“The argument we are now considering raises the issue of the wrongness of killing—an issue which, because it is so much more complicated than the wrongness of inflicting suffering, I have kept in the background up to this point. Our brief discussion near the close of the first chapter, however, was enough to show that for a being capable of having desires for the future there may be something particularly bad about being killed, something that is not equaled by the creation of another being. The real difficulty arises when we consider beings not capable of having desires for the future—beings who can be thought of as living moment by moment rather than having a continuous mental existence. Granted, even here, killing still seems repugnant. An animal may struggle against a threat to its life, even if it cannot grasp that it has “a life” in the sense that requires an understanding of what it is to exist over a period of time. But in the absence of some form of mental continuity it is not easy to explain why the loss to the animal killed is not, from an impartial point of view, made good by the creation of a new animal who will lead an equally pleasant life.21” (Peter Singer, Animal Liberation)