Defending Mary from Dennett

Since its initial publication in a 1982 article entitled “Epiphenomenal Qualia,” Frank Jackson’s thought experiment involving Mary, a brilliant scientist, has been met with a voluminous amount of literature intending to refute the experiment. This response was to be expected. After all, if the thought experiment stands, then physicalism becomes an untenable ontological position and the belief that mental states can be reduced to gray matter will be a shipwrecked enterprise. In this paper, I will defend Jackson’s thought experiment from one of its more radical critiques as given by Daniel Dennett. I will show that Dennett’s critique is actually a red herring and as such does no damage to Jackson’s argument.

            

In Jackson’s experiment, Mary a brilliant young scientist, is “forced to investigate the world from a black and white room via a black and white television monitor” (Jackson 1982, p. 130). In this condition Mary is completely deprived of any color experiences. However, through this investigation Mary is able to acquire all physical facts pertaining to color vision. She understands, in the most exacting of detail, everything that goes into the formation of a color experience. She “discovers, for example, just which wave-length 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”” (Jackson 1982, p. 130).

            

When Mary is eventually released from this controlled environment to experience color for the first time, it is clear that she will learn something new about color—specifically, what various colors look like. Even though Mary knows everything there is to know about the physiology and physics of blue, as experienced when looking at the sky, it is clear that upon first seeing a blue sky she is learning something new; viz. the phenomenal feel of “sky blue.” Yet, if Mary learns something new, “then it is 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” (Jackson 1982, p. 130).

            

It is hard to overestimate the ramifications of this thought experiment. If Jackson is right, then all facts in the universe are not physical facts. There are also phenomenal facts which are of a different kind. If this is the case, then physicalist ontology is a dead enterprise. For the sake of precision and forthcoming analysis, I will set forth Jackson’s argument into premise and conclusion format:

1.     Before her release from her black and white environment, Mary had all physical information about various color experiences.

2.     Upon her release Mary, for the first time, experiences what it is like to see various colors. Through these experiences Mary acquired new information—i.e. information pertaining to the phenomenal property of what it is like to see a particular color.

3.     If Mary were to acquire new information outside of the room, then that information would be nonphysical (by definition from 1)

C1. Upon her release, Mary obtained information which was nonphysical (modus ponens by 2, 3)

4.     If Mary acquired information which was nonphysical, then it pertained to a nonphysical property of the color experience.

C2. The information Mary received via experiencing color demonstrates that there is a nonphysical property pertaining to the experience of color (modus ponens by C1, 4).

5.     If color experiences have a component which is nonphysical it follows, by definition, that physicalism is false (by definition from physicalism).

C3. Physicalism is false (modus ponens by C2, 5).

Before moving onto Dennett’s attempted refutation of this argument, it is important to point out the full implications of Jackson’s thought experiment. Specifically, even though this thought experiment analyzes a singular sense modality, it could, in principle, be extended to all sense modalities. It is easy to imagine a similar thought experiment for tactile, auditory and olfactory experiences—in short for all sense experiences. Consequently, the Mary experiment purports to show that the most basic building blocks of conscious experience, qualia, cannot be accounted for via physicalism.

DANIEL DENNETT AND MARY

The philosopher Daniel Dennett objects to Jackson’s thought experiment outright. Specifically Dennett claims that Jackson has given us “a bad thought experiment, an intuition pump that actually encourages us to misunderstand its premises” (Dennett 1991, p. 399). In other words, Jackson’s thought experiment plays on un-tuned intuition as to what physical information can reveal. From here, he makes an easy transition to its conclusion “physicalism is false.” According to Dennett,

 “The image is wrong; if that is the way you imagine the case, you are simply not following directions! The reason no one follows directions is because what they ask you to imagine is so preposterously immense, you can’t even try. The crucial premise is that “She has all the physical information.” That is not readily imaginable, so no one bothers. They just imagine that she knows lots and lots—perhaps they imagine that she knows everything that anyone knows today about the neurophysiology of color vision. But that’s just a drop in the bucket, and it’s not surprising that Mary would learn something if that were all she knew.”

