Lynn White's thesis is that the main strands of Judeo-Christian thinking had encouraged the overexploitation of nature by maintaining the superiority of humans over all other forms of life on earth, and by depicting all of nature as created for the use of humans. His thesis is in the main focus of debates in the 1970s, together with the tragedy of the commons. These debates are primarily historical, theological and religious, not philosophical. Throughout most of the decade philosophers sat on the sidelines trying to determine what a field called environmental ethics might look like.
The environmental ethics field emerged almost simultaneously in three countries: the United States, Australia and Norway. In the first two, direction and inspiration largely came from the earlier twentieth century American literature of the environment. The Scottish-born American naturalist John Muir (April 1838 - December 1914), founder of the Sierra Club and known as the father of American conservation, wrote many letters, essays and books that advocated an appreciation and conservation of things natural, wild and free. Aldo Leopold supports the same view.
Muir and Leopold's concerns were motivated by a combination of ethical and aesthetic responses to nature as well as a rejection of crudely economic approaches to the value of natural objects.
The first philosophical conference on environmental ethics was organized in the United States in 1972. Also 1972 saw the publication of a book by an American United Methodist theologian John B. Cobb (9 February 1925 -) titled "Is It Too Late? A Theology of Ecology." In 1973, Australian philosopher Richard Sylvan (December 1935 - June 1996) presented a paper at the 15th World Congress of Philosophy "Is There a Need for a New, an Environmental, Ethic?" A year later another Australian philosopher, John Passmore, wrote "Man's Responsibility for Nature", in which he says that there was no need for an environmental ethics at all. Most of the debates among philosophers until the middle of the 1980s were focused on refuting Passmore.
According to environmental ethics, humans are part of the natural community rather than managers of it. Such an ethic places limits on human activities such as uncontrolled resource use that may adversely affect the natural community.
A sustainable ethic is an environmental ethic by which people treat the earth as if its resources are limited. This ethic assumes that the earth's resources are not unlimited and that humans must use and conserve resources in a manner that allows their continued use in the future. A sustainable ethic also assumes that humans are a part of the natural environment and that they suffer when the health of a natural ecosystem is impaired.
According to the sustainable ethic, humans share the resources with other living creatures and succeed best when they maintain the integrity of natural processes sand cooperate with nature.
Aldo Leopold says in his publications that humans have always considered land as property, just as ancient Greeks considered slaves as property. Mistreatment of land, according to Leopold, makes little economic or moral sense. Leopold suggested that land be included in an ethical framework, calling this the land ethic.