The Knowledge Argument (Discussion)

University of New Orleans

I want to discuss one of the chief objections to the knowledge argument, one that surfaced in the zombie thread. It’s known as the Ability Objection and it was offered by David Lewis and Lawrence Nemirow, independently.

The claim is that Mary does indeed acquire new knowledge when she leaves the room or we show her a ripe tomato. But the knowledge is know how, not know that. Not all knowledge consists in acquiring information; some of it consists simply in acquiring new abilities. Learning to ride a bicycle; learning to swim; learning to wiggle your ears. What Mary learns is how to visualize red things. She simply acquires a new ability but no new information about what it’s like to see red. This isn’t propositional knowledge or factual knowledge, there is no new fact she learns. So the physical facts are all the facts even though she learns something new.

In effect, this objection denies the arguments second line:

‘When Mary is released from her room, obviously she will learn something about human color vision...’

No, she learns nothing About human color vision. So she does learn something, she does acquire new knowledge, but that’s know how, not know that.

There were several responses to the Ability Objection.

She does acquire new abilities, but the claim that she learns nothing new about human color perception is implausible. For example, Mary might say: ‘I didn’t expect red to look like this!’ (Brian Loar) That would make perfect sense, but it’s hard to make sense of if she learns no new information about what seeing red is like.

In addition, what she learns, according to Frank Jackson, is what it’s like for us humans to see red. Suppose Mary immediately goes to a lecture on the problem of other minds. Afterwards she goes home and struggles all night with the skeptical question– how do I know that what it’s like for other people to see red is what it’s like for me to see red? She goes back and forth all night, to and fro, until finally she decides (without necessarily being sure how, as is common for us with this problem) that she really does know what it’s like for us humans to see red. What was she going back and forth about all night–her abilities? (Frank Jackson).

Another response is that it's possible to have the ability to imagine or visualize red, without knowing what seeing red is like. Suppose Sally has the ability to imagine colors
she's never seen. If we ask her to imagine a shade of red between regular red and burgandy (cherry red) she will. But she has never used it because we've
never asked her to. So Sally has the ability to visualize cherry red but she still doesn't know what experiencing cherry red is like, so the latter knowledge
isn't reducible to the ability to visualize cherry red.

These responses have persuaded most philosophers that the ability objection doesn’t stop the Knowledge Argument.

2010-04-15

The Knowledge Argument

Reply to Jim Stone

Derek Allan

Australian National University

RE; "Mary is the world's leading researcher on human colour perception, but she has never left her monochromatic room"

How would this be possible? And on what basis could one claim it possible? Has there ever, in the whole history of the world, been a "world's leading researcher on human colour perception" who has never in her whole life (and I guess she's not young) left the one room or seen any colours but black and white? Do we think it ever likely to happen?

I'm sure I read somewhere that analytic philosophy was trying to get away from its dependence on highly artificial, decidedly dubious "thought experiments"?

DA

2010-04-16

The Knowledge Argument

Reply to Jim Stone

University of New Orleans

An interesting fact about the Knowledge Argument is that Frank Jackson, its originator, after defending it ably for many years, abandoned it. He rejected it not because he found a fallacy in it but because he thought its conclusion was simply too implausible to be accepted. This represented a change of heart more than a change of mind.
Here’s a version of the argument Jackson gave in 1982.

‘Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a black and white room via a black and white television monitor. She specializes in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like ‘red’, ‘blue’, and so on. She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal chords and expulsion of air from the lungs that results in the uttering of the sentence ‘The sky is blue’.… What will happen when Mary is released from her black and white room or is given a color television monitor? Will she learn anything or not? It seems just obvious that she will learn something about the world and our visual experience of it. But then is it inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism is false.’

In later versions of the argument, Mary acquires the physical information about human color perception, not by her own research, but by watching lectures on a black and white TV monitor.

Jackson rejected the argument because he was convinced that a consequence of property dualism is that Qualia (the distinctive phenomenal properties of seeing red, blue, feeling an itch, tasting sugar, hearing a violin, and so on) are epiphenomena. They have no effect on what we do or say.
As these are extra-physical features of the world, and the physical features of the world are what make physical things happen in it, Qualia have nothing to do with causing human behavior. Jackson thought that was crazy. When Mary finally sees a ripe tomato and becomes acquainted with the quale of seeing red, she says ‘Wow!’ Jackson is convinced that the quale of seeing red is obviously part of the causal story why Mary says that. He concludes that the knowledge argument, which entails property dualism, must be fallacious some way or other, because property dualism entails epiphenomenalism, which is surely false. There has to be a fallacy in it somewhere,
Jackson thought. This is known as the 'There Must Be A Reply, Reply.'

Dave Chalmers, another property dualist, accepts epiphenomenalism. Other property dualists deny that dualism really does lead to epiphenomenalism.

