A practice is sustainable if it can be continued indefinitely within a system.
Indefinitely? Without limit, except as posed by external events truly beyond the control of those performing the practice that change the system. Resilience describes the ability to withstand external changes to the system but relies on changes not exceeding critical limits.
Is there a limit beyond which it is not possible to continue? Assuming planet earth as the system, the sun is expected to put an upper limit on any biosphere after several billion years. Other events beyond our control that make life impossible on this planet may or may not occur. For purposes of this discussion sustainable civilization is able to continue on this planet while the sun provides a suitable environment i.e., for billions of years.
More sustainable or less unsustainable?
A lot of efforts for which the term "sustainable" or "more sustainable" has been used, are actually concerned with stretching the remaining time a practice can be continued. That does not solve the underlying problem, only provides more time to implement different practices that can indeed be continued. As such the terms "more sustainable" or "less unsustainable" are misleading. "More sustainable" improvements so far postpone serious problems by no more than one generation (If someone can find examples that do better, please add). That is a far cry from the millions of generations that could be possible. Such efforts, such as conserving resources (e.g., a car that is more efficient and/or used less), are worthwhile because they provide more time, but they must not divert attention from the effort to come up with sustainable solutions. No matter how much effort is spent on finding "more sustainable" improvements, someone will eventually have to come up with a solution that can be continued. The damage and thus the burden placed on future generations will be greater the longer that takes.
Creating sustainability is an entirely different task from stretching the time to continue existing practices. Nature shows that it can be done. Every civilization should try. None has succeeded so far. We know more now. Admitting that "more sustainable" is not sustainable will help to intensify efforts to create sustainable solutions.
Meeting the needs of the present
The most frequently used perspective on sustainability talks about "meeting the needs of the present without compromising the ability of future generations to meet their own needs" which is traced back to the Brundtland comission's report "Our common Future". This puts the "needs of the present" first and anyone is free to define what these needs are. This seems to be a cause of the erosion of the concept, the remainder of the sentence is conveniently served with some notion of doing things in a less damaging manner. "Sustainability" has become an almost meaningless "buzzword", other terms have started to replace it ("resilient" seems to be coming en vogue now, even if its original meaning is different). The focus on the existence of civilization in the far future automatically implies that all real needs have been met in the time until then, including the present. Looking first at the need of future generations to exist provides the framework to understand what needs we have. Sustainable practices ensure future generations can exist. Stated in a bit over-simplified: sustainable practices meet the needs of the future.
Temporarily more unsustainable to get to the right kind of trajectory?
Nick Bostrom proposed that it was not so clear that sustainability is the most appropriate frame and expressed that he thinks we need to keep the rocket engines on until we've reached escape velocity, thus we may need to go deeper into a phase of unsustainability first in order to get to a different kind of sustainability at the other end (say rapidly outwardly expanding but inwardly sustainable multi-galaxy super-high-tech civilization with posthuman population size maybe billions of times greater than now...!). He thought the current focus should be not be so much to get into the right kind of state but to get onto the right kind of trajectory.
It may well be possible that temporary unsustainability can lead to better sustainability. It seems much wiser, though, to enter such a path only as a civilization that can be reasonably certain that such a better sustainability will be reached and has an alternative. Without that the current path seems foolishly dangerous.
The existence of intelligent individuals (be that machines, human generations or other types of being) in the future provides a worthwhile goal for any civilization. We should choose the wisest path to reach it. Dipping temporarily into unsustainability could be done when it is less risky. Right now it seems more important to find ways to achieve conditions that are necessary to allow civilizations to continue. That includes sustainable practices.
Philosophers have worked on if and why the living have obligations towards future individuals.
- 1787 The Constitution of the United States of America lists among its purposes to "secure the Blessings of Liberty to ourselves and our Posterity".
- 1972 R. I. Sikora and Brian Barry edited Obligations to Future Generations (ISBN: 0-87722-128-6)
- 1971 John Rawls' A Theory of Justice proposes a "contractarian" approach to the "justice between generations"
- 1976 Ernest Partridge: Rawls and the Duty to Posterity, PhD Thesis
- 1990 Ernest Partridge: On the Rights of Future Generations in D. Scherer (ed.): Upstream/Downstream: Issues in Environmental Ethics, Temple University Press
- 2001 Dale Jamieson (Ed): A Companion to Environmental Ethics (Blackwell), which contains a an excellent overview Future Generations by Ernest Partridge in which he explains why philosophical interest in the rights of posterity is relatively recent (moral responsibility arose only as advances in science and technology have led to an understanding that human activity has any lasting effect on the future) and discusses the moral status of future persons and the Libertarian and Utilitarian motivations and efforts to resolve various issues
- 2006 Tim Mulgan in Future People: A Moderate Consequentialist Account of Our Obligations to Future Generations (2006, ISBN: 0199556733) states that our obligations to future generations deserve to be the central topic of moral philosophy
- John Nolt explains why we care about future generations by motivating sustainability from classical humanistic utilitarianism: maximize happiness for “all people”, which obviously should include future generations. Nolt notes difficulties with shaping population policy from this premise and discusses ways to improve on it. He also dismisses common objections to the notion of a resposibility to future generations:
- argument from temporal location (we have no obligations to anything that doesn’t yet exist)
- argument from ignorance (we can’t know what future people will be like)
- disappearing beneficiaries argument (We have obligations only to specific people whom we can make better or worse off)
- 2009 Jeff Huggins discussed The Morality of Sustainability: A DIY Exploration
- The Center for Environmental Philosophy, CEP, operates a server providing access to Internet resources throughout the world which pertain to or focus on environmental ethics and environmental philosophy, including associations and a history of environmental ethics.
- The ISEE Bibliography of the International Society for Environmental Ethics ISEE lists academic work
- The International Association for Environmental Philosophy IAEP provides a forum for wide-ranging philosophical discussion of nature and the human relation to the natural environment.
- In 1713 Hans van Carlowitz used sustainable (nachhaltig, or initially nachhaltende Nutzung) in his publication Sylvicultura Oeconomica about forestry. Systematic management of forests for a sustainable yield of timber is said to have begun in the 16th century in German states and in Japan.
- In the 1972 report to the Club of Rome The Limits of Growth Dennis L. Meadows et.al. use "sustainable" in the sense of global equilibrium „We are searching for a model output that represents a world system that is: 1. sustainable without sudden and uncontrollable collapse (...)“
- 1987 The Brundtland comission's report concluded that Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. It contains within it two key concepts:
- the concept of 'needs', in particular the essential needs of the world's poor, to which overriding priority should be given; and
- the idea of limitations imposed by the state of technology and social organization on the environment's ability to meet present and future needs.
- 1994 Albert A. Bartlett published thoughs on Environmental Sustainability, including Laws of Sustainability
- 1995- Konrad Ott advocated the case for strong sustainability and discussed the sustainability of knowledge, see his list of publications.
- 2008 John R. Ehrenfeld of the International Society for Industrial Ecology bases his book "Sustainability by Design" (ISBN-13: 978-0300137491) upon the definition that sustainability is the possibility that humans and other life will flourish on Earth forever.
- The Foundation for the Rights of Future Generations has realized a substantial encyclopaedia of sustainability in the World Wide Web. It provides an overview of many definitions of “sustainability” and “sustainable development” by various economists, social scientists, natural scientists, philosophers and other scientists in German language.
- Mindfully.org has a collection of links regarding sustainability
- Project Worldview has list of links on sustainability and enoughness
- US Environmental Protection Agency EPA defines Sustainability as “meeting the needs of the present without compromising the ability of future generations to meet their own needs.”