Within environmental ethics, ecocentric views seem to have prevailed. Conservation rather than preservation is the dominant ecocentric ethic, the Hodsons write.
Environmental ethics is often thought to have originated in the 1970s, influenced by Rachel Carson's "Silent Spring" and the rise of environmentalism.
In 1971, J. Baird Callicott taught the first environmental ethics course in the world.
Much thinking concerning the ethics of the environment predated the 1970s. Here we will look at key thinkers and movements from the 1850s onward.
Conservationist George Perkins Marsh (1801-82) is seen by some as America's first environmentalist. He was ecocentric, believed in wise resource management and supported the creation of Adirondack Park in New York state.
Many early thinkers in this area were Americans who, like Marsh, were concerned with the preservation or conservation of wilderness and environmental degradation. They set the foundation for modern ecocentric thinking.
Henry David Thoreau (1817-62), polymath, philosopher and transcendentalist, was groundbreaking in calling for a simple lifestyle.
John Muir (1838-1914) was a preservationist who established Yosemite National Park in California and founded the Sierra Club.
Raised in a strict Christian family, Muir rejected his father's teaching but retained his faith, although he was also influenced by the transcendentalism of Thoreau and Emerson. He was unhappy with dominion theology and anthropocentric approaches but saw God at work in the natural world.
As a preservationist who believed in the protection of pristine wilderness, he clashed with conservationists, such as Gifford Pinchot (1865-1946), who were in favor of the wise use of resources.
Muir and Pinchot fought a major battle over plans to create a large reservoir in Hetch Hetchy Valley to supply San Francisco with water, which Pinchot won.
Muir and Pinchot represent different strands within ecocentric ethics.
What Pinchot did was to temper unrestrained anthropocentric thinking with a concern for long-term sustainability.
Pinchot's ideas can be seen as the precursors of the modern-day concepts of sustainable development and ecosystem services, which are also the product of a fusion of anthropocentric and ecocentric thinking.
Aldo Leopold (1887-1948), a forester and writer of "A Sand County Almanac," proposed the land ethic, an ecocentric concept.
Leopold saw three ethics: the first between individuals, and the second between individuals and society.
He felt that a third ethic, dealing with human relationships to land, plants and animals, was missing, but the embryonic conservation movement pointed toward it.
Leopold saw value in the productivity of land but believed land was valuable for its own sake.
Remarkably, one of the main weaknesses Leopold saw in conservation was that most plants and animals, and environments such as bogs and marshes, had no economic value.
In this he was ahead of his time. Leopold believed that individuals were interdependent members of a community, and he proposed with the land ethic to extend the community to include soils, water, plants and animals (the land).
The role of humanity would be changed from conquerors of the land community to being a member and citizen within it.
The Gaia Hypothesis, an ecocentric concept proposed by British scientist James Lovelock in the 1960s, was originally a scientific idea.
Put simply it postulates that the Earth is a self-regulating system made up of numerous interconnecting parts that cooperate to bring about suitable living conditions on the planet.
This led to the development of Earth system science. Gaia also proved an attractive concept for the New Age movement.
Biocentric thinking, at least within environmental ethics, is more recent and less prominent.
Deep ecology, the most known, was founded by Arne Næss (1912-2009), a Norwegian philosopher and environmentalist. Næss first coined the term deep ecology in 1973 and contrasted it with shallow ecology, which simply maintained the health and affluence of people in the developed West.
According to Næss, much of the conservation movement, with its interests in pollution control and resource depletion, was shallow. Self-realization in deep ecology goes beyond humanity to include the nonhuman world.
Biocentric equality suggests that all organisms have an equal right to flourish and equal intrinsic value. Humans are seen as on the same level as other organisms and should not decrease the richness of biodiversity unless for vital purposes.
Controversially, deep ecology has consistently argued for a substantial decrease in human population, as this is seen as consistent with a desire for nonhuman life to flourish. Not surprisingly, deep ecology has been the subject of much criticism from a variety of angles.
One of the biggest questions concerns the central concept of biocentric egalitarianism. Should we really regard all organisms as equal in all situations?
Ecofeminism arose as a movement in the 1970s and attempts to connect ecology with feminist thought. Ecofeminists often draw parallels between oppression of women and domination of the environment.
Some critics contend that setting up a strict dichotomy between men and women is not helpful. Another criticism of ecofeminism is its divergence from social feminist ideas.
Social feminists will often be aspiring for equality with men within present societal structures, but ecofeminists frequently wish to see those structures replaced. Many ecofeminists are ecocentric, but some are biocentric having a major concern for animal welfare.
In conclusion, within environmental ethics, ecocentric views seem to have prevailed. Conservation rather than preservation is the dominant ecocentric ethic.
On the ground, many environmental practitioners are pragmatists who do not hold strictly to one ethical view.
Conservation and environmental pragmatism match the prevailing ecological thinking of today: sustainability, the Sustainable Development Goals and ecosystem services.
Martin J. Hodson is a plant scientist and operations director for the John Ray Initiative. He has more than 100 research publications and speaks widely on environmental issues. Margot R. Hodson is an environmental theologian and an Anglican pastor of six churches near Oxford in the United Kingdom. The Hodsons have jointly taught environmental ethics at Oxford Brookes University and are authors of several publications in this area, which can be found through their website (Hodsons.org). You can follow Martin on Twitter @MartinHodson1 and Margot @MargotHodson.
Editor's note: This article is an adaptation of the more detailed Grove booklet "An Introduction to Environmental Ethics" E184, by Martin J. Hodson and Margot R. Hodson. It is available in PDF format at Grove Books and is used with permission. It is the second of a series of articles drawn from the booklet. Part one is available here, part three here, and part four here.