Consciousness is behaviour, yes; and to observe that behaviour we normally look at outward signs (the body) and also at what is stimulating that consciousness (the environment).
But if you confuse the easily visible signs of consciousness with the process of consciousness, then, um, you're confused. After all, we can also just shove a bunch of electrodes into your brain. It's just that this is considered impolite.
That's why I try not to confuse the two. When we use the word consciousness we typically refer to a kind of private behavior, most of which is not readily open to scrutiny by others. Why this has become somehow mysterious is beyond me. I know people play with the various meanings of the word 'objective' and argue that science is 'objective' so it cannot deal with the 'sujective'; but that is just word play and not worthy of serious thought. But you know that already.
First of all, language does make sense as a private property; you are confusing shared language with language in general. I can make my own language, and as long as it has meaning to me, it's a real language.
Second, we seem to be getting further and further away from a definition of what consciousness is. What are these higher functions that depend critically on language, and why are they labeled "consciousness"?
Consciousness is being aware and self-aware. What else is needed?
As to the private language issue, we do not create private languages de novo. We learn a language within a language community; language really only makes sense in that sort of context, since its function is communication. While we can create a private language after the fact, that is just a curiosity; that sort of thing does not serve the function of language. Private means of notation are ususally only markers, not full languages anyway (they don't generally follow full semantic/syntactic rules the way native human languages do). I think language is best viewed as an interaction between people. Meaning derives from that shared community.
As to the issue of how this relates to consciousness, well that depends on how consciousness is defined. There is a sense in which we are not aware (or at least fully aware) of things we cannot name or deal with linguistically (we almost define the external expression of 'being conscious' of some idea based on one's ability to communicate it; Billy cannot say what it is he is thinking, well that's because he isn't really aware of what is in his mind). But, from a neuro perspective, we use the word consciousness to refer to several different things -- which is all part of the problem. That word just doesn't mean one thing, and this allows folks to switch definitions around and pretend that there is something mysterious at play.
There is being awake. That is one level of consciousness and there are gradations within it ranging from coma to stupor to lethargy to fully awake. And there is a whole host of other mental functions allied to this -- and this includes the 'will' with situations like akinetic mutism throwing a wrench into our whole way of viewing wake/alert/aware issues.
Then there is awareness, which when examined gets really messy.
Then there are what we call the contents of consciousness, including language, concentration, executive functions, memory, etc.
It's all very messy. Then Thomas Nagel comes in and decides that what really matters is the feeling of what happens, which is a whole other issue.
You might as well say that breathing cannot be localised to any individual respiratory system, that digestion cannot be localised to any individual digestive tract.
Yes. Digestion and breathing are behaviors that depend critically on environmental influence. We speak of digestion as occurring in the gut, but it cannot occur in the gut without outside influence -- food. The same is true of perception. While the brain is capable of creating its own perceptions -- hallucinations -- it depends critically on outside influences in the first place to create categories of thought. And perceptions themselves are interactions between receptors and environment.
I know that we all speak of the brain as 'the locus' of consciousness, but this is only short-hand. I think that is what BDZ was trying to say -- to remind us that the brain isn't all there is to the equation. It isn't that big a deal, so I think he was overly harsh in his criticism of you. If he means something else, then I disagree with him.
People who look at this from a philosophical perspective -- particularly from a monistic viewpoint -- see the entire environment as one, and they are often not willing to give any special merit to the individual. I think that is all he was trying to say.
And, yes, when it comes to such discussions, I agree that this is overly pedantic.
