(compiled of Wikipedia, notes from my current Deep Ecology class, and personal knowledge)
Deep ecology is a contemporary ecological philosophy that recognizes the inherent worth of other beings aside from their utility. The philosophy emphasizes the interdependent nature of human and non-human life as well as the importance of the ecosystem and natural processes. It provides a foundation for the environmental, ecology and green movements and has fostered a new system of environmental ethics.
Deep ecology’s core principle is the belief that, like humanity, the living environment as a whole has the same right to live and flourish:

“The right of all forms of life is a universal right which cannot be quantified. No single species of living being has more of this particular right to live and unfold than any other species.” (Arne Næss)

1 The Name

Deep ecology describes itself as “deep” because it persists in asking deeper questions concerning “why” and “how” and thus is concerned with the fundamental philosophical questions about the impacts of human life as one part of the ecosphere, rather than with a narrow view of ecology as a branch of biological science, and aims to avoid merely anthropocentric environmentalism, which is concerned with conservation of the environment only for exploitation by and for humans purposes, which excludes the fundamental philosophy of deep ecology. Deep ecology seeks a more holistic view of the world we live in and seeks to apply to life the understanding that separate parts of the ecosystem (including humans) function as a whole.

2 The Deep Ecology tree

The movement can be seen as a tree. The picture relates to deepening levels of questioning, as well correspondingly, increasingly relevant practices.
Each person comes from its own direction, with its own fundamental beliefs and convictions, which constitute the roots of the tree. It is the basis for everything else.
Nevertheless, all supporters of the movement agree on the 8-point platform, which is the trunk of the tree. It is a unifying guideline, a common source of collaboration between many different kinds of movements, and it provides both strength and flexibility.
The values of the 8-point platform show in different branches on the level of society and lifestyle choices. People form projects, groups, organisations and are also part of general directions, like vegetarianism.
The particular decisions and actions taken each moment are regarded as the leaves of the Deep Ecology tree.

3 The 8-point platform

Supporters of the deep ecology movement (rather than being referred to as “deep ecologists” or followers) are united by a long-range vision of what is necessary to protect the integrity of the Earth’s ecological communities and ecocentric values. In order to establish shared objectives, Arne Næss proposed a set of eight principles to characterize the deep ecology movement as part of the general ecology movement.
Due to its inclusive character the platform is not meant to be a rigid set of doctrinaire statements, but rather a set of discussion points, open to modification by people who broadly accept them. Therefore it is natural that the wording of a version of the platform cannot be the same everywhere.

1. The well-being and flourishing of human and nonhuman life on Earth have value in themselves (synonyms: intrinsic value, inherent value). These values are independent of the usefulness of the nonhuman world for human purposes.
2. Richness and diversity of life forms contribute to the realization of these values and are also values in themselves.
3. Humans have no right to reduce this richness and diversity except to satisfy vital human needs.
4. The flourishing of human life and cultures is compatible with a substantial decrease of the human population. The flourishing of nonhuman life requires such a decrease.
5. Present human interference with the nonhuman world is excessive, and the situation is rapidly worsening.
6. Policies must therefore be changed. These policies affect basic economic, technological, and ideological structures. The resulting state of affairs will be deeply different from the present.
7. The ideological change is mainly that of appreciating life quality (dwelling in situations of inherent value) rather than adhering to an increasingly higher standard of living. There will be a profound awareness of the difference between big and great.
8. Those who subscribe to the foregoing points have an obligation directly or indirectly to try to implement the necessary changes.^[1]

4 Social ramifications

Individuals adopt appropriate lifestyles and actions consistent with, but not determined by the 8-point platform.

“The frontier is long. There are many ways of acting for good. You cannot do everything!” (Arne Næss)

In practice, deep ecology supporters work towards decentralization, the creation of ecoregions, the breakdown of industrialism in its current form, and an end to authoritarianism. Deep ecology calls for nothing less than a complete overhaul of the way humans live on the Earth. It wants to be the framework for future societies.

5 Development

The phrase “deep ecology” was coined by the Norwegian philosopher Arne Næss in 1973,^[2] and he helped give it a theoretical foundation.  

“For Arne Næss, ecological science, concerned with facts and logic alone, cannot answer ethical questions about how we should live. For this we need ecological wisdom. Deep ecology seeks to develop this by focusing on deep experience, deep questioning and deep commitment. These constitute an interconnected system. Each gives rise to and supports the other, whilst the entire system is, what Næss would call, an ecosophy: an evolving but consistent philosophy of being, thinking and acting in the world, that embodies ecological wisdom and harmony” (Stephan Harding)^[3]

Næss rejected the idea that beings can be ranked according to their relative value. For example, judgments on whether an animal has an eternal soul, whether it uses reason or whether it has consciousness (or indeed higher consciousness) have all been used to justify the ranking of the human animal as superior to other animals. Næss states that from an ecological point of view “the right of all forms [of life] to live is a universal right which cannot be quantified. No single species of living being has more of this particular right to live and unfold than any other species.”
This metaphysical idea is elucidated in Warwick Fox’s claim that we and all other beings are “aspects of a single unfolding reality”.^[4]
As such Deep Ecology would support the view of Aldo Leopold in his book, A “Sand County Almanac” that humans are “plain members of the biotic community”.
They also would support Leopold’s “Land Ethic”: “a thing is right when it tends to preserve the integrity, stability and beauty of the biotic community. It is wrong when it tends otherwise.”
Daniel Quinn in Ishmael, showed that an anthropocentric myth underlies our current view of the world, and a jellyfish would have an equivalent jellyfish centric view.^[5]
Deep ecology offers a philosophical basis for environmental advocacy which may, in turn, guide human activity against perceived self-destruction. Deep ecology and environmentalism hold that the science of ecology shows that ecosystems can absorb only limited change by humans or other dissonant influences. Further, both hold that the actions of modern civilization threaten global ecological well-being. Ecologists have described change and stability in ecological systems in various ways, including homeostasis, dynamic equilibrium, and “flux of nature”.^[6]
Regardless of which model is most accurate, environmentalists contend that massive human economic activity has pushed the biosphere far from its “natural” state through reduction of biodiversity, climate change, and other influences. As a consequence, civilization is causing mass extinction. Deep ecologists hope to influence social and political change through their philosophy.

