An Even Harder Problem of Consciousness (!): The qualia might be unique between individuals, without any way to compare a quale of a person with the same-name quale for another person. For example, we can't know (at least for now) if the redness of a rose is similar for person A versus B.
The question is if the redness for person A at time 00:00 is similar to the exact same person A, one hour later. How can we know that our qualia change or not over time? Can we?
I assumed we can't because all we have for us to compare our new experience of "redness" with older experiences of the very same quale is our memory. And it is not known if any subjectivity is attached to our memories.
So it is quite possible that each time I see red, I am actually experiencing a different quale but think it is the same red because I have no reference to compare quale 1 with quale 2. All I have is memory 1 and memory 2 (which are equal, because both of them are for the same color).
Preprint An Even Harder Problem of Consciousness®: The explanatory ...