Morrison responded that such use was surely justified in light of the benefits that animal use had produced for human health. Now, we have to be careful about assessing the benefits of animal research. An increasing number of health care professionals have expressed considerable skepticism about the scientific validity of animal experiments. But even if we do get benefits from animal experiments, benefit alone cannot justify morally the exploitation of animals. After all, no one would dispute that we would get even greater benefits if we used unconsenting humans in experiments.
Humans have certain rights.
And their most fundamental right is not to be treated as property, or as means to the ends of owners. If we are to justify this exploitation, it is necessary that we somehow distinguish animals from humans, and that is much easier said than done. Some people say that animals are different because they cannot think. But that is simply not true. We know that mammals and birds, for example, have very complex mental faculties.