Materialists......

[UndercoverElephant]

You are CLEARLY arguing that p-zombies are different from humans.

Correct, that is part of my position.

Since you say they have all the physical characteristics of humans.....

....by definition....

, then the difference MUST be non-physical.

That is the conclusion.

Therefore you are assuming the existence of non-physical characteristics.

Where did this "assumption" take place? Everything you posted made sense until the last line. Follow the logic. The claim that consciousness cannot be physical comes at the end, not the beginning.

 

[UndercoverElephant]

How about this:

1. There are physical characteristics of humans, this is supported by definition and evidence.

By definition, yes. Not by evidence. The whole structure of "evidence" you are talking about is the evidence provided by materialistic science. Not surprisingly, it only refers to physical things.

1. There are physical characteristics of humans, by definition. We don't need any more evidence. It is prima facie true.

2. There *might* be 'non-physical' characteristics of some sort. There is no evidence for this.

No physical evidence of the non-physical? WOOO!

This could be:

2. There might be non-physical characteristics of some sort.

However, I don't see how this changes the zombie argument.

Therefore, changing the *might* to *are* requires an assumption, or evidence.

We can depend on neither of these things. Assumptions are BANNED and empirical evidence is irrelevant, since it can say nothing on the relative merits of materialism, idealism, dualism and neutral monism.

What is required to turn the "might" into "are" is a valid and sound logical argument. That is, an argument whose conclusion logically follows from its premises and whose premises are true and where none of the premises includes an assumption of the conclusion. The critical premise in this case is the claim that one can easily distinguish between mental and physical properties - that is that one can easily distinguish between consciousness and a physical brain. The first two pages of this thread were a rant against anybody stupid enough to challenge this premise.

Geoff's Premise : We can easily, clearly and consistently distinguish between mental concepts and physical concepts. NO ASSUMPTIONS ABOUT ONTOLOGY HAVE BEEN MADE.

If you accept this premise, we can continue.

 

[Darat]

...snip...


Where did this "assumption" take place? Everything you posted made sense until the last line. Follow the logic. The claim that consciousness cannot be physical comes at the end, not the beginning.

The assumption is implicit in the idea that something can be identical to a human being but not be a human being.

the p-zombie argument says that:

We have x & y
When we compare x & y we find they are identical
But y is different to x

So the p-zombie is logically incoherent in any system that defines/assumes identical to mean the same. The p-zombie is logically coherent when you place it in a system that assumes/definesthat there is something other then what we can compare when we compare x & y.

 

[DreadNiK]

The assumption is implicit in the idea that something can be identical to a human being but not be a human being.

the p-zombie argument says that:

We have x & y
When we compare x & y we find they are identical
But y is different to x

So the p-zombie is logically incoherent in any system that defines/assumes identical to mean the same. The p-zombie is logically coherent when you place it in a system that assumes/definesthat there is something other then what we can compare when we compare x & y.

At least someone understands my point.

 

[UndercoverElephant]

I think the key problem is that JG views physicalism/materialism/whatever it is as a metaphysical assumption, rather than the fact it is based the evidence to hand.

Now it is you who are uttering absurdities, Dreadnik. Materialism is a metaphysical position. Whether or not you assume it is true depends on whether or not you assume it is true, not the position itself.

As for the claim that empirical science can support this metaphysical claim all I can say is.....where on Earth did you get that idea from?

Of course it can't. If it could, this argument would have been over before it started.

And as we have seen, he doesn't like pesky evidence getting in the way of his worldview or supporting someone elses. Words alone are enough for him. Sound familiar? Religious?

YOU are the one who starts his argument from a faith-based claim : The claim that materialism is true. This is not based on evidence. It is based on nothing but your faith. So not only is YOUR argument critically dependent on a faith-based claim, you are now also claiming empirical support for that faith-based claim.

That make you an enemy of science. Science does NOT answer metaphysical questions. Science should NOT be invoked in support of metaphysical assumptions.

 

[DreadNiK]

That make you an enemy of science. Science does NOT answer metaphysical questions. Science should NOT be invoked in support of metaphysical assumptions.

That's rich coming from someone who a) ignores evidence presented to him (neuroscience) and b) uses interpretations of QM to support his position.

 

[Paul C. Anagnostopoulos]

This appears to be the argument:

premise 1: A zombie is physically identical to a human.

premise 2: A zombie is missing some "mental attribute."

conclusion 1a: The mental attribute is physical.

conclusion 1b: The mental attribute is not physical.

So what are we asking? Are we asking which conclusion is correct under physicalism?

~~ Paul

 

[Belz...]

No, that's not true either. There are a lots of differences between my position and materialism.

<fly buzzing> Yet you don't really continue that sentence to actually NAME those differences. You're either deliberately stretching the conversation, or you don't have the answer.

So I'll bite: what are they ?

One is an electro-chemical process in a brain and the other is a set of subjective experiences. They aren't just different, they are completely different. Yet somehow they are also "the same".

