump #1: watching you eat cauliflower

just as different foods can taste different to me at different times/under different circumstances, and to different people

presumes that we can isolate the qualia from everything else that is going on

�What counts as the way the juice tastes to x can be distinguished, one supposes, from what is a mere accompaniment, contributory cause, or byproduct of this "central" way. One dimly imagines taking such cases and stripping them down gradually to the essentials, leaving their common residuum, the way things look, sound, feel, taste, smell to various individuals at various times, independently of how those individuals are stimulated or non-perceptually affected, and independently of how they are subsequently disposed to behave or believe. The mistake is not in supposing that we can in practice ever or always perform this act of purification with certainty, but the more fundamental mistake of supposing that there is such a residual property to take seriously, however uncertain our actual attempts at isolation of instances might be.�

Intuition pump #2: the wine-tasting machine

like Jackson�s Mary

the specialness of these properties is hard to pin down

�We now know enough about the relevant chemistry to make the transducers that would replace taste buds and olfactory organs, and we can imagine using the output of such transducers as the raw material--the "sense data" in effect--for elaborate evaluations, descriptions, classifications.�

even if it were to be more consistent + accurate than human wine-tasters, it still won't have the qualia of conscious experience

�Whatever informational, dispositional, functional properties its internal states have, none of them will be special in the way qualia are.�

what is special about qualia?

1. ineffable

�one cannot say to another, no matter how eloquent one is and no matter how cooperative and imaginative one's audience is, exactly what way one is currently seeing, tasting, smelling and so forth�

2. intrinsic

�they are somehow atomic and unanalyzable. Since they are "simple" or "homogeneous" there is nothing to get hold of when trying to describe such a property to one unacquainted with the particular instance in question�

3. private

�any objective, physiological or "merely behavioral" test--such as those passed by the imaginary wine-tasting system-- would of necessity miss the target (one can plausibly argue), so all interpersonal comparisons of these ways-of-appearing are (apparently) systematically impossible�

4. directly or immediately apprehensible in consciousness

�they are properties of my experiences � qualia are essentially directly accessible to the consciousness of their experiencer (whatever that means) or qualia are properties of one's experience with which one is intimately or directly acquainted (whatever that means) or "immediate phenomenological qualities" (Block, 1978) (whatever that means). They are, after all, the very properties the appreciation of which permits us to identify our conscious states�

they�re significant because they seem to de-rail any purely �third-person� objective viewpoint or approach to the world (Nagel, 1986), e.g. functionalism or materialism

so that he can't be accused of attacking a straw man with his four-fold definition, he considers an apparently milder alternative:

qualia are simply "the qualitative or phenomenal features of sense experience[s], in virtue of having which they resemble and differ from each other, qualitatively, in the ways they do." (Shoemaker, 1982, p. 367)

but it all depends on what �qualitative or phenomenal� comes to

Shoemaker contrasts qualitative similarity and difference with �intentional� similarity and difference

but what then of �phenomenal�? �Among the non-intentional (and hence qualitative?) properties of my visual states are their physiological properties. Might these very properties be the qualia Shoemaker speaks of? It is supposed to be obvious, I take it, that these sorts of features are ruled out, because they are not "accessible to introspection" (Shoemaker, private correspondence). These are features of my visual state, perhaps, but not of my visual experience. They are not phenomenal properties.�

he thinks �phenomenal� is just another way of referring to qualia

�The term "phenomenal" means nothing obvious and untendentious to me (typo???), and looks suspiciously like a gesture in the direction leading back to ineffable, private, directly apprehensible ways things seem to one�

he suspects that the attraction of qualia is as �the last ditch defense of the inwardness and elusiveness of our minds, a bulwark against creeping mechanism�

quotes Einstein + Wittgenstein

3. The Traditional Paradox Regained

Intuition pump #3: the inverted spectrum (Locke, 1690: II, xxxii, 15)

�Since we both learned color words by being shown public colored objects, our verbal behavior will match even if we experience entirely different subjective colors�

Intuition pump #4: the Brainstorm machine

feeds your visual experience into my brain, so that I can accurately report everything you are looking at, except the sky is yellow, the grass red etc.

are our qualia different then?

but if you reinsert the cable upside down, then I report that the sky is blue, the grass green etc.

which is the �right� orientation of the plug?

