Ethical projectivism isn't quite so much a theory of mind as it is a theory of ethical language. It's clear that in most cases where people say, "X is wrong" they ascribe the objective quality "wrongness" to X. Projectivism holds that there is no such objective quality, thus, the property of wrongness is in the mind, but it doesn't feel like it, much like how the concepts of beauty and disgust are in the mind, but don't feel like it. You can't smell something disgusting and say, "Well, that's just my opinion, that's not really a property of the smell;" it still smells disgusting. Thus, projectivism has the same rejection of objective morality as emotivism does, but it describes how we actually think and speak much better than emotivism does.
The attack on emotivism as not accurately expressing what we mean is largely orthogonal to realism vs. subjectivism. Just because we speak about objective moral principles as if they exist does not mean they actually exist, anymore than speaking about the Flying Spaghetti Monster as if it existed conjures it into existence. But the view that moral statements actually express mere approval or disapproval seems clearly wrong; that's just not what people mean when they talk about morality.
As I see it, you ignore the first and third bullet points and take the second bullet point to promote projectivism over emotivism. It's certainly true that projectivism takes speech more at face value than emotivism. But since emotivism is up-front about this, this is a pretty weak complaint. Maybe it means that emotivism has to do more work to fill in a psychological theory of morality, but producing a psychological theory of morality seems big enough that it's not obvious whether it makes it harder or easier.
What if I posited a part of the mind that trie...
For a long time, I wanted to ask something. I was just thinking about it again when I saw that Alicorn has a post on a similar topic. So I decided to go ahead.
The question is: what is the difference between morally neutral stimulus responces and agony? What features must an animal, machine, program, alien, human fetus, molecule, or anime character have before you will say that if their utility meter is low, it needs to be raised. For example, if you wanted to know if lobsters suffer when they're cooked alive, what exactly are you asking?
On reflection, I'm actually asking two questions: what is a morally significant agent (MSA; is there an established term for this?) whose goals you would want to further; and having determined that, under what conditions would you consider it to be suffering, so that you would?
I think that an MSA would not be defined by one feature. So try to list several features, possibly assigning relative weights to each.
IIRC, I read a study that tried to determine if fish suffer by injecting them with toxins and observing whether their reactions are planned or entirely instinctive. (They found that there's a bit of planning among bony fish, but none among the cartilaginous.) I don't know why they had to actually hurt the fish, especially in a way that didn't leave much room for planning, if all they wanted to know was if the fish can plan. But that was their definition. You might also name introspection, remembering the pain after it's over...
This is the ultimate subjective question, so the only wrong answer is one that is never given. Speak, or be wrong. I will downvote any post you don't make.
BTW, I think the most important defining feature of an MSA is ability to kick people's asses. Very humanizing.