If they're the same, then they're the same and they're not different. If they're different then they're not the same. Stop trying to have your cake and eat it, too.

What you meant to say is "IF we FAIL TO ASSUME that minds ARE brain processes."

Rather like Robin, you seem to think that anybody who has failed to assume your conclusion must have assumed theirs.

That's a nice strawman you've got there. Mind if I joint in demolishing it ?

Practically every defence of materialism I have heard on this board in the past five years was dependent on the materialist assuming his conclusion was true. Practically every time I accused them of assuming their conclusion they responded by stating that my position could only be supported if I had assumed their conclusion was false and that my own conclusion was true. I dunno. Maybe materialists just can't cope with logic.

Or maybe those who've told you this simply understand that we BOTH have to assume our initial and respective conclusions to get anywhere. But then there's this very nasty and sticky thing called evidence.

The materialists are assuming their conclusions. I do not assume my conclusion and I do not assume that materialism is false. I am starting from an analysis of concepts.

Then why is every argument you make based on the assumption that the mind ISN'T brain processes ?

Yes. Read Nagels paper.....

I don't think it'll help me understand that empirical reasons are the only reasons I consider valid in debates like this.

 

[UndercoverElephant]

Might I suggest a fresh start?

Sure, but first we have to get clear the "assuming ones conclusion" problem.

Geoff, why don't you present your complete zombie argument one more time, in one thread. Give us a short summary of the argument, the premises, and the conclusions. I, for one, am no longer sure what you are arguing.

~~ Paul

Are you sure it would be better to start another thread? I am worried it would attract a whole load of new people saying "But why can't you see? Minds are just like software!"

Here we go:

Premise: We can clearly, consistently and easily distinguish between mental and physical concepts/predicates/characteristics.

set H = The set of all physical characteristics of a normal human.
set H* = The set of all characteristics of a normal human (M&P).
set Z = The set of all characteristics of a p-zombie.
set C = The set of characteristics of conciousness.

Definition of a p-zombie:

1. The set Z contains all the members of the set H.
2. The set Z does not contain C.

Conclusion:

3. H does not contain C.

We are right on topic, Paul. You asked me on about page 2 whether there was any actual content in my rant. Now I hope you can see why I was ranting. The critical plank that holds my argument up is NOT an assumption that my conclusion is true. It is the observation that we can reliably and easily distinguish between mental and physical concepts. Once you accept this distinction, then the above argument goes through, and it does so without having to assume its conclusion. It is for that reason that I am now faced with a bunch of people who are doing one of three things in order to deny the validity of the proof:

1) The idiotic response:

Try to claim that we cannot distinguish between mental and physical concepts, the absurdity of which provoked the original rant in the opening post.

2) The question-begging response:

They assume that materialism is true and try to feed it into the zombie argument.

3) The "At least I'll take you down with me" response:

When accused of question-begging, they try to claim that my position is no better than theirs because I'm doing the same thing when in fact I am doing nothing of the sort.

All three objections are invalid. I am now taking a lunch break. I hope to come back and discover that sanity has spontaneously broken out in this thread.

 

[DreadNiK]

I am now taking a lunch break. I hope to come back and discover that sanity has spontaneously broken out in this thread.

Well, if you are taking a break from posting, I suppose it is quite possible.

 

[LW]

1. A p-zombie has all the physical characteristics of a human being.

2. A p-zombie is not conscious"

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.

 

[Paul C. Anagnostopoulos]

Premise: We can clearly, consistently and easily distinguish between mental and physical concepts/predicates/characteristics.

I do not accept this premise. Please define characteristic.

2) The question-begging response:

They assume that materialism is true and try to feed it into the zombie argument.

What does it mean to ask whether zombies can logically exist without assuming some metaphysic? Doesn't the logic depend on the premises of the metaphysic?

~~ Paul

 

[lifegazer]

(M1) What the materialist is actually entitled to say is the following:

"Somehow, in some way that we really do not understand, subjective experiences and brain processes are one and the same thing. They must be, otherwise we cannot understand where the additional "thing" has come from. It would be incompatible with physicalism."

(M2) What the materialist is not entitled to say:

"I cannot tell the difference between subjective experiences and brain processes. They are identical, and indiscernable. I do not know what you mean by "inherently subjective". No such things exist."

In M1, there is no rank absurdity. There is an admission that we really do know the difference between subjective experiences and brain processes, an admission that we don't know exactly how one "arises" from the other, and an admission that the position being defended is being based upon a desire to defend physicalism.

In M2, we have descended to sunday-school thinking in defence of physicalism. It is plainly absurd and nobody who was thinking honestly, critically and fearlessly could ever say it.

From your OP.
M1: "subjective experiences and brain processes are one and the same thing".
M2: "I cannot tell the difference between subjective experiences and brain processes. They are identical, and indiscernable.".

You say M1 is acceptable whereas M2 is not. Yet M1 reduces so-called subjective experience to brain processes, which means that M1 = M2. Each statement says the same thing using different words.

