First published: January 21, 2025
Last revised: January 21, 2025

Rather than asking whether Mary obtains new knowledge upon seeing color for the first time, we should ask what she can do after seeing it, that she could not do before. This goes straight to something measurable.

One thing that comes to mind is that a qualia gives her knowledge of the internal state of some part of her own brain. And this privileged access to qualia again brings me back to Maxwell's demon who knows the internal state of the gas in the chamber, even if this state is unknowable from the outside.

So what does it mean for her to "know" the state? I think here we can make a distinction between knowing the state and a description of the state. If she learned about the state of her brain by reading the results of some measurements, she would know a description of her brain, whereas by knowing the state of her brain without external measurements it's the brain knowing itself, because after all Mary *is* her brain.

Does this type of self-knowledge / self-reference lead to a measurable difference of any kind?