Comparative Politics

Lecture 11: Political Parties and Party Systems

Bogdan G. Popescu

John Cabot University

What Are Parties For?

The Puzzle

Parties dominate every democracy on Earth
Yet no constitution requires them
Most founders feared them (e.g., Washington, Madison)
So why do they emerge — and persist?

“Political parties created democracy and… modern democracy is unthinkable save in terms of the parties.” — E.E. Schattschneider (1942, p. 1)

Note the causal claim: parties did not merely follow democracy — they made mass democracy possible by organizing conflict and giving voters meaningful choices.

Aldrich: Solving Collective Action

Problem 1: Legislators cannot form stable coalitions alone
- Arrow’s impossibility: without fixed agendas, any majority can be overturned by a new coalition (cycling)
Problem 2: Voters cannot monitor every candidate
- Information costs are prohibitive
Parties solve both by bundling preferences
- Provide brand labels to voters
- Enforce cooperation among legislators

Downs’s Spatial Model

Figure 1: With single-peaked preferences, two office-seeking parties converge to the median voter.

Office vs. Policy: The Core Tension

Two logics of party behavior
	Office-Seeking	Policy-Seeking
Goal	Win elections	Implement preferred policy
Strategy	Move to median voter	Mobilize the base
Prediction	Convergence	Divergence
Key theorist	Downs (1957)	Aldrich (1995)

Most real parties combine both — but which dominates shapes party systems.

Key tension: Are parties causes or symptoms of political outcomes?

Exercise 1: Why Parties?

Discussion Exercise (5 min)

Prompt: Think of a democracy where a major party recently collapsed or a new party rapidly emerged (e.g., Italy’s Five Star Movement, France’s En Marche!).

Which theory — Aldrich’s collective action or Downs’s spatial model — better explains what happened?
Discuss with a partner and prepare a one-sentence answer.

The Cleavage Approach

Lipset & Rokkan: Two Revolutions, Four Cleavages

Lipset & Rokkan (1967): Party systems reflect historical conflicts from two great transformations.

Lipset & Rokkan’s cleavage schema
Cleavage	Revolution	Conflict	Party Examples
Center–Periphery	National	Language, region	SNP, Basque parties
Church–State	National	Secular vs. religious	Christian Democrats
Land–Industry	Industrial	Agrarian vs. urban	Nordic agrarian parties
Capital–Labor	Industrial	Workers vs. owners	Labour, SPD, PS

The Freezing Hypothesis

Mass suffrage arrived 1900s–1920s in most of Europe
By then, major cleavages were already organized
Parties “froze” the cleavage structure
Prediction: 1960s party systems mirror 1920s party systems

Empirical implication: If true, party systems should be remarkably stable. Are they?

The Freeze — and the Thaw

Figure 2: Combined vote share of traditional party families (Social Democrats, Christian Democrats, Conservatives, Liberals) shows remarkable stability through the 1960s, then gradual erosion.

Where the Thesis Strains: A New Cleavage

Post-1960s: new issues cut across old cleavages
- Environment, immigration, European integration
Kitschelt (1994): globalization creates winners and losers along a new axis
Kriesi et al. (2008): “demarcation vs. integration” — not just economic, but cultural
This new dimension is called GAL–TAN:
- GAL: Green, Alternative, Libertarian (cosmopolitan, progressive values)
- TAN: Traditional, Authoritarian, Nationalist (national identity, order)
A party can be economically left and culturally conservative (PiS) — or economically right and culturally liberal (Macron’s LREM)

GAL–TAN in Practice

Figure 3: European parties on two dimensions, Chapel Hill Expert Survey 2019 (Bakker et al., 2020).

Electoral Systems and Party Systems

Duverger’s Law

Single-member districts (SMD) tend to produce two-party systems
Proportional representation (PR) tends to produce multiparty systems
This works through two effects:
- Mechanical: how votes are translated into seats
- Psychological: how voters and elites anticipate the mechanical effect

The Mechanical Effect

In SMD: only the plurality winner gets the seat
Third parties win votes but very few seats
- UKIP won 12.6% of UK votes in 2015 → 1 seat
- Liberal Democrats won 7.9% → 8 seats
This mechanically crushes small parties

The seat share is far more concentrated than the vote share.

The Psychological Effect

Voters anticipate wasted votes
- “I prefer the Greens, but I’ll vote Labour to stop the Tories”
Elites anticipate futility
- Donors, activists avoid parties that cannot win
Strategic voting reinforces the two-party equilibrium

The psychological effect operates before election day; the mechanical effect operates after.

