Parent comment is asserting that consciousness/self-awareness is an evolutionarily important feature, that consciousness is favored by natural selection.
P-zombies are vivid counterexample that points to the possibility of epiphenomenalism. There's no reason to believe that consciousness is a necessary feature for an organism to respond to its environment in a survival-enhancing way. In fact, there is some neurological evidence that suggests nerve impulses to take an action precede conscious awareness: http://www.consciousentities.com/libet.htm
P-zombies don't exist, so they are not a counterexample to anything. In fact, they cannot possibly exist, so they don't even point to the possibility of anything interesting.
>There's no reason to believe that consciousness is a necessary feature for an organism to respond to its environment in a survival-enhancing way.
The reason to believe this is that systems with "consiousness" are a strict superset of systems with "responding to the environment." They are not unrelated ideas, and in fact, the ability of an organism to survive is closely tied to this kind of behavior.
I have never heard anyone try to defend P-zomies unless they were simply unaware of what the word 'meaning' means, or how our words acquire meaning. If you know how this works, you should be able to easily see why P-zombies are a meaningless idea -- an incongruous hypothetical. (Like "what would we be talking about if I didn't exist?")
Same goes for Searle's Chinese Room argument. If you assume something that is impossible, it is easy to conclude any ridiculous thing you like. P-zombies are impossible. They are not anymore useful than any other self-contained contradiction.
I don't understand how you can be so confident of this. How are you defining consciousness? How are you measuring it? What makes you believe with such emphatic certainty that I am a conscious being and not a p-zombie? (or, if you prefer, a bot that easily passes the Turing test)
> They are not unrelated ideas, and in fact, the ability of an organism to survive is closely tied to this kind of behavior.
That's what I'm saying, consciousness is not a "kind of behavior". There is nothing behavioral about your inner experience as a conscious entity.
I think the TL;DR of the argument against p-zombies goes like this: if you have two things that are by definition indistinguishable by any possible measurement even in principle, they are by this very definition the same. Since there is, by definition, no way to tell if someone is a p-zombie or not, the introduction of the term "p-zombie" doesn't make any sense at all, and therefore why would you ever do that?
The people who argue p-zombies often do this because they want to keep consciousness as something fundamentally different than the material world, something inaccessible to science. But it's wrong. Even magic is accessible to science. By the very definition and idea of science, anything that has any causal influence on the observable universe can be studied and is in the domain of science.
The TL;DR argument against philosophical zombies is more like: if consciousness is non-causal (the consequence if p-zombies can exist), then the answer to the question "Why do I think I'm conscious" can not in any way make reference of the fact that you actually are conscious. Suppose we take the two parallel universes, and we run the same experiment in each, where the conscious and non-conscious doppelgangers are both asked the question "are you a conscious, self-aware human being?" Both of them will answer "yes" of course, and we can record and observe whatever we want about their brain states on so on, and get exactly the same results for both.
So, only one of the versions is correct, but it's only by coincidence! All the reasons that the conscious brain has to think it's a conscious human being, and answer "yes" to the question, are also in play in the zombie universe, which also answers "yes". The only difference is that in the "real" world the non-zombie brain happens to be right, for literally no reason at all.
And I think it's around this point you're supposed to realize the absurdity of the thought experiment.
That's a very bad argument. Indistinguishability doesn't entail identity. One obvious way to show this is to note that only the latter is a transitive relation. In other words, if A = B and B = C, then A = C; but if A is indistinguishable from B and B is indistinguishable from C, it doesn't follow that A is indistinguishable from C.
Of course it does, by Voevodsky's Univalence Axiom ;-).
>One obvious way to show this is to note that only the latter is a transitive relation. In other words, if A = B and B = C, then A = C; but if A is indistinguishable from B and B is indistinguishable from C, it doesn't follow that A is indistinguishable from C.
In this case, you seem to be envisioning A, B, and C as points along a spectrum, and talking about ways to classify them as separate from each-other, in which we can classify {A, B}->+1 or {B, C}->+1, but {A, C}->-1 always holds.
That's fine, but when we say indistinguishable in the p-zombie argument, we're talking about a physical isomorphism, which doesn't really allow for the kinds of games you can get away with when classifying sections of spectrum.
This isn't really germane to the p-zombie thought experiment, but:
Indistinguishability does entail identity. If I have a sphere of iron X, and a sphere of iron Y which is atom-for-atom, electron-for-electron, subatomic-particle-for-subatomic-particle identical to sphere X, and I place sphere X in position A, and sphere Y in position B, then they are still distinguishable, because one is in position A and one is in position B.
Basically, I'm not sure what the two of you mean by "the same", but I suspect you're not in agreement on it.
Identity isn't what we're measuring here, it's "humanness" or "consciousness" -- things that are behaviorally distinguishable. Up to an abstract categorical similarity.
