Materialists......

[Belz...]

You have misread Geoff's position; both he and I agree a 100% materialist position is logical, and defensible.

I'll retract my earlier statement, then. Though I'm pretty sure that Geoff said that materialism couldn't be defended.

What he and I also agree is that we find that position "odd" in that one who makes that choice denies the most objective data point any of us have or will ever have so far as facts are available -- thought (I prefer 'intent') exists.

If you call that objective data, I can only assume you don't work in any scientific field.

 

[UndercoverElephant]

First, I'd need to know what the hell "quantum evolution" is!

I've already linked to it twice. Type it into google.

 

[UndercoverElephant]

I never admitted that science couldn't answer everything.

We know.

 

[Paul C. Anagnostopoulos]

No. What LW said was that the logical argument, as it was shown to him, assumed that zombies were possible (exactly what is meant by possible and whether this applies to all things which are concievable is another part of the argument and not relevant here - that's what the modal logic is for). What LW was not aware of was that there was another part of the argument, logically prior to the bit we are examining here, which establishes the conceptual possibility of p-zombies. So LW was correct - that portion of logic contains the unexamined assumption the p-zombies are possible. But in the complete argument, the assumption is replaced by an argument.

Now I don't know which argument we're talking about. I was talking about the original argument:

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

2. A p-zombie is not conscious"

Which one are you talking about?

~~ Paul

 

[Paul C. Anagnostopoulos]

(a) All men are mortal. (assumes that men can exist, and that we can agree what "mortal" means)

Does this assume that men can exist, or that they do exist?

(b) Socrates is a man. (assumes that Socrates is a man).

Conclusion: "Socrates is mortal".

Have we now committed the fallacy of assuming our conclusion? By the reasoning Robin uses, we have. Because if we add the sentence:

I don't understand "Because." Are you explaining why Robin thinks this assumes its conclusion?

(c) Nothing is mortal (assumes that nothing is mortal).

to the set we get an inconsistency.

~~ Paul

 

[UndercoverElephant]

Now I don't know which argument we're talking about. I was talking about the original argument:

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

2. A p-zombie is not conscious"

Which one are you talking about?

~~ Paul

There is no difference between what you just posted and:

(a) P-zombies are physically identical to humans but mindless. (assumes p-zombies are a meaningfull concept - that they can exist or are possible)

Your example just splits (a) into (a1) and (a2) as in :

(a1) P-zombies are physically identical to humans. (nothing controversial here).

(a2) P-zombies have no minds. (assumes same meaning of "mind" as given in (b)).

(b) Humans have minds. (assumes humans can agree that they have minds, assumes "mind" to mean "subjective experiences". Most people would accept both of these.)

And the conclusion that we get is "minds are non-physical". Have we now committed the fallacy of assuming our conclusion? By the reasoning Robin used above, we have. Because if we add the sentence:

(c) Everything is physical. (assumes that physicalism is true - this is an assertion of the truth of physicalism).

...then we get a contradiction.

 

[UndercoverElephant]

Does this assume that men can exist, or that they do exist?

It assumes there are such things as men (they can exist, and they also do exist - at least Socrates does/did/could), and that we all know what is meant by the term "man".

I don't understand "Because." Are you explaining why Robin thinks this assumes its conclusion?

Exactly. If the reasoning behind Robin's accusation that I assumed my conclusion is applied to the Socrates example, then it must also demand that the Socrates example is assuming it conclusion. His grounds for making the accusation was that "adding (c) creates a contradiction, therefore a conclusion contrary (c) must have been assumed at the beginning". He didn't do it in the Socrates example. He did it in the Zombie example. I am trying to show everybody why it's wrong to make this accusation in either case. Neither the Socrates example nor the zombie example actually involves an assumed conclusion until (c) is added. At this point, it is the person trying to add (c) who is assuming his conclusion (since (c) is the conclusion he wants to defend), not the person who supplied the original argument.

 

[I less than three logic]

(a) All men are mortal. (assumes that men can exist, and that we can agree what "mortal" means)
(b) Socrates is a man. (assumes that Socrates is a man).

