The knowledge argument is an argument designed with the aim of invalidating physicalism by showing that fullknowledge of the physical properties of a person does not mean that you know everything about that person andtherefore there are things which cannot be explained with physicalism. It’s thought that the argument originatedfrom C.D. Broad, where he argues that an archangel could fully understand everything about the chemical ammonia,including how it affected the nose in a human, yet, the angel couldn’t know what it smells like. This argument wasmodified by Frank Jackson in 1982, who produced a thought experiment about a neuroscientist, Mary.
She is avery gifted scientist and knows every single part of the physical process of human colour vision. Due to a strangeupbringing (maybe her mum was a philosopher and decided to implement one of these mad thought experiments),she had never seen a colour other than black and white. One day, she is allowed to leave her monochromatic prisonand she sees colour for the first time. Has she learnt anything? It seems that she had, even though she knew allthe physical information about the process of seeing.
Does this mean that there is a form knowledge that cannot beexplained with physicalism.1 The Physicalist ResponseFirstly, it would be helpful to formalise the argument:(i) Mary has all physical knowledge about human colour vision ? she knows all physical facts about human colourvision(ii) Mary cannot know what the colour looks like having never seen it ? there are facts about colour vision shecannot know.(iii) From (i) and (ii): There are non physical facts about colour vision.The first source of counter argument I shall look at is from Owen Flanagan. Owen Flanagan, though not in directresponse to Jackson provides a counter argument to point (i) with more physicalism. He argues that Mary cannotknow everything about colour vision without actually seeing the colours, saying that the phenomenal state of seeingred is a physical event whereby light in the correct frequency freehold triggers ‘red-channel activation’. Without thepresence of a red object, there is no causal event that could activate that area of the brain. Know physical knowledgecould activate this because knowledge of the sort that Jackson is referring to is purely linguistic.
There is no way ofstimulating I, however, don’t think that this is really a problem with the argument. The argument is not concernedwith experience, it is concerned with the ability to fully explain experience through physics alone. Flanagan hassurly reinforced the argument by explaining the process of seeing red colour, yet giving no physical explanation thatMary could use to see a red object after her escape and know it was red without asking. I would also like to pointout that she was in a black and white room.
White is the superposition of all wavelengths of visible light andtherefore contains red. The biological process of red-channel activation must have been triggered, yet, she will haveno knowledge of what red looks like. This surly leads you to conclude that there is a non physical aspect to vision,if the experience doesn’t follow from the stimulus.
Flanagan also argued that there is a distinction between linguistic physics and complete physics, arguing thatalthough physics can explain the system behind phenomenal states, it cannot be used to express that state so thatit can be understood phenomenally. Language is learnt through association of sounds or shapes with concepts, forexample, if I were to say red, I am hoping to trigger the concept in your mind that you have associated the word’red’ with. If you have no such concept you must therefore have no such association and I have no way of plantingthose in your head. You may have a great grasp of mathematics and physics, and me saying ‘red’ summons yourknowledge of red’s properties, but I cannot implant an experience. Jackson rejected that this, saying that such adivision couldn’t be made in physicalism, only when in opposition.
If knowledge is purely physical, it would be stored1in the brain. Where one piece of knowledge begins, and another ends would surely be impossible to identify, so thentrying to claim that there are two different types of knowledge, stored on the same medium, in the same way, is surlymad. And if there are two types, how do they communicate with each other? How can I see a colours object (aphenomenal experience) and know how to lift it (complete physical knowledge) if the two types are not compatible?And if they are compatible, why can’t I use one to infer about the other?Another attack on Jackson is an attack on (ii). Nemirow and Lewis argued that she does know everything abouthuman colour vision because it is a purely physical process, but, what she doesn’t know is what it is like to experiencecolour vision.The Ability Hypothesis says that knowing what an experience is like just is the possession of theseabilities to remember, imagine, and recognize. It isn’t knowing-that.
It’s knowing-how.- Lewis 1990, 516Lewis then argues that the only alternative to the Ability Hypothesis is the Hypothesis of Phenomenal Information -where the knowledge gained from seeing a colour is in a purely phenomenal form – but this hypothesis is incompatiblewith physicalism. Surly if you can find an explanation that is equivalent, but also compatible with physicalism, itis better because then the we answer the question and have the evidence that physicalism brings with it. Butcompatible doesn’t mean right.David Papineau took a completely different response. He, a physicalist, agreed with Jackson’s argument butconcludes something else. He claims that the knowledge argument is a fantastic way of distinguishing betweendifferent phenomenal concepts.
But he states that the difference between phenomenal and material concepts is adifferent level of sense, not reference. They refer to the same thing through different means. What we really meanwhen we experience things, it’s not really a phenomenal state, but really the concepts that we use to understandthem that seem phenomenal. She may know everything physical about human vision, but she doesn’t possess theability to assign the concept of red to the experience of red. The concept is knowledge that she had after all herphysical study, but the assignment (a purely physical, biological process), of that concept to the stimulus cannot bedone without the presence of that stimulus.
Now, you can say that this isn’t an acquisition of knowledge, so shehasn’t learnt anything new or if she has learnt anything new, there is a physicalist explanation that breaks (i).Nother responce is called the New knowledge/Old Fact view. This is the views that Mary’s new knowledge2 My Own SpeculationBut I wonder if there is a deeper issue with the conclusion.
I would question weather you can know what a colourlooks like. Patches of colour are merely photons wiggling at different speeds. You don’t see that, so are you justifiedin saying that you know what red looks like? You could say, “Well, I know what red looks like to me” But now wehave transgressed past what Mary could ever possibly know without studying you personally.
Surly the subjectivityand individuality of human experience means that any conclusions the draws about her own experiences that are notgeneral are surely invalid. Maybe, if she studies me for long enough, see will know what colour looks like to me. Shewill know exactly how I would react to it, and do we have reason to believe that seeing is anything else? But shewill not know how she would so would still learn another introspective facit about herself upon leaving her captivity.2