Materialists......

[UndercoverElephant]

"regardless of ontology" must mean - "there is no ontology where it would be inconsistent"?

Do you agree with my clarification?

Actually, yes. The definition a p-zombie isn't even inconsistent "under materialism". P-zombies aren't defined "under metaphysical positions". They are defined in terms of minds and brains. In doing so, their definition can cause problems for some metaphysical positions - namely materialism. But all you need to define a p-zombie is two definitions: that of a brain and that of a mind. We all know what brains are (except 'gazer). "Minds" are defined via their normal dictionary usage i.e. "mind" has to actually mean "my subjective experiences". Now - you can do all of the above without assuming any metaphysical positions at all. However, there is one special case, and it is eliminativism. Assuming elimativism at this point is banned, but it is not banned to deny that the word "mind" has a meaning. An eliminativist does not neccesarily need to invoke eliminativism in order to deny that minds exist. He just denies that minds exist. You will not find Paul Churchland arguing "If eliminativism is true, minds don't exist, therefore zombies cannot be defined and cannot exist." Instead, he provides other arguments as to why the word "mind" cannot mean anything. He claims it is part of folk psychology, which is an "incorrect theory" with "bad parentage". So Churchland cannot define a p-zombie, but not because he tries to "define it under eliminativism", but because he has other, non-metaphysical reasons for rejecting the word "mind". All the other forms of materialism allow definitions of mind which match the dictionary, they just go on to claim that mind is reducible to matter. This is irrelevant at this point. All that matters is the non-eliminative materialist knows what is meant by "my subjective experiences". So the zombie argument assumes materialism is a supervenience theory - and this has also already been stated. If you deny supervenience then you are either a non-materialist or you are an eliminativist, so the p-zombie argument either doesn't matter to you or fails on the grounds that you can't define "mind" and p-zombies need the word "mind". This causes an implicit problem for supervenience materialists because they have two usages of the word "mind" - they want it to mean two things at the same time. That's supervenience materialist's problem, not mine. As long I can agree with him that for the purposes of the p-zombie argument "mind" has it's original and proper usage, rather than his incoherent double-usage, there is no problem. The whole point of the argument is show that supervenience materialism is incoherent/false, so you cannot refute the argument by assuming supervenience materialism is true and then claiming that p-zombies are undefinable.

I hope the above is all clear now. I do not want you to define p-zombies "under materialism" or "under" any metaphysical position at all. All you need is the word "mind" and it's standard meaning of "the totality of my subjective experiences". Can you allow that definition of mind? If not, why not? *DO NOT ASSUME ANY METAPHYSICS*

Why not, aren't they any good? Or are you afraid that they will agree with me?

My lecturers are just fine. The problem is that LW is a better logician than me, and he already disagrees with you - so I see no reason at all to defer to you as an authority on logic.

Well if he is prepared to vouch his reputation on the statement that:

"T is a subset of S and a is not a member of S"

would be consistent whether or not a was a member of T then he ought to practice a little harder.

If he is prepared to commit himself to the assertion that the definition:

"A p-zombie contains all the physical characteristics of a human being and is not conscious"

...would be consistent whether or not consciousness was a physical characteristic of a human then I would have to ask in what capacity he practices as a logician.

Well, we are waiting to see what LW has to say for himself.

 

[Darat]

...snip..

So, to recap, the problem with the p-zombie "proof" is that it has a hidden assumption that there are p-zombies. Not that it assumes its conclusion. If we remove this assumption, the inconsistency vanishes. Also, then we can't conclude that consciousness is not physical.

Thanks for the post LW, I followed all of it apart from the stuff with symbols in it...

Just a point this may just be a matter of both everyday English usage being different from when we try to use English to make a "formal" statement of logic and how the p-zombie argument ends up being discussed.

I've posted many times that the p-zombie argument only stands up if you assume p-zombies do exist but since most definition of "materialism" would state they can't exist I have then gone on to say that a flaw in the p-zombie argument is that it "assumes its conclusion" i.e. that "materialism" is false. I think this is because the p-zombie is normally brought up by people who are saying "materialism is false" so I have conflated the "materialism is false" part with the p-zombie argument and as you have so clearly demonstrated that is in fact not part of the p-zombie argument.

