Editing Environmental ethics (section)

=== Libertarian extension ===
Marshall's libertarian extension echoes a civil liberty approach (i.e. a commitment to extending equal rights to all members of a community). In environmentalism, the community is generally thought to consist of non-humans as well as humans.

Andrew Brennan was an advocate of ecologic humanism (eco-humanism), the argument that all ontological entities, animate and inanimate, can be given ethical worth purely on the basis that they exist. The work of [[Arne Næss]] and his collaborator Sessions also falls under the libertarian extension, although they preferred the term "[[deep ecology]]". Deep ecology is the argument for the intrinsic value or inherent worth of the environment – the view that it is valuable in itself.<ref>{{Cite web|url=https://www.schumachercollege.org.uk/learning-resources/what-is-deep-ecology|title=What is Deep Ecology?|date=2007-09-28|website=Schumacher College|language=en|access-date=2020-03-19|archive-date=2021-03-08|archive-url=https://web.archive.org/web/20210308150641/https://www.schumachercollege.org.uk/learning-resources/what-is-deep-ecology|url-status=dead}}</ref> Their argument falls under both the libertarian extension and the ecologic extension.

[[Peter Singer]]'s work can be categorized under Marshall's 'libertarian extension'. He reasoned that the "expanding circle of moral worth" should be redrawn to include the rights of non-human animals, and to not do so would be guilty of [[speciesism]]. Singer found it difficult to accept the argument from intrinsic worth of a-biotic or "non-sentient" (non-conscious) entities, and concluded in his first edition of "Practical Ethics" that they should not be included in the expanding circle of moral worth.<ref>Peter Singer: Practical Ethics. Cambridge: Cambridge University Press 2011.</ref> This approach is essentially then, bio-centric. However, in a later edition of ''Practical Ethics'' after the work of Næss and Sessions, Singer admits that, although unconvinced by deep ecology, the argument from intrinsic value of non-sentient entities is plausible, but at best problematic. Singer advocated a humanist ethics.