Chapter 13: Parties, Party Systems, and Party Competition

Party System

A set of political parties and the interactions between them

Effective Number of Electoral Parties

A measure of how many meaningful parties get votes in an election, calculated using the formula: 1 / (v1² + v2² + … + vn²)

Effective Number of Legislative Parties

A measure of how many meaningful parties win seats in the legislature, calculated using the formula: 1 / (s1² + s2² + … + sn²)

Duverger’s Law

Single-member district plurality (SMDP) electoral systems encourage two-party systems

Duverger’s Hypothesis

Proportional representation (PR) electoral systems encourage multiparty systems

Mechanical Effect of Electoral Laws

The way votes are translated into seats; tends to reward large parties and punish small ones, especially under SMDP systems

Strategic Effect of Electoral Laws

The way electoral systems influence how voters and political elites behave, often encouraging strategic voting or entry

Strategic Voting

Voting for a less preferred but more viable candidate to avoid wasting a vote

Strategic Entry

When candidates or parties decide whether to enter based on electoral system incentives

Reinforcing Cleavages

Cleavages (like region and language) that overlap and reduce identity diversity, which may limit party formation

Cross-Cutting Cleavages

Cleavages that do not overlap and encourage the formation of more parties

Party System Nationalization

The extent to which party systems are consistent across districts and regions within a country

Clientelism

Exchange of material goods or services for political support, often based on personal or local networks

Programmatic Politics

Parties campaign and govern based on broad policy platforms and ideological positions

Issue Competition

Parties compete by emphasizing different issues that matter to voters

Issue Ownership

The idea that certain parties are better trusted to handle certain issues (e.g., Greens and environment)

Valence Issues

Non-policy traits like honesty, leadership, and competence that influence voter support

Broker

An intermediary who connects voters with politicians, often used in clientelistic systems to distribute benefits

Nationalized Party System

A system where the same parties compete in all regions and the support base is evenly spread

Non-Nationalized Party System

A system where different regions vote for different parties and the system is locally fragmented

District Magnitude

The number of representatives elected from a district; affects proportionality and party system size

Proportional Representation (PR)

A system where legislative seats are distributed roughly in proportion to votes received

Single-Member District Plurality (SMDP)

A winner-takes-all electoral system where the candidate with the most votes wins

Latent Social Cleavages

Potential identity-based divisions in society (e.g., race, language, religion) that may or may not be politicized

Politicized Cleavages

Latent social cleavages that become activated and drive political behavior or party formation

Minimum Winning Coalition

A coalition just large enough to control a majority of seats; common in coalition-building politics

Median Voter Theorem

The idea that parties in two-party systems converge toward the policy preference of the median voter

Party Competition

The way political parties interact and compete for votes, often through policy, issues, or clientelism