Why do you designate the experience of green as 'more subjective' than a thought or emotion?
Hi, it depends on what you mean by subjective. In general, subjectivity isn't the best term to use in philosophy of mind because it's not really well-defined.
What I mean, though, is that whether or not a person is having a given emotion, like anger, for instance, seems theoretically knowable to a third person. What a person's experience of anger is like, whether it's similar to my anger, does not seem theoretically knowable to a third person.
This type of question of "what it's like" is more-or-less the central issue in philosophy of mind. If you're interested in reading about it, I recommend David Chalmers' "The Conscious Mind".
No, I mean introspection into *noumenal states* (phenomenal states are accessible to science, no?), which takes us out of the realm of science and into the realm of metaphysics.
No, phenomenal states aren't accessible to science... at least I don't think so. As for noumenal states, that phrase rings a bell... it's something from Kant, I think. That type of thing is not really part of modern philosophical discourse on mind. What are you trying to express with it?
In any case, if whatever you're thinking of is outside the realm of science, then what does it have to do with the actual world? If it's outside of science, then what use can it be to treat a disease?
Actions, probably yes (though we haven't got the details worked out yet). Thoughts and emotions, that's going to be rather more difficult.
What do you mean? If you're saying that we won't be able to use neuroimaging to read thoughts, then I agree. But if you mean that our emotional states are determined by something outside of our brains, then I think that you're simply wrong. If emotional states aren't determined by brain states, then how can we pharmacologically alter mood?
To be honest, though, I don't think that's what you're really trying to say. What I think you mean is that the subjective experience of a thought or an emotion does not supervene on a brain state. Whether or not we are in a given mental state is an objective fact about the world, provided we have clear enough categories for mental states. What it is 'like' for us to be in that state is not an objective fact about the world.
But psychiatry doesn't have anything to do with "what it's like". If a patient claims that they are depressed all the time and are contemplating suicide, it doesn't really matter that their experience of depression is similar to what we experience when we hear a trumpet... What's important is the actual effect of that depression on the patients life.
My point is that "what it's like" to be in a state may be one of the most fundamental mysteries of the universe, but which neural mechanisms cause which brain states is not. That is a question for ordinary science. It's easy to let the mystery of consciousness spill over into our ordinary discourse of brain function, but when we do that we are ignoring the hundreds of years of philosophy of mind that has allowed us to study the brain at all, and we're effectively abandoning the entire neuroscientific enterprise.