Josh Samuel 20 January 2022

Really liked this article. Really clear, and well written. But the clarity makes it easier to disagree, and I found that I did. For what it's worth, here's why:
First, we never know anything with exact precision or with certainty. So, it's true that we can never perfectly know what it will be like to see a red tomato, without seeing it. But even after seeing one, we still only know something quite small, about what it's like to see a red tomato (just that particular tomato, in that light, at that moment etc, and even then, only if we have a pre-existing model of red and tomato - more on that later), and we might be mistaken (maybe it was an apple!).
Second, if we understood the "programme" that generates the qualia of the colour red, then I would guess that we could "know" what it would be like to see red, in much the same way that we can know what it would be like to see a green sky, or a blue tomato, even though we've never actually seen one (by combining other qualia and ideas that we have better knowledge of).
So, I find the Mary in the black and white room story unconvincing. It hinges on the fact that we don't understand qualia of colours yet, and tacitly assumes we never could. I believe we can. That said, I believe their explanation depends on understanding a programme that runs in the brain - a programee which is an abstract entity not a physical one (it is physically instantiated in the brain, but understanding it, means understanding the abstraction of the programme, not the physical instantiation). So, in a sense the story still refutes simplistic physicalism (there is more to understand than just the "fundamental" physical entities). But, in my version of what knowing about colours would mean, we could still learn about what it would be like to see red, from a book, in the black and white room. We would do so, in a similar way to how we can learn about the blue tomato, without seeing it, through conjectures from related qualia and ideas. In my imaginary Mary story, we would be doing it with fewer direct experiences of qualia to draw on, but with a much deeper understanding of what these qualia actually are. 

So, I accept the author's assertion that the crux of the seeming paradox, in the Mary story, lies in the idea that there are indeed no more physical entities for Mary to discover, rather she has abstract entities to discover. But I don't follow the author's contention that there are no more "book learned facts" for Mary to discover. This is a version of an empiricist view that certain truths are not book learned and can only be gained by experience. Confusingly, it's these truths based on experience that the author considers to be outside the scope of science (empiricists tend to consider truths "based on experience" to be scientific). This difference arises because the author is emphasising the need for direct personal experience to know what red looks like. But actually, I still see this as the classic empiricist error: Imagining that the rest of us "know what red looks like", because we've experienced it. No. We know what red looks like, because we have an inbuilt, evolved programme that makes conjectures about how best to group certain colours as "red", and experience merely helps us to refine that. Similarly, Mary in her room, if she fully understood colour qualia, could make such a conjecture. She would no doubt benefit from experience to refine her understanding, but the core of the knowledge could come from a book (despite the premise of the thought experiment, knowledge from a book, could never be perfect (hence the potential to refine and error correct it with experience), but that's only because no knowledge is perfect).

Eric Johnson 20 January 2022

There is one serious point of contention in the discussion about Mary and the color red. The premise assumes the color red is a fact. In reality, the color red is a perception in the brain and not a physical property. The physical properties are the spectrum of light from the source, the spectral response of the object (the apple's surface) and the sensitivity of the detecting elements in the eye. Two situations arise from this. First is the assumption Mary can see the color red. She may see that color for the first time, but it is not what everyone else would perceive since perception is unique to the observer. And different spectral interactions between a light source, an object and an observer can produce the same color perception. The physical facts are completely different but the human perception is identical and that's how paint colors are matched to a sample swatch. The physical facts are all different but in accordance to Mary's complete understanding of color appearance would know they produce the same perception.

The second point is that we live in a world where we can measure and quantify facts that have no human perception. We can measure orders of magnitude more spectrum than we can perceive with our eyes and much of our daily living is directly impacted by this. Facts can and do exist outside of the realm of direct human perception.

But this then gets deeper into this premise of perception. Is human experience a proper fact? If the complete neurological mechanism of the brain were thoroughly understood, we would see that experiences are merely biochemical responses and chemical developments in tissue and cells that may be non-quantifiable today but not in the future. As frightening as it sounds, we are really just biochemical processors that may well be scrutinized into quantifiable facts and, even more frighteningly, programmable and adjustable beyond the normal experience of natural perception and response. In such a scenario, then we, our human existence, everything we experience and our very essence, are also part of that book of facts. But just in chapters we have not read...yet.

Elrick 18 January 2022

Good article. The recent LHC announcement that looks like promoting the addition of a 5th force in this universe of ours certainly backs the the idea that there is no absolute 'Book of the World'. And like Mary being brought up in a black and white room most folk in our world are brought up with no or very little experience of stuff like telepathy/telekinesis/dowsing and so on. In my opinion and experience these are real and science ought to spend time on such things to add to a more real Book of the World!!!