What role does the black-and-white room play in the argument? Physicalism is the view that all facts are entirely physical facts. That is, all facts can be entirely described in principle in the language of physics and the other hard sciences like chemistry. These are facts about charm and spin and masse and shape and atoms and quarks and charge and so on. One feature of the properties that the language of physics is about is that they can be investigated from many different points of view. If Martian researchers have color spectra inverted to ours, so that when they see red they have the color experience we would call blue, and so on, they can learn about atoms and quarks and charge and mass nonetheless. And if Venusians ‘see’ by X-rays, they can learn about atoms and so on too. You don’t need human senses to do physics, because the properties of physics are available from multiple sensory points of view. And this is going to remain so, it’s reasonable to believe, through any continuation of the physical sciences. If the physical facts are all the facts, therefore, Mary can learn all the physical facts in her monochromatic room. As she learns a new fact about human color perception when she leaves the room, namely, what it’s like for us humans to see red, the physical facts about human color perception aren’t all the facts.Some of the facts about human vision and color perception are extra-physical, so physicalism is false.

The Knowledge Argument

Reply to Jim Stone

University of Szczecin

No need to apologize on my account. I did not intend to discuss criticisms of the knowledge argument in the other thread. I only wanted to mention a couple of them in order to indicate why I am not keen on giving the knowledge argument the benefit of the doubt. That's why I included the point in a post script, and not the body of my post. But at any event, at your invitation, I will repeat and expand upon the references.

Torin Alter (1998) offers an interesting argument against the premise that Mary can know all of the physical facts while inside her black-and-white room. He says the argument relies on a hidden premise which physicalists can reject: the premise that all facts about physical events can be discursively learned. So, when Mary leaves her black-and-white room, maybe she just learns discursively unlearnable physical facts.

Furthermore, there is the ability hypothesis, which questions the transition from (3) to (4). The fact that Mary learns something new does not entail that she learns new propositional knowledge. Instead, it is more plausible that she learns non-propositional know-how. The ability hypothesis is most famously stated in Nemirow (1990) and Lewis (1990). For a recent comprehensive defense of this view, see Nemirow (2006). (By the way, in Lewis (1990), he also argues that the knowledge argument can work against property dualism, too; because even if Mary learns all of the physical and non-physical facts about color vision while inside her black-and-white room, she'll still learn something new when she leaves.)

And, of course, Daniel Dennett (1991) has questioned the presumption that we can say anything at all about what Mary will know, because we have no idea what it means to have all of the physical facts.

Regards,
Jason
April 14, 2010

The Knowledge Argument

Reply to Jim Stone

University of Szczecin

Jim,

I know the ability hypothesis is sometimes treated as out of fashion, but I wonder if it really is so unpopular. It is still widely discussed and often supported. In fact, Frank Jackson himself has rejected the knowledge argument and now embraces the ability hypothesis. Also, while Daniel Dennett has carved out his own unique corner in this debate, his positive account is in substantive agreement with the ability hypothesis. For example, Dennett (2006) says, "the richness we appreciate, the richness we rely on to anchor our acts of inner ostension and recognition is composed of and explained by" a "complex set of dispositional properties" which just are "recognitional/discriminatory capacities" (pp. 19-20). (And, according to him, Tye should follow suit.) Other leading participants in the debate still respect the ability hypothesis, even if they are not wholly convinced by it: e.g., Torin Alter (in correspondence) says that he does not think the ability hypothesis has been disproved, even if he is not persuaded by it.

In any case, I think the objections you raised can be overcome.

First, there's Loar. If Mary says, "I didn't expect red to look like this!", what does she mean? She means that she was not prepared for her visual experience of redness. It does not mean that some new fact about color vision is now known to her. She is stating a fact about her own preparedness, and not anything about color vision. (Also, see Nemirow (2006) for a more elaborate treatment of Loar's objection.)

Second, there's Jackson's vision of Mary's skeptical dilemma. But why should this be troubling for us? (It's obviously not troubling for Jackson anymore, since now he accepts the ability hypothesis.) Mary, knowing all of the physical facts, would know all about the variations in individual color experiences which make color vision idiosyncratic. Mary would even know enough about her own brain to know how her color experiences will relate to those of other people. So why should Mary be skeptical? Why should she think she's missing some facts about what it is like to see red?

Third, there's Sally. I've always been skeptical of the idea that people can imagine or visualize colors they have not experienced. I know arguments about this go back at least as far as Hume, but without empirical support, I'm afraid I can't take them too seriously. In any case, let's say for the sake of argument that you are correct, and Sally is capable of imagining cherry red even though she has never exercised that ability. But why do you say she does not know what it is like to see cherry red? It seems that, if she can do what you say, then she does know what it is like. Or is your assumption that one must experience some phenomenal state of cherry red before one can know what it is like to see cherry red? What if Sally sees/imagines it, but then forgets about the experience?

I think vagueness might creep in here, with the case of Sally. Because if Sally knows what it is like to see colors close enough to cherry red so that she can imagine/visualize cherry red, then maybe her phenomenal experience was close enough to an experience of cherry red to give her the requisite phenomenal knowledge. (We don't have such strict rules for determining which exact hues we have phenomenal knowledge of, do we?)

