Philosophical Zombies and the Illusion of Qualia

Dennett imagines a dispute in which a right-handed person declares left-handed people to be philosophical zombies. A zimbo is a zombie with higher-order self-monitoring: it can track and report its own states just as a conscious person can. DCD is Dennett’s voice in the dialogue.

DCD: You say you’ve proved that we lefties are zombies? I never would have guessed! Poor us? In what regard?

RIGHTIE: Well, by definition you’re not conscious—what could be worse than that?

DCD: Worse for whom? If there’s nobody home, then there’s nobody in the dark, missing out on everything. But what are you doing, trying to have a conversation with me, a zimbo?

RIGHTIE: Well, there seems to me to be somebody there.

DCD: To me too! After all, as a zimbo, I have all manner of higher-order self-monitoring competences. I know when I’m frustrated, when I’m in pain, when I’m bored, when I’m amused, and so forth.

RIGHTIE: No. You function as if you knew these things, but you don’t really know anything. You only sorta know these things.

DCD: I think that’s a misuse of the sorta operator. What you’re calling my sorta knowledge is indistinguishable from your so-called real knowledge—except for your “definitional” point: zimbo knowledge isn’t real.

RIGHTIE: But there is a difference, there must be a difference!

DCD: That sounds like bare prejudice to me.

If this isn’t enough rehearsal of what it would be like to befriend a zimbo, try some more. Seriously, consider writing a novel about a zimbo stuck in a world of conscious people, or a conscious person marooned on the Island of the Zimboes. What details could you dream up that would make this a credible tale? Or you could take an easier path: read a good novel while holding onto the background hypothesis that it is a novel about zimboes. What gives it away or disconfirms your hypothesis? Novelists have a choice of standpoints or narrative modes, including the first-person narrative used by Herman Melville in Moby-Dick and by J. D. Salinger in The Catcher in the Rye:

“Call me Ishmael.” “When I really worry about something, I don’t just fool around. I even have to go to the bathroom when I worry about something. Only, I don’t go. I’m too worried to go. I don’t want to interrupt my worrying to go.”

Other novelists opt for the third-person omniscient narrative. Curiously, the first-person narrative mode might seem to lend itself more to sustaining the zombie hypothesis. After all, the entire story merely depicts that narrative behavior of Zimbo Ishmael or Zimbo Holden Caulfield. We see only their outsides, and what they purport to be accounts drawing on their inner lives! Compare those first-person narratives to these third-person narratives in Jane Austen’s Persuasion and Fyodor Dostoevsky’s Crime and Punishment, for example:

She [Elizabeth] felt that Mrs Musgrove and all her party ought to be asked to dine with them, but she could not bear to have the difference of style, the reduction of servants, which a dinner must betray, witnessed by those who had been always so inferior to the Elliots of Kellynch. It was a struggle between propriety and vanity; but vanity got the better, and then Elizabeth was happy again. He [Raskolnikov] looked at Sonia and felt how great her love for him was, and, strange to say, he felt distressed and pained that he should be loved so much. Yes, it was a queer and dreadful sensation.

Here, it seems, the authors let us “look right into the minds” of Elizabeth and Raskolnikov, so how could they be zimboes? But remember: where conscious people have a stream of consciousness, zimboes have a stream of unconsciousness. After all, zimboes are not supposed to be miraculous; their behaviors are controlled by a host of internal goings-on of tremendous informational complexity, and modulated by functional emotion-analogues that amount to happiness, distress, and pain. So both Elizabeth and Raskolnikov could be zimboes, with Austen and Dostoevsky using the terms we all know and love from folk psychology to render descriptions of their inner goings-on, just as chess programmers talk about the iterated “searches” and risky “judgments” of their computer programs. A zimbo can be embarrassed by a loss of social status, or smothered by love.

Never forget William Bateson’s failure of imagination. When I try my hardest to avoid that trap, hunting for loopholes in my background assumptions, keeping my eye peeled for ways in which I could be proved wrong about zombies, I always come up with imagined discoveries that show, at most, that the whole concept of consciousness is seriously confused. For instance, I can imagine that there might be two (or seven, or ninety-nine) different sorts of so-called consciousness, and lefties have one, and righties have another, and lobsters have yet another. But the only way I can imagine this (so far) is by imagining that they are distinguishable by the following functional differences: lefties can’t do X, and righties can’t do Y, and so on. But those distinguishable differences just go to show that we’re not talking about philosophical zombies after all, for (by definition) there are no distinguishable-from-the-outside differences between philosophical zombies and “genuinely conscious” people. And nobody has yet been able to articulate a distinguishable-from-the-inside mark of genuine consciousness that doesn’t somehow involve the putatively conscious person being able to do something “mental” that convinces us (and her) that she is conscious. But whatever this mental difference is would presumably have its counterpart sham version in the zombie’s “stream of unconsciousness.” If not, why not? So I am quite confident that the whole idea of a philosophical zombie is a sort of intellectual hallucination, an affliction one can outgrow. Try it.

