A redated post.
Someone asked me for a definition of consciousness. J. P. Moreland's essay "Hume and the argument from consciousness" in Sennett and Groothuis ed. In Defense of Natural Theology (IVP, 2005) delineates some features of conscious states that he thinks they have.
1. There is a raw qualitative feel or a "what it is like" to hve a mental state.
2. At least many states have intentionality--ofness or aboutness--directed toward an object.
3. They are inner, private, and immediate to the subject having them.
4. They require a subjective ontology--namely, mental states are necessarily owned by the first person sentient subjects who have them.
Now Moreland mentions a fifth feature, which I take it no physicalist is going to buy:
5. They fail to have crucial features (spatial extension, locatioin) that charcterize physical states and, in general, cannot be described using physical language.
Now I take it this last one is not one that a materialist could accept. But the first four seem to me to reflect what consciousness is. I would add that consciousness is importantly unified, that there is single entity that possesses all of the relevant conscious mental states; something that ties them together.
I take it that this is the common-sense conception of consciousness, and to reject it would be to accept a revisionist position.