To quail means to cringe in fear.
Qualia is the plural of quale, which basically means "the quality [or 'feel'] of an experience" (e.g., the redness of red).
In Paul Churchland's Matter and Consciousness -- by the way, you can remember which Churchland is which, Paul or Patricia, by noting Paul has M. for a middle initial and he is the M(ale) Churchland -- while he does not quail at qualia, he does display a refined contempt for them as a muddled throwback to "folk psychology." According to fold psychology, what makes consciousness so unique, and therefore (so to speak) non-artificible, are its rich qualia. We may able to describe red in words, or even program "recognizing redness" into a computer, but only the raw immediate feeling (quale) of redness in our minds can properly be called consciousness. And it just seems impossible to build that feeling up from scratch or put it into other terms; you either get it or you don't.
A connected aspect of consciousness is the apparent infallibility of our conscious states. While we may be tricked or confused by grammar, complex propositional statements, difficult logical puzzles, frenetic bursts of activity, and so forth, we simply can't be deluded about what we experience "on the inside." There is an infallible immediacy to conscious experiences, vivid in their qualia, which nothing but "feeling it firsthand" can produce. No verbal description or logical consideration can match the raw, infallible certainty of how we perceive something.
As a leading "qualophobe" Churchland is, of course, critical of all this. He examines a number of problems with the claim of conscious infallibility, criticisms which I feel are quite weak. His main argument against (so to speak) qualic infallibility is that we often in fact do err about what we perceive. When we glance at our friend's new shoes, at first we see them as purple, but then suddenly they shift into a deep blue. Or, for example, we reach for a glass of milk, take a gulp, and then suddenly nearly choke when we suddenly taste the fluid is actually water or orange juice. In such case, Churchland says, we're obviously victim to an all too fallible consciousness. If we can be wrong about our own qualia, then surely there's nothing so unique or special about qualia.
As I say, I find Churchland's criticisms weak, mainly because he seems not to grasp where the qualic immediacy actually lies. He seems to be confusing objective misperception with what I am here going to call subjective transception. (Here, about Hana Gitelman, and here, about the word itself, are two short discussions of the word "transception" in other senses than I intend, yet which do illuminate some of what I'm trying to say.) By subjective transception I mean the state of a qualia 'coming across' to a person subjectively. It is, in other words, just the action of qualic consciousness. It is perceiving, feeling, an experience's or object's qualia for ourselves. The difference between objective misperception, which Churchland raises as an objection against qualic infallibility, and subjective transception is crucial, but Churchland seems insensitive to it. (Is there a quale of qualophilia?) Even if we experience things incorrectly, we still do so immediately and infallibly. Even if our mistaken perception of the purple shoes shifts aright to seeing them as blue, we are still immediately aware of this shift by virtue or subjective transception. It is precisely subjective transception that allows us to notice our shift from misperception to accurate perception. Even when I mispronounce the word "equilibrium", say as "equilibrium", I still do so in exactly that way, with exactly that feeling of mispronunciation. Even when I am perceiving blue as purple, I am still immediately and infallibly perceiving purple as purple, and then, in a flash, blue as blue. Objective misperception stands between that qualic shift but, crucially, not between the subjective transception of the qualia themselves.
This may seem to undermine the reliability of qualia, and perception generally, since apparently even if we have it, we still could be dead wrong about what it is presenting to us. But this problem is no more troubling in my mind than what optical illusions do for perception. Consider my favorite example, the (so to speak) two-way box:
It may take a moment or two for you to see it, but at some point something will click for you visually and you will see this box can be seen in two ways. In one way, as from above, like down and left at a shoebox. In another way, as from below, as looking right and up into a transparent house. Once you grasp the illusion, you can even flip between the two perspectives. What does this mean? The perspective-flipping is an analogy for qualic-shifting (which we find in cases of objective misperception). If two people looked at the box at the same moment and said what they saw, one might see it from above while the other might see it from below. In this case, they would disagree about what's being seen (objectively), but in neither case would either deny what he's seeing subjectively. Further, once they'd come to agree the box can be seen in two ways, they'd still have an immediate awareness of which quale (or which angle) they were perceiving. Since, objectively speaking, they both couldn't be right about a box being in two different positions, would we be right to say one person was wrong (i.e., misperceiving reality)? No. The objective error or seeing the box "wrong" would have to be sorted out as an objective ambiguity; meanwhile though, the subjective transception of the box, as from above or from below, would not be subject to any "correction." So, even when I misperceive a C for an E (I have a mediocre musical era and little grasp of musical notation), I am still doing so "infallibly" in terms of what I am experiencing.
Churchland thinks that consciousness is adequately described by the role it plays in a causal network (viz., if "red" gets you to stop at the intersection, then it just is red, regardless how each driver subjectively experiences the light's color). I disagree, since the ambiguity of colors only amounts to objective errors, which would have to be sorted out with an objective optical apparatus, and does not count as evidence against the existence of qualia in conscious experience. When a bee looks at a flower, it perceives a swirl of chemicals and ultraviolet landing markers. When I look at it, I see petals, pistils and stamens. From one objective perspective -- depending on who wins the coin flip, the bee or me, for perceptual dominance in the thought experiment -- one of us is wrong: the flower is either a petal-pistil-looking thing or it is a glowing-swirling-ultraviolet-looking thing. While I may be wrong about how I see the flower (in bee terms), I am never wrong about how I perceive it as a discrete, vivid qualic encounter. Qualia are important because if I didn't 'have' them, I'd never know how to respond to objects. If all I had was objective data about what the object should look like, or about what response it should elicit, I would never have a subjective ability to form my own responses to objects.
I was agitated to write about all this not only because Churchland's qualic criticisms had been itching my brain for a few weeks, but also because, just last night, I heard of a fascinating (though tragic) case. A good friend of one of my good friends was in a serious motor accident several months ago. She suffered serious brain damage but, praise God, made surprising recovery. She can now walk, and talk and listen and function -- but she can't feel. She has no happiness, no stress, no anger, no fear, etc. If you invite her to join you for ice cream, your treat, she can only say, in a complete monotone, "Sounds good." If you threaten to take all her money and burn it right then and there, she can only say, in a complete monotone, "No, please don't." While this woman can produce the right verbal and behavioral responses (in a causal network), still she has no emotional feeling for anything. Her case is fascinating to me because it seems to be a crucial study for the consciousness debate. Does it count against qualia that a person can live without them (at least in emotional terms, though not in perceptual terms)? Or does it not count as evidence for the reality of qualia that they can exist separate from, and with causal powers distinct from, verbal and behavioral causal networks? Churchland, and other qualophobes, would seem to be inclined to say this woman is as conscious as conscious can be, since there is no metaphysical mystery to consciousness other than how it emerges as the interplay between stimulus and response. But surely just because she can recognize, and respond to, the appropriate causal triggers, does not mean she is truly conscious. Surely her lack of a qualitatively emotional life shows there is more to consciousness than its functions.