An Aggravating Mystery Named Mary

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

Where Are Colors?

I’ll now return to my series on mysteries of consciousness, and next on my list is the puzzle of qualia. To put it very briefly, qualia are the qualities of experience, and I’ll begin by talking about a kind of qualia that is especially vivid and interesting, the qualities of our color-experiences.

Although colors are one of the most widely discussed features of consciousness, it’s hard to know where they are actually located. Think of a bright yellow lemon, for example. When scientists examine the brain, they find grayish neurons, and when they examine the fruit itself, they just find a lot of molecules in motion – no color at all. So if we find no colors on the lemon, and no colors in the brain states that occur when we see the lemon, where is the experience that we call “yellow?”

Of course it seems as if colors are on the surfaces of objects, as if every speck of matter sports a paint job, but is that really so? Here are six ways of thinking about this problem:

  1. Colors are surface properties of physical objects. They are not inner experiences.
  2. Colors are inner experiences. Strictly speaking, it is a mistake to say that objects are colored.
  3. “Color” is a word for two different things – features of the surfaces of objects and color-experiences within the mind.
  4. Colors are one thing, located in two places – the surfaces we see and our experiences of those surfaces.
  5. Colors are whatever cause us to be in states that we refer to as colors. You could have a state that you call “seeing purple” on many different occasions, and each time it might be caused by something different.
  6. Colors don’t exist.

I accept option 2, and I’m also comfortable with 3 as long as we remember that surface colors and experienced colors are quite different. But it’s hard to override our common-sense view that “yellow” is both out there and in here, unproblematically one and the same. In any case, one of the deep mysteries of consciousness is the fact that experience seems to have certain qualities that we cannot locate anywhere in the physical world. More about that next time.

Roger Christan Schriner