A Comment on the Articles in the Kaplow Special Issue

The articles in this special issue discuss the application of economic models to antitrust problems in markets for differentiated goods. The analytical distinctions drawn by the various authors can be traced to differences in their approach to economic modeling. Kaplow and Hovenkamp accept the Lerner index as a generalizing model of economics, while Coate and Simons and Cameron, Click and Mangum (CCM) see the Lerner analysis as a special case-exemplifying model. For Kaplow and Hovenkamp, taking the Lerner index as a generalizing model eliminates the need to define a market, while for Coate and Simons and CCM, the special case nature of the Lerner analysis implies a need for market definition. When applied as a special case model, a Lerner-style analysis can be used within a relevant market, whenever that style of modeling is appropriate for a given fact situation. The market serves as an organizational structure for understanding the relevant information.