" You might as well say "If we set clear boundaries for something, its boundaries become clear." If X, then X. "
That's exactly my point.
" there's nothing inherently wrong with setting boundaries on identity, I just see no reason, evidential or otherwise, to do so. "
Who said reasons are required? The point is trying to understand, not trying to discover the truth.
" Assuming that these boundaries are valid, what do you think would happen when brains are combined or some other drastic change to the brain is made? "
Nothing! You are too stuck with the notion that a person's identity has anything to do with the brain. Not only that, you are also stuck with the notion that a person's identity has anything to do with subjective feelings.
Think of "your car". How many parts do you have to replace until it is no longer "your car"? Does it remain "your car" if you replace the horn? The bumpers? The engine? The whole body?
The truth is that your car is "your car" for as long as you and others think so. Saying that cars do not really exist, only parts do, doesn't explain what makes your car "your car". The same goes for a person's identity.
" Can these boundaries survive even cursory reductionism? "
Why does anything have to survive reductionism? Because reductionism is true?
" More importantly, do you think they should be able to? "
" If you'd like me to append the phrase "I'm not sure about this, but it sounds good to me" to every statement I make, I will. :) "
No, I don't. I was trying to make a different point.
" Personally I think it's implied. "
Nothing is implied.
" I'm just attempting to remove humans from the equation. "
Silly, silly... You can't remove humans from the equation and still keep the equation.
" Without us walking around, trying to describe things, terms like "red" or "lake" would have no meaning. "
Does that mean that terms like "red" or "lake" really have no meaning then?
" I see no reason why "life" or "sentience" would have meaning independent of themselves either. That's all I was trying to communicate. "
Somehow I miss your point.
" I try to limit it as much as I can. Of course it's not complete, in order to be totally successful I would have to stop being human, which can be quite a trick. Would you agree that there are *degrees* of arbitration, however? "
No, I don't agree. As Dick keeps bringing up, any explanation of anything is just a story, and all self-consistent stories are true. So you are not as free to add or remove concepts to your story as you think you are, at least not as long as you care about truth.
I probably lost you by now...