Conclusion: "Socrates is mortal".

Have we now committed the fallacy of assuming our conclusion? By the reasoning Robin uses, we have. Because if we add the sentence:

(c) Nothing is mortal (assumes that nothing is mortal).

to the set we get an inconsistency.

There is no assumption of conclusion in a,b and the conclusion. However, adding (c) does assume the conclusion "nothing is mortal". There is an inconsistency between (c) and the previous argument. But this (quite clearly in this case) does not mean that the previous argument has assumed its conclusion. It may just mean that (c) is wrong. If (c) is correct, then it means that there must be something else wrong with the argument. Either not all men are mortal or Socrates isn't a man.

I agree with all this.

So.......

--------------------
(a) P-zombies are physically identical to humans but mindless. (assumes p-zombies are a meaningfull concept - that they can exist or are possible)
(b) Humans have minds. (assumes humans can agree that they have minds, assumes "mind" to mean "subjective experiences". Most people would accept both of these.)

And the conclusion that we get is "minds are non-physical". Have we now committed the fallacy of assuming our conclusion? By the reasoning Robin used above, we have. Because if we add the sentence:

(c) Everything is physical. (assumes that physicalism is true - this is an assertion of the truth of physicalism).

...then we get a contradiction.

No, from this, exactly as stated, there is no contradiction. The definition of p-zombies also includes the assumption that they act identical to humans, not just their physical structure. Also, the definition of mind within the p-zombie argument assumes more than just subjective experience. The p-zombie would also have subjective experience or else it would be unable to act identical to humans. Say, you hold a red object in front of a p-zombie and ask it what color it is. If the p-zombie says it is red, then the p-zombie must have some way of detecting the color of the object, be able to remember what word is associated with that color, and, also, be able to detect and understand the sounds you used to ask the question. I don't see how this is any different than our subjective experience.

 

[DreadNiK]

I agree with all this.


No, from this, exactly as stated, there is no contradiction. The definition of p-zombies also includes the assumption that they act identical to humans, not just their physical structure. Also, the definition of mind within the p-zombie argument assumes more than just subjective experience. The p-zombie would also have subjective experience or else it would be unable to act identical to humans. Say, you hold a red object in front of a p-zombie and ask it what color it is. If the p-zombie says it is red, then the p-zombie must have some way of detecting the color of the object, be able to remember what word is associated with that color, and, also, be able to detect and understand the sounds you used to ask the question. I don't see how this is any different than our subjective experience.

I concur. If it looks like a duck...and quacks like a duck...

 

[UndercoverElephant]

I agree with all this.

Good.

No, from this, exactly as stated, there is no contradiction.

Yes there is. It's here:

So.......

--------------------
(a) P-zombies are physically identical to humans but mindless. (assumes p-zombies are a meaningfull concept - that they can exist or are possible)
(b) Humans have minds. (assumes humans can agree that they have minds, assumes "mind" to mean "subjective experiences". Most people would accept both of these.)

And the conclusion that we get is "minds are non-physical". Have we now committed the fallacy of assuming our conclusion? By the reasoning Robin used above, we have. Because if we add the sentence:

(c) Everything is physical. (assumes that physicalism is true - this is an assertion of the truth of physicalism).

That is an explicit contradiction.

The definition of p-zombies also includes the assumption that they act identical to humans, not just their physical structure.

Agreed.

Also, the definition of mind within the p-zombie argument assumes more than just subjective experience. The p-zombie would also have subjective experience or else it would be unable to act identical to humans.

That is not a safe assumption. There are various conceptions of mind (such as epiphenomenalism) which would claim that subjective experience cannot have causal power - that a p-zombie would act no different to a human. A p-zombie with mind simply isn't a p-zombie. I think you want to argue that p-zombie are impossible, in your case via the argument that something which lacked subjective experience couldn't possibly behave like a human. This is a reasonable objection but it does not make any difference to this demonstration about who was assuming their conclusion. It also has some important consequences, since you appear to be claiming that not only can you distinguish between a brain process and a mind, but also that minds are causally efficacious. Is that what you want to claim?

