You're all such analytic die-hards...
This a very long post, hope it's digestible...
Whats missing here is any appreciation for two crucial aspects - history and the other.
Maybe it's best to view consciousness as a spandrel, (a non adaptive trait that goes hand in hand with an adaptive one) something that came along with the evolution of the "psychological mind" as Dondante calls it. This is more or less what Dennett proposes - the subjective, phenomenal mind is a complex, constant redrafting of a narrative which glues all the psychological subsystems together. It does not have to be epihenomal - without the phenomenal mind perhaps the whole system of advanced human cognition would fall apart. This seems much more likely to be the case than a pure epiphenomena which we can conceive of doing without (the zombie argument)
Making claims to the logical possibilities of zombies is fairly redundant when we have no understanding of the logical relations between the phenomenal and the physical mind, and such thought experiments really on a slight of hand that the "common sense" position is correct. Dennett is very good again on the critique of such thought experiments (I can't remember where now sadly..)
Consider - we are fully aware of the logical relations of a cube, we can separate the elements essential and non-essential to it. It is logically possible that the cube could be another colour, or material or indeed a kind of being (a physical cube as opposed to an abstract one in vector space), it is not possible that the cube can have no corners. The premises of the zombie argument ("that there is a logically possible world in which zombies exist") assume that the relation between the phenomenal to the physical/psychological mind is analgous to that between the colour and the cube.
EDIT: Just realised psood0nym's post describes this better in terms of natural kinds and properties...
As for history... how we conceive consciousness has changed a lot through the history of man, and across cultures (it would make no sense, for instance, to pose the zombie problem within a Buddhist context - the problem would be meaningless). The very idea of phenomenal consciousness as Dondante conceives it has only been around since John Locke (300 years). If there's one thing that psychedelics have taught me, it's that it is possible to be conscious in different ways. To ask when historically phenomenal consciousness arrived, and where the cut off is between animals that have consciousness or not make no sense (as I think Dondante would agree). So it was that the full gamut of human modern human conscious has been built up over time, to where we are now, complex consciousnesses built on the core of phenomenal consciousness and self awareness. It previous times, our ancestors were not like this. At some point they were animals, consciousness is a broad spectrum not just across species but across time.
From Dondante's first post (I haven't read the thread he makes a distinction between self-awareness and phenomenal consciousness, which requires only awareness of the external world. Your tone suggest you think phenomenal consciousness is primary both historically and casually to self consciousness. I hope when you say self-awareness you mean reflective, future planning, disctinct awareness of a "self" in the modern sense, not simply the awareness of being a subject. Because to have awareness of the external world, you must have something to distinguish it from - the subject, self in the most primitive sense. There must be something the world is external to.
Where of course continental philosophy has much to say - Hegel & Heidegger both brought an awarness of the historicity of "being". Hegel's most famous work, The Phenomenology of Spirit is a history of consciousness, starting from pure undivided subject, no other, and works its way in steps thought the introduction of the other, the steps to consciousness and the metaphorical struggle to become self-conscious in the more complex sense. Self consciousness is only achieved finally through relationship with another consciousness. Specifically, the final step to being self-conscious is recognising that same self consciousness in another. Primitive, pre self consciousnesses together become self conscious by reciprocal recognition of each other, as being both the same (both conscious humans) and yet different (you and me). Ontologically, there are three kinds of things - me (my self consciousness), not-me (the world) and me-but-not-me (the self consciousness of another). Of course then Hegel goes on to build other more complex layers of consciousness through the development of society, art, religion etc.
Autopoesis is worth mentioning briefly too, when psood0nym bemoans the difficulty of drawing fixed jumps in kinds of being:
psood0nym said:
Up to and through the level of molecules, panexperientialism is pretty clean. When we make the jump to the cellular level things start to get muddy, and when we make the leap to the level of the organism it’s a damn swamp. What are the rules for deciding what constitutes an experiential property of a cell and what doesn’t (the removal of one ion channel or a lipid from the cell’s wall might change it’s properties subtly but not in a deeply functional way; does it change its experience)? What about the profoundly more complex level of the organism?!
Autopoesis proposes that the next kind catgory, between molecules and cells is that of a homeostatic boundary, which is simply defined as a system that maintains its integrity and distubances to that integrity with certain parameters (full definition of a autopoetic system here
http://en.wikipedia.org/wiki/Autopoesis ). Actually pinning down the details of it is a complex issue, but what is interesting to note is that the formation of the homeostatic boundary is strikingly similar to the first step in Hegel's analysis - the division into subject and object.
To try an tie this together - Hegel shows that full self consciousness requires the presence of the Other (i.e. other human consciousness, that which is both like you and not like you), and thus it is wrong to try and localise the consciousness to supervern on the physical/psychological structures of the brain. (In the same way that Putnam argued that "meaning just ain't in the head" and that Clark & Chalmers argue for the external nature of the mind). Rather, consciousness supervenes on the grouping of physical brain, the world and the Other. This, to me, is the only worthwhile notion of emergence - consciousness emerges from, and is created by the network of relations that exist between people and things in the world - it is self supporting, the actions of consciousness produce consciousness.
Putnam & Semantic Externalism -
http://en.wikipedia.org/wiki/Hilary_Putnam#Semantic_externalism
Clark & Chalmers "The Extended Mind" -
http://consc.net/papers/extended.html