(Reply to John Campbell-3)
JC: “(1) Characterizing the epistemic role of consciousness. In particular, there’s explaining the work that sensory experience does in (a) our having propositional knowledge of our surroundings, knowing that things are thus-and-so around us, and (b) having concepts of the objects and properties in our surroundings, knowing which objects and properties those are“
The trouble is that each of the mental states you mention has an easy aspect (doing and ability to do) and a hard aspect (feeling). So unless you specify which of the two you are referring to, it is difficult to know what you really mean:
JC: “(1) Characterizing the epistemic role of consciousness“
“Epistemic” is equivocal: it could refer to what can be known in the sense of unfelt knowing (doing, and ability to do: easy) or felt knowing (hard).
And until/unless there are further arguments to show that the distinction is coherent, a “conscious” state is a state that it feels like something to be in, hence a felt state.
JC: “In particular, there’s explaining the work that sensory experience does”
Unfelt sensory system activity (doing, and ability to do: easy) or felt sensory experience (hard)?
JC: “in (a) our having propositional knowledge of our surroundings”
Unfelt propositional knowledge (doing and saying, and ability to do and say: easy) or felt knowledge (hard)?
JC: “knowing that things are thus-and-so around us“
Unfelt knowing (doing, and ability to do: easy) or felt knowing (hard)?
JC: “and (b) having concepts of the objects and properties in our surroundings“
I have no idea what “having concepts” means! Does it mean being able to do/say certain things (easy) or does it also feel like something to have a concept (hard)?
JC: “knowing which objects and properties those are“
Unfelt knowing (doing, and ability to do: easy) or felt knowing (hard)?
JC: “(2) Explaining how conscious experience can be realized by a physical system.It seems to me that (1) is not well understood, and that arguably it’s prior to (2)“
I agree.
JC: “ I don’t think there’s much hope for a successful assault on (2) unless we have firmly in place a clear conception of exactly what explanatory work the notion of consciousness in general, and of sensory experience in particular, is doing for us“
I agree. And the hard part is that on the face of it the answer is: none!