Animal ethics widens the moral circle to creatures that can feel. Some thinkers go further, to every living thing or to whole ecosystems.

Schweitzer: reverence for life

Albert Schweitzer (1875 to 1965) was a theologian, musician and physician who ran a hospital at Lambaréné in what is now Gabon. In 1915, travelling on the Ogooué River, he hit on the phrase “reverence for life,” which he came to see as the foundation of ethics. As he explained it, every living thing has a will to live, and a thoughtful person feels responsibility toward all life, not just human life. Schweitzer did not claim we could avoid all harm; a doctor must kill bacteria to save a patient. But harm should be done only when necessary, and with a sense of responsibility, never thoughtlessly. Later philosophers developed this biocentric (life-centered) approach more formally, as in Paul Taylor's Respect for Nature (1986).

Leopold: the land ethic

Aldo Leopold (1887 to 1948) was an American forester and wildlife ecologist. His book A Sand County Almanac was published in 1949, a year after his death, and its essay “The Land Ethic” became a founding text of the field.

Leopold observed that ethics had gradually grown to include more of human society. The land ethic, he proposed, enlarges the boundaries of the community to include soils, waters, plants and animals, which he called collectively the land. It changes humanity's role from conqueror of the land to a plain member and citizen of it. His best known maxim, in paraphrase, holds that an action is right when it tends to preserve the integrity, stability and beauty of the biotic community, and wrong when it tends otherwise. Because this view places value in wholes, such as ecosystems and species, it is called ecocentric or holistic.

In another essay, “Thinking Like a Mountain,” Leopold recalled shooting a wolf as a young man. He assumed that fewer wolves meant more deer and better hunting. Over time he saw that without wolves, deer multiplied and stripped the mountains of plants. The mountain, he suggested, knew better than the hunter.

Deep ecology

In 1973 the Norwegian philosopher Arne Naess contrasted shallow ecology, which fights pollution and resource depletion mainly for the health and wealth of people in rich countries, with deep ecology, which questions the deeper assumptions behind environmental damage. In 1984 Naess and George Sessions summarized a platform whose central points, in paraphrase, are that the flourishing of human and non-human life has value in itself, that the richness and diversity of life has value, and that humans have no right to reduce that diversity except to satisfy vital needs. Naess also spoke of Self-realization: a widening sense of identity in which people come to see themselves as part of the larger web of life.

Criticisms

• Holism and individuals. Tom Regan charged that the land ethic amounted to a kind of environmental fascism, because judging actions by their effect on the whole could justify sacrificing individuals, even humans, for the good of the ecosystem. J. Baird Callicott, a leading defender of Leopold, replied that the land ethic adds to our older duties to fellow humans rather than replacing them.
• Political misuse. Historians warn that the language of nature and soil has been bent toward ethnic nationalism and hostility to migrants, sometimes called ecofascism. Mainstream ecocentrists, Naess among them, firmly reject it and insist that care for ecosystems must go together with human rights.
• Misanthropy. The social ecologist Murray Bookchin accused some deep ecologists of blaming humanity in general rather than particular social hierarchies. The Indian historian Ramachandra Guha argued in 1989 that a focus on untouched wilderness, exported to poorer countries, could push out rural people who depend on the land. Naess took such criticisms seriously and denied that deep ecology was anti-human.

Worked example: burning the prairie

Imagine a nature reserve that protects one of the last patches of tallgrass prairie in a farming region. Without fire, trees and shrubs creep in and the prairie slowly turns to scrub, crowding out rare grasses, wildflowers and the birds and insects that depend on them. Managers propose a controlled burn each spring. The fire will kill many insects, some small mammals and countless plants. How would the views in this course judge it?

• Singer's sentience view counts the suffering of animals that cannot escape. It may accept the burn if it prevents more suffering over time, but it gives no direct weight to grasses or to the prairie as a system.
• Regan's rights view would object to deliberately killing mammals that are subjects-of-a-life, though most of the creatures killed are insects and plants, which fall outside his view.
• Schweitzer's reverence for life takes every death seriously, plants included. It does not forbid the burn, but asks managers to be sure it is necessary and to reduce harm, for example by burning in patches so animals can flee.
• Leopold's land ethic is most comfortable with the burn. Prairies evolved with fire, set by lightning and often by Indigenous peoples. A burn that restores the integrity and stability of the community is right, even though individuals die.
• Deep ecology asks whether the burn serves the flourishing of diverse life, and also why so little prairie remains in the first place.

The case shows a real practical difference: individual-centered and ecosystem-centered ethics can reach opposite verdicts on the same action.