Dualism is not credible either. This means that the only way to attack the materialist position is to argue the non-reality of matter (brains) itself.

 

[DreadNiK]

The assumption is implicit in the idea that something can be identical to a human being but not be a human being.

the p-zombie argument says that:

We have x & y
When we compare x & y we find they are identical
But y is different to x

So the p-zombie is logically incoherent in any system that defines/assumes identical to mean the same. The p-zombie is logically coherent when you place it in a system that assumes/definesthat there is something other then what we can compare when we compare x & y.

JG, please address this when you return.

 

[UndercoverElephant]

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.

WOW! Two pickled herrings later and common sense has broken out in this thread! I basically agree with everything you say here, you simply don't take account of the wider context in which this logical argument arose. When Robin originally tried to formalise it, he only took account of one portion of a larger argument. However, the portion you have very nicely turned into predicate calculus is just fine. In effect, this logic proves that IF p-zombies can exist, consciousness can't be physical. So the argument then moves on to the Nagel paper. It becomes a question about the conceivability and the actual possibility that Zombies exist. Our current conceptual scheme makes them very easy to imagine. You just imagine something which has the physical attributes but not the mental ones. The reason we do not believe they are actually possible is because it seems to contradict empirical evidence, not because they are conceptually impossible. This is the origin of the explanatory gap. We have good (empirical) reason to believe there is a neccesary connection between minds and brain. But when we approach it using our current conceptual schemes, not only is it the case that we cannot find any explanation for the neccesity of this connection, we also have some a priori reasons for believing that it is impossible to ever find such an explanation within the current conceptual framework. And this leaves at an impasse. We have an apparently neccesary connection which we are conceptually incapable of explaining. Nagel's position is that this suggests there is something wrong with our concepts. He suggests we look for a new conceptual scheme, under which the neccessary connection between minds and brains becomes obvious and transparent. At this point, p-zombies will become conceptually impossible as well as actually impossible. Do you follow?

 

[Paul C. Anagnostopoulos]

1. A p-zombie has all the physical characteristics of a human being.

I believe, for complete clarity, this should be:

1. A p-zombie has all the physical characteristics of a fully conscious human being.

Otherwise we could confuse a zombie with a defective human being.

~~ Paul

 

[UndercoverElephant]

The assumption is implicit in the idea that something can be identical to a human being but not be a human being.

Right. What you meant to say was this:

"The assumption [that consciousness is non-physical] is implicit in the idea that something can be physically identical to a human being but not be a human being."

Not quite. The conclusion that consciousness is non-physical follows from the possibility that something can be physically identical to a human being but not be a human being. We do not merely assume that something can be physically identical to a human being but not be a human being. Far from it. As you can see from Nagel's paper, we can even state that there is empirical evidence to suggest this is not possible. This makes not the slightest bit of difference because the argument doesn't rest on empirical evidence, because none is relevant to the argument. It starts with an observation that we can distinguish between brains and minds and that we cannot see an obvious reason why they should be neccessarily connected. It then proceeds to establish that p-zombies are conceivable. At this point, we still haven't assumed our conclusion.

So the p-zombie is logically incoherent in any system that defines/assumes identical to mean the same.

You meant to say that a p-zombie contradicts any system which assumes "human being" is identical to "physical properties of a human".

Woo-hoo, Darat. There is only one system that makes that assumption, and its materialism. And, yes, we already know that if p-zombies exist, materialism is false.

 

[nescafe]

But when we approach it using our current conceptual schemes, not only is it the case that we cannot find any explanation for the neccesity of this connection, we also have some a priori reasons for believing that it is impossible to ever find such an explanation within the current conceptual framework.

And these a priori reasons are... ?
(ed. or would now be a good point to start a new thread?)

 

[UndercoverElephant]

At least someone understands my point.

Yes, but it's Darat.

 

[Mercutio]

As for the mind-body problem - everything I've seen and know indicates "brain" and "mind" should be one in the same, and that ultimately free will is just an illusion. It's just that it's a VERY persistant illusion.

Articulett / Mercutio what thoughts do you have on this?

I would disagree with the statement that mind and brain are one and the same. I would agree that free will is an illusion.

Look at how we use the term "mind", and how we learned to use it. We can't read each other's private behavior (thinking, etc.--the things we do that others cannot, even in principle, observe), so how do we learn to label our own "mind"? From watching the observable behavior of those around us. We see someone "change her mind" or "make up his mind" or "be of two minds about a problem", and a host of other terms, and we observe the behavior that corresponds to these uses. Just as we learn "red" by associating the label with publicly available examples of red things, we learn "mind" by associating the label with behaviors. So..."the mind" is not the same as the brain; that is too narrow a definition by far. "Mind" is a categorical label for a range of behaviors, both public and private. "Consciousness", the same, used slightly differently, with large areas of overlap.

This is the CliffNotes version; I could write a book about it.