So Dennett will run the thought experiment over again, taking very seriously the claim that Mary possess all physical information pertaining to color vision. This emphasis will be a key point in Dennett’s denial of the second premise in Jackson’s argument above. If Dennett can establish his case then the rest of Jackson’s argument from premise two onwards will be false. By encouraging us to take seriously the claim that Mary has all the physical information Dennett hopes to tune our intuitions into greater clarity, thus allowing us to see that Jackson’s thought experiment does not prove anything at all. In order to achieve the greatest clarity possible, I will simply cite the thought experiment Dennett gives at length:

And so, one day, Mary’s captors decided it was time for her to see colors. As a trick, they prepared a bright blue banana to present as her first color experience ever. Mary took one look at it and said “Hey! You tried to trick me! Bananas are yellow, but this one is blue!” her captors were dumfounded. How did she do it? “Simple,” she replied. “You have to remember that I know everything—absolutely everything—that could ever be known about the physical casues and effects of color vision. So of course before you brought the banana in, I had already written down, in exquisite detail, exactly what physical impression a yellow object or a blue object (or a green object, etc.) would make on my nervous system. So I already knew exactly what thought I would have (because, after all, the “mere disposition” to think about this or that is not one your famous qualia, is it?). I was not in the slightest surprised by my experience of blue (what surprised me was that you would try such a second-rate trick on me). I realize it is hard for you to imagine that I could know so much about my reactive dispositions that the way blue affected me came as no surprise. Of course it’s hard for you to imagine. It’s hard for anyone to imagine the consequences of someone knowing absolutely everything physical about anything!” (Dennett 1991, p. 399-400)

         

How Dennett envisions Mary being able to accomplish such a feat is not wholly clear. To be sure, she has all the physical facts, providing information far above and beyond anything our intuitions can currently imagine. However, even though Dennett assures this, it appears he believes Mary has to perform some type of inference in order to get at the phenomenal data of a color experience.

Specifically, Dennett claims that Mary has a great deal of knowledge at her disposal already. She already knows varying shades of gray; the difference between “such surface properties as glossiness versus matte, and she knows the difference between luminance boundaries and color boundaries” (Dennett 1991, p. 400). All of this information is combined with detailed knowledge of how her Nervous system will react to any given wavelength of light. In Dennett’s words,

the only task that remains is for her to figure out a way of identifying those neurophysiological effects “from the inside.” You may find you can readily imagine her making a little progress on this—for instance, figuring out  tricky ways in which she would be able to tell that some color, whatever it is, is not yellow, or not red. How? By noting some salient and specific reaction her brain would have only for yellow or only for red. But if you allow her even a little entry into her color space in this way, you should conclude that she can leverage her way to complete advance knowledge, because she doesn’t just know the salient reactions, she knows them all (Dennett 1991, p. 400-01)

So, it seems clear that Dennett’s explanation to render plausible exactly how Mary is gaining her knowledge of color experience is via inference from information she already has.

In the end, Dennett’s position seems strong and clear. We cannot possibly know what possessing all physical information pertaining to a given domain would be like. In order to reach a sweeping ontological conclusion (i.e. physicalism is false) based on our current intuitions as to what physical information can be said to provide, is premature at best.

WHY DENNETT IS WRONG

           

I think it can be established that Jackson has not given us a mere intuition pump and that Dennett has actually provided us with an elaborate red herring. In order to demonstrate that point I will run the thought experiment again, in a modified form, with the hopes that Dennett’s faulty reasoning can be exposed. However, before I undertake that endeavor, I would like to acknowledge two points by way of critique. These need to be set forth to adequately prepare the ground for my thought experiment.

           

First, I would like to hone in on Dennett’s Mary. In order to render plausible the idea that Mary has not learned anything new at all, Dennett focuses on her ability to distinguish colors. She knew she was being tricked when she was handed a bright blue banana. She was able to accomplish this feat through a detailed knowledge of her nervous system and how it would react with varying wavelengths of light. This characterization of the situation does not demonstrate that Mary hasn’t learned anything new though. All Dennett has demonstrated is that Mary has “know how” when it comes to distinguishing colors. To be sure, “know how” is likely a necessary condition in saying whether someone has knowledge of different colors. If May were unable to distinguish a blue banana from a yellow one, we would not say that she had the relevant knowledge of colors.