�Designing and building such a device would require that its "fidelity" be tuned or calibrated by the normalization of the two subjects' reports--so we would be right back at our evidential starting point. The moral of this intuition pump is that no intersubjective comparison of qualia is possible, even with perfect technology.�

Intuition pump #5: the neurosurgical prank � the intra-personal inverted spectrum

�You wake up one morning to find that the grass has turned red, the sky yellow, and so forth. No one else notices any color anomalies in the world, so the problem must be in you� � evil neurophysiologists have tampered with your neurons

�here it seems at first--and indeed for quite a while--that qualia are acceptable properties after all, because propositions about them can be justifiably asserted, empirically verified and even explained�

Intuition pump #6: alternative neurosurgery

but there are (at least) two different ways the evil neurosurgeon might create the inversion effect described in intuition pump #5

1. Invert one of the "early" qualia-producing channels, e.g., in the optic nerve, so that all relevant neural events "downstream" are the "opposite" of their original and normal values. Ex hypothesi this inverts your qualia
2. Leave all those early pathways intact and simply invert certain memory-access links--whatever it is that accomplishes your tacit (and even unconscious!) comparison of today's hues with those of yore. Ex hypothesi this does not invert your qualia at all, but just your memory-anchored dispositions to react to them.

�The intrapersonal inverted spectrum thought experiment was widely supposed to be an improvement, since it moved the needed comparison into one subject's head. But now we can see that this is an illusion, since the link to earlier experiences, the link via memory, is analogous to the imaginary cable that might link two subjects in the original version.�

intensification of the �verificationist� argument against qualia � if there are qualia, they are even less accessible to our ken than we had thought

4. Making Mistakes About Qualia

Intuition pump #7: Chase and Sanborn

their job is to that the taste of Maxwell House coffee stayed constant year after year

Chase: the coffee tastes the same today as 6 years ago but I no longer like it � my preferences have changed I've become a more sophisticated coffee drinker. I no longer like that taste at all.

Sanborn: my preferences haven't changed, but something has gone wrong with my taste buds or taste-analysing perceptual machinery Maxwell House coffee doesn't taste to me the way it used to taste; if only it did, I'd still love it, for I still think that taste is the best taste in coffee you other tasters all agree that the taste is the same, and I must admit that on a day-to-day basis I can detect no change either. So it must be my problem alone

so they both used to like Maxwell House, and now neither likes it

but Maxwell House tastes to Chase just the way it always did, but not so for Sanborn

�might their predicaments be importantly the same and their apparent disagreement more a difference in manner of expression than in experiential or psychological state? Since both of them make claims that depend on the reliability of their memories, is there any way to check on this reliability?�

Dennett is trying to contrast the two ways in which intra-personal experiential shift can manifest itself

Two possibilities:

Chase: (a) his coffee-taste-qualia have stayed the same, but his aesthetic preferences about those qualia have changed (b) Chase is wrong about his qualia staying the same � actually, they have gradually shifted, but his aesthetic preferences have stayed the same � just like Sanborn claims (c) mix of the two

Sanborn: (a) Sanborn is right; his qualia have shifted, due to some sort of change/problem in his perceptual machinery, but his standards have stayed the same (b) Sanborn's standards have shifted unbeknownst to him. He is thus misremembering his past experiences, in what we might call a nostalgia effect (c) mix of the two

few people would defend the infallibilist position, i.e. that (a) must be the case because people can't be wrong about such private, subjective matters

�one way to buy such infallibility is to acquiesce in the complete evaporation of content�

"Imagine someone saying: 'But I know how tall I am!' and laying his hand on top of his head to prove it." (Wittgenstein, 1958, p.96)

but that�s no good here � �one of the things we want Chase to be right about (if he is right) is that he is not in Sanborn's predicament, so if the claim is to be viewed as infallible, it can hardly be because it declines to assert anything.�

even if you want to say, at least: �I know how it is with me right now� � but absolutely nothing follows from this presumed knowledge

