Coase-Sandor Working Paper Series in Law and Economics

Sizing Up Categories

Lee Anne Fennell


Categories intentionally create discontinuities. By breaking the world up into cognizable chunks, they simplify the information environment. But the signals they provide may be inaccurate or scrambled by strategic behavior. This Article considers how law might approach the problem of optimal categorization, given the role of categories in managing and transmitting information. It proceeds from the observation that high categorization costs can be addressed through two opposite strategies—making classifications more fine-grained (splitting), and making classifications more encompassing (lumping). Although continuizing and other forms of splitting offer intuitive answers to inaccurate classification and gaming along category lines, lumping is sometimes a better solution. If category membership carries multiple and offsetting implications, the incentive to manipulate the classification system is dampened. To take a simple example, insurance that covers only one risk is more vulnerable to adverse selection than is an insurance arrangement that covers two inversely correlated risks. Making categories larger, more durable, and more heterogeneous can produce such offsets. These and other forms of bundling can arrest damaging instabilities in categorization.