For the past few weeks I’ve been posting comments about some of the deepest mysteries of consciousness. I’ve been focusing particularly on “qualia,” the qualities of sensory experiences such as colors, sounds, tastes, and pains. In 1982 Frank Jackson published a paper called “Epiphenomenal Qualia,” following up in 1986 with “What Mary Didn’t Know.” In the past three decades more than a thousand scholarly papers and several books have responded to these articles. Jackson’s two little essays seem to have hit a very big nerve.
Jackson eventually decided that his argument was flawed, but many believe he was right the first time and should never have recanted. So here is Jackson’s conundrum, as I understand it:
Imagine that we can peer into the distant future, hundreds of millions of years from now. Science has advanced so far that many fields of study are essentially complete. And biotechnology has expanded our memory and intelligence so that a single individual can understand everything there is to know about some complicated subject. One of these people is Mary, a neuroscientist who knows all that can ever be known about color experiences by studying their physical aspects. Mary has soaked up everything about the physical aspects of color perception that books, teachers, and information technology can possibly tell anyone – but Mary has never seen a color. She grew up in a black-and white room, she was prevented from looking at her own skin, etc. Then one day she is released from her colorless home, free to see the whole range of hues for the very first time.
Let’s say that the first colorful thing Mary sees is a garden full of dazzling red roses. And here is the crucial question: When she sees a red rose for the first time, does Mary gain new knowledge? Jackson claimed that she does, and he cooked up the Mary scenario because at that time he was a dualist. Dualists believe that mind and matter are two very different sorts of stuff, and Mary helped Jackson argue that mind is not matter. He claimed that after her release Mary gains new knowledge over and above the complete physical knowledge she already possessed. She learns what colors are as we experience them.
If all things are physical, including our visual experiences, and Mary already knew everything about the physical aspects of color perception, then she would not have learned anything new when she walked into that garden. But if she did learn something new when she actually experienced color, then our experiences of color are not physical. They are not made of matter, and do not occur within the brain. This also implies that qualia in general are not physical.
“Physicalism” (sometimes called materialism) claims that everything that exists is made of physical matter, and so any facts about things that exist are facts about physical things. But Jackson’s argument implies that knowledge of physical facts is not complete knowledge, because after her release Mary learns new facts over and above the complete physical knowledge she already possessed. Therefore, physicalism is false.
So what do you think? Was Jackson’s argument correct? If not, what’s wrong with it?
Perhaps more importantly, do you see why this thought experiment is so challenging? Why has it stimulated so much discussion? When I have led workshops for the public on consciousness, many participants have a hard time understanding that it’s the qualities of conscious experience that are difficult to explain physically. Until one sees the depth of this problem, the mystery of consciousness may seem soluble, even trivial. Soluble it may be. Trivial it’s not.
Roger Christan Schriner