Unfinished

The infallibilist line on qualia treats them as properties of one's experience one cannot in principle misdiscover, and this is a mysterious doctrine (at least as mysterious as papal infal libility) unless we shift the emphasis a little and treat qualia as logical constructs out of subjects' qualia-judgments: a sub ject's experience has the quale F if and only if the subject judges his experience to have quale F. We can then treat such judgings as constitutive acts, in effect, bringing the quale into existence by the same sort of license as novelists have to deter mine the hair color of their characters by fiat. We do not ask how Dostoevski knows that Raskolnikov's hair is light brown.

There is a limited use for such interpretations of subjects' protocols, I have argued (Dennett 1978a; 1979, esp., pp.109-110; 1982), but they will not help the defenders of qualia here. Logical constructs out of judgments must be viewed as akin to theorists' fictions, and the friends of qualia want the existence of a particular quale in any particular case to be an empirical fact in good standing, not a theorist's useful interpretive fiction, else it will not loom as a challenge to functionalism or materialism or third-person, objective science.

It seems easy enough, then, to dream up empirical tests that would tend to confirm Chase and Sanborn's different tales, but if passing such tests could support their authority (that is to say, their reliability), failing the tests would have to undermine it. The price you pay for the possibility of empirically confirming your assertions is the outside chance of being discredited. The friends of qualia are prepared, today, to pay that price, but perhaps only because they haven't reckoned how the bargain they have struck will subvert the concept they want to defend.

Consider how we could shed light on the question of where the truth lies in the particular cases of Chase and Sanborn, even if we might not be able to settle the matter definitively. It is obvious that there might be telling objective support for one extreme version or another of their stories. Thus if Chase is unable to reidentify coffees, teas, and wines in blind tastings in which only minutes intervene between first and second sips, his claim to know that Maxwell House tastes just the same to him now as it did six years ago will be seriously undercut. Alterna tively, if he does excellently in blind tastings, and exhibits considerable knowledge about the canons of coffee style (if such there be), his claim to have become a more sophisticated taster will be supported. Exploitation of the standard principles of inductive testing--basically Mill's method of differences--can go a long way toward indicating what sort of change has occurred in Chase or Sanborn--a change near the brute perceptual processing end of the spectrum or a change near the ultimate reactive judg ment end of the spectrum. And as Shoemaker (1982) and others have noted, physiological measures, suitably interpreted in some larger theoretical framework, could also weight the scales in favor of one extreme or the other. For instance, the well-studied phenomenon of induced illusory boundaries (see Figure 1) has

INSERT FIGURE 1 ABOUT HERE

often been claimed to be a particularly "cognitive" illusion, dependent on "top down" processes, and hence, presumably, near the reactive judgment end of the spectrum, but recent experimental work (Von der Heydt et al., 1984) has revealed that "edge detector" neurons relatively low in the visual pathways--in area 18 of the visual cortex--are as responsive to illusory edges as to real light-dark boundaries on the retina, suggesting (but not quite proving, since these might somehow still be "descending effects") that illusory contours are not imposed from on high, but generated quite early in visual processing. One can imagine discovering a similarly "early" anomaly in the pathways leading from taste buds to judgment in Sanborn, for instance, tending to confirm his claim that he has suffered some change in his basic perceptual--as opposed to judgmental--machinery.

But let us not overestimate the resolving power of such empirical testing. The space between the two poles represented by possibility (a) and possibility (b) would be occupied by phenomena that were the product, somehow, of two factors in varying proportion: roughly, dispositions to generate or produce qualia and dispositions to react to the qualia once they are produced. (That is how our intuitive picture of qualia would envisage it.) Qualia are supposed to affect our action or beha vior only via the intermediary of our judgments about them, so any behavioral test, such as a discrimination or memory test, since it takes acts based on judgments as its primary data, can give us direct evidence only about the resultant of our two factors. In extreme cases we can have indirect evidence to sug gest that one factor has varied a great deal, the other factor hardly at all, and we can test the hypothesis further by checking the relative sensitivity of the subject to variations in the conditions that presumably alter the two component factors. But such indirect testing cannot be expected to resolve the issue when the effects are relatively small--when, for instance, our rival hypotheses are Chase's preferred hypothesis (a) and the minor variant to the effect that his qualia have shifted a little and his standards less than he thinks. This will be true even when we include in our data any unintended or unconscious beha vioral effects, for their import will be ambiguous. (Would a longer response latency in Chase today be indicative of a process of "attempted qualia renormalization" or "extended aesthetic evaluation"?)

