Research Summary

The Political Power of Weak Interests

by J. Gunnar Trumbull


One of the most broadly accepted theoretical claims of public policy is the proposal that interests shared by a large set of actors tend to be under-represented in public policy. From Mancur Olson to George Stigler to James Q. Wilson, our most influential theorists of organization and public policy argue that diffuse interests must therefore be weak interests. The logic of their case is familiar and compelling. Large numbers of individuals are difficult to organize. And when the benefits of organization cannot be excluded from the general public, individuals will have insufficient incentives to support a collective lobbying effort. These coordination problems make organizing diffuse interests a harder job than organizing concentrated interests. Yet everywhere we look, diffuse interests are strongly represented. Consumers have benefited from progressive trade liberalization. Competition policy has broken apart concentrated producers with monopoly pricing power. Modern retailing has given rural consumer access to an extraordinary variety of products at extremely low prices. Small shareholders enjoy powerful legal protections against manipulation by powerful block-holders.

This book project explores why diffuse interests are so heavily represented in public policy, and why narrow interest groups that subvert more diffuse economic or social interests do so at their peril. Through a study of policies in agriculture, pharmaceuticals, retailing, and consumer credit, I explore how diffuse interest come to be represented, and the strategies that concentrated industry interests employ to achieve their interests.