Do we consume too much?

Paul R. Ehrlich and Lawrence H. Goulder examine this question in Conservation Biology (Is current consumption excessive? A general framework and some indications for the United States). They accept the idea that we can keep depleting resources as long as we find good substitutes that allow future generations to enjoy at least the same level of well-being as the current one. Then they say that uncertainty about the extent to which we are going to find such substitutes "helps justify a conservative, precautionary approach to natural resource preservation [and] widens the range of natural resources deserving preservation." From this premise they would be able to argue that any level of consumption is excessive. Still, they review the literature and tell us that the evidence is inconclusive.

Even if people do not consume too much there is always room for improvement:

Society can reduce the risk of losing the potential for sustainability by promoting policies that provide increased incentives toward invention and technological progress and that slow the rate of natural resource depletion. The latter policies could include tax policies that raise natural resource prices to their full social cost or that shift the composition of consumption toward goods and services that involve fewer natural resource inputs. They could also include policies to reduce population growth rates.

Calculating the "full social cost" of anything is not easy, to say the least - among other things because future social costs depend on future innovations. But I agree with Ehrlich and Goulder that current tax and subsidy policies tend to inefficiently decrease the prices of natural resources - they specifically mention prices related to agriculture, electricity, and transportation - and that those policies should be eliminated. Finally, they forget to mention that population levels affect not only consumption but also innovation. More population means more consumption and more innovation, with the net result being, at least until now, that well-being increases with the human population.