The limited evidential power of neurophysiology comes out particularly clearly if we imagine a case of adaptation. Suppose, in intuition pump #8: the gradual post-operative recovery, that we have somehow "surgically inverted" Chase's taste bud connections in the standard imaginary way: post-operatively, sugar tastes salty, salt tastes sour, etc. But suppose further-- and this is as realistic a supposition as its denial--that Chase has subsequently compensated--as revealed by his behavior. He now says that the sugary substance we place on his tongue is sweet, and no longer favors gravy on his ice cream. Let us suppose the compensation is so thorough that on all behavioral and verbal tests his performance is indistinguishable from that of normal subjects--and from his own pre-surgical performance.

If all the internal compensatory adjustment has been accomplished early in the process--intuitively, pre-qualia--then his qualia today are restored to just as they were (relative to external sources of stimulation) before the surgery. If on the other hand some or all of the internal compensatory adjustment is post-qualia, then his qualia have not been renormalized even if he thinks they have. But the physiological facts will not in themselves shed any light on where in the stream of physiological process twixt tasting and telling to draw the line at which the putative qualia appear as properties of that phase of the process. The qualia are the "immediate or phenomenal" properties, of course, but this description will not serve to locate the right phase in the physiological stream, for, echoing intuition pump #6, there will always be at least two possible ways of interpreting the neurophysiological theory, however it comes out. Suppose our physiological theory tells us (in as much detail as you like) that the compensatory effect in him has been achieved by an adjustment in the memory-accessing process that is required for our victim to compare today's hues to those of yore. There are still two stories that might be told:

(I) Chase's current qualia are still abnormal, but thanks to the revision in his memory-accessing process, he has in effect adjusted his memories of how things used to taste, so he no longer notices any anomaly.

(II) The memory-comparison step occurs just prior to the qualia phase in taste perception; thanks to the revision, it now yields the same old qualia for the same stimulation.

In (I) the qualia contribute to the input, in effect, to the memory-comparator. In (II) they are part of the output of the memory-comparator. These seem to be two substantially different hypotheses, but the physiological evidence, no matter how well developed, will not tell us on which side of memory to put the qualia. Chase's introspective evidence will not settle the issue between (I) and (II) either, since ex hypothesi those stories are not reliably distinguishable by him. Remember that it was in order to confirm or disconfirm Chase's opinion that we turned to the neurophysiological evidence in the first place. We can hardly use his opinion in the end to settle the matter between our rival neurophysiological theories. Chase may think that he thinks his experiences are the same as before because they really are (and he remembers accurately how it used to be), but he must admit that he has no introspective resources for distinguishing that possibility from alternative (I), on which he thinks things are as they used to be because his memory of how they used to be has been distorted by his new compensatory habits.

Faced with their subject's systematic neutrality, the physiologists may have their own reasons for preferring (I) to (II) or vice versa, for they may have appropriated the term "qualia" to their own theoretical ends, to denote some family of detectable properties that strike them as playing an important role in their neurophysiological theory of perceptual recognition and memory. Chase or Sanborn might complain--in the company of more than a few philosophical spokesmen--that these properties the neurophsyiologists choose to call "qualia" are not the qualia they are speaking of. The scientists' retort is: "If we cannot distinguish (I) from (II), we certainly cannot support either of your claims. If you want our support, you must relinquish your concept of qualia."

