Ian,
I repeat what I said before. You must demonstrate that p-zombies are logically impossible.
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Nonsense. You are claiming that materialism is impossible because p-zombies are logically possible.
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They seem to be as they are conceivable. If they are not then please explain why.
I did not say that they were not conceivable. I said that the fact that they are conceivable in no way implies that they are logically possible, or that I should have to prove that they are not, in order to hold a position which is contradictory to them.
Just because you can conceive of a scenario under which materialism would be false, does not mean that I have to formally refute that scenario as being impossible. You could spend the rest of your life making up such scenarios. Do I have to refute every single scenario you can dream up that would make materialism false?
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Materialism is incompatible with p-zombies. Unless you can somehow indicate that they are impossible how can you rationally subscribe to materialism?
I have already explained why I think they are impossible. If consciousness has
any effect on the physical world
at all, then they are logically impossible.
If someone mentions a problem in a particular metaphysic that someone espouses, a problem which seems to be very difficult to explain away, and whose existence ensures the falsity of that metaphysic, then yes, the defender of that metaphysic must defend it against that charge. Why on earth should materialists be exempt any more than idealists or dualists are??
I disagree. If there only
seems to be a problem, but I can't prove that it really is a problem, then he has no obligation to refute my
potential problem.
Doing so would, by definition, require that I know every physical fact about the world. I don't.
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No no no!!! You don't understand! I'm talking about the logical possibility. You can imagine any conceivable physical facts you like. They don't have to reflect what the world actually is.
That is where you are wrong. The p-zombie argument you posted:
1) In our world there are conscious experiences.
2) There is a logically possible world physically identical to ours, in which the positive facts about consciousness in our world do not hold.
3) Therefore, facts about consciousness are further facts about our world, over and above the physical facts.
4) So materialism is false.”
Notice the boldface. This hypothetical world must be
physically identical to ours. If I am going to prove that p-zombies are logically impossible, that means that I need to prove that a world
physically identical to ours would necessarily have to have consciousness in it. I cannot possibly prove that without knowing all of the physical facts about this world. What I can do is say that since what
I think of as consciousness clearly has an effect on this physical world, whatever aspect of consciousness these hypothetical p-zombies are missing cannot possibly be anything I have any reason to believe exists. It certainly isn't what I think of as consciousness, anyway.
If you think about it, the same must be true for you. libertarian free-will is no more compatible with epiphenomenalism than materialism is.
Are you being deliberately stupid or what?? I'm sick of repeating myself. P-zombies are conceivable, therefore we should provisionally suppose they are logically possible, therefore we should provisionally suppose materialism is false.
Should we also provisionally suppose that libertarian free-will is false? After all, I can certainly conceive of scenarios in which it is.
I do not see why you think that conceivability should imply that we assume something is true.
You are wrong, as usual. Science holds that Chemistry and Biology are logically reducible to Quantum Mechanics.
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Chemistry and Biology are clearly not logically necessitated by QM. For example we could imagine a logically possible Universe operating on the same principles as scientists in the late 19th century envisaged reality to be. In which case we would have chemistry and biology but no QM!
Well I guess that answers my question. You seriously think that we should assume that Chemistry and Biology are
not reducible to QM, until such time as we can formally prove that they are, simply because we can conceive of the possibility that they are not?
Does the concept of parsimony mean nothing to you?
Every "rule" in chemistry and biology is assumed to be logically deducible from QM, even though we cannot analytically perform that deduction.
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Why is reality logically necessitated to change according to the mathematical patterns entailed by QM?
How the Hell should I know? Do I have "God" tattooed on my forehead? But clearly science requires us to assume that it is. Otherwise we could make no predictions based on it.
Besides all this is just a false analogy anyway. Consiousness is dissimilar to biology and QM because phenomenological conscious experiences are only experienced by the subject.
Irrelevant. The point is that if we accept your notion that anything which is conceivable should be assumed to be logically possible until proven otherwise, then all of science goes right out the window, because you can
always construct an unfalsifiable conceivable scenario to contradict any scientific theory.
How about the fact that premise two flat-out claims that consciousness has absolutely no effect, whatsoever, on anything physical?
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{SIGHS HEAVILY}
This is not within any of the premises
Sure it is. In fact, that is
exactly what premise 2 means.
since one of the few things we do agree on is that consciousness has effects on the physical world.
