Brave rebels stay home

Sanctions and homogeneity of intra-party preferences are the two main pathways to party unity in roll-call votes. However, only a few works have managed to properly measure the degree of polarization within the party, and therefore the link between ideological preferences and parliamentary voting behaviour has not yet been fully tested. Looking at the internal debates held during party congresses and analysing motions presented by party factions through quantitative text analysis, the present article provides a new measure of intra-party polarization that is exogenous to the parliamentary arena. This measure is used to disentangle the effect of ideological heterogeneity on MPs voting behaviour, net of the party whip. Our results show that factional heterogeneity negatively affects party unity. This effect, however, is conditional on the strength of whipping resources available to the party leader. When the electoral system or the intra-party candidate selection process allows strong discipline to be enforced, the negative effect of heterogeneous preferences on party unity is lower or no longer significant. However, since absences can be a strategy by which to express dissent while avoiding sanctions, they should be considered as an additional voting option and this is crucial to understanding the impact of intra-party heterogeneity on party unity.

[1]  Stephanie Boehm,et al.  Electoral Systems A Comparative Introduction , 2016 .

[2]  Lauri Karvonen.  Preferential Voting: Incidence and Effects , 2004 .

[3]  John Polga-Hecimovich.  Legislative Voting and Accountability , 2010 .

[4]  P. Ignazi,et al.  Party organisational change in Italy (1991–2006) , 2010, Modern Italy.

[5]  B. Grofman,et al.  A natural experiment on electoral law reform : evaluating the long run consequences of 1990s electoral reform in Italy and Japan , 2011 .

[6]  S. Hix,et al.  Party Behaviour in the Parliamentary Arena , 2009 .

[7]  John M. Carey,et al.  Incentives to cultivate a personal vote: A rank ordering of electoral formulas☆ , 1995 .

[8]  William D. Berry,et al.  Improving Tests of Theories Positing Interaction , 2012 .

[9]  Leslie E. Papke,et al.  Panel data methods for fractional response variables with an application to test pass rates , 2008 .

[10]  F. Ferrara.  Frogs, mice and mixed electoral institutions: party discipline in Italy's XIV Chamber of Deputies1 , 2004 .

[11]  Will Lowe Mzes,et al.  Estimating Uncertainty in Quantitative Text Analysis ∗ , 2011 .

[12]  D. Giannetti.  Secret Voting in the Italian Parliament , 2010 .

[13]  D. Farrell,et al.  PARTY DISCIPLINE AND PARLIAMENTARY GOVERNMENT , 1999 .

[14]  R. Andeweg,et al.  Pathways to party unity: Sanctions, loyalty, homogeneity and division of labour in the Dutch parliament , 2011 .

[15]  Scott Desposato.  The Impact of Electoral Rules on Legislative Parties: Lessons from the Brazilian Senate and Chamber of Deputies , 2006, The Journal of Politics.

[16]  J. Bernauer,et al.  Intra-Party Preference Heterogeneity and Faction Membership in the 15th German Bundestag: A Computational Text Analysis of Parliamentary Speeches , 2009 .

[17]  J. Heckman.  Sample selection bias as a specification error , 1979 .

[18]  Carol Mershon,et al.  Dealing in Discipline: Party Switching and Legislative Voting in the Italian Chamber of Deputies, 1988–2000 , 2008 .

[19]  L. Curini,et al.  Government Alternation and Legislative Party Unity: The Case of Italy, 1988–2008 , 2012 .

[20]  K. Quinn,et al.  Identifying Intra-Party Voting Blocs in UK House of Commons , 2009 .

[21]  L. Bille.  Democratizing a Democratic Procedure: Myth or Reality? , 2001 .

[22]  Yael Shomer.  What affects candidate selection processes? A cross-national examination , 2014 .

[23]  B. Grofman,et al.  A Natural Experiment on Electoral Law Reform , 2011 .

[24]  T. Feddersen,et al.  Cohesion in Legislatures and the Vote of Confidence Procedure , 1998, American Political Science Review.