What is striking about this is not just that the empirical methods would fall short of distinguishing what seem to be such different claims about qualia, but that they would fall short in spite of being better evidence than the subject's own introspec tive convictions. For the subject's own judgments, like the behaviors or actions that express them, are the resultant of our two postulated factors, and cannot discern the component propor tions any better than external behavioral tests can. Indeed, a subject's "introspective" convictions will generally be worse evidence than what outside observers can gather. For if our subject is--as most are--a "naive subject", unacquainted with statistical data about his own case or similar cases, his imme diate, frank judgments are, evidentially, like any naive observer's perceptual judgments about factors in the outside world. Chase's intuitive judgments about his qualia constancy are no better off, epistemically, than his intuitive judgments about, say, lighting intensity constancy or room temperature constancy--or his own body temperature constancy. Moving to a condition inside his body does not change the intimacy of the epistemic relation in any special way. Is Chase running a fever or just feeling feverish? Unless he has taken steps to calibrate and cross-check his own performance, his opinion that his fever- perception apparatus is undisturbed is no better than a hunch. Similarly, Chase may have a strongly held opinion about the degree to which his taste-perceiving apparatus has maintained its integrity, and the degree to which his judgment has evolved through sophistication, but pending the results of the sort of laborious third-person testing just imagined, he would be a fool to claim to know--especially to know directly or immediately-- that his was a pure case (a), closer to (a) than to (b), or a case near (b).

He is on quite firm ground, epistemically, when he reports that the relation between his coffee-sipping activity and his judging activity has changed. Recall that this is the factor that Chase and Sanborn have in common: they used to like Maxwell House; now they don't. But unless he carries out on himself the sorts of tests others might carry out on him, his convictions about what has stayed constant (or nearly so) and what has shifted must be sheer guessing.

But then qualia--supposing for the time being that we know what we are talking about--must lose one of their "essential" second-order properties: far from being directly or immediately apprehensible properties of our experience, they are properties whose changes or constancies are either entirely beyond our ken, or inferrable (at best) from "third-person" examinations of our behavioral and physiological reaction patterns (if Chase and Sanborn acquiesce in the neurophysiologists' sense of the term). On this view, Chase and Sanborn should be viewed not as introspectors capable of a privileged view of these properties, but as autopsychologists, theorists whose convictions about the properties of their own nervous systems are based not only on their "immediate" or current experiential convictions, but also on their appreciation of the import of events they remember from the recent past.

There are, as we shall see, good reasons for neurophysiologists and other "objective, third-person" theorists to single out such a class of properties to study. But they are not qualia, for the simple reason that one's epistemic relation to them is exactly the same as one's epistemic relation to such external, but readily--if fallibly--detectable, properties as room temperature or weight. The idea that one should consult an outside expert, and perform elaborate behavioral tests on oneself in order to confirm what qualia one had, surely takes us too far away from our original idea of qualia as properties with which we have a particularly intimate acquaintance.

So perhaps we have taken a wrong turning. The doctrine that led to this embarrassing result was the doctrine that sharply distinguished qualia from their (normal) effects on reactions. Consider Chase again. He claims that coffee tastes "just the same" as it always did, but he admits--nay insists--that his reaction to "that taste" is not what it used to be. That is, he pretends to be able to divorce his apprehension (or recollection) of the quale--the taste, in ordinary parlance--from his different reactions to the taste. But this apprehension or recollection is itself a reaction to the presumed quale, so some sleight-of-hand is being perpetrated--innocently no doubt--by Chase. So suppose instead that Chase had insisted that precisely because his reac tion was now different, the taste had changed for him. (When he told his wife his original tale, she said "Don't be silly! Once you add the dislike you change the experience!"--and the more he thought about it, the more he decided she was right.)

Intuition pump #9: the experienced beer drinker. It is familiarly said that beer, for example, is an acquired taste; one gradually trains oneself--or just comes--to enjoy that flavor. What flavor? The flavor of the first sip? No one could like that flavor, an experienced beer drinker might retort:

Beer tastes different to the experienced beer drinker. If beer went on tasting to me the way the first sip tasted, I would never have gone on drinking beer! Or to put the same point the other way around, if my first sip of beer had tasted to me the way my most recent sip just tasted, I would never have had to acquire the taste in the first place! I would have loved the first sip as much as the one I just enjoyed.

