I was thinking about the famous Mary the Neuroscientist thought experiment today, and had a few thoughts I’d like to write down and try to make clear in my head. I’m not sure what follows is perfectly coherent, but here goes. In case you haven’t heard of it, the thought experiment goes something like this. Mary is a super scientist. So super that she has theoretical knowledge of all physical facts (emphasis on theoretical). She has the theoretical knowledge of a complete physics, biology, chemistry, and neuroscience. This sounds great, but there is a catch: Mary has been confined to a black-and-white room her entire life. For perhaps obvious reasons, Mary is very interested in scientifically explaining color vision. She knows every physical fact relevant to color vision. She knows, theoretically, exactly down to the quarks how every brain physically responds when it steps in front of a colored object. Now suppose Mary’s cruel captors finally let her out of her black-and-white room such that she sees a red rose for the first time. Here’s the big question: does she learn anything new upon seeing the red rose?
Many philosophers find it intuitive that she does learn something new. What does she learn according to these philosophers? Well, she learns what-it-is-like to see red. She knew all the relevant physical facts about how her brain would react to a red rose, but upon actually seeing one, she learns what-it-is-like to have red experiences. This thought experiment was originally designed to show that physicalism is false (although the creator, Frank Jackson, no longer thinks the argument shows physicalism to be false). But why conclude that physicalism is false from the thought experiment? The argument goes something like this. If physicalism is true then all facts are physical facts, including facts about consciousness. Since Mary by hypothesis knows all physical facts, there shouldn’t be any information about consciousness that she isn’t already privy to. But our intuitions strongly suggest that she learns something new upon stepping outside the room. If physicalism is true, and Mary knew all physical facts, then it seems like she wouldn’t learn anything new. There would be no epiphany. Mary would be like “Yep, already knew it.” But since most people think Mary does learn something new, physicalism can’t be right because there is nonphysical information to be learned, namely, information about what-it-is-like to have certain experiences. Physicalists have responded to this thought experiment in many ways. Some have suggested that Mary doesn’t learn any new fact, but rather, gains a new ability of some sort. Or some have suggested that Mary doesn’t learn any new fact, but rather, learns about these same facts from a different perspective.
As of right now I lean towards the idea that Mary does learn something new, but I don’t think it’s necessary to talk about her new knowledge as being about what-it-is-likeness. And I don’t really think Mary was surprised in anyway either. Rather, what I think Mary learns is that her color discriminatory capacities are in fact working. Having been confined to a black-and-white room all her life, Mary never got a chance to put her color discrimination skills to the test. Theoretically, she knew that given the state of her brain compared to other people that her visual capacities do work, but when she stepped out into the real world she got actual confirmation of her theoretical guess. Using her theoretical knowledge of science, she had previously hypothesized that if she stepped outside and looked at a rose, she would be able to discriminate the redness of the rose from the greenness of the grass behind the flower. She also obviously wasn’t surprised by how her brain reacted. In fact, Mary had rigged up a portable brain monitoring device such that when she stepped outside to see the rose her brain was completely monitored. Prior to stepping outside, she had made predictions about what her brain would do. And of course, checking the data later, Mary was not surprised at all. The brain data came out precisely as she predicted. After all, she has near God-like theoretical knowledge of science. So I don’t think she had any sort of epiphanies when stepping outside. All she learned was the fact that her visual discriminatory capacities do in fact work. Prior to stepping outside, she had only hypothesized that they worked based on good scientific guesswork. But when she stepped outside, the fact that she could see the redness of the rose as against the greenness of the grass confirmed her hypothesis.
On my story, we can talk about Mary learning something new without positing talk about what-it-is-likeness. But I suppose based on how it’s defined, there would have been something-it-is-like for Mary to have confirmed her theory about her visual system working. But what does what-it-is-likeness really mean anyway? I have written before on how I think the term is vague, ambiguous, and poorly defined. Usually people use it to talk about “phenomenal feels” like the feeling of redness when looking at a flower. But I have argued before that in talking about properties like the “sensation of redness” we need to be careful. We can’t be talking about the redness of the rose when we are introspectively aware of our looking at a rose, because the introspection severally distorts the mental content. But if we are talking about nonintrospective redness, then it’s unclear to me that the mental content is anything but purely discriminatory capacities. Imagine how a mouse looks at a rose. It doesn’t see redness qua redness but rather, redness qua some affordance. Seeing “pure” sensory qualities is something humans do in virtue of our introspective capacities. Otherwise we get absorbed into the affordances of things, like the hammerability of a nail when we have a hammer in our hands. If all what-it-is-likeness is referring to is these certain kinds of affordance-style mental content, then I’m not sure that Mary would be incapable of learning about this content from a theoretical perspective. What you couldn’t learn about affordance-style mental content in other creatures is what-it-is-like from the inside to discriminate information. But we shouldn’t be confused by metaphors like “from the inside” to think that there actually is some inside distinct from gushy brain bits. The “insideness” of cognition stems from facts about the individuality of being embodied creatures. But the fact that you can’t know for ourselves what-it-is-like for a bat to perceptually discriminate should not lead one to think physicalism is false, because surely discrimination is a purely physical process, and there is nothing “nonphysical” involved when a bat discriminates flies from nonflies.
So although we could translate what Mary learns about her own capacities into talk about what-it-is-likeness, I don’t see how this shows physicalism to be false. We might say Mary learned what-it-is-like to discover that her visual capacities for discrimination do in fact work, in addition to learning the fact that her ability to be introspectively aware of first-order color content was also working. But her inability to learn these facts in her black-and-white room is not a limitation of complete scientific knowledge. It’s a limitation in confirming a hypothesis. Obviously, Mary had pretty good confidence that her hypothesis was right given her knowledge of her own brain. But she was never sure it worked until she stepped outside. Stepping outside allowed her to experimentally confirm her prior hypothesis. But I don’t see why we should conclude physicalism is false just because there are limitations to what theoretical knowledge of science is capable of providing. If she made any hypotheses while in the room about her own capacities outside the room, theoretical knowledge would never translate into confirmed or corroborated knowledge until she steps outside and makes the relevant tests. So on my reading, the limitations of what Mary can know are really limitations of testing. Obviously if she is confined to the room she is unable to carry out certain tests related to her own person.