PS 11/Week 10: Parties and Party Systems

Lecture Outline

I. Why parties matter

A. Help politicians act collectively

B. Mobilize people into politics

C. Help voters choose

D. Aggregate and integrate voter preferences

E. Help voters hold parties accountable

F. Elite recruitment and socialization

II. Party systems

A. Social Explanations for number of parties in party systems

1. More social divisions => more parties

2. Why only two parties in US?

B. Institutional Explanations

1. Rules of electoral game

a. Electoral formula

- majority

- plurality

- proportional representation (PR)

b. District size: single member or multi-member

c. Typical combinations

- Single member plurality (SMP)

- List system multi-member PR

2. Duverger’s Rule

a. Mechanical effect: SMP is unkind to small parties

b. Psychological effect: SMP => strategic voting for big parties

c. SMP systems => two parties

C. Implications of Duverger’s Rule

1. Multiple parties => fragmentation

2. Multiple parties => more representation

3. Two parties => convergence, less polarization (Median Voter Theorem)

4. All potentially affect democratic stability

D. Critiques of Institutional approaches

1. The story is backwards: electoral rules are product political patterns, not cause

2. Story leaves too much out

a. Electoral rules are under-determining

b. South Africa: national list PR

- Why so few parties?

- Why is the ANC so dominant?

- Why is support for the ANC so fixed?

III. Conclusion: the interaction between institutions and their context

Terms

Cleavage structure

Electoral system

Electoral formula

Majority rule

Plurality rule

Winner-takes-all

Proportional representation

District magnitude

Single member district

Multi-member district

SMP

List system

Duverger’s Law

Strategic voting

Sincere voting

Representation

Fragmentation

Polarization

Median voter theorem

African National Congress (ANC)