Logically and psychologically, the best and easiest breakthrough past the traditional boundaries of interhuman ethics is made confronting higher animals. Animals defend their lives; they have a good of their own, suffer pains and pleasures like ourselves. Human moral concern should at least cross over into the domain of animal experience. This boundary crossing is also dangerous because if made only psychologically and not biologically the would-be environmental ethicist may be too disoriented to travel further. The promised environmental ethics will degenerate into a mammal ethics. We certainly need an ethic for animals, but that is only one level of concern in a comprehensive environmental ethics.
One might expect classical ethics to have sifted well an ethics for animals. Our ancestors did not think about endangered species, ecosystems, acid rain, or the ozone layer, but they lived in closer association with wild and domestic animals than do we. Hunters track wounded deer, the rancher who lets his horses starve is prosecuted. Still, until recently, the scientific, humanistic centuries since the so-called Enlightenment have not been sensitive ones for animals, owing to the Cartesian legacy. Animals were mindless, living matter; biology has been mechanistic. Even psychology, rather than defending animal experience, has been behaviorist. Philosophy has protested little, concerned to locate values in human experiences at the same time that it dis-spirited and devalued nature. Across several centuries of hard science and humanist ethics there has been little compassion for animals.
The progress of science itself smeared the human-nonhuman boundary line. Animal anatomy, biochemistry, cognition, perception, experience, and behavior, and evolutionary history are kin to our own. Animals have no immortal souls, but then persons may not either, or beings with souls may not be the only kind that count morally. Ethical progress further smeared the...