The Knowledge Argument

[Interesting Ian]

Originally Posted by Paul C. Anagnostopoulos

Where on Earth did people get this bizarre concept that Mary can know what it is like merely by reading? There is nothing in physicalism that says this. Mary can indeed obtain all the knowledge about color vision by reading. What she cannot do it obtain the brain state of a person who has seen color.

People do understand the difference between knowledge and brain state, yes?

~~ Paul

I really think talking about brain states is a red herring. But just consider Android Mary instead if it makes you feel better.

[Topher Cooper]

Originally Posted by Interesting Ian

Not at all. If knowledge is not exhausted by all possible information then physicalism is refuted.

No this only refutes the hypothesis that the brain is physically analagous to a single, primarily sequentially accessed static tape recorder. This is not a claim that anyone I have ever heard of has ever claimed.

The usual claim is that the brain is an incredibly subtle, complex, dynamic information structure, in which knowledge can be encoded in many different ways, most of which have nothing to do with rote memorization of raw information. That some knowledge cannot be encoded into the physical brain by a process of external, abstract, symbolic representation presented through the senses is not even faintly in conflict with this.

[Interesting Ian]

Originally Posted by Topher Cooper

No this only refutes the hypothesis that the brain is physically analagous to a single, primarily sequentially accessed static tape recorder. This is not a claim that anyone I have ever heard of has ever claimed.

The usual claim is that the brain is an incredibly subtle, complex, dynamic information structure, in which knowledge can be encoded in many different ways, most of which have nothing to do with rote memorization of raw information. That some knowledge cannot be encoded into the physical brain by a process of external, abstract, symbolic representation presented through the senses is not even faintly in conflict with this.

I'm not sure what a "single, primarily sequentially accessed static tape recorder" means but the brain is a machine. Physicalists hold that it operates according to physical laws like anything else in the Universe. Physical laws are essentially computer programs. So the brain is essentially a computer.

You dispute that from a physicalist perspective that knowledge is exhausted by all possible information. Well if that's not true then you are saying that physicalists hold there is knowledge which, since physics only deals with information, forevermore lies outside the scope of any possible physics!

Secondly there's the issue of the brain and the knowledge it can hold. How can knowledge which is not information be encoded?? By definition only information can be encoded.

Moreover I don't see how the fact that the brain is "incredibly subtle, complex, dynamic information structure" has to do with anything. It still can only encode information -- essentially a suitably long string of 0's and 1's.

Anyway the point is this. If physicalism is correct then a suitably complex Android Mary could come to understand what it is like to experience greenness by learning absolutely everything about colour vision. Otherwise you are saying that knowledge about colour vision is not exhausted by physics and therefore physicalism is incorrect.

[David Bailey]

Originally Posted by Interesting Ian

Anyway the point is this. If physicalism is correct then a suitably complex Android Mary could come to understand what it is like to experience greenness by learning absolutely everything about colour vision. Otherwise you are saying that knowledge about colour vision is not exhausted by physics and therefore physicalism is incorrect.

Or in my version of the story, Mary still can't deduce which piece of numbered coloured paper corresponds to the colour she knows is called red, and whose physiology she totally understands.

Maybe there is some force in this argument after all. Suppose that you were building a robot version of Mary. You would need a set of "colour qualia generators", and these would have to have circuit diagrams (or whatever) one for red, one for green, and one for blue (lets assume there are just three colours for simplicity).

How do you design the red qualia generator - other than copying what is in a real brain - because as we can already see, Mary with all her knowledge can't know which one will produce which colour. You can't design the thing from lower level principles because without actual colour experience the assignment of the colours is arbitrary.

I am aware that maybe I have not put that at its clearest, but anyway...

David

[Interesting Ian]

I'm just not understanding at all why Mary has to actually experience red before knowing what red looks like -- and we're just talking about a normal human being here rather than an android.

Put it this way. Assume physicalism is true. Mary looks at a red object. Even when Mary looks away she knows what red looks like because of her memory. Memory must be stored in the brain. So the memory of redness is captured by a suitably long string of 0's and 1's.

But why can't she read up this information -- this suitably long string of 0's and 1's -- before ever seeing red? As she is supremely intelligent she would understand this and therefore she would know what the experience of redness is like, would she not?

[Topher Cooper]

You are confusing information (or, alternately, data) with knowledge. Knowledge requires that the information be properly represented. If I hand you a data dump of an image, carefully recording every pixel as a hex value, you have all the information about the contents of that image at hand -- but it is useless to you: you have no knowledge of the image's content. If, however, I hand you a print of the image then you have in your hands the information in a form from which you can obtain knowledge of the image's content.

