The Basic Arithmetic of Legislative Decisions

Abstract

Despite the huge number of possible seat distributions following a general election in a multi-party parliamentary democracy, there are far fewer classes of seat distribution sharing important strategic features. We define an exclusive and exhaustive partition of the universe of theoretically possible n-party systems into five basic classes, the understanding of which facilitates more fruitful modeling of legislative politics, including government formation.Having defined a partition of legislative party systems and elaborated logical implications of this partition, we classify the population of postwar European legislatures. We show empirically that many of these are close to critical boundary conditions, so that stochastic processes involved in any legislative election could easily flip the resulting legislature from one type to another. This is of more than hypothetical interest, since we also show that important political outcomes differ systematically between the classes of party systemoutcomes that include duration of government formation negotiations, type of coalition cabinet that forms, and stability of the resulting government.

Political and institutional determinants of immigration policies

“…In comparative politics and political economy there now exists an abundance of measures for institutional fragmentation in general and veto points in particular (Keefer and Stasavage, 2003;Henisz, 2000;Schmidt, 2000;Huber and Stephens, 2001 and Benoit, 2014). Degrees of electoral competition should, thus, be understood as the relationship between changes in votes and changes in the legislative party position.…”

Marriages of Convenience: Explaining Party Mergers in Europe

“…To develop one explanatory account about how the goal of achieving a stronger bargaining position drives mergers, this research builds on the exhaustive classification of legislative party systems provided by Laver and Benoit (2015). This typology captures the impact of "constitutionally binding arithmetical constraints on legislative bargaining" (276) that arise due to the need for coalitions to win the majority support in the legislature.…”

“…This typology captures the impact of "constitutionally binding arithmetical constraints on legislative bargaining" (276) that arise due to the need for coalitions to win the majority support in the legislature. Specifically, Laver and Benoit (2015) distinguish between five types of party systems depending on whether the largest party can form a winning coalition on its own and, if not, whether two-party winning coalitions among the three largest parties are possible.…”

“…However, this approach is problematic because of the high uncertainty about the postmerger party system. Specifically, even small changes in the legislative seat shares of any of the parties due to, for example, party switching by individual legislators or changes in parties' electoral support, could lead to changes in the type of the party system (Laver and Benoit 2015).…”

“…This framework integrates some relatively well-established explanations with more innovative arguments on how potential gains in office benefits affect mergers. Specifically, building on the typology of legislative party systems by Laver and Benoit (2015), we argue that fusion may be motivated by the goals to establish a party that has a legislative majority, is "strongly dominant," or is one of the two or three key parties in the party system. Additionally, parties may merge to achieve legislative plurality.…”