Or like this (call it condition #2)?
Okay, I'm going a little too fast here. I should back up and say first why I am putting the question this way. (What question? I'll eventually get to that too.)
Robert Nozick has asks some very interesting questions about eating animals.
Suppose (as I believe the evidence supports) that eating animals is not necessary for health and is not less expensive than alternative equally healthy diets available to people in the United States. The gain, then, from the eating of animals is pleasures of the palate, gustatory delights, varied tastes. I would not claim that these are not truly pleasant, delightful, and interesting. The question is: do they, or rather does the marginal addition in them gained by eating animals rather than only nonanimals, outweigh the moral weight to be given to animals' lives and pain? Given that animals are to count for something, is the extra gain obtained by eating them rather than nonanimals products greater than the moral cost? How might these questions be decided? (Anarchy, State, and Utopia, pp. 36-37.)Yes, these are indeed the questions. Note that on this account of it the question is not whether killing and eating the duck violates its rights.
The idea of animal rights makes little or no sense to me, probably because I think of rights as freedom-extenders. The reason it is important that I have rights to this pencil, this computer, this car, etc. is that it means it is not wrong of me to use it without anyone's consent and, at least as important, that I can exchange them by mutual consent with other rights-holders, to get things I want more. Nothing a duck can do is either right or wrong in this sense, nor can it give or withhold consent. [Very different implications follow if you hold another view of rights: that they are security-enhancers. The fact that you have a right to something is important because it enhances the security of your holding on to it. Security, safety, is something animals can have.]
But supposing I am right about this, that animals do not have rights, it does not follow that they aren't morally considerable at all, that you can do just any old thing you want with them, without justifying your actions. What would a justification of eating animals be like, in that case? Again, Nozick asks an interesting and helpful question:
Suppose then that I enjoy swinging a baseball bat. It happens that in front of the only place to swing it stands a cow. Swinging the bat unfortunately would involve smashing the cow's head. But I wouldn't get fun from doing that; the pleasure comes from exercising my muscles, swinging well, and so on. ... Is there some principle that would allow the killing and eating of animals, but would not allow swinging the bat for the extra pleasure it brings? (ASU p. 37.)So now you can see why I put my question in the way I did at the beginning. The value humans get from moving the duck from condition #1 to condition #2: is it relevantly different from the pleasure of swinging that baseball bat? Nozick thinks the answer is "no."
I'll be talking to the students in my political philosophy class about this tomorrow. I'll post on possible answers to this question after that.