Overconsumption

Whether one can speak of overconsumption and what constitutes notions of excess depends on whether consumption is assessed from the consumer's point of view. The answers depend on whether consumption is assessed from the consumer's point of view (the “self-regarding” perspective) or from another point of view (the “others-regarding” position). The self-regarding perspective can be stated as follows: “Is my consumption behavior really good for me?” whereas the “others-regarding” perspective can be stated as “Does my consumption behavior harm someone?” Following Thomas Princen, a negative [Page 325]answer to the first question would better be called “misconsumption,” reserving the term overconsumption for patterns of consumption directly or indirectly incompatible with other people's welfare. However, both those defects matter for sustainable development: misconsumption because it raises questions about the effectiveness of a development model, and overconsumption because it calls into question its sustainability. The distinction is relevant because if objections to consumption from a consumer point of view are certainly relevant and have to be taken in consideration in an overall assessment of a development model, they are insufficient to legitimate pressing demands for more responsible behavior from the consumer (“Live simply so that others may simply live”) or public interventions for fostering such behavior, which should be based not on—necessarily relative—conceptions of the good life but on ethical reasons, that is, on arguments about justice and fairness.

Paul Ehrlich and John Holdren's equation I = PAT helps understand what can be wrong with overconsumption and why. It expresses the environmental impact (I) of any human collectivity as the product of three factors: P (for population, the size of that collectivity), T (for technology), and A (for affluence, or the level of consumption; i.e., consumption per capita). To take an example, the greenhouse gas emissions (I) of a given transportation mode (car, train) in a given country during a given time interval can be analyzed as the product of the population (P) of that country times the average miles traveled per capita during the time interval (A) times the greenhouse gas emission per traveled mile (T). According to the I = PAT framework, there is overconsumption of some good or service if its environmental impact exceeds some limit or threshold, I∗, beyond which unwanted deleterious consequences begin to show up that are likely to affect negatively other people's (including future generations') life chances. I∗ can denote the carrying capacity of an entire ecosystem or the maximum sustainable yield for a single renewable resource. Relevant indicators of overconsumption defined in this way are, for example, the ecological footprint, sustainability gaps, or material intensity of consumption, expressed in per capita units.

As such, the diagnostic that I > I∗ says nothing about the cause of the environmental problem: It can be any one of the three identified factors or some combination of them. Considering that the T factor (technology) depends more on production patterns than on consumption ones, the scope of the overconsumption notion could be restricted to the two other factors: P (population) and A (affluence). Controlling for technology, the environmental overload of consumption depends on these two parameters only: the size of the population of consumers and/or the average consumption per capita. The two factors are in inverse relation: the more consumers, the less consumption per capita allowed, and the fewer consumers, the more each of them can consume. There is, therefore, a fundamental tension between two objectives of social and economic development: extending the size of the population of prospective consumers (be it simply by population growth or by increasing the size of the group of people entitled to some consumption) and increasing per capita consumption in a given, stable population of consumers.

...