The Knowledge Argument

Say there's a woman named Mary who has monochromacy, or black/white color blindness, so that everything looks like a black and white film. Despite this disadvantage, Mary becomes a celebrated neurologist, and actually the foremost expert on color perception. She knows exactly what is happening in the brain when someone sees the color blue, for example, even though she can't see it herself.

Anyhoo, one day Mary is sitting underneath a tree reading a book about Isaac Newton when an apple falls on her head and momentarily knocks her out. When she wakes up her monochromacy is gone: she can see the green grass, she can see purple mountain majesties, and she can see the clear blue sky. She had never seen these colors before. She had never known what "blue" looks like. But she knew everything that happened in the brain when someone experienced the color blue. So the question is: does Mary know something now that she didn't know before? This is the Knowledge Argument.

This isn't as easy to answer as you might think. I've been asking my students this for years and it's usually a split vote. One point to make here is that knowing what blue looks like wouldn't be propositional knowledge, but does it count as knowledge then? Some people think it's obvious Mary knows something that she didn't know before (what blue looks like) and others think it's obvious she doesn't.

The issue here is about qualia (singular: qualium), the "what it's like" experiences. Thomas Nagel wrote an essay called "What Is It Like to Be a Bat?" which really brought this point home. Many philosophers of mind say that qualia are the heart and soul of the mind, and even human life in general. But the problem is that qualia can't be quantified and are effectively invisible to science. Science seeks to explain things from a third person perspective, but qualia are intrinsically first person in nature. Mary could describe color perception from a third person perspective but with no awareness of the qualium "what blue looks like". So the reason this is important is that, if Mary knows something after seeing the color blue that she did not know before, then there are important things -- foundational, fundamental things -- that science cannot address. If you had a complete physical, scientific description of the entire universe, it would be intrinsically incomplete, since it would not include qualia.

Moreover, the third person perspective is derived from the first person: to describe something from the third is to observe it from another standpoint, but ultimately this just means to observe it from what a first person perspective from that other standpoint would be. There can be no (to reference another Nagel work) view from nowhere. So science is utterly dependent on the first person perspective, and thus qualia, but cannot address them.

Naturally, all this is controversial. Some philosophers of mind, like Daniel Dennett, deny the reality of qualia. The philosopher who came up with the Knowledge Argument, Frank Jackson, eventually changed his mind about it because of the implications it had, viz., that there is more to reality than the physical world. Jaegwon Kim, who gives Nagel a run for his money as the greatest living philosopher in my opinion, fully accepts the reality of qualia and their centrality in human life, but still defends physicalism: see his books Mind in a Physical World and Physicalism, or Something Near Enough. And there's a collection of some of the most important essays about the Knowledge Argument which has the unfortunate title There's Something about Mary. So now you know what to read during the quarantine.

Your eyes are the darkest shade of light gray I've ever seen . . .