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I disagree with him in that I believe consciousness has causal power. Perhaps not the qualia per se though.
That's the whole point. If consciousness has causal power, then p-zombies are not logically possible. Don't take my word for it. Ask an epiphenomenalist. For that matter, ask Chalmers himself. Epiphenomenalism holds that consciousness has no causal power over the physical
at all.
If he defines "conscious experience" to be our actual mental experiences, then the fact that they do have an effect on the physical world implies that premise two must be false.
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OK, you're going to have to explain this one to me.
Premise two states that:
"There is a logically possible world physically identical to ours, in which the positive facts about consciousness in our world do not hold."
If consciousness has any effect at all on the physical world, then a world without consciousness would be missing those effects. The physical facts about our world include those effects that consciousness has had on it. Remove consciousness, and those physical facts
will not be the same.
If your consciousness affects your behavior, that behavior constitutes physical facts about this world. A world physically identical to ours would have to have that same behavior, but without the cause. Some other physical cause would have to account for your behavior in the p-zombie world. But then that other physical cause would constitute
different physical facts about that world!
No such alternative world is possible, because regardless of whether the physical world is closed or not, a world without consciousness would be physically different from ours.
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Would this then imply that it would be impossible for an android to have indistinguishable behaviour from a real human being, and yet not be conscious?
No. Because in spite of the fact that the android's behavior is indistinguishable from human behavior, the android is most definitely physically different than a human being.
You could try to allow p-zombies by claiming that some physical process in the p-zombie's brain serves the causal purpose that consciousness does in a normal human, but then you are claiming that the p-zombie is not physically identical to a human.
In other words, the outward physical behavior of a p-zombie could be the same, but only if their physical structure was different. Likewise their physical structure could be the same, but only if their outward physical behavior was different. In no case could the total physical facts about the world be the same.
I suppose if you say the world is physically closed then this would follow (from my argument earlier in the thread). I concede it might be possible for such an android to exist providing the world is not physically closed. One would know it is not conscious through anomalous cognition (possibly in speaking to it we might feel that there is nothing inside there. That there is a strange sort of emptiness).
You don't need anomalous cognition. Just look at the physical structure of its brain. If its behavior is the same as that of a normal person, but it doesn't have consciousness, then it must have some physical process in its brain
that a normal person does not have that takes the place of consciousness.
If consciousness is not a brain process, but affects the brain, then in principle it should be possible to observe those effects. In the real person there would be no apparent source of those effects (assuming your beliefs are true). The android would have to have the same effects in order for its behavior to be the same as a human's, but in the case of the android, the source of those effects would have to be some physical structure or process. That is a physical difference.
But the point here is that you can only claim that a p-zombie is impossible because you believe that certain physical facts about the world give rise to your phenomenal consciousness. This kinda begs the question though doesn't it?
No, that is just the point. I claim that a p-zombie is impossible because I know that consciousness has physical effects on the world.
This is silly Ian. You are not an epiphenomenalist, so how can you possibly expect to convince a materialist that materialism is false by trying to claim that epiphenomenalism is true?
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Huh? I have already explained that I am leaning towards the view that epiphenomenalism is incoherent since since it both stipulates the physical world is closed and there doesn't seem to be any meaningful distinction between human beings and p-zombies. This obviously doesn't rule out the logical possibility that everyone who has ever existed is a p-zombie.
Actually, it does. P-zombies can only exist if epiphenomenalism is true. That is the whole point of Chalmers' p-zombie argument. Chalmers is an epiphenomenalist, and his p-zombie conceivability argument is an argument for epiphenomenalism. The whole idea is that, like you, he thinks that conceivability implies logical possibility, and therefore argues that since p-zombies are logically possible, epiphenomenalism is true.
I think what you are trying to argue for is something different than what Chalmers calls a p-zombie. I think you are referring to a p-zombie whose outward behavior is identical to a normal person's, but who does not possess consciousness. Such a person could not be physically identical to a normal person.
Unfortunately (for you), the logical possibility of such a critter in no way invalidates materialism. Fortunately for you, it doesn't invalidate libertarian free-will either. In fact, it is completely irrelevant to both of our positions.
Dr. Stupid
