In this book, Carol Mershon and Olga Shvetsova explore one of the central questions in democratic politics: how much autonomy do elected politicians have to shape and reshape the party system on their own, without the direct involvement of voters in elections? Mershon and Shvetsova's theory focuses on the choices of party membership made by legislators while serving in office. It identifies the inducements and impediments to legislators' changes of partisan affiliation, and integrates strategic and institutional approaches to the study of parties and party systems. With empirical analyses comparing nine countries that differ in electoral laws, territorial governance and executive-legislative relations, Mershon and Shvetsova find that strategic incumbents have the capacity to reconfigure the party system as established in elections. Representatives are motivated to bring about change by opportunities arising during the parliamentary term, and are deterred from doing so by the elemental democratic practice of elections.

In this book, Carol Mershon and Olga Shvetsova explore one of the central questions in democratic politics: How much autonomy do elected politicians have to shape and reshape the party system on their own, without the direct involvement of voters in elections? Mershon and Shvetsova's theory focuses on the choices of party membership made by legislators while serving in office. It identifies the inducements and impediments to legislators' changes of partisan affiliation, and integrates strategic and institutional approaches to the study of parties and party systems. With empirical analyses comparing nine countries that differ in electoral laws, territorial governance, and executive legislative relations, Mershon and Shvetsova find that strategic incumbents have the capacity to reconfigure the party system as established in elections. Representatives are motivated to bring about change by opportunities arising during the parliamentary term, and are deterred from doing so by the elemental democratic practice of elections.

"The Costs of Coalition" tackles big questions of enduring interest in real-world politics and in political science. The substantive aim of the book is to understand and explain who governs, and for how long, under the institutions of parliamentary democracy. Its epistemological purpose is to investigate the nature of political scientists' knowledge of coalitional behavior and how to advance it.
The book starts from the well-known fact that governments in postwar Italy are extremely short-lived, and identifies a puzzle about coalition politics posed by the Italian experience. In postwar Italy until 1992, cabinets fell frequently but the same parties returned to office again and again. This book focuses on that stability--the perpetual incumbency of the Christian Democrats and the limited degree to which parties alternated between government and opposition in Italy. It probes how stability was tied to instability in Italian governments. It also compares Italian coalitions with those in nine other parliamentary democracies: Belgium, Denmark, Finland, France, Germany, Ireland, the Netherlands, Norway, and Sweden.
The author argues that the costs and benefits of building and breaking coalitions vary in systematic ways. The variations arise in part from parties' deliberate efforts to redefine payoffs in coalition politics, and they also reflect the constraints and opportunities created by the institutions of parliamentary democracy and the configuration of the party system. Under some conditions, such as those in Italy, coalitions are cheap, and politicians can easily make coalitions cheaper.
The picture of strategic behavior drawn in the book illuminates Italy's extremes and the degrees of stability found in other parliamentary democracies. In addition, the book advocates and embodies a rethinking of the relationship between game-theory literature in political science and empirical research on political institutions.

A formal model in the social sciences builds explanations when it structures the reasoning underlying a theoretical argument, opens venues for controlled experimentation, and can lead to hypotheses. Yet more importantly, models evaluate theory, build theory, and enhance conjectures. Formal Modeling in Social Science addresses the varied helpful roles of formal models and goes further to take up more fundamental considerations of epistemology and methodology. The authors integrate the exposition of the epistemology and the methodology of modeling and argue that these two reinforce each other. They illustrate the process of designing an original model suited to the puzzle at hand, using multiple methods in diverse substantive areas of inquiry. The authors also emphasize the crucial, though underappreciated, role of a narrative in the progression from theory to model. Transparency of assumptions and steps in a model means that any analyst will reach equivalent predictions whenever she replicates the argument. Hence, models enable theoretical replication, essential in the accumulation of knowledge. Formal Modeling in Social Science speaks to scholars in different career stages and disciplines and with varying expertise in modeling.