Thank you all for your comments. They were enlightening. However, I noticed an area of misunderstanding. There are some distinctions that I hoped were clear from post, that I now realize are not. They are not intuitive, and though simple, they are not easy to see.
First, Killing a Vegan: Degrees of Subjectivity is a discussion on ethics. It is a hoping to find some sort of understanding in the area of animal rights, and our ethical responsibility to them. Sometimes emotions clutter our reasoning, and while they motivate moral actions, sometimes they prevent progress in dialogue. Like the abortion debate, the animal rights debate is cluttered with allot of emotion that obscures a deeper progress in ethical and legal understanding.
Why are we worried about animals? Why do we care? Well, because we are equipped with a machinery that allows us to experience another's---including an animal's---pain as if it were our own. Our empathy allows some access to another's suffering. It does this by using external cues. We see it squirm, we hear it squeal and we watch it run in fear. However, there is a difference between a feeling, like suffering, and the behavior, like squirming. It is the case that many times these are associated in humans. But, the feeling and the behavior are not the same and they don't always correspond. Also, what we consider pain isn't always suffering. I stab myself with a pen and I feel pain, but today it is a distraction from my excessive anxiety, and distracts me from my emotional suffering. The pain at that point is not suffering. The anxiety is.
What I want to know is what causes suffering. And, in order to say anything about suffering, we need to know the difference between suffering, pain and the behavior associate with the two. If we know what causes suffering in a person (what brain region or trait), we can say when it happens in an animals or which animal it occurs in and which it does not. In this way, animal right activist can say something that has substance in the debate, something that would be very hard to fight, something that people can relate to and conveys truth.
If I am doing research on nervous system tissue in my lab, should I be concerned with the pain I am causing it? Does it suffer? If that doesn't suffer, then how much more tissue and complexity is required for it to suffer? At what point should we living tissue become a being worthy of ethical consideration? At what point does it really suffer as we as humans suffer? If my finger (which has a great deal of neural complexity) fell off and could be reattached, but was still alive, should I be concerned about how it feels? Killing a Vegan: Degrees of Subjectivity is an article that wants to know where we draw the line? We need to know where we draw the line so we can advance in our discussion, in our ethics and in our laws.
So, at what point does a piece of tissue gain moral consideration? When is it aware of itself as a suffering beings?