Thus they only need to be indistinguishable up to some feature of similarity that allows them to be classified in the same group. That's why, for example, we don't have to worry about "A is the same as B except that it is 2 meters to the left."
>I don't understand how you can be so confident of this. [...] How are you measuring it? What makes you believe with such emphatic certainty that I am a conscious being and not a p-zombie?
Because p-zombies are self-contradictory. The definition of a p-zombie is a contradiction. It's like saying "suppose 1 = 2 and 1 != 2. Call this a p-zombie quality."
When you suppose that the behavior of a thing is separate from the reality of a thing, you are failing to account for how the words 'behavior' and 'reality' acquire meaning -- through observation. They cannot be different because the processes that establish their meaning are identical.
To suppose that a p-zombie could be different from a person, yet measurably identical in all aspects is a contradiction.
>How are you defining consciousness?
There is a big difference between meaning and definition. I don't have to define consciousness, I only need to know what it means. I only need to identify the use-cases where it is appropriate.
>There is nothing behavioral about your inner experience as a conscious entity.
Yes there is: behavior is the activity that you measure, and you can measure brain activity.
> behavior is the activity that you measure, and you can measure brain activity.
You've shifted your definition of "behavior" now. I thought we were talking about behaviors that impact survival and are acted on by natural selection, not minute differences in MRI scans. For purposes of the thought experiment, I certainly don't care if the p-zombie has a slightly different brain-wave. Let's say they're permanently sleepwalking, then.
I really feel like you're hand-waving at supposed contradictions here, rather than engaging with why this is a difficult problem. If you firmly reject the idea of a p-zombie, let's leave that aside for now.
Do you believe that it would be possible, in principle, to build a robot that looked and acted extremely similar to a human being? It could carry on conversations, make decisions, defend itself against antagonists, etc. in a similar manner to a human being? In your view, would such a robot be necessarily a conscious entity?
> Do you believe that it would be possible, in principle, to build a robot that looked and acted extremely similar to a human being? It could carry on conversations, make decisions, defend itself against antagonists, etc. in a similar manner to a human being? In your view, would such a robot be necessarily a conscious entity?
I don't even know that other humans are conscious entities. At least not with the level of rigor you seem to be demanding I apply to this hypothetical robot. However, if you and I were to agree upon a series of test that, if passed by a human, we would assume for the sake of argument that that human was a conscious entity, and if we then subjected your robot to those same tests and it also passed, then I would also assume the robot was also conscious.
You might have noticed I made a hidden assumption in the tests though, which is that in establishing the consciousness or not-consciousness of a human they do not rely on the observable fact that the subject is a human. Is that reasonable?
>For purposes of the thought experiment, I certainly don't care if the p-zombie has a slightly different brain-wave.
Yes, you do. Because if the p-zombie has a slightly different brain-wave, it remains logically possible that p-zombies and a naturalistic consciousness can both exist. The goal of the thought-experiment is to prove that consciousness must be non-natural -- that there is a Hard Problem of Consciousness rather than a Pretty Hard Problem. Make the p-zombie physically different from the conscious human being and the whole thing fails to go through.
Of course, Chalmers' argument starts by assuming that consciousness is epiphenomenal, which is nonsense from a naturalistic, scientific point of view -- we can clearly observe it, which means it interacts causally, which renders epiphenomenalism a non-predictive, unfalsifiable hypothesis.
Do you believe that it would be possible, in principle, to build a robot that looked and acted extremely similar to a human being? It could carry on conversations, make decisions, defend itself against antagonists, etc. in a similar manner to a human being? In your view, would such a robot be necessarily a conscious entity?
>I thought we were talking about behaviors that impact survival and are acted on by natural selection, not minute differences in MRI scans.
I was talking about the stupidity of p-zombies. Either way, those 'minute' differences in MRI scans build up in such a way to determine the survival of the mind being scanned.
>Do you believe [...] such a robot be necessarily a conscious entity?
Yes, it would. Because in order to cause such behavior to be physically manifest, you must actually construct a machine of sufficient complexity to mimic the behavior of a human brain exactly. It must consume and process information in the same manner. And that's what consciousness is: the ability to process information in a particular manner.
Even a "sleepwalking zombie" must undergo the same processing. That processing is the only thing necessary for consciousness, and it doesn't matter what hardware you run it on. As in Searle's problem: even if you run your intelligence on a massive lookup table, it is still intelligence. Because you've defined the behavior to exactly match a target, without imposing realistic constraints on the machinery.
P-zombies are vivid counterexample that points to the possibility of epiphenomenalism. There's no reason to believe that consciousness is a necessary feature for an organism to respond to its environment in a survival-enhancing way. In fact, there is some neurological evidence that suggests nerve impulses to take an action precede conscious awareness: http://www.consciousentities.com/libet.htm