The Four System Conditions
Left to its own devices, the earth is a sustainable system. As we continue to learn, however, the accumulated impacts of human activity over the past two centuries are now threatening our continued well-being. An international network of scientists have unanimously and publically concluded that human society is damaging nature and altering life-supporting natural structures and functions in three fundamental ways. Consequently, they were able to define three basic conditions that must be met if we want to maintain the essential natural resources, structures and functions that sustain human society. Further, acknowledging that human action is the primary cause of the rapid change we see in nature today, they included a fourth system condition that focuses on the social and economic considerations that drive those actions and the capacity of human beings to meet their basic needs.
While written to be clear scientifically, the specific wording of the four system conditions can be confusing to non-scientists who try to put them to work. Fortunately, the system conditions can be reworded as basic sustainability principles that provide explicit guidance for any individual or any organization interested in moving towards sustainability. The table below contains the four system conditions on the left and the reworded the basic sustainability principles on the right. In most instances, we refer to the basic sustainability principles.
| The Four System Conditions... |
. . . Reworded as The Four Principles of Sustainability |
| In a sustainable society, nature is not subject to systematically increasing: | To become a sustainable society we must eliminate our contribution to... |
| 1. concentrations of substances extracted from the earth's crust | 1. the systematic increase of concentrations of substances extracted from the Earth's crust (for example, heavy metals and fossil fuels) |
| 2. concentrations of substances produced by society | 2. the systematic increase of concentrations of substances produced by society (for example, dioxins, PCBs, and DDT) |
| 3. degradation by physical means | 3. the systematic physical degradation of nature and natural processes (for example, over harvesting forests and paving over critical wildlife habitat); and |
| 4. and, in that society, people are not subject to conditions that systemically undermine their capacity to meet their needs | 4. conditions that systematically undermine people’s capacity to meet their basic human needs (for example, unsafe working conditions and not enough pay to live on). |
At first reading, the system conditions and basic principles might seem to imply that we must rid society of all materials extracted from the earth and all substances produced by society and that, further, we must never disturb a natural landscape. But that’s not what they mean. The problem is not that we mine and use heavy metals, or use chemicals and compounds produced by society, or disrupt natural processes, or even temporarily interfere with people’s capacity to meet their basic needs. It is, rather, that our industrial system has developed so that substances extracted from the earth and produced by society will continue to build up indefinitely in natural systems. That means a progressive buildup of pollutants and substances that not only harm us directly but damage natural processes that have taken billions of years to develop.
With respect to the fourth sustainability principle, The Natural Step’s understanding of human needs is based on the work of the Chilean economist Manfred Max-Neef. Max-Neef identifies nine fundamental human needs that are consistent across time and cultures: subsistence, protection, affection, understanding, participation, leisure, creation, identity and freedom. Max-Neef points out that these fundamental human needs cannot be substituted one for another and that a lack of any of them represents a poverty of some kind.
Backcasting from Principles
The Framework for Strategic Sustainable Development bases its planning approach on a concept called backcasting from principles. Despite its fancy name, backcasting is something we are all familiar with. We usually backcast whenever we think about some future possibility, whether it be a new job, a new relationship, or a sustainable society.
Backcasting is a way to plan for the future that starts not with today but with a vision of what sort of future we want. What would success look like for us if we achieved what we wanted? What would that job, that relationship, that society really look like? With a vision of a desired future in mind, we can take stock of where we are today and ask, “What actions do I need to take to achieve my vision?” By taking those actions we begin to bridge the gap that exists between our currently reality and our desired future.
The Natural Step’s understanding of what a sustainable society would look like is defined by the four basic sustainability principles. They provide the description of success – the vision – of a sustainable future that we need to be able to backcast. With the sustainability principles to guide us, we can take stock of what we’re doing that is un-sustainable today, and begin to identify actions that will move us towards becoming more sustainable tomorrow.
More on backcasting.

