chalmers' theory of consciousness

Great Debates
1

I recently finished David Chalmers’ “The Conscious Mind: In Search of a Fundamental Theory.” seems to me this guy has got a watertight theory—consciousness, in the sense of “actually experiencing something rather than just reacting mechanistically to stimuli” is non-empirical, and therefore, for all practical scientific purposes, it is a non-physical thing.

My question is this: have any Dopers read this book and if so, have you formulated or heard from elsewhere any serious (i.e. crippling) criticisms of this theory? As far as I can tell, Chalmers has really come up with something revolutionary here.

2

For anyone who hasn’t read the book (like me), you’ll have to expand on his theory a bit, because what you said is completely opaque.

3

Uhmm, I don’t know how that can be “revolutionary.” While I doubt that your recapitulation of the “theory” is quite as exhaustive as the book, it sounds to me like it basically says, “It is untestable so you can’t prove it’s wrong.” This is not a theory, in the scientific sense of the word. It leaves no room for debate.

4

I read the book, and though it was quite interesting, I just couldn’t buy it. Here are some flaws as I see them:

  1. Chalmers concluded that consciousness is a physical phenomenon, as opposed to a logical one. In other words, it is entirely logically possible that we could live in a “zombie” world – one in which all observable physical facts are identical but consciousness does not exist.I read Chalmers’s book about six months ago, and though his theory was quite interesting, I just couldn’t buy it. Bear with me if I don’t remember everything perfectly. Here are the flaws with his theory as I see them:

Chalmers concluded that consciousness is a physical phenomenon, as opposed to a logical one (In his terminology, it is physically but not logically supervenient on the physical state of the world). In other words, it is entirely logically possible that we could live in a “zombie” world – one in which all observable physical facts are identical but consciousness does not exist.

Chalmers believes that, though a zombie world is logically possible, we do not live in one. The reason for this is that the physics of our universe cause certain types of informational systems to be subjectively conscious. The only evidence for this theory comes from personal experience.

As I see it, one of the major goals of any theory of consciousness is to refute solipsism. Chalmers’s theory fails to do this. Going by his theory, you see, there is no reason to believe that the laws of physics necessarily cause every human being to be conscious. Because it is logically possible that zombies can exist, and the only consciousness that any person can have evidence of is his or her own, his theory lacks any way to establish the consciousness of those around us.

Any theory that proposes that zombies are logically impossible avoids this trap.

Like many who attempt to study consciousness, Chalmers focuses heavily on a description of qualia. The word “qualia” is considered to apply to the subjective aspects of experiences, as opposed to anything objectively measurable in the physical world; e.g. the feeling of redness as opposed to a red object or the behavior of a person upon perceiving the color red. He proposes that, though they cannot be detected by any scientific apparatus, qualia have an existence just as real as anything material.

How does Chalmers decide the properties of qualia? It seems to me that he merely states them as obvious. In one section of the book, he deals with objections to his theory. Some others in his field propose that the idea of qualia is useless because the idea cannot be nailed down. How can a person know that sensations that caused the qualia of redness yesterday don’t cause the qualia of blueness today? Chalmers states that such a thing is impossible, because it would be noticeable. He fails to take account the fact that, by his own theory subjective experiences are merely affected by the material world and cannot affect the material world themselves.

Let’s say that your red and blue qualia were switched. (note that such speculation is possible because Chalmers considers qualia to be physically existen though non-material phenomena which could, then, logically have any properties whatsoever). Now, Chalmers admits that subjective experiences are determined by neurological factors. A change in qualia wouldn’t alter the fact that the sight of a red object will call back memories of previous red sights, and the equivalent for blue. If a change in qualia were to alter our subjective experience in any way, then there are two possible outcomes:

  1. This change will cause a change in behavior, i.e. the spoken phrase: “Hey, why did this apple just turn blue?” If this is the case, qualia can change the physical world. This would change Chalmers’ theory from one that is merely non-materialist to one that is downright vitalist; a step that few would be willing to take.
  2. This change will not cause a change in behavior. Instead, behavior will become divorced from consciousness In this case, you would be aware of seeing red and blue switch, but would be unable to voice this observation. Instead, you would become aware of losing control of your own actions. Your body, which is affected only by physical laws and not by qualia, would continue on as if nothing had happened, leaving you trapped and powerless.