Regards,
Jason
April 15, 2010

The Knowledge Argument

Reply to Jim Stone

Jonathan C. W. Edwards

University College London

Arguments about physicalism, like Mary and zombies appear to make heavy weather and it would be useful to know why. Maybe the fact that Jackson should think that the knowledge argument implies an implausible epiphenomenalism gives a clue.

As Newton made clear, physical laws like his optics and mechanics are not intended to give a complete explanation of our experiences. We need a further set of facts/rules about which (for instance) 'phantasms of colours' correspond to which neural events. Nobody widely educated in physical science can be a Jacksonian physicalist. There seems to be some confusion here because Stevan Harnad calls himself a physicalist, but presumably by another definition since he holds that physical laws alone do not explain experience.

But why should this need for further facts beyond the sort we currently call physics, raise a problem of causality? What if the extra facts are simply facts of translation? If Jacinta joins Mary in her black and white room full of English biophysics textbooks she will need the extra facts of translation of English to Spanish to know what Mary does. If the extra facts Mary needs are merely facts about translating a physical dynamic account of the world into an experiential account, as they would seem to be, why do we have a problem (other than the tricky practicalities of the 'dictionary', which might need Mary to pop some electrodes in her head)?

The answer might seem to be that if we have two sorts of account of the world then two sorts of property are being described - hence property dualism. But what are these properties? One, as per Descartes, is that of having experience: the property of sentience. The other, that physics deals with, is the dispositional property of regularity or predictability of experience. In the folk language of Dr Johnson kicking a stone 'physical' implies qualities like 'solid' that are in fact experiential, but in the sense of physics, 'physical properties' are purely dispositional properties. Mass, spin, charge and the like are all merely parameters of dispositions to generate observations. Any other aspects they might seem to have are just dressing up in experiential features for heuristic purposes. If sentience is what physical disposition is like from the viewpoint of an entity on the receiving end of that disposition it is unclear that we need to propose two sorts of property rather than just two accounts of one property.

Perhaps what Mary learns is (partial) translational knowledge. She does not learn precise local rules of translation in neural tissue because neuroscience has not mastered that. But she gets a glimpse of the other account in a way that is at least of some practical use (maybe a bit as if she learns 'Jacinta' but does not know it means hyacinth in Spanish). But her knowledge is currently useless as part of a causal dispositional account of local neural events, making 'red' seem epiphenomenal. However, when the day comes when we know what physical dispositional properties cash out as 'red' locally in a given situation (maybe not for the Martian) then qualia will be usable in causal descriptions, rather as English biophysics can be translated into Spanish (even if the translation is not analogous in all respects).

The Knowledge Argument

Reply to Jason Streitfeld

University of New Orleans

[Hi Jason, my comments are in brackets, below.]

First, there's Loar. If Mary says, "I didn't expect red to look like this!", what does she mean? She means that she was not prepared for her visual experience of redness. It does not mean that some new fact about color vision is now known to her. She is stating a fact about her own preparedness, and not anything about color vision. (Also, see Nemirow (2006) for a more elaborate treatment of Loar's objection.)

[She also says ‘If this is what red looks like, I would expect blue to look less saturated.' Note that ‘This is what red looks like’ occurs in the antecedent of a conditional,
one of the marks of sentences that express propositions. It's hard to construe this to be a proposition about her preparedness. She also says ‘Now I understand why people told me that seeing red is like hearing the sound of trumpets.’ Very hard to construe this as stating a fact about her preparedness and nothing about color vision. She says 'I didn't expect red to look like this--I thought it would be a bit more subdued.' On the face of things what Mary says looks propositional. The claim that these assertion merely report abilities is implausible on its face.]

Second, there's Jackson's vision of Mary's skeptical dilemma. But why should this be troubling for us? ... Mary, knowing all of the physical facts, would know all about the variations in individual color experiences which make color vision idiosyncratic. Mary would even know enough about her own brain to know how her color experiences will relate to those of other people. So why should Mary be skeptical? Why should she think she's missing some facts about what it is like to see red?

[The problem of other minds exercised many philosophers in the first half of the 20th century, people like Gilbert Ryle and Ludwig Wittgenstein. As I don’t have internal access to anyone else’s experiences, how can I know whether their experiences are like mine? Perhaps they have different Qualia or no qualia. Maybe if I had the color sensation you have when you say you see red, I would call it blue. How can I generalize from just one case, my own, to billions of other people? I may know very well that their brains are in the same state mine is in what I see red, but how can I know that what they experience is like what I experience? It’s conceivable, isn't it, that the phenomenal quality of seeing red is like electron-jumps in quantum mechanics, merely probabilistic, not strictly deterministic.Can I be sure that brain state determines a particular experience? Indeed, most laws of nature turn out to be merely probabilistic. Why should this be an exception? That their brains are in the same state as mine when I see red provides no compelling reason to conclude that their color experiences are like mine–at best I’m warranted in concluding only that probably this is so for many of them.
There's no way to know what they experience without having their experiences, and that's impossible.

