|
|
|
||||||||
|
||||||||||
|
What is the knowledge argument? Is it successful?The Knowledge Argument is an attempt to show that our experiences are non-physical properties of our mind, and thus to undermine the purely physicalist theories. In this essay I shall examine the Knowledge Argument, some objections to it, and some responses to those objections. I hope to show that, while none of the objections are knock-down, they cast sufficient doubt on the Knowledge Argument to make its success partial at best. Physicalism is the theory that all aspects of our mind can be reduced to explanations concerning physical properties and interactions within our brain. The Knowledge Argument tries to show that even if we know every physical fact about sensory experience, there is still something to learn about what the conscious experience is like. If we know everything physical, yet there is still something we don't know, then what we don't know must be non-physical. Therefore consciousness must be a non-physical property [Frankish, pp39-40]. The Knowledge Argument is demonstrated using thought experiments, the most commonly discussed being that of 'Mary'. Mary is a brilliant neurologist who has dedicated her life to the study of vision. She now knows everything there is to know about the physical facts and properties of the visual process, from the properties of light, through the interactions with the retina, to the activities of neurons. However, from birth she has been imprisoned in a controlled, entirely monochromatic environment. Thus she has never herself had any experiences of colour. One day she is released from her prison and sees colour for the first time. Finally she learns what it actually feels like to see the colour yellow [Jackson, pp195-196]. The argument is that this new experience constitutes a new objective fact. As, by hypothesis, Mary knows all the facts about the physical properties of vision, this new fact must therefore be of a non-physical property. If this seems far fetched consider Knut Nordby - a real-life Norwegian vision scientist and achromat - who has extensive knowledge of vision while never having been able to perceive colour [Nordby]. If in the future a surgical operation cures his achromatopsia he will learn what it is like to see colours, and we will have a real 'Mary' scenario. However, no matter how extensive Nordby's knowledge of vision gets, he will never know everything. Such omniscience is impossible for humans, and perhaps even impossible to imagine. This leads us to the first objection to the Knowledge Argument - the "no-learning" objection put forward by Daniel Dennet. Dennet maintains that if Mary really did know everything about visual experience, this would include knowing what it was like to see yellow. She would know what visual receptors would be fired, which neurons would be activated, right down to what thoughts she would be disposed to have [Dennett, pp217-218]. From within her monochromatic environment she would be able to say "If/when I see yellow, it will feel like this". Upon her release and first experience of yellow she thinks not "So this is what seeing yellow feels like", but "Aha! I was right. This is indeed what seeing yellow feels like". She learns nothing new [Audio CD 5, track 21]. Does Mary really know what it will be like to see colour, or does she merely know a few cunning tricks? Knut Nordby tells of how he can distinguish colour prints from monochrome by examining the glossiness of the surface [Nordby, sec.6, para.3]. This clearly has nothing to do with seeing colour, but can we be certain that distinguishing colours by introspectively identifying neural interactions is any different? Predicting the effects of experience is not the same as having that experience. Dennet's objection does not disprove that Mary learns something, but it does cast doubt on whether the original thought experiment proves that she does [Dennett, p217][Frankish, p76]. No matter how much information we have about something, it may require direct experience to truly appreciate. No matter how much data you have on how big the Grand Canyon is, or how cold the Antarctic is, when you first experience it directly you can still be surprised. It seems intuitively clear that you are learning something over and above the facts. This brings us to the second objection to the Knowledge Argument - the "New Ability" objection (or "Ability Hypothesis") as put forward by David Lewis. The New Ability objection concedes that Mary does indeed gain new knowledge but not new pertinent facts. It turns on the difference between propositional knowledge and practical knowledge, or between "knowing that" and "knowing how" [Frankish, p78]. I may know all the physical facts about how guitars are made, and how they work. I may know all the musical theory required to construct chords. However, I will never be able to play the guitar unless I practice. I have all the facts - the "knowledge that" - but no ability - the "knowledge how". The Ability Hypothesis claims that sensory experience is a form of "knowledge how". When Mary first experiences a colour, she gains the ability to recall, recognise and imagine that colour. The hypothesis goes further, maintaining that sensory experience is pure ability involving no factual knowledge whatsoever. Thus Mary gains an ability and nothing else. Merely gaining an ability tells us nothing new about the world. If Mary learns nothing new about the world then the Knowledge