5.1 Scientific basis

Næss and Fox do not claim to use logic or induction to derive the philosophy directly from scientific ecology ^[7] but rather hold that scientific ecology directly implies the metaphysics of deep ecology, including its ideas about the self and further, that deep ecology finds scientific underpinnings in the fields of ecology and system dynamics.
In their 1985 book “Deep Ecology”^[8], Bill Devall and George Sessions describe a series of sources of deep ecology. They include the science of ecology itself, and cite its major contribution as the rediscovery in a modern context that “everything is connected to everything else”. They point out that some ecologists and natural historians, in addition to their scientific viewpoint, have developed a deep ecological consciousness—for some a political consciousness and at times a spiritual consciousness. This is a perspective beyond the strictly human viewpoint, beyond anthropocentrism. Among the scientists they mention specifically are Rachel Carson, Aldo Leopold, John Livingston, Paul R. Ehrlich and Barry Commoner, together with Frank Fraser Darling, Charles Sutherland Elton, Eugene Odum and Paul Sears.
A further scientific source for deep ecology adduced by Devall and Sessions is the “new physics” which they describe as shattering Descartes’s and Newton’s vision of the universe as a machine explainable in terms of simple linear cause and effect, and instead providing a view of Nature in constant flux and the idea that observers are separate an illusion. They refer to Fritjof Capra’s “The Tao of Physics” and “The Turning Point” for their characterisation of how the new physics leads to metaphysical and ecological views of interrelatedness, which, according to Capra, should make deep ecology a framework for future human societies. Devall and Sessions also credit the American poet and social critic Gary Snyder—with his devotion to Buddhism, Native American studies, the outdoors, and alternative social movements—as a major voice of wisdom in the evolution of their ideas.
The scientific version of the Gaia hypothesis was also an influence on the development of deep ecology.

5.2 Spiritual basis

The central spiritual tenet of deep ecology is that the human species is a part of the Earth and not separate from it. A process of self-realisation or “re-earthing” is used for an individual to intuitively gain an ecocentric perspective. The notion is based on the idea that the more we expand the self to identify with “others” (people, animals, ecosystems), the more we realize ourselves. Transpersonal psychology has been used by Warwick Fox to support this idea.
In relation to the Judeo-Christian tradition, Næss offers the following criticism: “The arrogance of stewardship [as found in the Bible] consists in the idea of superiority which underlies the thought that we exist to watch over nature like a highly respected middleman between the Creator and Creation.”^[9] This theme had been expounded in Lynn Townsend White, Jr.’s 1967 article “The Historical Roots of Our Ecological Crisis“, in which however he also offered as an alternative Christian view of man’s relation to nature that of Saint Francis of Assisi, who he says spoke for the equality of all creatures, in place of the idea of man’s domination over creation.

5.3 Experiential basis

Drawing upon the Buddhist tradition is the work of Joanna Macy. Macy, working as an anti-nuclear activist in the USA, found that one of the major impediments confronting the activists’ cause was the presence of unresolved emotions of despair, grief, sorrow, anger and rage. The denial of these emotions led to apathy and disempowerment.
We may have intellectual understanding of our interconnectedness, but our culture, experiential deep ecologists like John Seed argue, robs us of emotional and visceral experience of that interconnectedness which we had as small children, but which has been socialised out of us by a highly anthropocentric alienating culture.
Through “Despair and Empowerment Work” and more recently “The Work that Reconnects”, Macy and others have been taking Experiential Deep Ecology into many countries including especially the USA, Europe (particularly Britain and Germany), Russia and Australia.

5.4 Philosophical basis

Arne Næss, who first wrote about the idea of deep ecology, from the early days of developing this outlook conceived Spinoza as a philosophical source.^[10]
Others have followed Naess’ inquiry, including Eccy de Jonge, in Spinoza and Deep Ecology: Challenging Traditional Approaches to Environmentalism, and Brenden MacDonald, in Spinoza, Deep Ecology, and Human Diversity—Realization of Eco-Literacies
One of the topical centres of inquiry connecting Spinoza to Deep Ecology is “self-realization”. See Arne Naess in The Shallow and the Deep, Long-Range Ecology movement and Spinoza and the Deep Ecology Movement for discussion on the role of Spinoza’s conception of self-realization and its link to deep ecology.

6 References

1. ↑ Devall, Bill; Sessions, George (1985). Deep Ecology, p.70
2. ↑ Næss (1973) ‘The Shallow and the Deep, Long-Range Ecology Movement.’ Inquiry 16: 95-100
3. ↑ Harding, Stephan (2002), “What is Deep Ecology”
4. ↑ Fox, Warwick, (1990) Towards a Transpersonal Ecology
5. ↑ Quinn, Daniel (1995), Ishmael: An Adventure of the Mind and Spirit
6. ↑ Botkin, Daniel B. (1990). Discordant Harmonies: A New Ecology for the Twenty-First Century
7. ↑ The Shallow and the Deep, Long Range Ecology movements A summary by Arne Naess
8. ↑ Devall, Bill; Sessions, George (1985). Deep Ecology
9. ↑ Næss, Arne. (1989). Ecology, Community and Lifestyle: Outline of an Ecosophy. p. 187
10. ↑ Spinoza and Deep Ecology