Materialists......

[UndercoverElephant]

No. You need to think about this. Would the definition of a p-zombie be consistent if consciousness was physical?

In effect:

"Would the definition of a p-zombie be consistent if I assume my conclusion?"

 

[Robin]

I would have to give the zombist the benefit of the doubt that Peter Marton is presenting a straw man version of the argument to make it seem more silly than it is.

Take for example this glorious circularity:

(CT) Conceivability is sufficient for logical possibility.

(1b) Theories containing no explicit contradiction are conceivable. (PNC)

So conceivability is sufficient for logical possibility and logical possibility is sufficient for conceivablility.

And of course we cannot forget that the definition contains no explicit contradictions just so long as the conclusion of the argument is true.

Hopeless, hopeless. Can’t we find a complete formalisation of the argument from someone who believes it has merit?

 

[UndercoverElephant]

I have lost track of who is on who's side in this debate.......

 

[UndercoverElephant]

Hopeless, hopeless. Can’t we find a complete formalisation of the argument from someone who believes it has merit?

Marton believes it has merit. He just doesn't believe it is an outright falsification of materialism. Specifically, I think he is probably correct in believing that the zombie argument needs S5 modal logic to force its conclusion through, and I think he is also correct to claim that the same scheme can be used to throw a counter-zombie argument back at the zombist, thus neutralising the zombist's supposed falsification of materialism.

I don't think you are going to find a better logical explanation of what is going on here.

I've personally learned something from this thread. I've learned some details about where the zombie argument ends up (for which I thank both Paul and LW), and my curiousity has been provoked regarding S5 logic - specifically its relationship to conceptions of time. This is not the first time that S5 logic turned out to be of critical importance to something I am interested in and questions about the nature of time are also very important to me.

That said, I doubt I'm going to end up studying modal logic. Logicians are a strange type - the drummers of the philosophical world.

 

[Robin]

In effect:

"Would the definition of a p-zombie be consistent if I assume my conclusion?"

Not quite the same since the answer to this question might be "yes" or "no" depending entirely on the conclusion that I assume. (And I assume neither).

If I were to assume that consciousness is non-physical then the answer would be yes. If I were to assume the opposite then the answer would be no.

How can you not see that this definition is invalid if it's consistency depends upon assuming a particular conclusion?

If the consistency of a definition depends in any way upon the truth or falsity of the conclusion then it cannot be used to argue for that conclusion.

That is not just me. That is a hard and fast rule of logic. Ask any of your lecturers at your university and they will tell you the same thing.

 

[Robin]

It refers to things which are extended in space and persist over time, and other describable properties of the word which is extended in space and persists over time. Mental things have no location in space (we certainly can't say they are located in ones head - you can search my brain but will not find any euphoria or depression).

Well I have euphoria over finally getting what I have been asking you for so many times. Why didn't you just say this in the first place?

 

[Robin]

Marton believes it has merit. He just doesn't believe it is an outright falsification of materialism. Specifically, I think he is probably correct in believing that the zombie argument needs S5 modal logic to force its conclusion through...

Perhaps it does, but first it needs a definition that does not depend upon the truth or falsity of it's conclusion.

Without that, finer details are somewhat moot.

I don't think you are going to find a better logical explanation of what is going on here.

You are probably right. The argument has never even been semi-formalised by any of it's proponents. For obvious reasons.

I've personally learned something from this thread. I've learned some details about where the zombie argument ends up (for which I thank both Paul and LW)

I would be satisfied to find out where it starts. I await LW's answer to my question.

That said, I doubt I'm going to end up studying modal logic. Logicians are a strange type - the drummers of the philosophical world.

Perhaps, but even the guitarist is expected to be able to keep the beat when necessary.

 

[UndercoverElephant]

Not quite the same since the answer to this question might be "yes" or "no" depending entirely on the conclusion that I assume. (And I assume neither).

If I were to assume that consciousness is non-physical then the answer would be yes. If I were to assume the opposite then the answer would be no.

What if you didn't assume a conclusion at all?

How can you not see that this definition is invalid if it's consistency depends upon assuming a particular conclusion?

Because it is possible to define and concevie of it without assuming anything about metaphysics. Why assume a conclusion?

If the consistency of a definition depends in any way upon the truth or falsity of the conclusion then it cannot be used to argue for that conclusion.

But it doesn't depend on assuming anything at all. Zombies are concievable regardless of ontology. That is the whole point.

That is not just me. That is a hard and fast rule of logic. Ask any of your lecturers at your university and they will tell you the same thing.

