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I still don't know what it is supposed to mean to know what it's like to see red. Having seen red, I have a memory of having been in a state of seeing red. Not

I still don't know what it is supposed to mean to know what it's like to see red. Having seen red, I have a memory of having been in a state of seeing red. Not having seen red I wouldn't have such a memory. But this has no consequence for physicalism. I can imagine myself in the situation of having seen red, e.g. imagining myself viewing a red apple. But I have aphantasia and so I'm certainly not remembering or imagining red in any meaningful sense. In no way is my memory of being in a state of seeing red presently constituted by phenomenal red. When we imagine red or some visual experience, we know the early visual areas of the brain involved in those sensory experiences are reactivated by feedback signals from the frontal cortex. Presumably seeing red gives me this ability which one lacks before seeing red. But this has no consequences for physicalism either. Besides, the article claims the issue isn't about being able to imagine red. So what is the nature of this supposed knowledge? The whole concept seems dubious.

atdixon 4y ago
It might help to imagine a different world. One in which Mary steps out of her room, sees a rose, and absolutely nothing new is added to her understandings. She already had it all sorted out in her study. In many people’s understanding of “naturalism” that wouldn’t be any surprise. But that’s not this world.
- theresistor 4y ago
  If she truly possesses all physical knowledge, then she knows exactly what every possible rose looks like from every possible angle, in every possible setting and lighting. She knows in excruciating detail, at the level of every individual atom, how the scent of the rose will reach her brain, and exactly what responses it will trigger. And indeed had she that knowledge, nothing new would be added by seeing one in person. The implausible part is presupposing any person could ever have a complete enough understanding of all physical knowledge to achieve that.

atdixon 4y ago

It might help to imagine a different world. One in which Mary steps out of her room, sees a rose, and absolutely nothing new is added to her understandings. She already had it all sorted out in her study. In many people’s understanding of “naturalism” that wouldn’t be any surprise. But that’s not this world.

theresistor 4y ago
If she truly possesses all physical knowledge, then she knows exactly what every possible rose looks like from every possible angle, in every possible setting and lighting. She knows in excruciating detail, at the level of every individual atom, how the scent of the rose will reach her brain, and exactly what responses it will trigger. And indeed had she that knowledge, nothing new would be added by seeing one in person. The implausible part is presupposing any person could ever have a complete enough understanding of all physical knowledge to achieve that.