What is Consciousness?
(Please, ahem, see another site for a precise and complete definition.)
There is general agreement that consciousness is not a unitary phenomenon.
If it's not one kind of thing, what kinds of things is it?
Some kinds of consciousness, defined in terms of what is missing when they are not present:
H-consciousness
(higher-order consciousness): missing when, for example, a driver gets home without "introspective awareness" of performing the task. Evidenced by the driver's failing to remember performing the task, and hence, by a lack of reportability.D-consciousness
(discriminatory consciousness): missing when, for example, a birdwatcher is looking right at a bird but cannot pick it out. Also evidenced by lack of reportability, though also by a failure to be able to perform the task in question.
R-consciousness (responsive consciousness): a general capacity to react rationally to the environment, which can be lacking in degrees. E.g., A drunk person passed out on the floor has very little, if any, R-consciousness; the drowsy person has some, and the alert person still more.
P-consciousness
(phenomenal consciousness): the (perhaps quintessential?) aspect of consciousness; the "what-it-is-like". Reportability can vary with H-consciousness (a headache may not come and go, even when one is intermittently not "introspectively aware" of having it).
Arguably, P-consciousness is what unifies these conceptions-after all, what temptation would there be to say that someone was H-conscious of driving home if she lacked the capacity to be P-conscious? In fact, many taxonomies distinction rather sharply between P-consciousness and what Block calls Access-consciousness, where the latter are states "poised for free use in reasoning and for direct 'rational' control of action" (1997, p. 382) H-, D-, and R- consciousness are, presumably, forms of access-consciousness.
With what sort of consciousness is the issue addressed in this poster concerned?
This varies, sad to say, with the approach under discussion. For many empirical studies, the focus is, of necessity, on reportable states. Hence, H-consciousness turns out to be the topic of enquiry in those cases.
However, this focus on reportability need not be illegitimate, since:
Furthermore, if P-consciousness is a necessary condition for the others, as most agree, then discussion of the others ipso facto involves P-consciousness.