Environmental ethics stretches classical ethics to a breaking point. All ethics seeks an appropriate respect for life. But we do not just need a humanist ethic applied to the environment, analogously to the ways we have needed one for business, law, medicine, technology, international development, or nuclear disarmament. Respect for life demands an ethic concerned about human welfare, like the others and now concerning the environment. But environmental ethics in a deeper sense stands on a frontier, as radically theoretical as it is applied. Alone, it asks whether there can be nonhuman objects of duty (Marshall: 227).
Neither theory nor practice elsewhere needs values outside of human subjects, but environmental ethics must be more biologically objective--nonanthropocentric. It challenges the separation of science and ethics, trying to reform a science that finds nature value free and an ethics that assumes that only humans count morally. Environmental ethics seeks to escape relativism in ethics, to discover a way past culturally based ethics. However much our world views, ethics included, are embedded in our cultural heritages, and thereby theory-laden and value-laden, all of us know that a natural world exists apart from human cultures. Humans interact with nature. Environmental ethics is the only ethics that breaks out of culture. It has to evaluate nature, both the nature that mixes with culture and wild nature, and to judge duty thereby. After environmental ethics, you will no longer be the humanist you once were.
Environmental ethics requires risk. Environmental ethics explores poorly charted terrain, where it is easy to get lost. One must hazard the kind of insight that first looks like foolishness. Some approach environmental ethics with a smile--expecting rights for rocks and chicken liberation, misplaced concern for chipmunks and daisies. Elsewhere, you think, ethicists deal with sober concerns: medical ethics, business ethics, justice in public affairs, questions of life and death, peace and war. But the questions here are no less serious: the degradation of the environment poses as great a threat to life as nuclear war, and a more probable tragedy (Marshall: 228).
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 ...