           

Even though “know how” may be necessary condition in saying whether someone has knowledge of color, it is not sufficient. We can imagine Mary distinguishing colors merely by the behavior of her central nervous system. She may have no clue that blue has that type of look and feel and yet “know how” to distinguish it from yellow merely by noting that the patterns of firing produced in her central nervous system do not conform to the physical information she already possesses in regards to color interaction with her nervous system. So, “know how” is not sufficient to prove Dennett’s case. In effect, it appears that Dennett has tried to conflate notions of “know how” with “know that” in order to make his thought experiment more plausible. However, in so doing he has presented us with a red herring that detracts us from the original question: Does Mary learn anything new? We are looking for indications that Mary has gained “know that,” not merely “know how.” The possession of “know how” with all physical information is not all that implausible, even for Jackson’s Mary.

           

Second, Dennett is encouraging us to dispel our intuitions in regards to what type of knowledge physical information could provide. Essentially, he is claiming that with a complete inventory of all the physical information—a situation we can’t currently imagine—qualia will come along for free. In other words, complete physical information will allow us to gain knowledge of qualia experiences free of those experiences themselves. Dennett recognizes that physical facts, as currently envisioned, cannot perform the feat he is requiring of them. So, he asks us to write a blank check against our well-trained intuitions in anticipation of the problem being resolves with an exhaustive inventory of the physical facts. The problem with this whole set up, is that Dennett emphasizes the problem as being one of quantity—we do not have all the physical information—not one of quality.  Knowledge gained via inference from physical facts to particular quale is qualitatively different than knowledge gained by a direct experience of those quale themselves.

In essence, all physical information gives Mary a foothold from where she can infer her way to a full knowledge of qualia. As Dennett puts it, “if you allow her even a little entry into her color space in this way . . . she can leverage her way to complete advance knowledge, because she doesn’t just know the salient reactions, she knows them all” (Dennett 1991, p. 400-01). The difficulties associated with a serious defense of this position are paramount. Perhaps foremost is the difficulty of establishing that knowledge of qualia gained by inference has the same modal quality as knowledge gained by direct experiences. No matter how sound an inference may be, the possibility of error is always looming and with it the possibility that our judgment concerning some entity or entities, in this case qualia, may in fact be incorrect. The same cannot be said of a direct experience of a quale, say the color red. It is not in doubt whether or not I am seeing that color, there, right in front of me. Furthermore, it is not in doubt whether or not that color there has the properties I see it to have. My knowledge is direct and therefore indubitable. To be sure, I can doubt whether or not I am applying the term “red” in the same manner as the community at large. However, that is tangential to the issue. Our knowledge, from a direct experience of a quale is of a different modal quality than knowledge gained by an inference. Consequently, it seems clear that all the physical facts does not get us the same type of knowledge that direct experience does. Hence, Mary would learn something new upon leaving her black-and-white room for the first time.

So, with Dennett conflating notions of “know how” and “know that” and with it apparent that we cannot even conceive of what type of physical information would provide us undubitable knowledge of qualia experiences free from those experiences themselves, it becomes clear that Dennett has not made his case that Jackson has given us a mere intuition pump. Jackson is not solely playing on our intuitions. He is leveraging our best understanding of what physical information can be taken to demonstrate. Free of some radical new understanding of how physical information, even all physical information in a given domain, could be used to achieved knowledge with the characteristics ascribed to qualia, we are not compelled to accept Dennett’s conclusions. Dennett asks us to write a blank check, claiming that some day all physical information will be able to account for all the facts within the universe. With no indication of whether or not Dennett’s gamble is right, it would be unwise to accept his invitation.

           

MARY THOUGHT EXPERIMENT CONTRA DENNETT

With the key information in place, and with a preliminary critique, I can now run Jackson’s thought experiment over again from a different angle. This time, I will employ two Marys, Mary 1 and Mary 2. Running the thought experiment with separate Marys in tandem will allow me to use one Mary as a control. This control will allow us to see the difference between “know how” and “know that” knowledge, as well as demonstrating that knowledge via nervous system inference is not of the same character as knowledge via direct experience.