If we let this speech pass, we must admit that beer is not an acquired taste. No one comes to enjoy the way the first sip tasted. Instead, prolonged beer drinking leads people to experience a taste they enjoy, but precisely their enjoying the taste guarantees that it is not the taste they first experienced. Endnote 9

But this conclusion, if it is accepted, wreaks havoc of a different sort with the traditional philosophical view of qualia. For if it is admitted that one's attitudes towards, or reactions to, experiences are in any way and in any degree constitutive of their experiential qualities, so that a change in reactivity amounts to or guarantees a change in the property, then those properties, those "qualitative or phenomenal features," cease to be "intrinsic" properties, and in fact become paradigmatically extrinsic, relational properties.

Properties that "seem intrinsic" at first often turn out on more careful analysis to be relational. Bennett (1965) is the author of intuition pump #10: the world-wide eugenics experiment. He draws our attention to phenol-thio-urea., a substance which tastes very bitter to three-fourths of humanity, and as tasteless as water to the rest. Is it bitter? Since the reactivity to phenol-thio-urea is genetically transmitted, we could make it paradigmatically bitter by performing a large-scale breeding experiment: prevent the people to whom it is tasteless from breeding, and in a few generations phenol would be as bitter as anything to be found in the world. But we could also (in principle!) perform the contrary feat of mass "eugenics" and thereby make phenol paradigmatically tasteless--as tasteless as water--without ever touching phenol. Clearly, public bitterness or tastelessness is not an intrinsic property of phenol-thio-urea but a relational property, since the property is changed by a change in the reference class of normal detectors.

The public versions of perceptual "qualia" all seem intrinsic, in spite of their relationality. They are not alone. Think of the "felt value" of a dollar (or whatever your native currency is). "How much is that in real money?" the American tourist is reputed to have asked, hoping to translate a foreign price onto the scale of "intrinsic value" he keeps in his head. As Elster (1985) claims "there is a tendency to overlook the implicitly relational character of certain monadic predicates." Walzer (1985) points out that ". . . a ten-dollar bill might seem to have a life of its own as a thing of value, but, as Elster suggests, its value implicitly depends on 'other people who are prepared to accept money as payment for goods.'" But even as one concedes this, there is still a tendency to reserve something subjective, felt value, as an "intrinsic" property of that ten- dollar bill. But as we now see, such intrinsic properties cannot be properties to which a subject's access is in any way privileged.

Which way should Chase go? Should he take his wife's advice and declare that since he can't stand the coffee anymore, it no longer tastes the same to him (it used to taste good and now it tastes bad)? Or should he say that really, in a certain sense, it does taste the way it always did, or at least it sort of does--when you subtract the fact that it tastes so bad now, of course?

We have now reached the heart of my case. The fact is that we have to ask Chase which way he wants to go, and there really are two drastically different alternatives available to him if we force the issue. Which way would you go? Which concept of qualia did you "always have in the back of your mind," guiding your imagination as you thought about theories? If you acknowledge that the answer is not obvious, and especially if you complain that this forced choice drives apart two aspects that you had supposed united in your pretheoretic concept, you support my contention that there is no secure foundation in ordinary "folk psychology" for a concept of qualia. We normally think in a confused and potentially incoherent way when we think about the ways things seem to us.

When Chase thinks of "that taste" he thinks equivocally or vaguely. He harkens back in memory to earlier experiences but need not try--or be able--to settle whether he is including any or all of his reactions or excluding them from what he intends by "that taste". His state then and his state now are different-- that he can avow with confidence--but he has no "immediate" resources for making a finer distinction, nor any need to do so. Endnote 10

