As a contribution to this ongoing refinement of the concept, I recently formulated five axioms (self-evident truths) of sustainability. My goal was simply to distill ideas that had been proposed previously and put them into a concise, easy-to-understand form.
In formulating these axioms, my criteria were as follows:
• To qualify as an axiom, a statement must be capable of being tested using the methodology of science.
• Collectively, a set of axioms intended to define sustainability must be minimal (with no redundancies).
• At the same time, the axioms must be sufficient, leaving no glaring loopholes.
• The axioms should be worded in terms a layperson can understand. Here are the axioms, each followed by a brief discussion:
The First Axiom
Any society that continues to use critical resources unsustainably will collapse.
Exception : A society can avoid collapse by finding replacement resources.
Limit to the exception : In a finite world, the number of possible replacements is also finite.
Archaeologist Joseph Tainter, in his classic study The Collapse of Complex Societies (1988), demonstrated that collapse is a frequent if not universal fate of complex societies and argued that collapse results from declining returns on efforts to support growing levels of societal complexity using energy harvested from the environment. Jared Diamond's popular book Collapse: How Societies Choose to Fail or Succeed (2005) similarly makes the argument that collapse is the common destiny of societies that ignore resource constraints. This axiom defines sustainability by the consequences of its absence—that is, collapse. Tainter defines collapse as a reduction in social complexity—that is, a contraction of society in terms of its population size, the sophistication of its technologies, the consumption rates of its people, and the diversity of its specialized social roles. Historically, collapse has often meant a precipitous decline in population brought about by social chaos, warfare, disease, or famine. However, collapse can also occur more gradually over a period of many decades or even centuries. There is also the theoretical possibility that a society could choose to reduce its complexity in a controlled, gradual manner.
While it could be argued that a society can choose to change rather than collapse, the only choices that would substantively affect the outcome would be to cease using critical resources unsustainably or to find alternative resources.
A society that uses resources sustainably may collapse for other reasons, some beyond the society's control (as a result of an overwhelming natural disaster or of conquest by another, more aggressive society, to name just two of many possibilities), so it cannot be said that a sustainable society is immune to collapse unless many conditions for sustainability are specified. This first axiom focuses on resource consumption because that is a decisive, quantifiable, and, in principle, controllable determinant of a society's long-term survival.
The question of what constitutes sustainable or unsustainable use of resources is addressed in the third and fourth axioms.
Critical resources are those that are essential to the maintenance of life and basic social functions—including (but not necessarily limited to) water and the resources necessary to produce food and usable energy.
The first axiom's “exception” and “limit to the exception” address the common argument of free-market economists that resources are infinitely substitutable, and that therefore modern market-driven societies need never face a depletion-led collapse, even if their consumption rates continue to escalate. In some instances, substitutes for resources become readily available and are even superior, as was the case in the mid-nineteenth century when kerosene from petroleum was substituted for whale oil as a fuel for lamps. In other cases, substitutes are inferior, as is the case with oil sands as a substitute for conventional petroleum, given that oil sands are less energy dense, require more energy input for processing, and produce more carbon emissions. As time goes on, societies will tend first to exhaust substitutes that are superior and easy to get at, then those that are equivalent, and increasingly will have to rely on ever more inferior substitutes to replace depleting resources—unless rates of consumption are held in check.