Mary¹ and Mary² have been forced to investigate the world through a black-and-white room. In this condition they are able to obtain all the physical facts pertaining to color vision. To have all the physical facts pertaining to color vision is to fully and completely exhaust all possible physical information on the subject. To be sure, we cannot imagine what it would be like to have all physical information on this given subject, since our current understanding of the human nervous system is in its infancy. The information it provides may be far grandeur than we could imagine, exceeding even our greatest expectations.

Those who have placed Mary¹ and Mary² in there black-and-white cells have every intention of releasing them into the world. However, before they do, they decide, at random, to use Mary¹ as a control. In essence, the put Mary¹ under the knife, ablating critical connections to the cortical regions responsible for color processing. Since Mary¹ has all physical facts pertaining to color vision, she knows exactly how this procedure has effected her nervous system and will be able to compensate for it when seeing color. As Mary¹ and Mary² first color experience, her captures have prepared a bright blue banana. Upon being presented with this banana, Mary¹ appears shocked. She cannot believe that her captors have played such a trick on her. She tells them that the banana is a lighter shade of blue and not yellow like bananas are supposed to be. When they asked her how she accomplished such a feat, she responded that she knew in acute detail how the wavelengths would react with her retina and the associated portions of her cerebral cortex, including how the ablations would effect the flow and process of visual information. She knew how to distinguish sky blue from yellow due to this information.

In a parallel room, Mary² is also handed a sky blue banana. Upon being handed the banana Mary² is also stunned that her captors would play such a trick on her. When asked how she knew that the banana was not yellow, she gave much the same response as Mary¹. However, unlike Mary¹, Mary² is actually having the experience of sky blue. This experience, or “the what it feels like” of sky blue is information which Mary¹ does not have at her disposal. Consequently, it seems clear that mary² has gained nonphysical information not available to Mary¹. Therefore, not all facts in the universe are physical facts and physicalism is false.

Dennett may be inclined to respond with the same line of attack with which he started, i.e. I am not taking seriously the claim that Mary¹ has all physical information about color vision. This includes her exhaustive information of Mary² and her healthy, functioning nervous system. Consequently, she would know, in rich detail, how such an experience must be for Mary². So, Mary², has not gained information unavailable to Mary¹. In response, it may become immediately clear how inadequate this line of response is. For Mary¹ to know, in rich detail, the experience that Mary² is having, via Mary²’s nervous system, would require an inference from the physical information to the quale of sky blue itself. However, as I have already pointed out, knowledge via inference is not of the same modal kind as knowledge of qualia via direct acquaintance. This modal difference should be sufficient to establish that even if Mary¹ we able to infer Mary²’s experience, should would not gain information of the same modal kind, and consequently, Mary² still has access to information not available to Mary¹. So the above conclusion that physicalism is false, must hold.

CONCLUSION

Frank Jackson’s thought experiment with Mary, a brilliant young scientist, has been faced severe criticism on many fronts. One critic, Daniel Dennett, has given perhaps the most radical critique claiming that Jackson has given us a mere intuition pump. Dennett further argues that given all physical information it is possible that Mary learns nothing at all. I have demonstrate that Dennett’s argument is a red herring in so far as he conflates notions of “know how” with “know that.” We are not interested in whether or not Mary can distinguish colors, we want to know if she learns something new. Additionally, Dennett’s claim that Mary can gain information of qualia via an inference from the physical facts is implausible on modal grounds. Consequently, in running the Mary experiment again and providing a control I was able to demonstrate that Jackson’s thought experiment avoids Dennett’s criticisms and that Jackson’s initial conclusion can hold. Consequently, barring stronger arguments from Dennett, it appears that physicalism is false and some form of ontological dualism or pluralism is implied.

Works Cited:

Dennett, Daniel. Consciousness Explained (New York: Back Books Company/Little, Brown and Company, 1991)

Jackson, Frank. “Epiphenomenal Qualia.” The Philosophical Quarterly (Apr. 1982) pp. 127-136