How Duverger Works

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flowchart LR
    A["Electoral<br/>Rule: SMD"] --> B["Mechanical<br/>Effect"]
    A --> C["Psychological<br/>Effect"]
    B --> D["Small parties<br/>win few seats"]
    C --> E["Voters desert<br/>small parties"]
    D --> F["Two-party<br/>system"]
    E --> F

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Cox: Beyond Duverger

Duverger gives us a “law” — Cox gives us a mechanism
Strategic coordination among voters and elites
The “M+1 rule”: in a district of M seats, expect M+1 viable candidates
- SMD (M=1) → 2 candidates
- 5-seat PR (M=5) → 6 viable candidates
Key insight: institutions interact with social structure

The Endogeneity Problem

Does PR cause multipartyism — or do multiparty societies adopt PR?

Many European countries adopted PR because they already had multiple parties
Rokkan (1970): PR was a defensive move by old parties facing new competitors
The causal arrow is genuinely contested
Students should leave knowing this is an open question

Focused Comparison: UK vs. Netherlands

Different rules, different outcomes. Source: Author’s compilation. ENPP = Effective Number of Parliamentary Parties (Laakso & Taagepera, 1979).
	United Kingdom	Netherlands
Electoral system	SMD (FPTP)	PR (party list)
Threshold	~30–40%	0.67% (effective)
Parties in parliament	2–3 major	10–15
ENPP (2020s)	~2.4	~8.5
Strategic voting?	Pervasive	Minimal

UK House of Commons: adversarial benches

Effective Number of Parties Across Democracies

Figure 4: Effective number of parliamentary parties (ENPP) by electoral system.

Sartori: Beyond Counting Parties

Sartori (1976) — qualitative distinctions that ENPP alone cannot capture
Type	ENPP (approx.)	Example	Key Feature
Predominant	~1.7	Japan (1955–93), Mexico (–2000)	One party dominates; others exist but cannot win
Two-party	~2.0	US, UK	Two parties alternate in power
Moderate pluralism	3–5	Germany, Sweden	Centripetal competition, coalition government
Polarized pluralism	5+	Italy (1st Rep.), Israel	Centrifugal, anti-system parties, bilateral opposition

ENPP tells you how many; Sartori (1976) tells you how they interact.

Exercise 2: Duverger in Practice

Discussion Exercise (5 min)

Prompt: India uses single-member districts but has many parties (ENPP ≈ 6.6). Canada uses SMD but regularly has 3–4 major parties.

Does this break Duverger’s Law, or can you explain it within the theory?
Hint: Think about the difference between national and district-level competition.
Discuss with a partner.

Party System Institutionalization

Mainwaring & Scully: Four Dimensions

Stability of interparty competition
- Same parties compete election after election
Party roots in society
- Voters have stable attachments
Legitimacy
- Parties accepted as necessary institutions
Organizational coherence
- Parties are more than personal vehicles

Why Institutionalization Matters

Weakly institutionalized systems are vulnerable to:
- Populist outsiders capturing power
- Electoral volatility destabilizing governance
- Democratic backsliding
Institutionalized parties serve as gatekeepers
- They screen out extremists (Levitsky & Ziblatt, 2018)
- They enforce norms of democratic competition

Electoral Volatility Across Regions

Figure 5: Electoral volatility (Pedersen index) by region, 1990s–2010s averages.

Katz & Mair: The Cartel Party

Party evolution: cadre (19th c.) → mass (early 20th c.) → catch-all (1960s) → cartel (1990s–)
Cartel parties colonized the state: public funding, media access, patronage
Traded societal rootedness for state resources
The cartel thesis is the missing link: parties became vulnerable because they engineered their own disconnection
Outsiders exploit the gap between cartelized elites and disconnected voters

Case: Venezuela

Punto Fijo pact (1958–1998): AD + COPEI won ~85% of votes through the 1980s
By 1993: combined vote share collapsed to ~46%; by 1998: ~36%
Pedersen volatility surged from ~15 to ~55 in a single decade
Hugo Chávez (1998): outsider captures presidency
- Dismantled party system, built personal movement
Lesson: institutionalization without societal roots is fragile

Case: Poland

Post-1989: fluid system; Pedersen volatility ~35
SLD: 41% of seats (2001) → 11% (2005)
PiS: conservative social policy + welfare expansion
37% (2015) → 44% (2019); governed until 2023
Outsiders can be organized, not just populist

Exercise 3: Gatekeeping

Discussion Exercise (5 min)

Prompt: Levitsky & Ziblatt argue that parties should serve as “gatekeepers” against extremists. Katz & Mair argue that mainstream parties became cartels disconnected from voters.