So speaks the skeptic. Mary, who is not a philosopher, hears this lecture soon after she’s released from the room. She’s not a physicalist or a dualist, she’s not much thought about these things. Whatever you or I think about the skeptic’s argument, she is troubled by it. She says:

‘A little while ago I said ‘At last I know what it’s like for human beings to see red, the one fact of human color perception I did not yet know!’ But wasn’t that rash of me?
How can I really know what others experience when they are in the same brain state I was in when I saw the ripe tomato?

And she goes back and forth all night, to and fro, about whether she really does know what it’s like for humans to see red. Finally she decides that she just DOES know, even if she cannot refute the skeptical argument. What was she to-ing and fro-ing about all night– her abilities?]

Third, there's Sally. I've always been skeptical of the idea that people can imagine or visualize colors they have not experienced. I know arguments about this go back at least as far as Hume, but without empirical support, I'm afraid I can't take them too seriously.

[I don’t know whether people can do this but the argument doesn’t depend on it. It’s conceivable that they can, or that some of them can. Suppose Sally is somebody who can. That’s all the argument requires.]

In any case, let's say for the sake of argument that you are correct, and Sally is capable of imagining cherry red even though she has never exercised that ability. But why do you say she does not know what it is like to see cherry red? It seems that, if she can do what you say, then she does know what it is like. Or is your assumption that one must experience some phenomenal state of cherry red before one can know what it is like to see cherry red? What if Sally sees/imagines it, but then forgets about the experience?

I think vagueness might creep in here, with the case of Sally. Because if Sally knows what it is like to see colors close enough to cherry red so that she can imagine/visualize cherry red, then maybe her phenomenal experience was close enough to an experience of cherry red to give her the requisite phenomenal knowledge. (We don't have such strict rules for determining which exact hues we have phenomenal knowledge of, do we?)

[Suppose I’ve been blind since birth. Never had any color experiences whatsoever. Neurologists tell me good news. They cannot restore my sight but there are chips such that, if you put them in my brain, I can, simply by saying the name of the color, immediately visualize the color. The ‘color chips’ were discovered by accident. They were implanting chips in the brains of epileptics to control seizures and the epileptics (sighted) reported vivid visualizations of standard colors. Nobody knows why the chips have this affect or how they work.

The neurologists have arranged my brain so that if I say ‘Red now!’ the chip will be activated for the first time and it will produce a visual image of red. They implanted this last night in my sleep.
The chip has never been activated. I just received the news. I have the ability to visualize any color I choose, just by saying it’s name! I decide not to exercise the ability till tomorrow morning, my birthday. I go to sleep tonight eagerly anticipating the morning. At last I will learn what it’s like for people to see red! A strongly counterintuitive consequence of the ability hypothesis is that I already know what it’s like.]

The Knowledge Argument

Reply to Jonathan C. W. Edwards

University of New Orleans

I think it’s helpful to set out clearly what the causal problem is supposed to be if property dualism is correct. Property dualism is the view that mental properties like Qualia are properties of the brain all right, not of an immaterial soul, but are nonetheless extra-physical properties.

Suppose that’s true.

A principle widely accepted in science and philosophy is the Causal Closure of the Physical:

When physical events are caused there are physical causes sufficient to produce them. Physical events have physical causes--if they have causes.

So human behavior and neurological events, when they are caused, are caused by physical causes.

Suppose that extra-physical mental properties are often causes of physical behavior. Then either the causal closure of the physical is mistaken, since physical causes are insufficient to produce that behavior. Or there is widespread over determination of human behavior, both physical and extra physical causes exist sufficient to produce the same behavior.

But it is terribly hard to believe that the causal closure of the physical is mistaken and that the brain is operating by different causal principles from the rest of nature. It would mean that the laws of physics as we know them break down badly in explaining human psychology and behavior. That’s conceivable but very unattractive.

In widespread over determination of human behavior is extraordinarily implausible, though once again conceivable. Why would nature go to the trouble of producing two sets of causes, each sufficient for our behavior, for most of what we do?

So the dualist must choose between a) rejecting the causal closure of the physical, b) widespread over determination of human behavior, and c) epiphenomenalism.

These are all so unappealing, that we had better reject property dualism. So the argument goes.
I reckon the property dualism to reject epiphenomenalism is probably going to have to reject the causal closure of the physical. I’m game. But this does commit the dualist to the prediction that we are going to have to introduce extra physical causes to explain the operation of the brain; the physics of the brain will turn out not to be the whole story. Bit of a longshot, yes?

(Another argument against mental causation of human behavior, where mentality is extra physical, is that causation requires an mechanism between cause and effect. When I turn the ignition, the automobile starts because of an intervening causal mechanism. But there is no mechanism between the extra-physical mental event ended nor logical or physical behavior it’s supposed to cause. So they really cannot be causation here.

