Irreversibility*

Abstract

The concept of ‘irreversibility’ plays a large role in many domains, including public health, medical practice and environmental protection. Indeed, the concept is explicit in some statements of the precautionary principle. But the idea of irreversibility remains poorly defined. Because of the flow of time, any loss is, in a sense, irreversible. On one approach, irreversibility might be understood as a reference to the value associated with taking precautionary steps that maintain flexibility for an uncertain future (‘option value’). On another approach, irreversibility might be understood to refer to the qualitatively distinctive and even unique nature of certain losses—a point that raises a claim about incommensurability. The two conceptions fit different problems. These ideas can be applied to a wide assortment of environmental and public health questions, including overuse of antibiotics, genetic modification of food, avian flu and climate change.

Author notes

*

This essay was completed before the author began work in the Obama Administration, first as a Senior Adviser to the Director of the Office of Management and Budget, and later as Administrator of the Office of Information and Regulatory Affairs. Nothing said here represents an official position in any way of the United States government.