Thanks - always good to learn!

 

[UndercoverElephant]

I would love to see the Zombie argument posted in full. Definitions, premise, argument and conclusion, with details of how each statement is justified.

I believe that if anybody were ever to try this they would see the illogicality of the argument straight away.

*ASSUME NO METAPHYSICS*

However, assume that materialism is a supervenience theory, not an eliminativist theory.
Also, assume S5 modal logic is validly applicable in this case.

"Mind" = "the totality of subjective experiences"
"Brain" = "squidgy meat in your head"
"Zombie" = Brain but no mind.

*STILL ASSUME NO METAPHYSICS*

Could you do the above? If not, why not? Was it because you failed to assume no metaphysics?

If you managed to get this far, the rest is simple:

(1) Zombies are possible.
(2) If zombies are possible then materialism fails.
(C0) Therefore, materialism fails.

 

[Darat]

*ASSUME NO METAPHYSICS*

However, assume that materialism is a supervenience theory, not an eliminativist theory.
Also, assume S5 modal logic is validly applicable in this case.

"Mind" = "the totality of subjective experiences"
"Brain" = "squidgy meat in your head"
"Zombie" = Brain but no mind.

*STILL ASSUME NO METAPHYSICS*

Could you do the above? If not, why not? Was it because you failed to assume no metaphysics?

If you managed to get this far, the rest is simple:

(1) Zombies are possible.
(2) If zombies are possible then materialism fails.
(C0) Therefore, materialism fails.

"Mind" = "behaviour"
"Brain" = "squidgy meat in your head"
"Zombie" = Brain but no mind.

*STILL ASSUME NO METAPHYSICS*

Could you do the above? If not, why not? Was it because you failed to assume no metaphysics?

If you managed to get this far, the rest is simple:

(1) Zombies are not possible.
(2) If zombies are not possible then nothing.
(C0) Therefore, nothing.

 

[UndercoverElephant]

As we saw before, the set P is consistent. So the only possible answer to this is: "Yes". You get only the contradiction when you add in M.

Exactly.

When we are examining pure mathematical logic, we have no reason to prefer the set M over P or P over M. The situation is completely symmetric. Any reason for us to choose one has to come from outside logic.

Exactly.

Consider this final example that is perhaps THE standard example of valid reasoning:

(a) All men are mortal.
(b) Socrates is a man.

And the conclusion that we get is "Socrates is mortal". Have we now committed the fallacy of assuming our conclusion? By the reasoning you used above, we have. Because if we add the sentence:

(c) Nothing is mortal

to the set we get an inconsistency. This is exactly the same that happened with P and M. Adding M to P results in inconsistency. Adding (c) to (a) and (b) results in inconsistency. So, if one is assuming the conclusion, then the other is also. Using your expression, "the syllogism is consistent only if we assume that its conclusion is true".

Exactly.

So, to recap, the problem with the p-zombie "proof" is that it has a hidden assumption that there are p-zombies. Not that it assumes its conclusion. If we remove this assumption, the inconsistency vanishes. Also, then we can't conclude that consciousness is not physical.

Almost. Nobody has "assumed" that p-zombies are possible. They are instead arguing that they are conceptually very easy to construct, and (Chalmers) that concievability leads to possibility. By this line of reasoning, the possibility of p-zombies has been established by a line of reasoning, not assumed. That line of reasoning is itself dependent on observing that mental and physical predicates are clearly and easily distinguishable, a fact which is true regardless of ontology. So the critical point in the argument is the jump from conceptual possibility to actual possibility.

 

[UndercoverElephant]

Thanks for the post LW, I followed all of it apart from the stuff with symbols in it...

Just a point this may just be a matter of both everyday English usage being different from when we try to use English to make a "formal" statement of logic and how the p-zombie argument ends up being discussed.

I've posted many times that the p-zombie argument only stands up if you assume p-zombies do exist but since most definition of "materialism" would state they can't exist........

