Mary, the scientist who has never seen red
The knowledge argument (Mary's room)
There are facts that are not physical: physicalism, which says that everything is physical, is false.
Mary knows every physical fact about colour, yet learns something on seeing red: so a fact was missing from her knowledge.
"Mary, the scientist who has never seen red" is an argument by Frank Jackson ("Epiphenomenal Qualia", 1982; "What Mary Didn't Know", 1986, 1982) on the question "Is the mind the brain?" (answer: the mind is not matter). Its claim: There are facts that are not physical: physicalism, which says that everything is physical, is false. According to AskPhilosophy's logic check (Z3 solver), the conclusion does follow from its 3 premises. AskPhilosophy presents 4 objections, 1 of them with a documented reply, and the original text behind each premise, checked word for word.
Mary is a brilliant scientist. She has spent her life in a black and white room and studies colour vision through a black and white screen. She knows everything about the physics of colour, of light and of the brain that sees. One day she leaves and sees a red tomato. Does she learn something? Frank Jackson (1982) says yes: she learns what it is like to see red. But then she already knew all the physics and still lacked something, so not everything is physical. The argument shows that the mind cannot be reduced to physics. At the time Jackson concluded that qualia exist but cause nothing (epiphenomenalism). An important point: he later changed his mind, and he now defends physicalism.
click a premise to reject it
Without the implicit premise: Without P4, one could accept the whole story and say that Mary discovers a physical fact she already knew in another form, as one can know water without knowing it is H2O.
Objections
4Each objection is a conversation: click to see who replies and where the debate stands.
David Lewis (after Laurence Nemirow) 1988 · attacks premise 3Mary learns no new fact. To know what it is like to see red is to have abilities: to remember, imagine and recognise that experience. An ability is not a piece of information. Physics lessons give information, not abilities; so it is no surprise that Mary does not have them before seeing red. This is the "Ability Hypothesis" which Laurence Nemirow had launched in 1980, saying that we understand the experience of seeing red if we can visualise red at will.
no reply
Mary learns no new fact. To know what it is like to see red is to have abilities: to remember, imagine and recognise that experience. An ability is not a piece of information. Physics lessons give information, not abilities; so it is no surprise that Mary does not have them before seeing red. This is the "Ability Hypothesis" which Laurence Nemirow had launched in 1980, saying that we understand the experience of seeing red if we can visualise red at will.
BBrian Loar 1990 · attacks premise 4Mary does learn something new, but not a new fact. She acquires a new concept, a "phenomenal concept", which lets her think in a different way about a brain state she already knew. The same physical fact can be thought of in two ways: with the vocabulary of neuroscience, or with the concept one has once one has seen red. As with "water" and "H2O", one reality, two ways of thinking about it.
Jackson replies
Mary does learn something new, but not a new fact. She acquires a new concept, a "phenomenal concept", which lets her think in a different way about a brain state she already knew. The same physical fact can be thought of in two ways: with the vocabulary of neuroscience, or with the concept one has once one has seen red. As with "water" and "H2O", one reality, two ways of thinking about it.
Daniel Dennett 1991 · attacks premise 2We are wrong to imagine that Mary really knows everything. If she knows absolutely everything about the physics of vision, she can work out in advance what red, yellow or blue will be like for her. Dennett therefore tells the end of the story differently: they show her a blue banana to trick her, and she answers "you tried to trick me, bananas are yellow". In his view, we think Mary learns something because we imagine poorly what complete knowledge would be.
no reply
We are wrong to imagine that Mary really knows everything. If she knows absolutely everything about the physics of vision, she can work out in advance what red, yellow or blue will be like for her. Dennett therefore tells the end of the story differently: they show her a blue banana to trick her, and she answers "you tried to trick me, bananas are yellow". In his view, we think Mary learns something because we imagine poorly what complete knowledge would be.
Frank Jackson (change of mind) 2003 · attacks the conclusionJackson himself gives up the conclusion. He writes that he once dissented from the majority, but has rallied to it, and now looks for where the arguments from our intuitions against physicalism go wrong. His answer rests on representationalism: an experience represents that things are a certain way, and our way of thinking about that experience misleads us.
no reply
Jackson himself gives up the conclusion. He writes that he once dissented from the majority, but has rallied to it, and now looks for where the arguments from our intuitions against physicalism go wrong. His answer rests on representationalism: an experience represents that things are a certain way, and our way of thinking about that experience misleads us.