>So, it’s merely a problem of communication. Much worse. Qualia elude not only communication, but observation and experiment as well. Suppose that, with sufficiently advanced technology, you obtain the fullest real-time description of what goes on in my brain - every neuron, synapse and neurotransmitter molecule - when I see a red rose. We have thus broadened the meaning of "percept" to the entire neurophysiological process that occurs when the stimulus is processed in the brain. Paradoxically, the problem now becomes worse: You know better than I do what goes on in my brain when I perceive red, and yet, that doesn't bring you any closer to my quale of red. Worse still, it is not only that you cannot be sure that my qualia are similar to yours - you cannot even be sure that I have any qualia at all.
Okay, so I have a computer hooked up to some really advanced nanotech that can read and fiddle around with brain states. So I take a snapshot of your brain. Then I tell you to go into a room, and look at a red rose. You gain that memory; you can picture the red rose in your mind's eye, and experience the quale that is red. Next, I take another snapshot. My computer can diff the two states and isolate that state change that created your memory. Now, I knock myself out, and have someone hook me up to the computer and merge that state change into my own current brain state. This is advanced nanotech, so it can of course do this without fucking up my own ego. So now I wake up. What do I experience when I recall your memory of the red rose? I am going to bet it's the same quale of red that you did. Sure, you could say, but wait, maybe when YOU recall the memory you get YOUR red, but when I recall the memory, I get what YOU would see as blue! But then you're straying back into epiphenomenalism, which you (correctly) stated was retarded. There has to be SOME connection between the quale and the physical world, right? Otherwise it wouldn't be "interactive" dualism.