At which point you have assumed your conclusion. You are claiming that p-zombies are impossible "under materialism". The zombists aren't arguing "Materialism is false, therefore zombies are possible." YOU are arguing "Materialism is true, therefore zombies are impossible." You assume your conclusion, the zombist does not. See previous post.

I have then gone on to say that a flaw in the p-zombie argument is that it "assumes its conclusion" i.e. that "materialism" is false.

And you are wrong. The p-zombie argument does not assume its conclusion. YOU, however, are doing exactly that in attempting to refute it.

I think this is because the p-zombie is normally brought up by people who are saying "materialism is false" so I have conflated the "materialism is false" part with the p-zombie argument and as you have so clearly demonstrated that is in fact not part of the p-zombie argument.

Thanks - always good to learn!

Yes, you've got it. The p-zombie argument starts from observations about concepts and language, NOT from assumptions about metaphysics.

 

[UndercoverElephant]

Actually I have just seen LW's original argument. In essence he is saying the same as me - the Zombie argument does not demonstrate that consciousness is non-physical.

Inevitably there are different routes to the same conclusion.

Yes, but your route assumes its conclusion and mine starts from trying to establish p-zombies are possible based on an argument from concepts and language, NOT from "an assumption that materialism is false". You explicitly assume your conclusion. You try to justify this by claiming that I am implicitly assuming mine. I am doing no such thing.

 

[UndercoverElephant]

There are two issues here.

1. Does "extended over space" and "not extended over space" necessarily represent a mutual exclusion?
2. Can we distinguish between mental and physical attributes even using these definitions?

My answer would still be "no" to both - I am happy to argue to both if anybody is interested.

This is progress. So are you now trying to join Paul in arguing that you cannot distinguish between mental and physical attributes instead of simply assuming your conclusion is true? If so, I direct you to the opening post of this thread, which was a rant against people making claims of this sort.

 

[Darat]

Yes, but your route assumes its conclusion and mine starts from trying to establish p-zombies are possible based on an argument from concepts and language, NOT from "an assumption that materialism is false". You explicitly assume your conclusion. You try to justify this by claiming that I am implicitly assuming mine. I am doing no such thing.

But as LW has shown in both English and formal logic the p-zombie argument you use has a problem (one which has been pointed out to you before you know... ) i.e. "the problem with the p-zombie "proof" is that it has a hidden assumption that there are p-zombies."

When your argument is reformulated to remove that assumption as LW also showed ".. we can't conclude that consciousness is not physical".

 

[UndercoverElephant]

"Mind" = "behaviour"

Sure, if "mind" = "behaviour" then zombies can't be defined. However, it means you are committed to being a behaviourist with respect to philosophy of mind, and if there's an utterly dead position in philosophy of mind, it's behaviourism. NOBODY defends it. So you've escaped the zombie argument by denying materialism is a supervenience theory. Your definition of "mind" is a waste of space. You might just as well declare that it doesn't mean anything at all - it's just "behaviour". P-zombies have behaviour. What they lack is a mind.

 

[Darat]

At which point you have assumed your conclusion. Y

...snip...

Geoff re-read what I said:

I've posted many times that the p-zombie argument only stands up if you assume p-zombies do exist...

My criticism of the p-zombie argument as put forward by you and others is that it only makes sense if you assume that p-zombies exists. So I have always "objected" to it in the same way LW apparently has, what I was saying however is that because it is often used as part of a longer chain of reasoning i.e. "p-zombies prove consciousness is not physical therefore materialism is false" I have in the past conflated the two parts of that argument in my refutations.

What I have learnt from LW's posts that is 1) when dealing with logical arguments I should remember there is a very strict meaning (in terms of logic) to the phrase "assuming your conclusion" and also that I should be much more careful when arguing against the p-zombie argument put forward as you do since my objection to the p-zombie argument has nothing to do whether materialism is false or not. (Don't forget I am not a materialist.)

 

[UndercoverElephant]

But as LW has shown in both English and formal logic the p-zombie argument you use has a problem (one which has been pointed out to you before you know... ) i.e. "the problem with the p-zombie "proof" is that it has a hidden assumption that there are p-zombies."

