Black, white and red all over
Contents
Synonyms
Definition
Mary knows everything there is to know about the colour red. As a scientist, it has been her life’s work. If you want to know why we can’t see infrared, why tomatoes are red or why red is the colour of passion, Mary is your woman. All this would be unremarkable, if it weren’t for the fact that Mary is an achromat: she has no colour vision at all. The world, for Mary, looks like a black and white movie. Now, however, all that is to change. The cones on her retina are not themselves defective, it is simply that the signals are not processed by the brain. Advances in neurosurgery now mean that this can be fixed. Mary will soon see the world in colour for the first time. So despite her wide knowledge, perhaps she doesn’t know everything about the colour red after all. There is one thing left for her to find out: what red looks like.
Source
‘What Mary Didn’t Know’ by Frank Jackson, republished in The Nature of Mind, edited by David Rosenthal (Oxford University Press, 1991).
Motivation & Background
Most educated people don’t have much time for the view that mind and body are two different kinds of stuff, which somehow coexist side by side. The idea that we have an immaterial soul that inhabits our animal bodies – a ghost in the machine – is outmoded, implausible and anti-scientific.
Simply rejecting one erroneous worldview, however, does not guarantee you will be left with a true one. If you kick out mind–body dualism, what is to replace it? The obvious candidate is physicalism: there is only one kind of stuff, physical stuff, and everything, including the human mind, is made of it. For sure, this ‘stuff’ may turn out to be energy rather than little sub-atomic billiard balls, but whatever chairs are made of, everything else is made of too.
And so it may be. But physicalist zeal can go too far. Even if there is just one class of ‘stuff’, that doesn’t necessarily mean the word can be understood in entirely physical terms. This is what the story of Mary illustrates. As a scientist, Mary knows everything about red in physical terms. Yet there is something she doesn’t know: what it looks like. No scientific account of the world can give her this knowledge. Science is objective, experimental, quantitative; sense experience – indeed all mental experience – is subjective, experiential and qualitative. What this seems to show is that no physical description of the world, however complete, can capture what goes on in our minds. As philosophers put it, the mental is irreducible to the physical.
This presents a challenge to physicalists. How can it be true both that there is nothing in the world apart from physical stuff, and yet the same time, that there are mental events that cannot be explained in physical terms? Is this a case of jumping out of the dualist frying pan into the physicalist fire?
Let us imagine that Mary is herself a physicalist. What might she say? Perhaps she would start by pointing out that there is a difference between appearances and reality: there is a way things are and a way they appear to be. Science concerns itself with the former, not the latter, because knowledge is always of how things are, not as they merely seem to be. Mary knows everything about what red is, she just doesn’t ‘know’ how it appears to most people. She does know how it appears to her, of course, which is like a particular shade of grey.
So when Mary sees colour for the first time, the world will appear a new way for her. But is it true to say she will know anything new about it? It may seem natural to say she now ‘knows’ what red looks like. But sometimes our ordinary ways of talking can blind us to the subtler distinctions a philosopher elaborating on Qualia should take care to make.
Cross-References
Recommended Reading
The Nature of Mind, edited by David Rosenthal (Oxford University Press, 1991).