But surely it’s false that causation requires a causal mechanism between cause and effect.
That leads to an infinite regress of causal mechanisms. The parts of the causal mechanism, that cause one another, would themselves need intervening mechanisms, and so on forever. It’s possible that reality is like that, but nobody believes that that’s how our universe is. In short, as a matter of fact, either there is no causation at all, or some causation involves no intermediate mechanism. A just causes B and that’s the end of it. How does it do it? It just does. There are basic causal connections, finally. Physical reality contains them. And there doesn’t seem any reason to deny that mental physical causation can be basic in this way, too.)

As I understand your comments, you really are denying the conclusion of the knowledge argument. That maintains that there really are extra-physical properties. It isn’t the case that there is one property described in two ways. On your account, if I understand you, all properties are entirely physical, though we may talk about some as if they aren’t (but that’s just a problem of translation). Well, you may be right. But then you really do need to find a fallacy in the knowledge argument. All the best, Jim

2010-04-25

The Knowledge Argument

Reply to Jim Stone

University of Szczecin

Hi Jim,

1. Loar: I did not claim that all statements including "what it is like" expressions are statements about preparedness. So, yes, I grant that the other examples you mentioned are hard to construe as statements about preparedness. But I do not grant that they suggest new propositional knowledge for Mary.

So, yes, Mary can also say something like, ‘If this is what red looks like, I would expect blue to look less saturated.' We agree that this is not a proposition about her preparedness, but rather about a particular experience or family of experiences. However, the ability hypothesis does not require that we abandon all talk of experiences. It only requires that we regard a certain variety of knowledge as non-propositional know-how. Nemirow (2006) thus observes that the ability hypothesis is in no way put out by such examples. We can say that "this" denotes a particular experience, or a family of experiences. But why should we think that Mary did not already know the facts of such experiences, or how they are compared to other experiences, like the experience of blue? It is implausible that a fact about relative appearances of red and blue would be unknown to Mary prior to her release from black-and-white captivity, considering how vast her knowledge is of color vision.

Mary can also say, ‘Now I understand why people told me that seeing red is like hearing the sound of trumpets.’ And, again, we agree that this is not a fact about Mary's preparedness. But, again, this is a fact Mary could have known from inside her black-and-white room. Mary would have understood why people told her what they did before she ever experienced color vision. All Mary can say, upon her release, is that now she has the ability to use her own imagination to compare experiences of red and trumpets directly. But any facts she can state about such comparisons were already known to her.

Now, I don't think Mary would say something like this: 'I didn't expect red to look like this--I thought it would be a bit more subdued.' I don't see why Mary would think red would be more anything. Mary could not imagine colors before, so how could she imagine subdued colors? In any case, we can allow that Mary is not prepared for her first experience of colors--that she acquires some new knowledge or understanding when she experiences colors for the first time. And she might say, "I did not expect it to be like this!" But, in this case, she is talking about her preparedness with respect to her experiences--and this is not a new fact about color vision. Indeed, Mary would have already known that her experience of color vision would be impossible to anticipate.

2. The skeptical dilemma: I find it surprising that you mention Ryle and Wittgenstein here, since I think their views are very much in line with my own. Seminal statements of the ability hypothesis make explicit reference to both Ryle and Wittgenstein. In any case, as you say, the skeptical dilemma rests on this premise: "as I don’t have internal access to anyone else’s experiences, how can I know whether their experiences are like mine?" But why should we regard experiences are necessarily beyond our access? Mary will understand the science of perception fully, and so she will not think that there is any information beyond her reach. Of course, Mary could end up being irrational, and she might suppose that despite her complete understanding of perception, there was something mysterious which still eluded her. Of course, she would have no reason to think this. But she could end up tossing and turning all night, as you say. But why should we think that she is plagued with a serious problem here? It rather seems that she is tossing and turning about nothing at all.

3. Sally: I find the whole scenario highly implausible, and possibly incoherent. What you seem to be describing is a chip that creates an actual color-perceptual experience, and not an experience of imagining a color. Perhaps you will say that I am wrong here, and that it really is a voice-activated experience of imagining a color. But in that case, I think the story is incoherent. I don't think imagining can be voice-activated, or automatic. Imagining is an intentional process, not a passive experience. But in any case the whole line of argument does not matter, because you are not treating all of the Lewis abilities. You are claiming that Sally can be able to visualize red, but not that she can remember or recognize it. The Lewis abilities involve the ability the remember, imagine, and recognize. If you separate them, then you start to lose phenomenal knowledge. Nemirow (2006) makes this same point. On p. 37: "Though the Lewis abilities normally accompany one another, knowing what it is like begins to fail when they are separated from each other."

So, as interesting as your objections are, I do not think they cause any problems for the ability hypothesis.

Regards,
Jason
April 19, 2010

2010-04-25

The Knowledge Argument

Reply to Jim Stone

University of Szczecin

I should give a more general presentation of my own views on the knowledge argument and the ability hypothesis. My main goal here is to explain why I think the ability hypothesis is important. But first I want to get a clearer picture of the knowledge argument.