When we write a program for a computer we tend to distinguish "program" and "data". The program is more or less static and operates on the data, which is distinct.

This is not how the brain appears to operate. When we gain information it in essence modifies the software itself -- the program that the brain is running (regardless of whether or not that program is identified as "mind" including consciousness) is changed, modified to respond, internally and externally, appropriately to the new information.

If by "all of the knowledge about color" you mean objective information about color, then clearly Mary will not have gained knowledge about the experience of perceiving color -- that, from a physicalist perspective would require that the information be incorporated into the structure of the brain in a way that is simply not possible from symbolically processed abstract data. Just like a picture of something is not at all the same as the thing itself, knowledge about something is not the same thing as knowledge of that thing.

This is true even if the information that Mary receives includes knowledge about how color perception affects the brain, or even very specific knowledge on how it would affect her unique and individual brain.

If, on the other hand, by "all of the knowledge about color" you mean to include knowledge of the experience -- what it "feels like" to see color, then the question answers itself. A mental idealist would say that this is an impossible situation, a paradox, and could never occur.

A "physicalist" on the other hand, would say that this knowledge would essentially be the program itself as modified by the experience of seeing color: a list of tweaks to the neurons and (possibly) other brain parts to bring it into conformance with this experience, and "learning it" would be applying this patch to Mary's brain, after which Mary would have the knowledge of what it feels like to see color every bit as much as anyone else.

The argument then simply becomes circular. If you believe such knowledge is beyond physical representation than you conclude that the knowledge cannot be conveyed by modifying the brain and therefore this is a telling example, and disproves that knowledge is beyond physical representation. If, however, you believe that such knowledge is represented in the brain structure, then you can conclude that, at least in principle, such information can be transmitted and "learned" without direct experience.

This is the fallacy of "begging the question", i.e., using the desired conclusion to prove the conclusion.

[DysonSphere]

Originally Posted by Paul C. Anagnostopoulos

Mary can indeed obtain all the knowledge about color vision by reading.
~~ Paul

No, She cannot gain all the knowledge about color vision by reading. She can know all the things about how the brain integrates the experience of red but She does not know what it is like to see red.

(BTW I forgot that the thought experiment does not say Mary is colorblind, just that she never saw the color red until after figuring out all the physical facts about color vision. I thought I would clarify.)

And what do you mean 'where did I get this bizarre idea'? That is exactly what the philosopher Dan Dennett claims.

He (Dennett) argues that Mary would not, in fact, learn something new if she stepped out of her black and white room to see the color red. Dennett asserts that if she already truly knew "everything about color", that knowledge would include a deep understanding of why and how human neurology causes us to sense the "quale" of color. Mary would therefore already know exactly what to expect of seeing red, before ever leaving the room.

That is where I got the bizarre idea. Although Dennett does not speak for all physicalists I would argue that he presents the only coherent physicalist position.

So, is Dennett right? I wouldn't count on it.

[Topher Cooper]

I would say that Dennet is absolutely and trivially right. If Mary truly knew "everything about color" -- not just what can be conventionally represented symbolically for communication -- then by definition Mary knows that specific thing about color. The disagreement is whether it is possible, even in principle, for Mary to know everything about color -- specifically whether it is possible for Mary to have true knowledge of the experience of color without having had the experience. No one is claiming that knowing about the experience is adequate.

This is a circular argument whichever side of it you are on.

[Interesting Ian]

I'm not really sure what the point you're getting at Topher Cooper.

Is this Mary argument supposed to disprove physicalism?

Or is it a response to the physicalists claim that even qualia are physical?

If the physicalists are right then a complete knowledge of the science of colour vision should tell you what it is like to experience redness.

But this Mary thought experiment seems to suggest she would indeed learn something new on first seeing red.

Of course Dennett may deny this and maintain Mary would know what it is like to see red before she does so, but his claim is the extraordinary one and therefore requires extraordinary evidence -- or at least compelling reasons (although perhaps he gives them. I don't know!).

In the absence of any such extraordinary evidence or compelling reasons we should assume physicalism to be false.

So I don't understand how this Mary thought experiment is circular. It gives a prima facie reason to reject physicalism.

[Paul C. Anagnostopoulos]

Originally Posted by Ian

I really think talking about brain states is a red herring. But just consider Android Mary instead if it makes you feel better.

Yes, it's treated as a red herring by neurologically illiterate philosophers who don't want to lose one of their cherished intuition pumps.

So let's consider Android Mary: What kind of vision system does she have?


~~ Paul