Have you read any of the posts I have made this morning? Because several of them address this point directly. There is no hidden assumption. There is an explicit argument from language/concepts. Because it has been declared, it's not hidden. Because it is an argument, it's not an assumption.

When your argument is reformulated to remove that assumption as LW also showed ".. we can't conclude that consciousness is not physical".

Not correct. The zombie argument cannot be said to conclusively prove that materialism is false, but not for the reasons you are giving. The reasons are explained in post #2519. The zombie argument fails because it depends on S5 modal logic, and the same logic can be used to push the zombie argument even further - to the point it effectively self-destructs.

 

[UndercoverElephant]

Geoff re-read what I said:

I've posted many times that the p-zombie argument only stands up if you assume p-zombies do exist...

My criticism of the p-zombie argument as put forward by you and others is that it only makes sense if you assume that p-zombies exists.

For about the seventh time this morning, it does no such thing. Please respond to any of my posts explaining why it is not an assumption. You can't just ignore those posts and go on claiming it is an assumption. You need to respond to what I've written on this subject.

What I have learnt from LW's posts that is 1) when dealing with logical arguments I should remember there is a very strict meaning (in terms of logic) to the phrase "assuming your conclusion" and also that I should be much more careful when arguing against the p-zombie argument put forward as you do since my objection to the p-zombie argument has nothing to do whether materialism is false or not. (Don't forget I am not a materialist.)

What are you if you aren't a materialist, just out of interest?

 

[Darat]

Sure, if "mind" = "behaviour" then zombies can't be defined. However, it means you are committed to being a behaviourist with respect to philosophy of mind, and if there's an utterly dead position in philosophy of mind, it's behaviourism. NOBODY defends it. So you've escaped the zombie argument by denying materialism is a supervenience theory. Your definition of "mind" is a waste of space. You might just as well declare that it doesn't mean anything at all - it's just "behaviour". P-zombies have behaviour. What they lack is a mind.

No Geoff what it does is again show that your argument only works if you start with the assumption that p-zombies could potentially exist in your definitions - again you've tried to "hide" this.

All I've done is used another way to show what LW did with his formal logic to your p-zombie argument, i.e. when you remove your hidden assumptions from your argument we can't conclude anything.

It would appear you've still not understood what LW has proved (according to yourself) with his formalization of your p-zombie argument i.e.

i.e. "the problem with the p-zombie "proof" is that it has a hidden assumption that there are p-zombies." and when your argument is reformulated to remove that assumption ".. we can't conclude that consciousness is not physical".

 

[UndercoverElephant]

No Geoff what it does is again show that your argument only works if you start with the assumption that p-zombies could potentially exist in your definitions - again you've tried to "hide" this.

No, Darat, you still don't get it, even though it's very simple. Since you obviously won't believe it from me, I'll let LW explain it to you. You are completely wrong, and apparently incapable of reading. You aren't actually responding to the content of my posts on this page. You are just repeating the words "You made an assumption, LW said so!" like a demented parrot.

It would appear you've still not understood what LW has proved (according to yourself) with his formalization of your p-zombie argument i.e.

NO, Darat. I understand it. YOU don't. I know what he wrote. I know why he wrote it. I have explained why it's not strictly true. You have ignored that explanation and keep quoting LW's original statement.

Pretty Polly Wants A Cracker.

 

[Darat]

No, Darat, you still don't get it, even though it's very simple.

...snip...

You are right in one sense I have made a mistake I should have been quoting from LW's original post where he demonstrated the error in your logical reasoning.

Because it is such an elegant post I think it's worth re-posting, with a few parts er.. highlighted...:

Let's put that one into modern syntax and look it more closely. I'll use the notation where "A(x)" denotes that x is an attribute of a human being, "P(x)" denotes that x is physical, "Z(x)" that x is a zombie, "H(x, y)" denotes "x has y", and finally, the constant "c" denotes the specific property of consciousness.

The first proposition becomes:

[latex]$P_1$: $\forall p\forall a ( A(a) \land P(a) \land Z(p) \rightarrow H(p, a))$[/latex]

Or in plain English: "If 'a' is a physical attribute and 'p' is a zombie, then 'p' has the attribute 'a'."

