This volume is the result of a collective effort made by its authors to reason and write about environmental policy from an empirical, rather than from a prescriptive perspective. Since the authors, like most people, care about the environment and, as professional economists or political scientists, have some expertise to offer in the area of policy-design, it was not always easy for them to keep on the intended track. Whereas they knew that it is unusual to follow a strictly empirical approach in such a 'practical' field as environmental policy, they discovered only during the effort what...