The Bryant I have in mind is, of course, Levi Bryant, who has come in for severe criticism on this blog. And Mary, of course, is the fictional Mary invented by the philosopher Frank Jackson and much beloved by philosophers of mind (discussed, for example, HERE). As you may recall, she's an expert in the neuroscience and physics of color but is, alas, herself colorblind. Being an expert she knows everything there is to know about color. Then she gets an operation and is able to see the redness of the rose and the greenness of grass for the very first time. Now, so the story goes, she knows something she didn't know before.
Since she knew all the physical facts back in her color-blind days, it follows that whatever it is that her new-found consciousness has supplied cannot be physical. Hence consciousness is not physical, not even in the rarified way of electrochemical processes in nervous systems.
Something like that.
Jackson’s thought experiment has generated a tremendous amount of controversy (and a huge literature), and it seems to me, at least, that it is deeply problematic and almost sophistical. Whenever I reflect on the thought experiment, I feel as if a trick has been played on me, that there is some sort of fundamental confusion at work here.
I understand the feeling. I felt the same way, and still do. And, as far as I can tell, something like that seems to be the general feeling among philosophers, as most of them are interested in figuring out just what it is that went wrong (see this review article by Martine Nida-Rümelin).
Bryant, however, has something else in mind, and sets things up like this:
I’ll set all that aside, however. We can adapt the form of the thought experiment– not its content pertaining to issues of consciousness –and instead use a variation of the thought experiment to think about the mysteriousness of matter. The paradox of matter is that no matter how much we know about it, we still seem unable to say or think what it is. In other words, there’s a way in which everything we say about matter fails to get at what it is.All of us are acquainted with matter. In a lot of ways it is the most familiar thing in the world. We experience the resistance of walls, the pain of a rock or bowling ball falling on our foot, the failure of hallucinations to satiate our hunger, the swoon of drunkenness from alcohol and other drugs and so on, the fatigue of our bodies when we run out of energy, the pull of gravity on our bodies, and so on. We experience the materiality of matter all the time and in every aspect of our lives. Saying just what this materiality or physicality is proves more difficult.Aristotle, in his own way, already articulated this issue. Among other things, Aristotle distinguishes between material and formal causes.
What Bryant then goes on to argue is that thought captures the form of things, but not the materiality, which eludes thought. As Graham Harman is ever fond of saying, no matter how much you know about something, the thought can never itself be the thing.
And that, more or less, is my objection to the orignal thought experiment. The redness of the rose, the quale that is red, as the philosophers sometimes call it, is not a fact about red, it is the very thing itself. The thought experiment confuses facts about color with the colors themselves. What Mary gains through her operation is acess to the things themselves, the colors, not to facts about those colors.
One of the oddities about language (and thought constructed upon it) is that it can function as a repository of facts about the world in the absence of those facts. That is also one of the things that makes language so useful. It allows us to exchange facts about things without having to be in the presence of the things themselves.
What this thought experiment thus demonstrates is not that consciousness is not physical (thought in a rather subtle and rarefied sense), but that colors themselves are outside our collection of facts about colors, just as, in Bryant's argument, material things are outside our collections of facts about them.