Philosophy is chock-full of fantastical thought experiments. Sometimes, though, the scenario we’re asked to imagine is so fantastical that it undermines the point of the experiment. From my perspective, the “Mary’s Room” experiment is one such.
This thought experiment was proposed by Frank Jackson in 1982, though the basic idea for it has a far longer history. It is meant to cast doubt on materialist understandings of the mind. Here’s the essence of it, as presented by Daniel Dennett (quoting Jackson) in his book Intuition Pumps and Other Tools for Thinking:
Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a black and white room via a black and white monitor. She specializes in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like “red”, “blue”, and so on. She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal chords and expulsion of air from the lungs that results in the uttering of the sentence “The sky is blue”. (It can hardly be denied that is in principle possible to obtain all the physical information from black and white television, otherwise the Open University would of necessity need to use color television.) What will happen when Mary is released from her black and white room or is given a color television monitor? Will she learn anything or not? It seems just obvious that she will learn something about the world and our visual experience of it. But then it is inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism [i.e., materialism, the denial of dualism] is false.
My knee-jerk reaction is precisely the one Jackson wants me to have. Of course Mary learns something new upon encountering color for the first time. What it feels like to experience color is just obviously not something you can know from a catalog of physical facts. Right? Sometimes, though, knee-jerk reactions need to be resisted.
This particular experiment has attracted quite a voluminous literature. The ever-useful Wikipedia has a nice summary, and the Stanford Encyclopedia of philosophy provides more detail still. There is rather a lot of thrust and parry, much of it fascinating and ingenious.
It’s just that the more I think about it, the more I think that the scenario I’m being asked to imagine is just too bizarre to clarify much of anything. Complete knowledge of every possible physical fact related to color vision is something we are so far from having that I do not know how to imagine what it would be like to have it. Perhaps the possession of so much physical knowledge simply entails also knowing everything about the sensation of experiencing color. If that seems bizarre or implausible, it is only because the scenario itself is bizarre and implausible.
Dennett makes a similar point in Intuition Pumps:
All the physical information there is to obtain? How much is that? Is that like having all the money in the world? What would that be like? It’s not easy to imagine, and nothing less than all will serve to make the thought experiment’s intended point. It must include all the information about all the variation in responses in all the brains, including her own, especially including all the emotional or affective reactions to all the colors under all conditions. So she will know in exquisite detail which colors calm her, annoy her, would grow on her with exposure, distract her, repel her, and so on. Is she forbidden to perform experiments on herself (without cheating, without smuggling any colored things into her cell)? If you didn’t imagine all this (and more), you didn’t follow directions.
…If Jackson had stipulated that Mary had the God-like property of being “physically omniscient”–not just about color but about every physical fact at every level from the quark to the galaxy–many if not all readers would resist, saying that imagining such a feat is just too fantastical to take seriously. But stipulating that Mary knows merely all the physical facts about color vision is not substantially less fantastical.
As I have written before, I find it very hard to understand how entirely physical processes within the brain can give rise to consciousness and subjective experience. I regard it as the most likely explanation, however, because everything we have learned from cognitive science and neuroscience points strongly to that conclusion. Moreover, I can see the many practical benefits of taking a physicalist view of mind; the success of drug therapies in combating mood disorders is one obvious example. This all strikes me as strong evidence for physicalism, to the point where something more than armchair philosophy will be required to make me abandon it.
When someone finds a way to turn non-physical theories of mind to practical advantage I will take them more seriously. Go treat an illness, or make someone’s life measurably better by tending to the non-physical side of their minds. That would be impressive. But as long as such theories amount to hand-waving, or worse, as gateways for a variety of New-Agey, spiritualist or religious ideas, I think I will continue to scoff.
To wrap this up on a grandiose note, I see a tenuous analogy here with the cosmological argument for God’s existence. My main problem with the Mary’s room experiment is that I am being asked to imagine something so far removed from actual experience that I have no reliable intuition to fall back on. I have a similar problem with cosmological arguments, in their various forms. They generally rely on using categories we find useful for organizing phenomena in our daily lives–like cause/effect or necessity/contingency–and then extrapolating them to assertions about the origins of the universe. Even without getting into the often byzantine details, it is hard to see how any argument of that general form could possibly be convincing. We know nothing at all about what brings universes into being, and we have no basis for thinking that intuitions useful in daily life retain any value in pondering the origins of everything.
And when you factor in what I take to be the many good reasons for thinking there is no designing intelligence to the universe, it will take more than philosophy can offer to make me convert to theism!