Let's go back to your original statement:
A creature isn't conscious until there's a brain with a concept of 'consciousness' that identifies it as such.
OK, so according to you, we have concepts existing before and independently of consciousness, and we also have that consciousness is not a property that is objectively present (or else there'd be no need to appeal to the conceptual judgement of a brain, as a necessary cause of consciousness's existence). Both of these have to be true if you are to avoid circularity.
The second one already falsifies your account of consciousness. The difference between being conscious and not being conscious is not a matter of convention. It's an internal fact about you which is not affected by whether I am around to express opinions.
It sounds like you want the consciousness of a brain to depend on the conceptual judgements of that same brain, which is at least less abjectly dependent on the epistemology of outsiders. But it's still false. If you are conscious, you are conscious regardless of whatever opinions or concepts you have. Your conceptual capacities limit your possible conscious experience, in the sense that you can't consciously identify something as an X if you don't have the concept X, but whether or not you're conscious doesn't depend on how you are using (or misusing) your conceptual faculties at any time.
Just to clarify, by consciousness I mean awareness in all forms, not just self-awareness. What I said still applies to self-awareness as well as to awareness in general, but I thought I would make explicit that I'm not just talking about the sense of being a self. Even raw, self-oblivious sensory experience is a form of consciousness.
If these disembodied qualia-properties don't help you make any actionable predictions beyond what physicalism could do, and their presence is unfalsifiable, I can't see any point to this debate. Is it a social-signaling contest of some sort?
Maybe my very latest comments will clear things up a little. The immediate problem with physicalism is that reality contains qualia and physicalism doesn't. In a reformed physicalism that does contain qualia, they would have causal power.
Just to clarify, by consciousness I mean awareness in all forms, not just self-awareness. What I said still applies to self-awareness as well as to awareness in general, but I thought I would make explicit that I'm not just talking about the sense of being a self.
Ah, so we're arguing over definitions.
The immediate problem with physicalism is that reality contains qualia and physicalism doesn't. In a reformed physicalism that does contain qualia, they would have causal power.
Let's say you take an organism capable of receiving and interpreting inform...
...at least not if you accept a certain line of anthropic argument.
Thomas Nagel famously challenged the philosophical world to come to terms with qualia in his essay "What is it Like to Be a Bat?". Bats, with sensory systems so completely different from those of humans, must have exotic bat qualia that we could never imagine. Even if we deduce all the physical principles behind echolocation, even if we could specify the movement of every atom in a bat's senses and nervous system that represents its knowledge of where an echolocated insect is, we still have no idea what it's like to feel a subjective echolocation quale.
Anthropic reasoning is the idea that you can reason conditioning on your own existence. For example, the Doomsday Argument says that you would be more likely to exist in the present day if the overall number of future humans was medium-sized instead of humongous, therefore since you exist in the present day, there must be only a medium-sized number of future humans, and the apocalypse must be nigh, for values of nigh equal to "within a few hundred years or so".
The Buddhists have a parable to motivate young seekers after enlightenment. They say - there are zillions upon zillions of insects, trillions upon trillions of lesser animals, and only a relative handful of human beings. For a reincarnating soul to be born as a human being, then, is a rare and precious gift, and an opportunity that should be seized with great enthusiasm, as it will be endless eons before it comes around again.
Whatever one thinks of reincarnation, the parable raises an interesting point. Considering the vast number of non-human animals compared to humans, the probability of being a human is vanishingly low. Therefore, chances are that if I could be an animal, I would be. This makes a strong anthropic argument that it is impossible for me to be an animal.
The phrase "for me to be an animal" may sound nonsensical, but "why am I me, rather than an animal?" is not obviously sillier than "why am I me, rather than a person from the far future?". If the doomsday argument is sufficient to prove that some catastrophe is preventing me from being one of a trillion spacefaring citizens of the colonized galaxy, this argument hints that something is preventing me from being one of a trillion bats or birds or insects.
And this could be that animals lack subjective experience. This would explain quite nicely why I'm not an animal: because you can't be an animal, any more than you can be a toaster. So Thomas Nagel can stop worrying about what it's like to be a bat, and the rest of us can eat veal and foie gras guilt-free.
But before we break out the dolphin sausages - this is a pretty weird conclusion. It suggests there's a qualitative and discontinuous difference between the nervous system of other beings and our own, not just in what capacities they have but in the way they cause experience. It should make dualists a little bit happier and materialists a little bit more confused (though it's far from knockout proof of either).
The most significant objection I can think of is that it is significant not that we are beings with experiences, but that we know we are beings with experiences and can self-identify as conscious - a distinction that applies only to humans and maybe to some species like apes and dolphins who are rare enough not to throw off the numbers. But why can't we use the reference class of conscious beings if we want to? One might as well consider it significant only that we are beings who make anthropic arguments, and imagine there will be no Doomsday but that anthropic reasoning will fall out of favor in a few decades.
But I still don't fully accept this argument, and I'd be pretty happy if someone could find a more substantial flaw in it.