Robin, please stop defering to my lecturers on logic. YOU are the person telling a practising logician (LW) he doesn't know how to do his job, remember?

 

[UndercoverElephant]

Well I have euphoria over finally getting what I have been asking you for so many times. Why didn't you just say this in the first place?

I thought I did, I just qualified it with the explanation that most materialists also mean something else by this word.

 

[UndercoverElephant]

Perhaps it does, but first it needs a definition that does not depend upon the truth or falsity of it's conclusion.

You appear to be confusing the definition of a p-zombie with an argument about p-zombies.

I would be satisfied to find out where it starts. I await LW's answer to my question.

Me too. I'd also like to see lifegazer go head to head with Bubo...

Perhaps, but even the guitarist is expected to be able to keep the beat when necessary.

LW, the stage is yours.

 

[Paul C. Anagnostopoulos]

But it doesn't depend on assuming anything at all. Zombies are concievable regardless of ontology. That is the whole point.

I don't agree, but let's say I do for the sake of discussion. I'm now confused about the next step.

Zombies are conceivable. What does that say about materialism?

~~ Paul

 

[UndercoverElephant]

I don't agree, but let's say I do for the sake of discussion. I'm now confused about the next step.

Zombies are conceivable. What does that say about materialism?

~~ Paul

What do you want me to post in reply to this? A man banging his head on a computer keyboard or a bowl of petunias and the words "Oh no, not again."?

 

[Paul C. Anagnostopoulos]

What do you want me to post in reply to this? A man banging his head on a computer keyboard or a bowl of petunias and the words "Oh no, not again."?

I want you to post a succinct argument. I honestly don't undertand where you think we are.

~~ Paul

 

[Robin]

What if you didn't assume a conclusion at all?
...
Because it is possible to define and concevie of it without assuming anything about metaphysics. Why assume a conclusion?

I don't. A definition must be consistent regardless of the conclusion.

If a definition depends upon the truth or falsity of the conclusion then it cannot be used to argue for that conclusion.

But it doesn't depend on assuming anything at all. Zombies are concievable regardless of ontology. That is the whole point.

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

Do you agree with my clarification?

Robin, please stop defering to my lecturers on logic.

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

YOU are the person telling a practising logician (LW) he doesn't know how to do his job, remember?

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.

 

[Robin]

I want you to post a succinct argument. I honestly don't undertand where you think we are.

~~ Paul

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.

 

[Robin]

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.

 

[Bubo]

At this point I would like to call into question what is meant by the term "physical." If it is meant, that which is observable, then...

[edit- Just saw this]

It refers to things which are extended in space and persist over time, and other describable properties of the word which is extended in space and persists over time. Mental things have no location in space (we certainly can't say they are located in ones head - you can search my brain but will not find any euphoria or depression).

Mind you, space-time would still require an agreeable definition, which I think still ultimately hinges on one's own observations. This is my point. Materialism would appear to implicitly assume "consciousness," "mind," or what-have-you. For what is an object without a subject? This is where we take a "leap of faith..."

 

[Robin]

At this point I would like to call into question what is meant by the term "physical." If it is meant, that which is observable, then...

[edit- Just saw this]



Mind you, space-time would still require an agreeable definition, which I think still ultimately hinges on one's own observations. This is my point. Materialism would appear to implicitly assume "consciousness," "mind," or what-have-you. For what is an object without a subject? This is where we take a "leap of faith..."

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.

 

[UndercoverElephant]

I want you to post a succinct argument. I honestly don't undertand where you think we are.

~~ Paul

What do you think post #2519 was about?

Perhaps its so succinct that you can't quite believe it:

(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.

It is really is that simple. Robin keeps assuming his conclusion and offering the claim: "If materialism is true, there can be no such things as zombies." If you stop this question-begging and put the horse before the cart this becomes: "If zombies are possible, materialism fails." Robin interprets this as reverse-question begging by claiming that anyone who says zombies are possible must have assumed that materialism is false, but this is simply not the case. If I had said "If dualism is true zombies are possible. If zombies are possible, then materialism fails" then it would be as assumption of my conclusion. But if one has concluded that zombies are possible based upon something other than metaphysical assumptions, then there is no assumption of ones conclusion. That is why the argument ends up being about whether concievability entails possibility. Very few people try to challenge the conceivability of zombies, because they are so easy to describe and imagine. So they are left arguing about whether the concievability of zombies entails their possibility.

 

[LW]

Reading my previous post again I realised that in (at least) one case I wrote confusingly. I try to be more clear in this.

