First, let me distinguish two different issues: what can we eat, and what can we kill. For the first, I don’t think there are major issues; I see no reason why, if we accept that an animal, or a person, or anything else, is dead, we can’t eat it. Now, I’d prefer not to eat my grandfather, but if I were trapped and starving and he were dead, I’d do it. On the subject of ‘utilizing’ grandma’s teeth, I’m all for it. When I die, at least, I really hope someone does something more productive with my corpse than bury it. Donate it to science, give the organs, whatever; but don’t waste it.
What we’re allowed to kill is a different question. I see nothing wrong with eating dead people; I see a lot wrong with killing living people. However, I don’t think I really do agree with the classification of ‘moral subject.’ I don’t think you can just assume a moral obligation exists without being able to show why it exists. A moral agent has rights, not just because I say so, but because I can show why this is so (an argument I made in this thread: http://boards.straightdope.com/sdmb/showthread.php?threadid=230016&pagenumber=2. I’d repost it, but the two posts I made in that thread added up to nine pages in Word; I don’t want to hog that much space). A moral subject, on the other hand, is just a being that is asserted to have some sort of rights. Looking at specific cases:
The baby. Probably the most sensitive case here. I’d classify the baby as a moral agent of sorts, with rights, because even if the baby can’t make decisions now, the potential for decision-making is still there. Assuming the child isn’t miserably deformed, it will as it grows develop the capacity to make moral decisions, thus qualifying it as a moral agent.
Mentally retarded persons: divided into two groups. The first group is peopel retarded but still functional. These people still have some measure of decision-making ability; even if they can’t reason as well as you or I can, their mental ability is still somewhere above a cow’s (I’m taking my mother’s word on this; she worked on a cow farm one summer). Even if they have more limited rational capacities, those capacities still exist.
The second group is the totally braindead. These people have no thought-process whatsoever. I’m going to get attacked for saying this, but I’m used to it: I have no problem with killing those people whatsoever. As far as I’m concerned, a person who isn’t capable of thinking, at all, isn’t really alive. He’s just dead and waiting for his heart to stop beating. Thus, I would consider a full lobotomy teh moral equivalent of murder, even if the body were put on life-support.
Now, the subject of this thread, animals: I think it depends on the specific animal/species in question. I would have issues with eating a dolphin or a chimpanzee; I don’t know that they have rational capacities, but it’s certainly immanently possible, so I wouldn’t kill one of them. However, there does seem to be a difference between chimpanzees and chickens or cows, so I have no problem with killing the latter.
Next, I disagree with those of you who say that Blonde and the other pro-vegetarians are too harsh in their approaches to meat eaters; in fact, I almost think they’re too mild. If you accept the premise (which they seem to; forgive me if I misrepresent) that animals have as much right to live as we do, then it seems to follow that you should treat a person who kills an animal the same way you would treat someone who kills another human being. I would be utterly horrified to talk to someone responsible for the deaths of hundreds of innocents; but if you class cows and chickens in with those ‘innocents,’ I’m surely guilty of that many, if not more. I don’t find this reprehensible simply because, to be blunt, I don’t care what happens to the chicken, and see no reason to care. In contrast to those of you who say we can kill the animal but we have to be humane, I don’t care how they’re treated. I see no reason to torture animals (especially if it’s true that stress makes the meat taste worse), but I see no reason not to either.
Conversely, I, oddly enough, get nearly as offended at vegetarians as most strict vegetarians do at meat-eaters. This is because I place a great deal of value on a quality (rationality) that separates humans from animals; any degradation of the value placed on that quality tends to make me bristle. Thus, I tend to be somewhat upset by people who equivocate animals and humans because they are, as I see it, trying to avoid acknowledging the part of humanity that makes humans valuable and relevant.
Finally, to those of you who ask about my killing my pets: if my mother weren’t sure to get upset, and the dog were slightly more annoying, I’m sure I’d find some way to get rid of it.