Say, you hold a red object in front of a p-zombie and ask it what color it is. If the p-zombie says it is red, then the p-zombie must have some way of detecting the color of the object.....

Sure. But you could program a computer attached to a video camera to tell you when a red object had been placed before it. Does it follow that the computer now has a mind?

, be able to remember what word is associated with that color, and, also, be able to detect and understand the sounds you used to ask the question. I don't see how this is any different than our subjective experience.

It is different because in the case of ourselves we know that in addition to mindless data-processing, there is also the direct experience associated with seeing something red. The computer needs no such thing and almost certainly lacks it.

Geoff

 

[Mercutio]

I concur. If it looks like a duck...and quacks like a duck...

It must be an m-zombie.

 

[UndercoverElephant]

I concur. If it looks like a duck...and quacks like a duck...

....it might be a p-duck?
....it might be a remote-controlled android duck?

See #2590.

 

[Darat]

It must be an m-zombie.

Do m-zombies eat your brain but spit out your mind?

 

[Mercutio]

Sure. But you could program a computer attached to a video camera to tell you when a red object had been placed before it. Does it follow that the computer now has a mind?

Depends on your definition of mind. What implicit assumptions does your definition contain?

It is different because in the case of ourselves we know that in addition to mindless data-processing, there is also the direct experience associated with seeing something red. The computer needs no such thing and almost certainly lacks it.

Geoff

It also lacks the awareness of the direct experience, the perception of the awareness, the realization of the perception, and all the other turtles, all the way down. You have yet to tell us what it is, in addition to the mindless data-processing, that the mind does.

 

[Paul C. Anagnostopoulos]

Exactly. If the reasoning behind Robin's accusation that I assumed my conclusion is applied to the Socrates example, then it must also demand that the Socrates example is assuming it conclusion. His grounds for making the accusation was that "adding (c) creates a contradiction, therefore a conclusion contrary (c) must have been assumed at the beginning". He didn't do it in the Socrates example. He did it in the Zombie example. I am trying to show everybody why it's wrong to make this accusation in either case. Neither the Socrates example nor the zombie example actually involves an assumed conclusion until (c) is added. At this point, it is the person trying to add (c) who is assuming his conclusion (since (c) is the conclusion he wants to defend), not the person who supplied the original argument.

What does "nothing is mortal" or its negation have to do with the conclusion, which is "Socrates is mortal"? What are you using as the conclusion to the Socrates problem?

In this post, LW used "Socrates is mortal" as the conclusion:

http://www.internationalskeptics.com/forums/showthread.php?postid=1800010#post1800010

Yet LW also seems to be talking about "something is not mortal" as the conclusion.

~~ Paul

 

[Belz...]

I've already linked to it twice. Type it into google.

Well, I can't find any links from you on that subject since page 66, where you mentionned it, and Google doesn't give me much in the way of a definition or actual explanation, so far.

 

[Belz...]

deleted.

 

[LW]

OK, I've read this paper now, and it's opened up a new line of attack. It is strong stuff.

I agree. It is strong stuff. Um... No, I meant to say that I need strong stuff. The last time I've felt like this was after I graded exam papers of group of students who were on a quick conversion track from almost-bachelor's-degree to master's-degree and who hadn't taken lectures before coming to the exam.

It is not clear whether the author of this paper is as dependent on S5 as Marten thinks he is.

I don't know about other zombie-provers, but he certainly isn't dependent on S5...

[Edited to add: I should have proof-read this one more time before posting, I'm using 1., 2., and 3. in two different meanings in different places, hopefully it doesn't confuse too much.]

Like I wrote, there is much that I could say about the paper. A lot of it would be unprintable in polite circles. I might start by stating that there is no chance on earth that a paper like that would be accepted in any serious conference on mathematical logic. His proof leaves too much undefined. I have once reviewed a paper that contained a side result that was left on the air in a similar way. Even though the paper was otherwise relatively good, all three referees (I don't know who the other two were) quoted that theorem as one of the reasons why it should be rejected. [Side note: I wrote this paragraph before I realized what is really happening in the proof. If I was writing a review for, I would be very tempted to include nasty comments in it, something that I have never done.]

