Why (Ever) Define Markets? An Answer to Professor Kaplow

Abstract:     
Professor Louis Kaplow has argued that market delineation in antitrust should be abandoned because it is not useful in assessing market power or evaluating competitive effects. This article takes issue with that view, explaining that market delineation serves purposes overlooked by Professor Kaplow. Most importantly, market delineation separates active forces of competition from those in the background. This separation is significant in the application of economic models and in the narrative of presenting an antitrust case. This article also explains why Professor Kaplow’s proposed analyses dispensing with market delineation would break down in important circumstances.

Number of Pages in PDF File: 21

Keywords: antitrust, relevant market, market delineation

JEL Classification: K21, L40

working papers series