Is there a tension between these two arguments?
Can parties be effective gatekeepers and remain connected to voters — or does one inevitably come at the expense of the other?
Discuss with a partner.

Synthesis

Three Frameworks Compared

Each answers a different question about the same phenomenon
Framework	Key Question	Unit of Analysis	Prediction
Cleavage theory	Which conflicts exist?	Social structure	Stability
Duverger/Cox	How many parties survive?	Electoral rules	Format
Institutionalization	How strong are parties?	Organizations	Quality of democracy

No single framework is sufficient. The best analysis combines all three.

The Hard Case: France

Cleavage theory: Left–Right frozen since Revolution? But post-materialist cleavages cut across
Duverger: Two-round system → moderate multipartyism? But Macron shattered the duopoly in 2017
Institutionalization: PS and LR had deep roots — yet collapsed in a single cycle
Why? Cartelized parties + new GAL–TAN cleavage + two-round system enabling outsider coordination
All three frameworks are necessary — and insufficient alone

Key Takeaways

Parties solve collective action problems for voters and legislators
Cleavages determine which conflicts parties organize
Electoral rules constrain how many parties survive
Institutionalization determines how stable the system is
The cartel thesis explains why even institutionalized systems erode
No single framework suffices — comparative analysis requires all three

References I

Aldrich, J. H. (1995). Why parties? The origin and transformation of political parties in America. University of Chicago Press.

Bakker, R., Hooghe, L., Jolly, S., Marks, G., Polk, J., Rovny, J., Steenbergen, M., & Vachudova, M. A. (2020). 2019 Chapel Hill Expert Survey. Version 2019.3. Chapel Hill, NC: University of North Carolina.

Boix, C. (1999). Setting the rules of the game: The choice of electoral systems in advanced democracies. American Political Science Review, 93(3), 609–624.

Cox, G. W. (1997). Making votes count: Strategic coordination in the world’s electoral systems. Cambridge University Press.

Downs, A. (1957). An economic theory of democracy. Harper & Row.

Duverger, M. (1954). Political parties: Their organization and activity in the modern state. Wiley.

Gallagher, M. (2024). Election indices dataset. Trinity College Dublin. Retrieved from https://www.tcd.ie/Political_Science/people/michael_gallagher/ElSystems/

References II

Katz, R. S., & Mair, P. (1995). Changing models of party organization and party democracy: The emergence of the cartel party. Party Politics, 1(1), 5–28.

Kitschelt, H. (1994). The transformation of European social democracy. Cambridge University Press.

Kriesi, H., Grande, E., Lachat, R., Dolezal, M., Bornschier, S., & Frey, T. (2008). West European politics in the age of globalization. Cambridge University Press.

Laakso, M., & Taagepera, R. (1979). “Effective” number of parties: A measure with application to West Europe. Comparative Political Studies, 12(1), 3–27.

Levitsky, S., & Ziblatt, D. (2018). How democracies die. Crown.

Lipset, S. M., & Rokkan, S. (1967). Cleavage structures, party systems, and voter alignments: An introduction. In S. M. Lipset & S. Rokkan (Eds.), Party systems and voter alignments (pp. 1–64). Free Press.

Mainwaring, S., & Scully, T. R. (Eds.). (1995). Building democratic institutions: Party systems in Latin America. Stanford University Press.

Morgan, J. (2011). Bankrupt representation and party system collapse. Penn State University Press.

Powell, E. N., & Tucker, J. A. (2014). Revisiting electoral volatility in post-communist countries: New data, new results and new approaches. British Journal of Political Science, 44(1), 123–147.

References III

Rokkan, S. (1970). Citizens, elections, parties. Universitetsforlaget.

Sartori, G. (1976). Parties and party systems: A framework for analysis. Cambridge University Press.

Schattschneider, E. E. (1942). Party government. Holt, Rinehart and Winston.

Stanley, B. (2016). Populism in Central and Eastern Europe. In C. Rovira Kaltwasser, P. Taggart, P. Ochoa Espejo, & P. Ostiguy (Eds.), The Oxford handbook of populism (pp. 140–160). Oxford University Press.