Download this Paper Open PDF in Browser


22 Pages Posted: 1 Sep 2008 Last revised: 2 Dec 2008

Cass R. Sunstein

Harvard Law School; Harvard University - Harvard Kennedy School (HKS)

Date Written: July 12, 2008


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.

Keywords: irreversibility, incommensurability, option value, public health, climate change

Suggested Citation

Sunstein, Cass R., Irreversibility (July 12, 2008). Oxford University Press, Law, Probability and Risk, Forthcoming; Harvard Public Law Working Paper No. 08-25; Harvard Law School Program on Risk Regulation Research No. 08-1. Available at SSRN:

Cass R. Sunstein (Contact Author)

Harvard Law School ( email )

1575 Massachusetts Ave
Areeda Hall 225
Cambridge, MA 02138
United States
617-496-2291 (Phone)

Harvard University - Harvard Kennedy School (HKS) ( email )

79 John F. Kennedy Street
Cambridge, MA 02138
United States

Paper statistics

Abstract Views