[1] This is another one of those places where some philosophers would like to accuse me of confusing a metaphysical question with an epistemological question: “Don’t ask how we would know someone is a zombie! Ask what it is to be a zombie!” Metaphysics so isolated from epistemology is, at best, an exercise in fantasy.

56. THE CURSE OF THE CAULIFLOWER

I see you tucking eagerly into a helping of steaming cauliflower, the merest whiff of which makes me faintly nauseated, and I find myself wondering how you could possibly relish that taste, and then it occurs to me that to you, cauliflower probably tastes (must taste?) different. A plausible hypothesis, it seems, especially since I know that the very same food often tastes different to me at different times. For instance, my first sip of breakfast orange juice tastes much sweeter than my second sip if I interpose a bit of pancakes and maple syrup, but after a swallow or two of coffee, the orange juice goes back to tasting (roughly? exactly?) the way it did during the first sip. Surely (ding!) we want to say (or think about) such things, and surely (ding!) we are not wildly wrong when we do, so... surely (ding!) it is quite okay to talk of the way the juice tastes to Dennett at time t, and ask whether it is just the same as or different from the way the juice tastes to Dennett at time t’, or the way the juice tastes to Jones at time t. Call these ways things can seem to us qualia.

This “conclusion” seems innocent, but right here we have already made the big mistake. The final step presumes that we can isolate the “qualia” from everything else that is going on—at least in principle or for the sake of argument. What counts as the way the juice tastes to x can be distinguished, one supposes, from what is a mere accompaniment, contributory cause, or by-product 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.

The examples that seduce us are abundant in every modality. I cannot imagine, will never know, could never know, it seems, how Bach sounded to Glenn Gould. (I can barely recover in my memory the way Bach sounded to me when I was a child.) And I cannot know, it seems, what it is like to be a bat (Nagel, 1974), or whether you see what I see, color-wise, when we look up at a clear “blue” sky. These everyday 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 act of philosophical distillation. Thus are qualia born.

“Qualia” is a “technical” term for something that could not be more familiar to each of us: the ways things seem to us. Nothing, it seems, could you know more intimately than your own qualia; let the entire universe be some vast illusion, some mere figment of Descartes’s evil demon, and yet what the figment is made of (for you) will be the qualia of your hallucinatory experiences. Descartes claimed to doubt everything that could be doubted, but he never doubted that his conscious experiences had qualia, the properties by which he knew or apprehended them.

This definition of qualia may seem clear enough—the ways things seem to us—but although qualia thus introduced have been the subject of much analysis and discussion by philosophers, there is still no consensus about just what the term means or implies, technically speaking. Many cognitive scientists have made the charitable assumption that philosophers must know what they are talking about when they use this special term, and have added the term to their working vocabulary, but this is a tactical mistake. Controversy still rages on what qualia are and aren’t, quite independently from any empirical issues. Some years ago, in an essay, I (1988a) proposed that the root concept of qualia has four conditions. Qualia are

1. ineffable,
2. intrinsic,
3. private, and
4. directly apprehensible ways things seem to one.

That is to say, they are (1) somehow atomic to introspection, and hence indescribable (“you had to be there”); (2) not relational or dispositional or functional (the color red may be anxiety-provoking to some people, but that subjective disposition is not a quale of red); (3) “You had to be there, but you can’t be; they’re mine and mine alone!”; and (4) your qualia are known to you more intimately than anything else.

This is still regarded as a good starting place in most circles, but since the point of that essay was to show that nothing could meet these four conditions, there has been ample discussion of revised or improved versions of the concept, with no emerging consensus. It is not unusual for a much-used and generally highly regarded technical term to have multiple incompatible definitions—think of “gene” or “species” in biology and “cause” almost everywhere in science—but the disarray surrounding “qualia” strikes me as worse, a Trojan horse to anyone in other disciplines who thinks of the concept as a gift from philosophy that might come in handy in their own research.

I trotted out thirteen other intuition pumps (in addition to the cauliflower) in that essay, and I will not repeat any of them here, but over the years I have devised other, probably more powerful tools to wield in my continuing battle against the complacency expressed in a famous response to the challenge to say what, exactly, qualia are. Ned Block (1978, p. 281) dismissed this obstreperous query “only half in jest” by invoking Louis Armstrong’s legendary reply when he was asked what jazz was: “If you got to ask, you ain’t never gonna get to know.” This amusing tactic perfectly expresses the presumption that is my target. If I succeed in my task, this response of Block’s, which still passes muster in most circles today, will look as quaint and insupportable as a jocular expression of disbelief by a vitalist, when confronted with a person—“a living thing, mind you!”—claiming to doubt the very existence of élan vital.