Robin, the thing that I was trying to convey is that you misidentified the flaw in the p-zombie proof. The proof doesn't hold water. But the reason is not assuming the conclusion.

It is simply the first two of Geoff's statements with variables assigned. You can substitute back and get to the original.

Well, let's look at that original formalization with the modern syntax and see where it leads us:

[latex]$P_1$: $\forall x . (T(X) \rightarrow S(X))$ \\
$P_2$: $\neg S(a_1)$[/latex]

And consider the set P = { P₁, P₂ }. Now, this set P corresponds with a definition of p-zombies.

A definition of logical consistency is: A set of logical sentences is consistent if and only if it has at least one model. (You can state this in several equivalent ways).

The semantics of predicate calculus is defined in terms of structures, where you have an universe U and interpretations for the predicate symbols and function symbols that occur in the statements that we are examining. The idea is that the structure tells us when each predicate is true, effectively turning them to atoms of propositional logic. We then evaluate the statements using the truth values given by the structure. If it happens that all statements are true in the structure, then it is a model of the set.

In the case of P, we can create a structure that is a model for it easily. The simplest one is:

[latex]$U = \{ a_1 \} \\
$T = \emptyset$ \\
$S = \emptyset$[/latex]

Here P₁ is satisfied because its only instance is T(a₁) -> S(a₁) and T(a₁) is false, and P₂ is satisfied because S(a₁) is false.

So, we have here a model for P which means that P is consistent. Note that the model we found does not really represent any feature of the real world. Here we examined P alone, with absolutely no assumptions about the context where we might want to place it. And before adding in the context, let's examine P's logical consequences.

A formula f is a logical consequence of P if and only if adding its negation to P results in an inconsistent set. In this case we examine the formula neg T(a_1). So, we will now examine the set:

[latex]$P_1$: $\forall x . (T(X) \rightarrow S(X))$ \\
$P_2$: $\neg S(a_1)$ \\
$C$: $\neg \neg T(a_1)$
[/latex]

Next let's examine where this leads us:

[latex]$P_1$: $\forall x . (T(X) \rightarrow S(X))$ \\
$P_2$: $\neg S(a_1)$ \\
$C$: $\neg \neg T(a_1)$ \\
$N_1$: $T(a_1)$ (from $C$) \\
$N_2$: $T(a_1) \rightarrow S(a_1)$ (from instantiating $P_1$) \\
$N_3$: $S(a_1)$ (modus pones from $N_1$ and $N_2)
[/latex]

Since both S(a₁) and its negation are entailed, the set is inconsistent and neg T(a₁) is a logical consequence of P.

To recap: when we examine only P and absolutely no other assumptions whatever, we notice that P is consistent and it entails neg T(a₁).
Note that neg T(a₁) is not itself in P. We didn't assume it, it followed from P.

Next, we can try to see what happens when we include context for it. Since we are using simplified P, we might stay simple and consider only the formula:

[latex]$M_1$: $\forall x . T(X)$[/latex]

And define the set M = { M₁ } so that we don't later have to worry about mixing statements and set of statements. The meaning for M in the zombie context is "everything is physical".

Now M is also consistent and it is trivial to construct models for it.

But if we try to put P and M together, we get an inconsistency. None of the models of P are models of M and vice versa.

It is simply the first two of Geoff's statements with variables assigned. You can substitute back and get to the original.

Well, it is a formalization of those statements (and roughly the same that Geoff intended). However, as I pointed out before, it is flawed. It is flawed because "x has y" is a binary property, something has something. When you formalize this using a unary predicate, you essentially move one of the arguments into the predicate symbol itself. So, instead of having "has(zombie,property)" as a predicate you now have "zombie-has(property)". This means that you have built the existence of zombies directly into the formalization itself so it is no wonder that it leads into a contradiction when the assumptions of materialism are added.

No. You need to think about this. Would the definition of a p-zombie be consistent if consciousness was physical?

The definition of a p-zombie is the set P (well, the flawed definition, that is). 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. So, you could have equally well used the red color to ask the question: "Would the definition of materialism be consistent if p-zombies existed?" And the answer to this too would be: "Yes", since M is a consistent set.

There is a way to phrase the questions so that the answer will be: "No". That would be: "Is P satisfied in any of the models of M?" or "Is M satisfied in any of the models of P?".

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.

In the particular case of p-zombies we can escape the inconsistency by using an altered definition P' (that was presented some pages back) that doesn't assume the existence of zombies.

If the logical consistency of the definition depends entirely on the truth or falsity of the conclusion then you have assumed your conclusion.

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".

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.