Pollution: the mess around us, by M.I. Goldman.--The great and dirty lakes, by G. Hill.--Air pollution, by A.C. Nadler and G.L. Paulson.--What is pollution? by I.M. Goldman and R. Shoop.--The role of government in a free society, by M. Friedman.--Social costs of business enterprise, by K.W....

The paper looks at a model of directed technical change in an environmental-economics context. Firms can do conventional or "green" R&D or they can abate emissions at the end of pipe. The paper has two main foci. On the one hand, it investigates the impact of environmental regulation on the...