Moral absolutes

I found that a lot of the theoretical arguments, especially in chapter 5 were dependent on the definitions or interpretations of words. The logic in each was sound, but it presupposed an acceptance of a set definition of "interests" or "life." While this battle in semantics, like the hair splitting between acting on behalf and in behalf of something, is interesting, a larger issue caught my attention.

Michael discussed the potential for moral rights to be both individual and universal, but I wonder whether moral right must be absolutes. That is, if one subscribes to a certain moral rights theory does that theory dictate that person's beliefs across the whole spectrum of moral rights or can they pick and choose which moral rights theory they choose to believe for different moral rights?

For example, if someone wants to ensure environmental rights and thinks that Goodpaster's spin on Feinberg's theory is the best way to achieve those rights, would that mean that by extension they would have consider all living organisms to have interests and thus rights? By extension, wouldn't fetuses come under the heading of "living organism" and thus anyone who agrees with the theory as it applies to environmental rights would have to follow that same theory when it came to the right to abortion?

I am not saying that it does, but I think it would be interesting to consider moral rights as a whole, removed from the categories Wellman has put them in to see how the rights theories conflict and complicate each other when trying to establish the beliefs a single individual has on which moral rights exist.