First, let's consider Dennett's claim that the knowledge argument is just an "intuition pump," and not a plausible argument. His main point of contention is with the premise that Mary has all of the physical facts. Dennett does not reject this premise; he just says that we cannot use it to draw any conclusions, because we have no idea what it means. It's hard to argue with Dennett here, though many have certainly tried. Ultimately, as Dennett says, it just comes down to competing intuitions.

In trying to understand these competing intuitions, I find it helpful to distinguish between abstract and concrete physical facts. This distinction can probably be construed in a number of ways, but for our purposes, I think it can be put this way: Abstract physical facts are theoretical facts which define relationships between scientifically discoverable entities, whereas concrete physical facts describe particular entities, events or processes. Abstract facts are used to make predictions about concrete events. This is why we say science is a fundamentally predictive activity.

Now, having all of the abstract facts means one can make every possible correct prediction about the concrete physical facts. (If we allow for quantum indeterminacy, then having all of the abstract facts does not equate to predictive infallibility.) A person can have all of the abstract physical facts without having all of the concrete physical facts. The knowledge argument stipulates that Mary learns a completed physics (or a completed science, if we do not want to be reductionists about, for example, biology). It follows that Mary has theoretically unlimited predictive powers. However, it does not follow that she has practically unlimited predictive powers. So there may of necessity be physical facts which she cannot ever know. A physicalist has no problem with Mary becoming master of a completed science and still having an indefinite number of physical facts to learn. Thus, the fact that she learns new facts when she leaves her black-and-white room is not a problem for physicalism.

Furthermore, we need not suppose that there is such a thing as "all of the concrete physical facts." Indeed, it is reasonable to suppose that nobody could ever have all of the concrete facts, because that would require omniscience and the inability to learn from new experiences. If Mary had all of the concrete facts, she could never be surprised by any concrete event. She could not think about what to do, because she would already know what she was going to do. Such a person is inconceivable. A being who could not learn from an experience would not be a person under any common sense of the term. So we should promptly reject the premise that Mary can have all of the concrete facts.

Finally, a physicalist need not assume that it is possible to have all of the abstract physical facts. Physicalism does not require the possibility of a completed science, though I grant that many physicalists are open to it.

In sum, we can reject the knowledge argument on the grounds that it is formulated against an impoverished version of physicalism. It is, in effect, a straw man argument.

This is not the end of the knowledge argument, however. We just need to more clearly get at its motivation. To better indicate the driving intuition behind the knowledge argument, I propose the following reformulation: Mary does not learn every physical fact while inside her black-and-white room. Rather, she learns any arbitrarily large set of physical facts about color vision. She learns some vast, though incomplete, set of abstract and concrete facts about color vision. Yet, our intuition still tells us that Mary will not learn what it is like to see colors until she leaves her room. No matter what she learns while insider her room, she will not have a certain sort of phenomenal knowledge. Thus, phenomenal knowledge cannot be a physical fact.

Dennett's objection does not hold against this revised knowledge argument. Yet, our other responses are still on the table. On the one hand, we might still suppose that Mary learns physical facts which can only be learned by direct acquaintance with color vision. Or, we might suppose that the knowledge gained by Mary's color experiences is not propositional knowledge, but non-propositional know-how.

I wonder what sense there is in claiming that there are facts which can only be known through direct acquaintance. The notion of "fact" seems to entail discursive learnability. At least, some philosophers have supposed as much. See, for example, Ryle (1949, Chapter 9). However, perhaps we can adopt a notion of "fact" which does not entail discursive learnability. This is probably an open question, though we should like some explanation for why some factual knowledge is not discursively learnable.

More generally, why should any knowledge only be learnable through direct acquaintance, and not description?

Remember that Lewis (1990) shows that the knowledge argument can be formulated against property dualism just as easily as it can be formulated against physicalism. So, if we do want to say that Mary cannot learn the right phenomenal knowledge while insider her black-and-white room, we want to know why that knowledge is not discursively learnable. It is not enough to say that it is not physical, because that does not explain anything. Even a property dualist needs some answer to the knowledge argument. This is where the value of the ability hypothesis is found.

Consider the relationship between knowledge and experience. As we gain new experiences, we are directly acquainted with new phenomena. Direct acquaintance gives us phenomenal knowledge. According to the ability hypothesis, this knowledge consists in capacities which underlie our descriptive understanding of the world. In other words, the reason why phenomenal knowledge is not discursively learnable is because it is a set of capacities which are more primitive than our descriptive understanding of the world and experience. I think Ryle (1949) and Wittgenstein (2009) showed rather well that factual knowledge relies upon a sort of knowing which is not factual, but which is manifest in our abilities to follow rules and procedures. The fact that we can follow rules and procedures for identifying colors means that our understanding of color vision is not wholly propositional, or factual. To put it another way, the fact that we can follow rules about how to identify colors is evidence that we have an understanding of color vision which does not itself depend upon factual knowledge--and which itself cannot be discursively learned. (As I noted in a post in another thread, Ruth Millikan may also be counted as a supporter of this view, even if she never to my knowledge explicitly remarked on the ability hypothesis.)

