From PhilPapers forum Philosophy of Mind:
The 'Explanatory Gap'
Reply to Jamie Wallace
I am equally curious as to how professionals variously constitute "explanation" re this question. Materialist/determinist folks appear to require explanations to express absolute conformity to strict logical templates of cause-effect, etc. Others, myself included, consider explanation to be the most fruitful, if not normative, when it partially and/or putatively explains so as to assist further avenues of pursuit. While such explanations are hardly formal, often imprecise and rarely rigorous, nonetheless they are "partial" explanations whose veracity only awaits other kinds of validation. I might add that this distinction is a profound source of miscomprehension (animosity?) as between theorists and those adhering to a very strict "experimental" approach to the "scientific method". I also note as an aside that it does not seem to me that philosophy has adequately distanced itself from the science purists (as I term them).
Now if we restrict attention solely to the "consciousness" aspect of this question, I am of the school holding that sleep, dreams and consciousness are so essentially related as to require answers to any two to obtain any third. Ergo, a putative explanation may hold that to the extent the common modalities of identificative and projective mechanisms run in common as between REM and consciousness of the awake state, we would look to hypnogogic mechanisms of explanation. While there aren't necessarily a lot of those to go aropund, the theoretical material is astounding. If, therefore, we can better grasp the role of hypnosis in positive and negative hallucinations, most all of which entail awake consciousness, we will need only verify through more physical/lab approaches--some of which are already available.
I truly believe that sleep and dream research holds the answers--the 'explanation'--for the origin and nature, as also much of the functionality, of consciousness. And once we have a better handle on that, well, the explanatory elements enable generalization to qualia of varying sorts, and so forth. So I guess I allow the presence of a "gap" but presume that substantive progress awaits, though I also am fully open to the view that some 'gap' will always remain, to the extent that "emergent" qualities are likely to remain without satisfactory explanations long into the future, though Batterman (Devil in the Details) has an approach that seems to me to offer promise even here.