The question of human limits, both cognitive and moral, is a persistent theme in the history of religion and philosophy. Both Siddhartha Gautama (Buddha, c. 563–c. 483 b.c.e.) and Socrates (469–399 b.c.e.) argued, in quite different ways, for the human acceptance of limits. Indeed, in general premodern traditions in human culture widely acknowledged both theoretical and practical limits on human knowledge and action.
Thus ever since the founding of modernity, with its appeals to transcend many traditional limits in the development of science and technology—and even certain aspects of the human condition—the question of whether and to what extent there might be new limits to the modern project has been a recurring theme. Late eighteenth and early nineteenth century poets such as Johann Wolfgang von Goethe (1749–1832) and William Blake (1757–1827) called for recognition of cognitive limits in modern science; nineteenth and early twentieth century novelists such as Charles Dickens (1812–1870) and John Steinbeck (1902–1968) argued for placing social and political limits on industrial technological practices; and philosophers of limits such as Karl Marx (1818–1883), Friedrich Nietzsche (1844–1900), and Oswald Spengler (1880–1936) proposed the existence of historical and cultural limits to modern development as a whole.
Limits to Growth
Such general discussions were given a new, specialized form with the 1972 publication of The Limits to Growth by the team of Donella Meadows, Dennis Meadows, and Jørgen Randers, which brought the environmental predicament of industrial progress to the attention of a world audience. On the basis of a computerized world model, the celebrated but controversial study claimed that continuing high rates of growth would lead to (a) a depletion of vital global resources, (b) increasing pollution, and (c) population outrunning the world's potential food supplies. The study suggested that, unless swift action was taken, absolute limits to growth would appear in the course of the twenty-first century, causing population size and industrial capacity to drop rapidly. This message was instantly seen as a blow against the creed of economic growth dominating at the time, both in the Western and the Communist world. Subsequently, the rift between growth advocates and growth skeptics has continued to divide the contemporary world of science and of politics; in fact, this division reaches deeper than conventional distinctions such as conservative/progressive or right/left.
Do Limits Exist?
The debate on limits carries on where classical economics had left off. Thomas Malthus (1766–1834), for example, still had the implicit vision of the Earth as a closed space, with limits to the size of population and level of human achievement it could sustain. He argued that lack of food supply would ultimately constrain population growth, throwing into doubt the idea of the inevitability of progress. However, he underestimated both the variability of growth and the capacity of technology to overcome natural limits. In contrast, neo-classical economics, operating on the background assumption of the infinite power of science and technology, had subsequently ignored the dependence of economic systems on natural systems completely. This shortcoming had left economic science blind to the impending environmental crisis in the twentieth century.
The attempt of Meadows, Meadows, and Randers to expose this failure set off a replay of the controversy between the "closed space" and "infinite ingenuity" schools of thought. While the former insists on the finiteness of both resource inputs and waste sinks, the latter emphasizes the practically infinite substitutability of natural resources by technology and organizational innovation (Simon 1981). What matters to the biosphere is the scale of resource flows, not just their efficient allocation (Daly 1996). Markets may reduce the volume of resource use through substitution of natural inputs, but continuing growth will eventually cancel out these efficiency gains, increasing volumes again. It is the overall scale of resource flows with respect to both input sources and waste sinks that determines the relationship between the economy and the biosphere.
Scientific findings suggest that for the first time in history, human-induced material flows are presently outgrowing nature-induced flows. In other words, the technosphere eclipses the biosphere. Some well-known facts are symptoms for this imbalance: Humankind has already exhausted 40 percent of known oil reserves, transformed nearly 50 percent of the land surface, appropriates more than half of all accessible freshwater, increases greenhouse gases in the atmosphere over and above natural variability, and causes extinction rates to increase sharply in marine and terrestrial ecosystems (Steffen et al. 2004, p. 6). In general terms, human impacts on the Earth are approaching or exceeding in magnitude the impact of some of the great forces of nature. In addition, they operate on much faster time scales than rates of natural variability. Estimates following the ecological footprint methodology imply that human activities presently exceed the Earth's capacity by 15 to 20 percent—without taking the needs of other living beings into account (Wackernagel et al. 2002). Ecological overshoot has become the distinguishing mark of human history.
What To Do about Limits?
The way "limits" are understood has consequences for politics and ethics. One metaphor for conceptualizing limits is that of a cliff face: The concept implies a fixed line beyond which collapse looms. It insinuates that crucial changes happen in an abrupt as well as catastrophic fashion, making everyone suffer equally. However, changes may also occur in a gradual as well as insidious fashion, and may burden some more than others. A metaphor based on a tapestry—each act of destruction is like pulling a thread from the tapestry—would emphasize linear and not just non-linear processes, multiple smaller losses and not just overall collapse. In particular, it would highlight the presence of political choices along the gradient of degradation (Davidson 2000). The tapestry metaphor, more than the cliff metaphor, encourages one to judge wreckage not only as prelude to the collapse, allows one to trace the differential impact of losses on social groups, and stimulates the politically and ethically essential question: What thresholds are considered tolerable/intolerable for whom and on what grounds?
Thresholds of ecosystem changes represent "limits" only for humans; any definition of limits is therefore a political act. Moreover, limits are rarely scientifically knowable; their definition is therefore an ethical act as well. As a consequence, any definition implies choices in terms of human welfare, equity, and the common good. A first approach centers on risks, putting the spotlight on possible physical, technical, and economic losses resulting from the technology or economic policy in question. Emphasis is placed on the precautionary principle of preventing the worst from happening. Guardrails, for instance, are suggested in order to avoid abrupt and irreversible changes from which human societies would find it difficult or impossible to recover (German Advisory Council on Global Change 1997).
A second approach focuses on institutions, because the rise of external limits is brought about by structures of growth and accumulation that are internally insatiable and limitless. This approach highlights the constellation of social and economic factors driving perilous developments (Harvey 1996). Proposals range from the reform of price structures to the containment of the profit motive, from the reallocation of research funds to the phase-out of certain technologies.
Finally, a third approach calls for a reconsideration of values, bringing into sharp relief the civilizational losses incurred by the predominance of the logic of growth. Natural limits are often preceded by the appearance of social and cultural limits; before growth causes physical perturbations, collective and individual well being has suffered (Illich 1973, Hirsch 1976). Recognizing limits, therefore, implies the emergence of fresh opportunities by restoring a balance. In this approach, limits acquire a positive connotation, making a more accomplished life possible. They turn out to be productive for a civilization that regards economic power and growth only marginally important.
Daly, Herman E. (1996). Beyond Growth: The Economics of Sustainable Development. Boston: Beacon Press.
Davidson, Carlos. (2000). "Economic Growth and the Environment: Alternatives to the Limits Paradigm." BioScience 50: 433–440.
German Advisory Council on Global Change. (1997). World In Transition: The Research Challenge. Berlin: Springer
Harvey, David. (1996). Justice, Nature, and the Geography of Difference. Cambridge, MA: Blackwell.
Hirsch, Fred. (1976). Social Limits to Growth. Cambridge, MA: Harvard University Press.
Illich, Ivan. (1973). Tools for Conviviality. New York: Harper & Row.
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Simon, Julian L. (1981). The Ultimate Resource. Princeton, NJ: Princeton University Press.
Steffen, Will, et al. (2004). Global Change and the Earth System: A Planet Under Pressure. Berlin: Springer.
Wackernagel, Mathis; Niels B. Schulz; Diana Deumling; et al. (2002). "Tracking the Ecological Overshoot of the Human Economy." Proceedings of the National Academy of Sciences 99: 9266–9271