Blogosophy

Hi again Joshua,
I need to reply to your last comment because I feel we are understanding differently the concept of zombie. For me, a zombie is an organism that has the exact same fisical structure and dynamic of a normal human being, and yet it has no qualitative properties to its "mental" states. Because every aspect of its behavior is identical to a normal human being, there is no empirical assumption backing up the concept of zombies (you seem to think there is). It is just a mental experiment, a possibility (maybe not in the real world, but at least in our minds).
So when you say:
"If neuroscientist pin down a specific brain-state that correlates exactly with "seeing" or "not seeing", that is being both aware of the perception when it's there, and aware of its absence and the peculiarity of that absence when it's not, then is there any reason not to identify that brain-state with having qualia?"
My answer is no. There is no reason not to identify that brain-state with having qualia, but at the same time, there is no reason to identify it with it. And that is the whole point of the zombies.
What do you think?

I think, as I said, that if there's nothing whatsoever empirical about Zombiehood, then you might as well jump directly to Solipsism. At least it's more parsimonious. If qualia are an indetectible metaphysical add-on, why posit that they exist in the first place? You might think that you experience them, but then so would a Zombie. A Zombie might even argue as you do, that although it's not a Zombie such creatures are conceptually possible.

Basically, I think that if you can conceive of X having or lacking metaphysical property A completely independently of any empirical facts about X, then property A is ill-defined and you're not really conceiving of X+/-A clearly in the first place. It's trading on a laxity in what it means to conceive of something, like a stone so heavy that not even God can lift it, or a square circle, or the color bleen. This relates to the whole discussion, that I think started on Brian Weatherson's blog, about imaginative resistance, and whether you can read a story in which, say, there is an even number not divisible by two and imagine it in the same way as a story in which, say, Godel's Incompleteness Theorem is false.

That's what my Deadite example is supposed to be getting at. As far as I know nobody seriously entertains the notion that being alive is a metaphysically distinct thing from having all the empirical properties and behaviors of a living being, so that you could have a being that appears to every conceivable test to be a living human being, but actually lacks "vitality" and is really an inanimate that just appears alive (a Deadite). Yet people seem to find the exactly analogous case of a Zombie plausible, even inevitable. I think that's because people think that they have an immediate, unitary, irrefutable experience of "qualia" in a way that they don't for "vitality"--but I also think that modern neuroscience indicates that they're fooling themselves: subjective sensations are complex, mediated, take place over time, are fragmentary, and are fallible. There's hardly anything about a sensation that somebody can't be mistaken about--sometimes this only manifests itself in people with certain kinds of damage, but in many other aspects mistakes can be induced in normal people on demand.

So here's two questions:
1) If Zombies, why not Solipsism?

2) If having certain brain-states isn't the essence of experiencing certain qualia, how is it that qualia are dependent on brain-states? I.e., If qualia are independent of brain-states, how come inability to have certain brain-states absolutely prevents certain qualia from ever occuring (e.g. damage to the brain that prevents the perception or memory of color)?

You said: I think, as I said, that if there's nothing whatsoever empirical about Zombiehood, then you might as well jump directly to Solipsism. At least it's more parsimonious.

Yeah, you might if you want to. Although there is no logical link between the possibility of Zombiehood, and concluding that if a Zombie can exist, then the rest of humanity must be a Zombie as well. It could be though. I have to point out that, to my knowledge, people that make use of the concept of Zombies (such as Chalmers of Koch) do not really believe in their existance… it’s just a theoretical construct to make a point. And the parsimony is greatest if we think that Zombies do not exist, given that I know I am not a zombie (but parsimony doesn’t prove or disprove anything).

You said: If qualia are an indetectible metaphysical add-on, why posit that they exist in the first place?

Because we feel them (so they are not indetectables… we detect them always)

You said: You might think that you experience them, but then so would a Zombie.

Sure, but the difference is that a Zombie, by definition, wouldn’t feel them. And since I feel them, I know I’m not a Zombie (you could also say that the Zombie wouldn’t “think” that he is experiencing them, because he doesn’t think. He is just a structure with behaviour. He can say he thinks, without thinking, just as a computer could).

You said: A Zombie might even argue as you do, that although it's not a Zombie such creatures are conceptually possible.

Yeah, that’s why it’s a hard problem this one on qualia… if it was amenable for experimental approaches, then it would be an easy problem (using Chalmer’s definitions).

You said: Basically, I think that if you can conceive of X having or lacking metaphysical property A completely independently of any empirical facts about X, then property A is ill-defined and you're not really conceiving of X+/-A clearly in the first place.

I couldn’t agree more with you.

You said: That's what my Deadite example is supposed to be getting at. As far as I know nobody seriously entertains the notion that being alive is a metaphysically distinct thing from having all the empirical properties and behaviors of a living being, so that you could have a being that appears to every conceivable test to be a living human being, but actually lacks "vitality" and is really an inanimate that just appears alive (a Deadite).

Again I agree. But also I think that the Deadite analogy can only be taken so far… for the reasons you put in the next paragraph.

You Said: Yet people seem to find the exactly analogous case of a Zombie plausible, even inevitable. I think that's because people think that they have an immediate, unitary, irrefutable experience of "qualia" in a way that they don't for "vitality"—

I agree with that. Do you EXPERIENCE qualia? Do you EXPERIENCE vitality? This is a bit of a trap, and tautology at the same time, since experience, as we are using the term, is inseparable with the concept of qualia, whereas it has no relation to “vitality”. It would be like saying, Do you live Qualia? Do you live Vitality?

You said: but I also think that modern neuroscience indicates that they're fooling themselves: subjective sensations are complex, mediated, take place over time, are fragmentary, and are fallible.

So when you say that “subjective perceptions are complex…” you mean to say that you know what a subjective perception is? Even if they are fallible, you “feel” them. You know what we are talking about. If so, can’t you imagine the possibility of a “machine” that reacts exactly like you, and at the same time has no “subjective” feelings?

You said: There's hardly anything about a sensation that somebody can't be mistaken about

Except for the fact that they ARE, in fact, having a sensation

You said: So here's two questions:
1) If Zombies, why not Solipsism?

This we already answered

You said: 2) If having certain brain-states isn't the essence of experiencing certain qualia, how is it that qualia are dependent on brain-states? I.e., If qualia are independent of brain-states, how come inability to have certain brain-states absolutely prevents certain qualia from ever occuring (e.g. damage to the brain that prevents the perception or memory of color)?

That is precisely the question we want to answer. My guess is that all your intuitions about this are right on target (and it seems that they are quite close to Dennett’s). But that is no reason to discredit the concept of Zombie a priori.

ses plate il a pas histoire de zombies

For a history of Zombies, at least in philosophy try "The Stanford Encyclopedia of Philophy entry":http://plato.stanford.edu/entries/zombies/