Argument fails [Lewis, p220]. For this argument to work, sensory experience must be a kind of knowledge with no factual component. However, this point is debatable. If I am looking at my bland magnolia walls I know at that moment what that particular colour looks like. This seems unrelated to any ability I may have gained. Indeed, given that magnolia is an unremarkable colour and my colour appreciation is not very refined, it is likely I will not be able to accurately recall it or recognise it. While I stare at my wall, I know a fact but I have gained no ability. This response may not knock down the objection though. It could, for example, be argued that it requires practice to fully develop the ability to recall and recognise shades of insipid beige. However, there is another response. It is possible that a new sensory experience can trigger new thoughts. If I visit an art gallery and discover a painting composed of a vivid purple that I've never before seen, I may be profoundly moved. It might inspire me to wax lyrical in poetry or music about this new vibrancy and lushness I have discovered, inventing new metaphors in my attempts to describe it. Can new thoughts be formed without new knowledge? Intuitively it seems not, but this is far from beyond question. Again the objection is not knocked down, but doubts are raised. In turn the objection casts doubt on the Knowledge Argument without striking it down. We turn now to the final objection I shall consider: the Perspectivalist objection, as advocated by Michael Tye. Like the New Ability objection, the Perspectivalist objection concedes that Mary gains new knowledge but disputes that it is a type of knowledge that threatens physicalism. Instead, what she gains is a new perspective. This objection hinges on a division of usage of the word "fact" into fine-grained and coarse-grained [Frankish, pp81-82][Tye, p221]. Coarse-grained facts are objective facts about the world. To learn a new coarse-grained fact is to learn something new about the world. In a physicalist universe, there can be no course-grained facts about non-physical concepts. However, it is precisely this kind of fact that proponents of the Knowledge Argument claim Mary learns. By contrast, fine-grained facts are conceptual representations of the world. To learn a new fine-grained fact is to learn a new way of describing the world, but not to learn anything substantively new about it. There can be fine-grained facts about any concept at all, physical or otherwise. The perspectivalist objection maintains that this is the kind of fact that Mary learns. To illustrate, consider water. It can be a drink, a solvent or a home to fish. These are fine-grained facts - different ways of representing the same concept. Some are physical concepts, some (e.g. "a home") are not. Underlying them all are the same coarse-grained facts concerning the properties of water. Let's apply this to Mary. She knows all the course-grained facts about colour. However, when she first gets to actually experience colour, she learns a new way of looking at it. Rather than "yellow" being "the colour of reflected 580nm wavelength electromagnetic radiation stimulating neurons XYZ...", it becomes something more like "a bright, vibrant colour that reminds me of summer". Yellow is still yellow - she has learnt nothing new - but she now looks at it differently. Again this objection relies on Mary learning no new pertinent facts, but again it can be argued that she does. Michael Lockwood suggests the following response [Frankish, pp86-87]. If we learn a new conceptual representation of something, it must be because we learn a new pertinent fact. For example, initially Lois Lane regards Clark Kent as a mild-mannered reporter. Later she learns a new conceptual representation of him as a caped super-hero from the planet Krypton. However, she can only do this after learning a new course-grained fact - the fact that "Clark Kent" and "Superman" describe the same person. So, if Mary learns a new conceptual representation of yellow, it can only be because she has learnt some new objective fact about it. As she knew all the physical facts, this new fact must be non-physical, and so the Knowledge Argument stands. However, this response only works if we consider perception as represented by a collection of descriptive facts. If perception is represented in the mind directly, perhaps by an indexical reference such as "this colour", then we learn new perceptual concepts without learning new facts and this response fails [Frankish, pp88-89]. So where does this leave the Knowledge Argument? Despite the objections, I think it still succeeds in one area. It highlights the fact that we think that consciousness is an extra, non-physical property. We believe Mary learns something new. We are somehow aware of the phenomena of consciousness occurring within us - the so-called "Cartesian Theatre". For physicalism to succeed, it needs to address this intuition [Audio CD 5, tracks 13, 23, 27]. There are too many good objections to the Knowledge Argument to say it wholly succeeds. However, none of the objections wholly succeed either. What we're left with is an argument that partially succeeds, in that it highlights some of the deficiencies of physicalism, even it it can't defeat it entirely. Bibliography
|
|
Except where stated, this site and its contents are copyright ©2009 Alec Harkness and licensed under a Creative Commons Attribution-Share Alike 2.5 License.