The second proposition becomes:

[latex]$P_2:$ $\forall p (Z(p) \rightarrow \neg H(p, c))$[/latex]

In plain English: "If 'p' is a zombie, then 'p' does not have consciousness."

I hope that you agree with this formulation.

Then there was also the zeroth premise, that consciousness exists as an attribute. I am willing to grant this to you for the sake of this argument so let's formalize it also:

[latex]$P_0$: $A(c)$[/latex]

The question then is that is nonphysicality of consciousness a logical consequence of the above set of three formulas.



In predicate calculus a formula f is a logical consequence of a set S of formulas if and only if f is true in all models of S. That is, if all premises are true, then f has to be true also. There is a nice theorem that states that f is a consequence of S if and only if the set of formulas that we get by adding the negation of f to S is inconsistent.

So, we add the negation of our desired conclusion to the set of propositions and check what happens. In effect, we are trying to prove that the following set of formulas is inconsistant:

[latex]$P_0$: $A(c)$ \\
$P_1$: $\forall p\forall a ( A(a) \land P(a) \land Z(p) \rightarrow H(p, a))$\\
$P_2:$ $\forall p (Z(p) \rightarrow \neg H(p, c))$ \\
$C$: $\neg \neg P(c)$[/latex]

(Note that the double negation in C is in purpose, the desired conclusion is that c is not physical, so by negating that we get the second negation symbol).

What happens is that we are not able to derive a contradiction from the set. In fact, we can easily construct a model for it. The model is the following structure:

[latex] $U = \{ c \}$ \\
$A = \{ c \}$ \\
$P = \{ c \}$ \\
$Z = \emptyset$ \\
$H = \emptyset$
[/latex]

Let's go through the set of sentences to verify that all of them are satisfied. Since c is in interpretation of A, P₀ is satisfied. Since the interpretation of Z is empty, the left sides of the implications P₁ and P₂ are trivally false, so the implications themselves are satisfied. Finally, since c is in the interpretation of P, neg neg P(c) is also true.

So the above structure is a counter model for the claim that neg P(c) was a logical consequence of the three premises.

What does this mean in plain English? It means that from the set of premises we can't conclude that consciousness is necessarily not physical.

Why was my conclusion different from yours? It is because your syntax hid one crucial assumption, and it did it so well that you probably didn't notice it yourself: That p-zombies exist. It is there: "a p-zombie has... a p-zombie is not". If we add the premise that there exists at least one p-zombie, then neg P(c) becomes a consequence. But without it, it doesn't work.

In effect, your proof says: "If p-zombies exist, then consciousness is not physical". I have nothing to say against that. I fully agree.

Of course, I don't believe that p-zombies exist, but that is a completely different matter.

 

[UndercoverElephant]

Posted by Darat:

Because it is such an elegant post I think it's worth re-posting.....

http://upload.wikimedia.org/wikiped...Gray_parrot.jpg/200px-Buberel_Gray_parrot.jpg

 

[Belz...]

(1) Zombies are possible.

(2) If zombies are possible then materialism fails.

(C0) Therefore, materialism fails.

It's that simple. Clearly, the materialist is embarrassed by this argument.

Well, (1) is only true if materialism is false. How ISN'T that circular ?

How about this one:

(1) Pink flying unicorns are possible
(2) If pink flying unicorns are possible, then evolution fails
(CO) therefore, evolution fails.

 

[Darat]

Posted by Darat:




http://upload.wikimedia.org/wikiped...Gray_parrot.jpg/200px-Buberel_Gray_parrot.jpg

I take it then you concede that LW and I are both correct when we spotted the assumption you have been making all along? In LW's words:

Why was my conclusion different from yours? It is because your syntax hid one crucial assumption, and it did it so well that you probably didn't notice it yourself: That p-zombies exist. It is there: "a p-zombie has... a p-zombie is not". If we add the premise that there exists at least one p-zombie, then neg P(c) becomes a consequence. But without it, it doesn't work.

 

[Belz...]

concievability leads to possibility.

No. No it doesn't.