Just an aside, you should look up some of the writings by my old (and favourite) Professor Dr. (James?) Weaver of McMaster University. He argues that it was the social technology of institutions, banking, land speculating, and established commerce that allowed whites to take over North America, not individual hostility. The key players he notes are the empire (who vacillated between expansionist and not-expansionist), the homesteaders, and the land speculators.
The Indians were harsh and intelligent bargainers, but they were playing by the rules of a game that white people wrote and created - the house always wins.
Fact: All Historians approach historical documents with their own set of contexts and biases - all Historians except Dr. Weaver, that is. Fact: Most Historians have to cite sources - Dr. Weaver is able to go back in time and create them.
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.