[25]  Jonathan B. Slapin,et al.  Position Taking in European Parliament Speeches , 2010 .

[26]  Charles Richardson.  Party Government , 1892 .

[27]  Tom Louwerse.  The Spatial Approach to the Party Mandate , 2011 .

[28]  C. Ai,et al.  Interaction terms in logit and probit models , 2003 .

[29]  J. Carey.  Competing Principals, Political Institutions, and Party Unity in Legislative Voting , 2007 .

[30]  Sven-Oliver Proksch,et al.  A Scaling Model for Estimating Time-Series Party Positions from Texts , 2007 .

[31]  Sam Depauw,et al.  Legislative party discipline and cohesion in comparative perspective , 2005 .

[32]  M. Gabel,et al.  Off the Record: Unrecorded Legislative Votes, Selection Bias and Roll-Call Vote Analysis , 2006, British Journal of Political Science.

[33]  Andrea Ceron,et al.  Bounded oligarchy: How and when factions constrain leaders in party position-taking , 2012 .

[34]  William D. Berry,et al.  Testing for Interaction in Binary Logit and Probit Models: Is a Product Term Essential? , 2010 .

[35]  L. Curini,et al.  Testing the theories of law making in a parliamentary democracy : a roll call analysis of the Italian Chamber of Deputies , 2008 .

[36]  S. A. Rice.  Quantitative Methods in Politics , 1938 .

[37]  S. Hix,et al.  Power to the Parties: Cohesion and Competition in the European Parliament, 1979–2001 , 2005, British Journal of Political Science.

[38]  Reuven Y. Hazan Senior.  Introduction: Does cohesion equal discipline? towards a conceptual delineation , 2003 .

[39]  Marc Debus,et al.  Intra-Party Factions and Coalition Bargaining in Germany , 2009 .

[40]  Reuven Y. Hazan,et al.  Electoral Systems and Candidate Selection , 2006 .

[41]  Sven-Oliver Proksch,et al.  How to Avoid Pitfalls in Statistical Analysis of Political Texts: The Case of Germany , 2009, German Politics.

[42]  Simon Hug,et al.  Legislative Voting Behavior, Seen and Unseen: A Theory of Roll-Call Vote Selection , 2008 .

[43]  Mathew D. McCubbins,et al.  Legislative Leviathan: Party Government in the House , 1993 .

[44]  Reuven Y. Hazan.  Does Cohesion Equal Discipline?: Towards a Conceptual Delineation , 2003 .

[45]  Krister Lundell,et al.  Determinants of Candidate Selection , 2004 .

[46]  L. Curini,et al.  Rebels with a cause-But which One?: Defections from legislative party unity in Italy and their individual and institutional determinants , 2011 .

[47]  Yael Shomer,et al.  Models of Nonresponse in Legislative Politics , 2008 .

[48]  Paul V. Warwick.  Ideological Diversity and Government Survival in Western European Parliamentary Democracies , 1992 .

[49]  Arthur Spirling,et al.  Identifying Intraparty Voting Blocs in the U.K. House of Commons , 2010 .

[50]  Riccardo Pelizzo,et al.  A Spatial Analysis of the Italian Second Republic , 2013, The Journal of Legislative Studies.

[51]  Voters and their representatives: Electoral institutions and delegation in parliamentary democracies , 2000 .

[52]  André Kaiser,et al.  Does the mode of candidate selection affect the representativeness of parties? , 2014 .

[53]  Ulrich Sieberer.  Party unity in parliamentary democracies: A comparative analysis , 2006, The Impact of Legislatures.

[54]  K. Benoit,et al.  Challenges for Estimating Policy Preferences: Announcing an Open Access Archive of Political Documents , 2009 .

[55]  Scott Desposato.  The Impact of Federalism on National Party Cohesion in Brazil , 2004 .

[56]  Françoise Boucek,et al.  Rethinking Factionalism , 2009 .

[57]  Piero Ignazi,et al.  Finanziamento pubblico e mutamenti organizzativi nei partiti italiani , 2011 .