Mary's Room

 Lately I have been thinking about Frank Jackson's thought experiment, variously called Mary the super-scientist or Mary's Room. I have even preached about it a couple of times, and a recording of the last time, at St. Matthew's Dunedin, is here. The thought experiment goes something like this:

Mary is the world's most brilliant neurophysiologist. her specialty is the perception of colour. She knows absolutely everything there is to know about colour: how the retina is affected by light, how the brain processes the information etc. When it comes to colour perception,  there is not one fact that it is possible to know that she does not know. By a huge irony, however, Mary is herself only able to see monochromatically. That is, though she knows all it is possible to know about colour, she has never experienced colour vision herself. One day, due to some freak happenstance,  her monochromatism is ended, and she is able to see colours. The question is: does she know anything after the happenstance that she didn't know before?

Jackson's experiment is part of his knowledge argument against Physicalism: the belief that the universe is entirely physical; Jackson's argument is that if Mary knows something after her monochomatism is ended that she didn't know before, then there are things in the universe, most notably various mental states, that are not physical. Personally I find Jackson's argument overwhelming, and the counterarguments I have seen, at least to date, rather less than convincing. As another example of one of these non physical realities, you could give an exhaustive description of a piece of music by describing everything physical about it: the way the vibrations of wood or brass or catgut are produced, how they travel in the air, how they affect the eardrum and the intricate mechanism behind it, how the resulting nerve impulses are processed by the brain - but you would not have mentioned anything of importance about the piece of music as MUSIC.

So what is it that Mary knows now, that she didn't know before? Well, it's almost impossible to say, precisely because what is known is not physical: it is subjective rather than objective and to describe it in objective terms is impossible. A physicalist might, of course agree with this, and reply that because only physical things exist, the subjectively discerned thing, that cannot be described in objective terms, do not in fact exist and are some kind of illusion. Which is impossible to answer, except by looking at the purple of a thistle or the yellow of a Swiss dandelion meadow or the red of blood and knowing that what you are seeing and are so moved by is real enough to need no evidence other than its own witness. Richard Rohr sums it up quite well, here.

Of course our knowledge of the divine is of the same sort as our knowledge of colour, or of music, or of beauty, or of our own existence for that matter: it is subjective. Such knowledge is no less important for not being objective and perhaps we should abandon the futile attempt to make it so but rather "be still and know..."