I haven't actually checked what I intended to check about the semantics, yet. That is because I came up with a simpler proof for refuting computationalism using similar methods as what the author uses. And the proof is so simple that it, in my opinion, demonstrates that the formalization used in the paper is fatally flawed.

For starters, the author gives three natural language propositions that come from Searle:

1. Brains cause conscious mental phenomena.
2. There is some sort of conceptual or logical connection between conscious mental phenomena and external behavior.
3. The capacity of the brain to cause consciousness is conceptually distinct from its capacity to cause motor behavior. A system could have consciousness without behavior and behavior without consciousness.

I'm not a philoshopher but from what I understand, the idea is that computationalism implies proposition two. He gives later an altered version of the statement that is essentially equivalent but speaks of computations, instead. But since his proof is about this formulation, I use it here. The third proposition corresponds with the claim that mind is not physical.

He then gives a modal logic formalization for these propositions. It goes like this:

[latex](1) $\exists x . (B(x) \land M(x))$ \\
(2) $\Box\forall x . (B(x) \land M(x) \rightarrow E(x)) \land
\Box\forall x . (B(x) \land E(x) \rightarrow M(x)) $ \\
(3) $\Diamond(B(a) \land M(a) \land \neg E(a)) \land \Diamond( B(a)
\land \neg M(a) \land E(a))$[/latex]

I could go on quite long about the reasons why (1) isn't a good formalization but that would be a lenghty tangent to non-monotonic logics and it is not relevant to the main content of this post, especially since Bringsjord doesn't use it for anything anywhere.

When I read these the first time I wondered why he fixed the system to 'a' in (3) instead of using quantifiers and variables as in (2). Because now he only says that there exists one specific brain whose external behavior may be separated from the consciousness. I'm not a native English speaker but how I understand 3. is that it speaks of the brains of all fully functioning human beings. He should have written something like this (I'm not certain whether this is the best form):

[latex]$\forall x . (B(x) \rightarrow \Diamond ((M(x) \land \neg E(X)) \lor
(\neg M(x) \land E(X))))$[/latex]

[Side note: Yes, some variants of quantified modal logic forbid modal operators inside quantiers but Bringsjord himself uses them so later in the paper so it shouldn't have been an issue. And if your logic prevents you from expressing a vital proposition accurately, you should be using some other logic anyway.]

It took me three readings of his proof before I realized that there is a very good reason for this specific formulation. Stay tuned, film at 11.

Now, this set of modal formulas is inconsistent under the modal logic M (or T as it is called in the paper). The proof is in the paper, it is nothing really important. However, it is important to note that inconsistency comes from (2) and (3) together, and (1) has no function in it.

Next, Bringsjord sets to resolve this inconsistency by proving that (2) has to be false. He does this by using the thought experiment where a persons neurons are replaced one by one by their functional equivalents. He states that Searle has identified that there are at least three possible results from it:

• V1: Everything goes smoothly and nothing strange manifests itself.
• V2: The person loses his conscious experience but the body keeps on working as usual.
• V3: The person maintains his concsiousness but the body stops working.

Bringsjord formalises these propositions (well, the latter two, he is not interested in the first case) by simply using propositional letters V2 and V3. He doesn't stop to wonder if the thought experience and its result even can be expressed using his logic and he certainly doesn't express it. [Side note: I would go for option V4: the operation is so involved that he dies under the knife losing both consciousness and the body functions.]

Next, comes his argument A1 that is the actual proof that in his opinion refutes computationalism (well, he doesn't spell it out completely, I add the missing steps. Possible mistakes in missing steps are mine). His idea is to prove that (3) is true, and then from that conclude that (2) has to be false.