Chalmers only considers possibility #2. Because this (he believes) clearly does not occur, qualia cannot shift. Nor, by similar reasoning, can they fade away, or blink on and off, or behave in any other non-static way. (It’s not that the world would be any different if they did, it’s that he–David Chalmers, as a conscious observer–would notice.

I consider this a weak defense. Chalmers determines the properties of qualia based on what properties are necessary for his theory to work. If their properties are, in fact, different, then they do not describe what we normally think of as consciousness, and therefore might as well not exist. One must simply postulate that qualia correspond perfectly to whatever factors determine measurable behavioral factors.

Chalmers determines that material “stuff” cannot have the properties that we normally ascribe to consciousness. However, his attempt to get around this comes down to the postulation of a new type of “stuff” – one that, because it is unknown and undetectable, can be proposed to have any properties that we want it to have. What he does not realize is that by defining qualia as objectively existent phenomena he allows them to fall victim to the same arguements that showed that physical “stuff” cannot give rise to consciousness.

In his theory, Chalmers uses pure reason to speculate about consciousness – which he determines to be a phenomena describable by physical laws. Pure reason, untempered by observation, has been shown to be an unreliable means of accurately ascertaining physical law – just look at the “science” of the ancient Greeks from Aristotle to Ptolmy.

My fundamental objection to Chalmers’s theory is that he believes that there is no reason in the laws of logic for consciousness to arise from a human brain. If we wish to believe that this is true, we must postulate that the laws of physics must be set up just so for this to occur. I do not believe that this assumption is adequately justified.

5

Doh! Please ignore the obvious error at the top of my post. The post should begin with the text in the second paragraph: “I read Chalmers’s book about six months ago, and though his theory was quite interesting. . .”

I also see a few places where I could have written much more coherently, but what’s done is done. . . :rolleyes:

6

first of all, thanks for your enlightening response, minor editing problems notwithstanding.

“Chalmers believes that, though a zombie world is logically possible, we do not live in one… The only evidence for this theory comes from personal experience… Going by his theory, you see, there is no reason to believe that the laws of physics necessarily cause every human being to be conscious.”

Doesn’t Chalmers cover that point (at least logically) by saying, “Well, I can tell that I am conscious, and therefore not a zombie. What are the odds that, of all the humans walking around me and claiming to be conscious, I am in fact the only one who is?” Any theory in which only David Chalmers achieves qualia-producing consciousness would be, one expects, rather weak. Not that this is bulletproof, but given the nature of the question, I don’t see a much better way around it, considering that the zombie world IS logically possible.

“His theory lacks any way to establish the consciousness of those around us.”

As a more specific criticism of this point, I don’t really think Chalmers is TRYING to establish the consciousness of anyone outside the individual—especially since it is so crucial to his theory that consciousness is non-empirical, completely incapable of being measured, duplicated or verified by any source other than the first-person experiencer of consciousness. It doesn’t seem fair to nail chalmers for not providing that which he claims from the beginning to be impossible.

"Let’s say that your red and blue qualia were switched. If a change in qualia were to alter our subjective experience in any way, then there are two possible outcomes:

  1. This change will cause a change in behavior, i.e. the spoken phrase: ‘Hey, why did this apple just turn blue?’ If this is the case, qualia can change the physical world."

I’m assuming that you mean the actual, nebulous “qualia” have shifted, and that you don’t just mean that a physical change has caused me to perceive things differently (ie there’s a big difference between you somehow “repolarizing” my rods and cones and, alternatively, me actually perceiving red as blue even though no physical changes have been effected).

This is an interesting point, and I’m not sure what to do with it. Supposing, for example, i had built a computer that could recognize and distinguish between red and blue light. Anything i do to “confuse” the computer into reversing its colors would fall under the “empirical” category i just ruled out—and since there is no evidence that the computer actually experiences color at all, i would have no idea how to affect the computer’s qualia, if in fact it had any.

Which brings us to the interesting point of how one would go about switching a human’s qualia, in light of the non-empirical fiat (this only applies if you bought that part of chalmers’ argument, but i’m assuming you have). It seems impossible to do this.