This suggests that qualia are no more essential to the professional vocabulary of the phenomenologist (or professional coffee taster) than to the vocabulary of the physiologist (Den nett, 1978b). To see this, consider again the example of my dislike of cauliflower. Imagine now, in intuition pump #11: the cauliflower cure, that someone offers me a pill to cure my loathing for cauliflower. He promises that after I swallow this pill cauliflower will taste exactly the same to me as it always has, but I will like that taste! "Hang on," I might reply. "I think you may have just contradicted yourself." But in any event I take the pill and it works. I become an instant cauliflower-appreciater, but if I am asked which of the two possible effects (Chase-type or Sanborn-type) the pill has had on me, I will be puzzled, and will find nothing in my experience to shed light on the question. Of course I recognize that the taste is (sort of) the same--the pill hasn't made cauliflower taste like chocolate cake, after all--but at the same time my experience is so different now that I resist saying that cauli flower tastes the way it used to taste. There is in any event no reason to be cowed into supposing that my cauliflower experiences have some intrinsic properties behind, or in addition to, their various dispositional, reaction-provoking properties.

"But in principle there has to be a right answer to the question of how it is, intrinsically, with you now, even if you are unable to say with any confidence!" Why? Would one say the same about all other properties of experience? Consider intuition pump #12: visual field inversion created by wearing inverting spectacles, a phenomenon which has been empirically studied for years. (G. M. Stratton published the pioneering work in 1896, and J. J. Gibson and Ivo Kohler were among the principal investigators. For an introductory account, see Gregory, 1977.) After wearing inverting spectacles for several days subjects make an astonishingly successful adaptation. Suppose we pressed on them this question: "Does your adaptation consist in your re- inverting your visual field, or in your turning the rest of your mind upside-down in a host of compensations?" If they demur, may we insist that there has to be a right answer, even if they cannot say with any confidence which it is? Such an insistence would lead directly to a new version of the old inverted spectrum thought experiment: "How do I know whether some people see things upside-down (but are perfectly used to it), while others see things right-side-up?"

Only a very naive view of visual perception could sustain the idea that one's visual field has a property of right-side- upness or upside-downness independent of one's dispositions to react to it--"intrinsic right-side-upness" we could call it. (See my discussion of the properties of the "images" processed by the robot, SHAKEY, in Dennett, 1982.) So not all properties of con scious experience invite or require treatment as "intrinsic" properties. Is there something distinguishing about a certain subclass of properties (the " qualitative or phenomenal" sub class, presumably) that forces us to treat them--unlike subjec tive right-side-upness--as intrinsic properties? If not, such properties have no role to play, in either physiological theories of experience, or in introspective theories.

Some may be inclined to argue this way: I can definitely imagine the experience of "spectrum inversion" from the inside; after all, I have actually experienced temporary effects of the same type, such as the "taste displacement" effect of the maple syrup on the orange juice. What is imaginable, or actual, is possible. Therefore spectrum inversion or displacement (in all sensory modalities) is possible. But such phenomena just are the inversion or displacement of qualia, or intrinsic subjective properties. Therefore there must be qualia: intrinsic subjective properties.

This is fallacious. What one imagines and what one says one imagines may be two different things. To imagine visual field inversion, of the sort Stratton and Kohler's subjects experienced, is not necessarily to imagine the absolute inversion of a visual field (even if that is what it "feels like" to the subjects). Less obviously, imagining--as vividly as you like--a case of subjective color-perception displacement is not necessarily imagining what that phenomenon is typically called by philosophers: an inverted or displaced spectrum of qualia. Insofar as that term carries the problematic implications scouted here, there is no support for its use arising simply from the vividness or naturalness of the imagined possibility.

If there are no such properties as qualia, does that mean that "spectrum inversion" is impossible? Yes and no. Spectrum inversion as classically debated is impossible, but something like it is perfectly possible--something that is as like "qualia inversion" as visual field inversion is like the impossible absolute visual image inversion we just dismissed.

5. Some Puzzling Real Cases

6. Filling the vacuum

note Dennett�s commentary on chalmers

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Questions

�I don't deny the reality of conscious experience�???

what happens if we posit some �neural correlate of qualia� � surely that has to be placed somewhere in the processing stream???

am I able to conclude that I still believe in qualia, but I just don't know how to talk about them???

I think Dennett thinks he�s made that impossible too

why can't I say that the qualia is a composite of the taste + my reaction to it, i.e. it�s relational to some extent(???), but not extrinsic???