Possibly true, I am not sure.
Ok fine, but then you might just be inventing a new meaning for the term "conscious" which bares no essential relationship to the ordinary subjectively understood usage.
If you insist on appealing to the "ordinary subjective understood usage" of the term "consciousness" you have lost your case before you have even started. Ask a random sample of persons whether "chairs are conscious" matches their subjectively understood usage of the term "conscious", and the result will be desastrous.
I reckon that for instance if the word "consicous" is to be categorically defined as such and such brain activity it would have to be shown that "consciousness if and only if such and such brain activity" is true.
No, it wouldn´t have to be shown. It would simply follow from the definition.
IOW I think that the statements "there is consciousness" and "there is such and such brain activity" would have to be
materially equivalent. We could then say "A: if consciousnss then such and such brain activity
AND B: if such and such brain activity then consciousness" (which conjunctive proposition is just another way of stating material equivalence). However although I might accept B I cannot accept A.
I would assume B and don´t see how A follows logically (unless you employ a fallacious reverse conclusion).
Merely defining consciousness as necessarily involving brain activity doesn't help, just as defining a tree as necessarily having leaves doesn't help (because as we all know there may be a tree without leaves).
If I define "tree" as something that necessarily has leaves then something without leaves is not a "tree". That would be a practically useful (albeit unusual) definition.
"We all know there may be trees without leaves" merely appeals to an equally rigorous (albeit more common) definition.
Since this distinction is more common and does not define "trees" into obscurity (it gives clear criteria how to distinguish trees from not-trees in the given definition) I have no problem using the term in this definition.
Ok like I said you can stipulate a new meaning for the term, but don't try and conflate it with the original meaning unless you can show them to be identical or interchangable without a change in denotation.
That´s exactly why I neither see much use in establishing this definition that includes apples into the group of conscious entities: This definition would be contrary to the intuitive meaning that everyone "knows" (as you call an agreement on semantics): Apples aren´t conscious.
However, the idea that consciousness depends on there being a brain can matches exactly any traditional and/or commonly accepted connotation, denotation and implication of the term "conscious". This definition does not stipulate
a new meaning, it simply summarizes the intuitive and broadly subjectively understood meaning of the term.
Unadvertantly, though, you have shot your own foot here:
Your idea that quarks, chairs, apples may be conscious,
albeit in a completely different understanding of consciousness than we have now, rests squarely on the very approach you are criticizing here so vehemently.
If you are going to say "I have not invented a new term, but elucidated on the original meaning of "consciousness" by means of science" you have to show that tese "definitions" you give actually have an essential relationship to subjectively apprehended awareness.
As I have said above, your appeal to subjectivity and intuitivity is damaging your own cause rather than mine. Ask some randomly picked persons whether they consider apples to be conscious, capable of love and emotions, and you will get 99% "No, that´s absurd" (or something to that effect) for a response.
What I mean is that your definition of consicousness may involve physical states that are not conscious in the ordinary sense of the word, or there may be consicous states that are not covered by your "definition".
Well, since I have given a clear definition for "conscious states", there can´t be any "conscious states" that are not covered by this definition. That´s how language works.
I can (I suppose) "define" consciousness as the wave function of an electron if I like, or any object with a mass above 15 grams, and that would give me a "testable definition". Great! If I have my physics right I can test for mass with weighing scales, sure. Does that mean I have understood what consciousness (in the ordinary sense) is by defining it as mass over 15 grams? No.
At any rate, you have at least given a definition that allows for a meaningful discussion based on your definition. That´s far more than you have done so far. The claim that there may be consciousness of a kind that is completely different from what our current "understanding of consciousness" neither allows for such a meaningful discussion,
nor does it accept the "consciousness (in the ordinary sense) - au contraire, it postulates "consciousness" to go beyond that which it is understood as in the ordinary sense.
Well if there is no testing for the original term, how does "redefining the term materially" actually do anything constructive, except perhaps to inadvertantly change the subject without realising and give everyone illusory relief?
It helps meaningful conversation, whereas your approach establishes obscurantism as a virtue.