Preferences, parties and pragmatic fidelity : party unity in European legislatures

Abstract

Voting unity in parliamentary parties is an inescapable phenomenon in parliamentary democracies. Knowing only which party a legislator belongs to and how the majority of that party voted allows for the identification, with extremely high levels of accuracy, how said legislator actually voted. However, most explanations of why this is the case rests of unsustainable assumptions about the effects of institutions and electoral systems on the behaviour of parliamentarians. Further, most work ignores the most basic explanation of why legislators vote the way they do: Their policy preferences. Without first explaining the role they play in legislative behaviour, little else can be explained with confidence. This work first theorises and develops measures of how parliamentarians’ policy preferences lead to incentives for them to vote against their party’s line in floor votes, and then applies them to a series of diverse institutional setups, showing that while parliamentarians’ preferences may explain significant parts of parliamentary party voting unity, it is also clear that they cannot, except in rare circumstances, explain all of it. Having shown that preferences cannot explain unity, this work then argues that by analysing MPs’ attitudes to party unity, we can understand why MPs choose to vote contrary to what their preferences alone would predict. Applying this logic to parliaments at either extreme of the spectrum of parliamentary institutionalisation, it is shown that there is little evidence that legislators are compelled to act in ways they do not want. Rather, what is found is that they recognise the value of party voting unity and can overcome the temptation to free-ride on their co-partisans. Finally, analysing floor votes in the European Parliament, it is shown that what explains defection are the long-term rather than short-term goals of parliamentarians, complementing the previous findings.