In conclusion, the ability hypothesis is called upon to explain why phenomenal knowledge is not discursively learnable. This explanation is required for property dualists as well as for physicalists. Furthermore, the ability hypothesis accounts for the intuitions motivating the knowledge argument without abandoning physicalism. The ability hypothesis is a physicalist doctrine, because it defines phenomenal knowledge wholly in relation to physical processes, events and capacities. Therefore, in accounting for the intuition motivating the knowledge argument, the ability hypothesis offers explanatory power in favor of physicalism.

Regards,
Jason
April 20, 2010

2010-04-25

The Knowledge Argument

Reply to Jim Stone

William F. Suttle

University of Southern Mississippi

Hi,

I am a grad student. I would like to briefly post on what seems to me mistaken about the Knowledge Argument. Any feedback is greatly appreciated.

It seems to me that Mary's undergoing an experience of seeing red is neither knowledge nor learning. When she sees red for the first time, she is not gaining knowledge that she did not have before (not even know how, at this point). Mary is undergoing a new experience -- which seems consistent with the physical facts being all of the facts -- even her having propositional knowledge of all of the facts (unless one presupposes from the outset that an experience being physical is incoherent). Furthermore, for her to learn that what she is seeing is red, is not to learn a new physical (or non-physical) >fact about the world<, but to learn how to correctly apply propositional knowledge to its experiential referent -- which again seems consistent with physical facts being all of the facts.

Also, Mary could not have really expected red to look like anything before she experienced it. Her conceptual framework (having only experienced black and white) is just too impoverished for this. However, surely she does have some kind of emotional / cognitive reaction when experiencing the color for the first time.

Trey

2010-04-26

The Knowledge Argument

Reply to Jim Stone

Jonathan C. W. Edwards

University College London

Thanks Jim. I am familiar with the background arguments but I fail to see how they follow each other. Throughout the debate it is unclear that people are clear what they mean by 'physical' and I am unhappy that it can have the same meaning in 'physical fact' as in 'physical property'. Barbara Montero gives a nice account of some of the difficulties in the current issue of Journal of Consciousness Studies.

If we accept both that Mary learns new facts beyond the causal dispositional facts of physics and that this implies that realities have two properties, which seems tendentious but I can let through, then I still do not see why both properties need be 'causes'. Put another way, if this is what Jackson thought he had proven, then I do disagree.

I was brought up to consider physics the study of causes, so for me all causal facts are physical facts and in that sense 'causal closure' is almost tautology. I do not know by what criteria one would judge a cause non-physical. However, discussion of causality only works in a refined cultural framework (years at school) that carefully cancels out the need for other sorts of facts by assuming that we have a common language and that our brains work in similar ways. If we want to account for experience that canceling out is not an option because we have to address how causal dynamics and experience match up in brains. So 'causal closure' and 'completeness of physics as explanation of phenomena' (rainbows are a good example) are not the same thing.

It may be interesting to ask how many sorts of physical property there are. Physical properties are generally thought of as causally effective disposition properties. Even within this we can cover half of the distinction between res extensa and res cogitans because in Fermi statistics (Pauli exclusion) one entity excludes another from its space (has extension) and in Bose statistics (light, gravity, sound, thought?) it does not. More importantly, physical interactions are asymmetric because of the directional aspect of sequence (time itself may not be asymmetric). So if A influences B we have an asymmetric state that requires two properties. A is disposed to influence B and B is disposed to be influenced by A. 'Causal closure' says that "A is disposed to influence B in way X such that B is disposed to influence C in way Y …" is all we need to know to predict how … J will appear to an observer who has learnt the 'look up tables' that relate his experience back to the notation of the physical laws. So sneakily, always at the end of the 'causally closed' string of processes we have reference to the other type of property - the disposition to be influenced in the form of experience. Mary's new knowledge relates to accessing the look-up tables (aka the dictionary).

Put another way, causal or dispositional properties do not have any meaning without there being some property that is actualized by such causal or dispositional properties. Otherwise these would be causes of, or dispositions to, nothing. And they cannot just be causes of or dispositions to physical properties if these are just further causes of or dispositions to nothing. So causal physical properties entail another type of property - which in our case seems to be that of sentience, or having experience. The physicist is a hard core property dualist, at least inn the two senses above. Or at least 'physical property' is a seriously ambiguous term.

(We might say hang on, the dispositional properties dispose to the presence of 'physical stuff'. However, 'physical' has no known meaning here. All we have are experiences and evidence of dispositions to regularity of those experiences. The stuff option has long gone.)

This analysis does not run into any problems with epiphenomenality. An epiphenomenon is something on a causal branch line. In this analysis the disposition to be influenced is part of the causal chain. Experiences are how X, Y, … are received three paragraphs up. We might have had, instead of an A, B, C physics an X, Y, Z physics and we probably do in a sense in psychology. If I see red blood you may hear me gasp and Mary may hear you say 'catch him before he passes out'. What even Mary does not know yet is how the two sorts of descriptions tie up inside a brain, but I see no need to think that we need to invoke anything not considered necessary by either Newton or Leibniz - a 'compleat physics' maybe.

