'Qualia' is an unfamiliar term for something that could not be more familiar to each of us: the ways things seem to us. (381)

I want to make it just as uncomfortable for anyone to talk of qualia- or 'raw feels' or 'phenomenal properties' or ' subjective and intrinsic properties ' or ' the qualitative character' of experience - with the standard presumption that they , and everyone else, knows what on earth they are talking about.(p. 382)

Pump 1: Watching you Eat Cauliflower. Say someone who hates cauliflower watches someone eat cauliflower, which leads the person to wonder how someone could possibly enjoy the taste. We may hypothesize that cauliflower tastes different to them, which seems plausible. Surely things taste different to me once I have mixed them with other things, or had I a different palette. However, if these processes are subjective in nature, how could we possibly narrow them down to some fundamental properties about which we could make serious discussion? I could categorize every "qualia," then, into the times and subjectivities of the qualia experienced, but that gets us no closer to understanding some fundamental property of cualiflower or maple syrup. The homely cases convince us of the reality of these special properties --those subjective tastes, looks, aromas, sounds-- that we then apparently isolate for definition by this philosophical distillation.

Pump 2: The Wine-Tasting Machine. It is feasible for us to create a machine that, associating what professional wine tasters find pleasing in wine to the chemical makeup of wine, judges the taste of the wine for us. However, no qualia believer would assent that our experience of tasting wine is anything remotely similar to the way a robot tastes wine. The arguments defending this, though, are not very good, relying on a sense that qualia in are "ineffable", "intrinsic," "private," and "directly or immediately comprehensible to consciousness." But if this is so, how can we be certain that robots do not experience them? Or worse yet, how do we even talk about such a thing objectively? (cf Wittgenstein's Philosophical Investigations).

Shoemaker contrasts qualitative similarity and difference with 'inten - tional ' similarity and difference - similarity and difference of the properties an experience represents or is of ' . That is clear enough , 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 'accessibleto introspection ' (S. Shoemaker, personal communication). These are features of my visual state, perhaps but not of my visual experience.

Pump 3: The Inverted Spectrum. It asserts that our learning a common language of associating experiences of properties to things does not imply that we experience the same thing. People who see green instead of red may use the same word to refer to it, but this confuses this objective qualia that we are supposed to intuit.

Pump 4: The Brainstorm Machine. Supposing we had some sort of machine that could fit on my head and report someone's inverted spectrum experience, I would report the findings invertedly. But then say the technician inverts the plug such that the socket reads as I am used to reporting my experiences (matching his experiences to mine, if you will). How would we determine which orientation was the correct one?

Pump 5 and 6: The Neurosurgical Prank and Alternative Neurosurgery. Assuming that we awaken with an inverted spectrum, we seem perfectly capable of explaining the changes in our perception and even place blame, but this runs into a problem of finding which operation the neurophysiologist actually performed. Did he change all of my memories of past qualia, or was my qualia switched at the ocular nerve? Both stories are plausible explanations for a perceptive switch, but we couldn't then pinpoint what the "original" qualia were with any accuracy, and so the issue remains.

'Egad! Something has happened! Either my qualia have been inverted or my memory -linked qualia reactions have been inverted . I wonder which !' The outcome of this series of thought experiments is an intensification of the 'verificationist ' argument against qualia. If there are qualia, they are even less accessible to our ken than we had thought . Not only are the classical intersubjective comparisons impossible (as the Brainstorm machine shows), but we cannot tell in our own cases whether our qualia have been inverted —at least not by introspection. It is surely tempting at this point - especially to non -philosophers - to decide that this paradoxical result must be an artefact of some philosophical misanalysis or other, the sort of thing that might well happen if you took a perfectly good pretheoretical notion - our everyday notion of qualia- and illicitly stretched it beyond the breaking point. The philosophers have made a mess; let them clean it up; meanwhile we others can get back to work, relying as always on our sober and unmetaphysical acquaintance with qualia.

Pump 7: Chase and Sanborn. Two Maxwell House tasters (a famous coffee house), Chase and Sanborn, agree in their acquired distaste for Maxwell House coffee. However, Chase bases his distaste for coffee on a change in his tastes, while Sanborn claims that his distaste comes from some change of his tasters. Who are we to believe? Is there any more value to claiming that the taste has remained constant, but that the cause of their distaste is his experience with better coffees, or that the cause of their distastes is caused by some modification in their anatomy, making them taste the original coffee differently?

My reason for introducing two characters in the exampleis not to set up an interpersonal comparison between how the coffee tastes to Chase and how it tastes to Sanborn, but just to exhibit, sideby side, two poles between which cases of intrapersonal experiential shift can wander.

(a) Chase's coffee-taste qualia have stayed constant, while his reactive attitudes to those qualia, devolving on his canons of aesthetic judgment ,etc., have shifted- which is what he seems,in his informal, casual way, to be asserting.
(b) Chase is simply wrong about the constancy of his qualia; they have shifted gradually and imperceptibly over the years, while his standards of taste have not budged- in spite of his delusions about become more ' . having sophisticated. He is in the state Sanborn claims to be in, but just lacks Sanborn's self-knowledge.
(c) Chase is in some predicament intermediate between (a) and (b); his qualia have shifted some and his standards of judgment have also slipped .

(a) Sanborn is right ; his qualia have shifted , due to some sort of derangement in his perceptual machinery, but his standards have indeed remained constant.
(b) Sanborn's standards have shifted unbeknownst to him . He is thus misremembering his past experiences, in what we might call a nostalgia effect. Think of the familiar experience of returning to some object from your childhood (a classroom desk, a tree-house) and finding it much smaller than you remember it to have been. Presumably as you grew larger your internal standard for what was large grew with you somehow, but your memories (which are stored as fractions or multiples of that standard) did not compensate, and hence, when you consult your memory, it returns a distorted judgment. Sanborn's nostalgia-tinged memory of good old Maxwell House is similarly distorted. ( There are obviously many different ways this impressionistic sketch of a memory mechanism could be implemented, and there is considerable experimental work in cognitive psychology that suggests how different hypotheses about such mechanisms could be tested.)
(c) As before, Sanborn's state is some combination of (a) and (b)