So, has Chalmers just proposed the ultimate in circular reasoning, as you suggest in the below quote? Or has he found a way to think outside the box so profoundly that it just SEEMS circular to us?

“Chalmers determines the properties of qualia based on what properties are necessary for his theory to work.”

This seems harsh. Chalmers is in a bind from the beginning, seeing as how he is writing a book about consciousness based on the notion that, fundamentally, only Chalmers knows that Chalmers has consciousness, and Chalmers doesn’t know for sure about anybody else. But the only properties of qualia that Chalmers seems confident about are those properties that he observes in his own consciousness, and they consist of “the actual experience of experiencing something.” I didn’t realy notice him changing his definition as the book went on. Then again, perhaps you did.

“Chalmers determines that material ‘stuff’ cannot have the properties that we normally ascribe to consciousness.”

such as we can PERCEIVE it. however, given the example of the just-technically-conscious-because-it-has-two-states light switch, i think it is hasty to say that chalmers does not think consciousness arises out of material properties. It’s just that these are properties with which we are, and evidently shall forever remain, familiar with ONLY by dint of our own personal experience. Material but non-empirical.

“My fundamental objection to Chalmers’s theory is that he believes that there is no reason in the laws of logic for consciousness to arise from a human brain. If we wish to believe that this is true, we must postulate that the laws of physics must be set up just so for this to occur.”

Explain this more, please. How must we set up the laws of physics “just so” according to Chalmers.

Thans for bearing with me on this one…

7

You are quite right; Chalmers was very likely not attempting to establish the consciousness of those around us. It may be merely that my idea of what a theory of consciousness ought to be differs from his.

What makes Chalmers’s theory of consciousness fascinating to me is that it is a physical theory. Most writers in the field, or at least those that I am aware of, that attempt to develop a scientific theory of consciousness try to explain it either as an inherent property of certain informational systems or as something “metaphysical” and beyond comprehension. Chalmers, on the other hand, proposes that consciousness is an irreducible element of the physical world. In his theory, consciousness need not be inherently beyond human understanding, and he attempts to make a start at a fundamental theory that can explain it.

However, it seems to me that Chalmers’s theory is relatively simple; in essence, he has an intuitive conception of what consciousness is like and postulates it to be true.

With this example, I was attempting to make two point (though perhaps not very well!). One is that Chalmers’s theory makes some very big assumptions about the behavior of qualia. The other is that even these assumptions allow for behavior that would

In Chalmers’s theory the qualia that make up subjective experience are dependent entirely on the material state of the universe. If the qualia generated in one moment are different from those produced in the previous moment, by, say, red and blue sensations being reversed, there will be no subjective experience of anything strange going on.

It might seem intuitive that a person in this situation would react to the switching of red and blue. My argument is that this would not be the case. There is no pathway through which the notice of a change could alter the material processes that determine the course of thought. Given that Chalmers has not proposed any means through which a person could become aware of such a “mutation” of qualia, I propose that a person would, in fact, not be aware of it.

This doesn’t seem intuitive, but I believe that it points to a fundamental flaw in the “qualia” concept as Chalmers visualizes it. If qualia can mean anything at all, if they can rotate or blink on and off or exist in a state of quantum uncertainty, and yet not change the fact that a person remains conscious for each individual moment, then the concept has little value.

I suspect that if Chalmers were to accept my reasoning for this argument, he would correct it with an additional postulate regarding the behavior of qualia. In a similar matter he has shaped his theory to avoid other objections.

Going back to my original point: I believe that neither Chalmers’s present theory nor any more refined version of it can produce any real understanding. His qualia are physical, and therefore physical law must govern their behavior. For them to have precisely the behavior that seems intuitively right, the physical law regarding subjective experiences must be postulated to fit very tight confines. As is shown by my “color” example, unless the is tuned to great precision it produces nonsensical results.

For a theory to be useful in understanding, it must be capable of producing more information than is put into it in the form of axioms. The axioms of Chalmers’s theory merely codify what seems intuitively correct to him, and therefore it cannot produce any understanding beyond what to him seems intuitively obvious. Therefore his goal of producing the beginnings of a theory of consciousness that could ultimately be extended into a comprehensive explanation of subjective experience cannot be achieved by any explorations along this path.