2010-04-26

The Knowledge Argument

Reply to Jim Stone

University of Szczecin

Jim,

In the discussion of zombies, you write, "The proposition Mary learns when she escapes from her room is this: 'The phenomenal quality of my visual experience right now (name it 'QR') is typical of human visual experiences of the color red. Humans, when they see red, token QR" (Stone, post 3688).

Yet, you also claim that Mary can undergo a skeptical dilemma about other people's experiences. You write: "How can I generalize from just one case, my own, to billions of other people? I may know very well that their brains are in the same state mine is in what I see red, but how can I know that what they experience is like what I experience?" (Stone, post 3640) Your view seems to be that Mary cannot know whether or not her experience is like that of other humans. So how could she learn what you say she learns?

I wonder how you might reconcile this apparent contradiction.

Regards,
Jason
April 23, 2010

2010-06-04

The Knowledge Argument

Reply to Jim Stone

Jordan Taylor

University of Pennsylvania

On a quick (but, I hope, interesting) tangent, anyone interested in the history of philosophy may enjoy the following passage from Nicolas Malebranche's The Search after Truth (last edited 1712):

There is nothing so unreasonable as to imagine an infinity of beings based on the simple ideas of logic, to attribute to them an infinity of properties, and to wish thus to explain things we do not understand through things we not only do not conceive but even cannot conceive. This is to act like blindmen, who, wishing to converse about colors and to have opinions about them, would use definitions philosophers give them to draw conclusions. For as these blindmen could produce only comical and ridiculous arguments about colors - because they would have no distinct ideas of them, and because they would reason on the basis of general ideas and ideas of logic - so philosophers cannot reason solidly on the effects of nature when to this end they employ only general ideas and ideas of logic, i.e., act, potency, being, cause, principle, form, quality, and other such ideas of thought and extension, and those ideas contained in them or that can be deduced from them (III.2.ix, LO 250).

(Bear in mind that in Malebranche's time, what we call science is called "natural philosophy"; thus when he uses the term "philosophers" in the passage, he's more specifically talking about scientists a la Descartes and Newton.)

If I'm interpreting this passage correctly, then not only is the Knowledge Argument "arguably the single most influential argument for property dualism in recent philosophy" (as Jim Stone claims above), then it's quite a bit older (in essence, at least) than many of us have thought. Of course, the example of blind men discussing colours isn't used by Malebranche in quite the same way as is Mary, but the inference is there at least.

Can anyone think of any even earlier accounts of the Knowledge Argument?

2010-07-24

The Knowledge Argument

Reply to Jim Stone

J. W. K. Matthewson

I'm sorry but your version of the Knowledge Argument is faulty:

1. Mary, before she is released from the room, knows all the physical information there is about human color vision.

3. Her previous knowledge about human color vision was incomplete.

1 and 3 entail

4. There is knowledge about human color vision that is not physical information

Not "4. There is information about human color vision that is not physical information"

If knowledge is not physical information it does not prove that physicalism is false.

If we consider the real conclusion of the Knowledge Argument which is that "4. There is knowledge about human color vision that is not physical information" this seems quite reasonable. Information is a change in state of a substrate in response to a change in state of another substrate (ie: a separation of charge might cause a deflection of a voltmeter etc.). Science deals with the relationships between states so scientific physicalism holds that all of the world can be described by relationships between states (ie: in terms of information). Knowledge is altogether more problematical.

If experience is a set of concurrent and simultaneous objects arranged in space and time then knowledge would be the presence of an object in experience. The object is a thing in itself, not information - which is a state change resulting from a state change in another thing. This idea of "things in themselves" is consistent with scientific physicalism, after all, there must be something there to change state for information to be generated!

So my conclusion is that the true form of the Knowledge Argument is exactly what we would expect if scientific physicalism is true: the world is composed of objects that can all be described by scientific relationships. Mary is indeed fortunate to have one of the objects in her experience that she had previously only been able to infer from its relationships.

2010-07-27

The Knowledge Argument

Reply to J. W. K. Matthewson

Jonathan C. W. Edwards

University College London

But, JWK, what is this scientific physicalism that has objects? Science does not have objects. Objects are philosophers' (and man on Clapham omnibus's) things - and only philosophers other than philosophers-of-physics. At the recent philosophy of physics conference on Emergence at the Institute of Philosophy (University of London) the one thing that everyone seemed happy about was that there are no objects. Quantised space maybe, lots of dynamic structure yes, but no trace of objects. David Wallace even wanted to abolish subjects although I tried to protest (without much success). Of course if you are talking about not-of-physics philosophers' physicalism I tend to agree with your arguments.
Best wishes

Jo E

2010-07-28

The Knowledge Argument

Reply to J. W. K. Matthewson