The Logic of Gamson's Law: Pre-election Coalitions and Portfolio Allocations

Authors


  • We thank the NSF for support under grant SES-0518192. We thank the participants in NYU's law and politics seminar (October 2004) and the University of Chicago's political economy seminar (February 2005). We also thank James Druckman, Orit Kedar, Michael Laver, Massimo Morelli, and Paul Warwick, as well as the anonymous reviewers, for their comments. Finally, we thank Paul Warwick and James Druckman for their data on portfolio allocations in Western Europe.

Royce Carroll is a Ph.D. candidate in political science, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0521 (rcarroll@ucsd.edu). Gary W. Cox is professor of political science, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0521 (gcox@ucsd.edu).

Abstract

Gamson's Law—the proposition that coalition governments will distribute portfolios in proportion to each member party's contribution of seats to the coalition—has been one of the most prominent landmarks in coalitional studies since the 1970s. However, standard bargaining models of government formation argue that Gamson's Law should not hold, once one controls for relevant indicators of bargaining power. In this article, we extend these bargaining models by allowing parties to form pre-election pacts. We argue that campaign investments by pact signatories depend on how they anticipate portfolios will be distributed and, thus, signatories have an incentive to precommit to portfolio allocation rules. We show that pacts will sometimes agree to allocate portfolios partly or wholly in proportion to members' contributions of seats to the coalition; this increases each signatory's investment in the campaign, thereby conferring external benefits (in the form of a larger probability of an alliance majority) on other coalition members. Empirical tests support the model's predictions.

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