[latex]P1. $\Diamond V2$ [V2 can be conceived] \\
P2. $\Diamond V3$ [V3 can be conceived] \\
P3. $\Diamond V2 \rightarrow \Diamond (B(a) \land E(a) \land \neg
M(a))$ ["clearly"] \\
P4. $\Diamond V3 \rightarrow \Diamond (B(a) \land M(a) \land \neg
E(a))$ ["just as clearly"] \\
5. $\Diamond (B(a) \land E(a) \land \neg M(a))$ [1, 3] \\
6. $\Diamond (B(a) \land M(a) \land \neg E(a))$ [2, 4] \\
7. $\Diamond (B(a) \land E(a) \land \neg M(a)) \land \Diamond (B(a)
\land M(a) \land \neg E(a))$ [5, 6]
[/latex]

Bringsjord's view is that everything that can be conceived is logically possible. That is his justification for including premises P1 and P2.

His justification for premises P3 and P4 are really "clearly" and "just as clearly" in the paper. This is the first case of Proof by Blatant Assertion that I see in the wild. [There is one "unclear" part here: is it allowed to use the same constant 'a' in both P3 and P4? I skip this problem because I didn't bother to find out what exact first-order modal semantics Bringsjord is using.]

And here we see the real reason why the (3) is defined for one specific brain instead of all brains: Because otherwise Bringsjord couldn't have concluded it from 5. and 6.. He wants to prove that 3. is true, so he formalizes it into a weaker form that he then proves.

The great irony of this cheap trick is that it was completely unneccessary. His real aim is to disprove 2. Proving (3) was just a tool to that aim.

There is a shorter, more direct proof for this result that uses less blatant assertions and that doesn't need (3) at all:

[latex]
P1. $\Box\forall x . (B(x) \land M(x) \rightarrow E(x)) \land
\Box\forall x . (B(x) \land E(x) \rightarrow M(x)) \rightarrow \neg
\Diamond V2$ ["clearly"] \\
P2. $\Diamond V2$ \\
3. $\neg \Box\forall x . (B(x) \land M(x) \rightarrow E(x)) \land
\Box\forall x . (B(x) \land E(x) \rightarrow M(x))$ [P1, P2]
[/latex]

This "clearly" is just as justified as his two instances were. He said that "it is possible that a person loses his mind while body keeps working" implies one half of statement (3). So it should be equally clear that the formula that states that minds and external behavior are equivalent implies that it is not possible for a person to lose only one of them. And we get the conclusion that (2) is false.

So, I needed only 3 steps and one blatant assertion while he needed 7 steps and two blatant assertions. I didn't even have to assume that the one person whose brain we are messing with just happens to be the only guy in the whole universe whose brain is guaranteed to produce funny effects when messed with.

But there is still more. Note that the above proof doesn't use any modal logic machinery whatsoever. We don't use any fancy inference rules involving boxes and diamonds at all. In fact, we could have saved us some trouble in writing if we had used the principle of substitution to abstract the modalities from it, and simply used C to denote (2) and T to denote diamond V2. The the proof would be:

[latex]
P1. $C \rightarrow \neg T$ \\
P2. $T$ \\
3. $\neg C$ [P1, P2]
[/latex]

See, we can reduce Bringsjord's argument to one textbook application of modus tollens!. And his own proof doesn't use any modal logic constructs, either. You can do similar substitutions there. All the boxes and diamonds in the definitions are pure smoke screen, Bringsjord could as well have worked with propositional logic from start! Even his cheating in formalizing 3. was unnecessary. I don't even go to his quite peculiar usage of "physically possible" later in the paper.

In conclusion: Bringsjord's key argument A1 can be represented in propositional logic. But we already agreed that you need modalities to discuss zombies. So his formalization is inadequate to the extreme.

 

[nescafe]

In conclusion: Bringsjord's key argument A1 can be represented in propositional logic. But we already agreed that you need modalities to discuss zombies. So his formalization is inadequate to the extreme.

I wondered why Citeseer had no other papers listed as citing this one.

 

[DreadNiK]

....it might be a p-duck?
....it might be a remote-controlled android duck?

See #2590.

Does the phrase "for all intents and purposes" mean anything to you?