Types of Electoral Systems

Why This Matters

Electoral systems are the rules that translate votes into political power. Those rules have major consequences for everything you'll study in comparative politics. The choice between different systems shapes party systems, coalition formation, representation of minorities, government stability, and even voter behavior. When you see a country with dozens of parties in parliament versus one dominated by two major parties, the electoral system is almost always a key explanation.

You're being tested on your ability to analyze how institutional design creates political outcomes. Don't just memorize which countries use which systems. Understand the mechanisms behind them. Why does First-Past-the-Post tend to produce two-party systems? Why does Proportional Representation lead to coalition governments? These cause-and-effect relationships are what FRQs will ask you to explain. Know what Duverger's Law predicts, understand the tradeoffs between representation and accountability, and you'll be well prepared.

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Majoritarian Systems: Winner-Takes-All Logic

These systems prioritize clear winners and government accountability over proportional representation. The underlying logic: whoever gets the most votes wins, even without a majority. This creates strong incentives for voters to consolidate around viable candidates and for parties to build broad coalitions before elections rather than after.

First-Past-the-Post (FPTP)

• Single-member districts with plurality rule: the candidate with the most votes wins, no majority required.
• Duverger's Law in action: strategic voting and wasted votes push systems toward two dominant parties over time. Voters don't want to "throw away" their vote on a third-party candidate who can't win, so they gravitate toward the two frontrunners.
• Used in the UK, US, India, and Canada: produces clear government mandates but can create significant gaps between vote share and seat share. In the 2015 UK election, UKIP won 12.6% of the national vote but only 1 out of 650 seats. That gap between votes earned and seats won is the central critique of FPTP.

Two-Round System

• Majority requirement triggers a runoff: if no candidate wins more than 50% in round one, the top two candidates (or all candidates above a certain threshold, depending on the country's rules) face off in round two.
• Encourages coalition-building between rounds as eliminated candidates endorse remaining contenders, allowing parties to negotiate and consolidate support.
• Common in French presidential elections: ensures winners have broader legitimacy than simple plurality systems, since the eventual winner must secure majority support in the final round.

Block Voting

• Multiple votes in multi-member districts: voters cast as many votes as there are seats available.
• Amplifies majoritarian effects because a dominant party can sweep all seats in a district even with a modest vote lead.
• Risks diluting minority representation: even substantial minority groups may win zero seats if their votes are dispersed across candidates.

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Proportional Systems: Seats Match Votes

Proportional Representation (PR) systems aim to make legislatures mirror the electorate. The core mechanism allocates seats based on vote share, so a party winning 30% of votes gets roughly 30% of seats. This dramatically lowers the threshold for representation and encourages multi-party systems.

Party-List Proportional Representation

• Voters choose parties, not individual candidates: seats are distributed according to each party's vote percentage.
• Closed vs. open lists matter: in a closed list, party leaders decide the order of candidates on the list, controlling who actually enters parliament. In an open list, voters can influence candidate ranking by marking preferences for specific individuals. This distinction affects how much power voters have versus party elites.
• Most countries using Party-List PR also set an electoral threshold (often around 5%, as in Germany) to prevent extreme fragmentation. Parties below the threshold win no seats, which keeps very small or fringe parties out of parliament.
• Produces coalition governments because single-party majorities are rare. Israel, the Netherlands, and Brazil all use variants of this system.

Single Transferable Vote (STV)

STV works through ranked-choice voting in multi-member districts. Voters order candidates by preference (1st, 2nd, 3rd, etc.).

Here's how the count works:

1. A quota is calculated based on the number of votes cast and seats available, typically using the Droop quota: $\frac{\text{total votes}}{\text{seats} + 1} + 1$.
2. Any candidate who meets or exceeds the quota is elected.
3. Surplus votes from elected candidates transfer to voters' next preferences.
4. If no candidate meets the quota, the lowest-ranked candidate is eliminated and their votes transfer to next preferences.
5. Steps 2–4 repeat until all seats are filled.

STV balances proportionality with candidate choice. It's used in Ireland and for Australian Senate elections. Because voters rank individual candidates rather than parties, STV weakens party control over who gets elected compared to closed-list PR.

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Mixed Systems: Seeking the Best of Both Worlds

Mixed systems attempt to combine majoritarian accountability with proportional fairness. Voters typically get two votes: one for a local representative (majoritarian) and one for a party (proportional). The balance between these components varies significantly depending on the design.

Mixed Electoral Systems

• Dual ballot structure: voters cast one vote for a district candidate (usually FPTP) and one for a party list (PR).
• Compensatory vs. parallel designs: this is the critical distinction.
  • In compensatory systems (like Germany's MMP), the PR seats are used to correct the disproportionality created by the district seats. If a party wins fewer district seats than its vote share warrants, it receives extra PR seats to make up the difference. The final seat distribution closely matches overall vote share.
  • In parallel systems (like Japan's), the two tiers operate independently. District results and PR results are simply added together, so disproportionality from the district tier carries through to the final result. This means parallel systems are less proportional overall than compensatory ones.
• Germany's Mixed-Member Proportional (MMP) is the classic compensatory example: local representation plus overall proportionality. Know this as the textbook case for exam questions.

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Preferential Voting: Rankings Over Single Choices

These systems let voters express nuanced preferences rather than choosing just one candidate. They use ranked ballots and either eliminate candidates sequentially or assign points based on ranking position. This reduces wasted votes and can produce consensus winners.

Alternative Vote (AV) / Instant Runoff Voting (IRV)

AV uses ranked ballots in single-member districts. The counting process works like this:

1. All first-preference votes are counted.
2. If a candidate has more than 50%, they win.
3. If not, the candidate with the fewest first-preference votes is eliminated.
4. Voters who ranked the eliminated candidate first have their votes redistributed to their second preference.
5. Steps 2–4 repeat until one candidate crosses 50%.

This reduces the vote-splitting problem because supporters of similar candidates can rank them 1-2 without "wasting" their vote. AV is used in Australian House elections, maintaining single-member districts while ensuring majority winners. Note that AV is still a majoritarian system (single-member districts, one winner), not a proportional one. It just finds that winner differently than FPTP does.

Borda Count

• Points-based ranking system: candidates receive points based on ballot position. With 5 candidates, for example: 1st place = 4 points, 2nd = 3 points, down to 0 for last place.
• Favors consensus candidates who are broadly acceptable rather than intensely preferred by a narrow plurality. A candidate ranked 2nd by almost everyone can beat a candidate ranked 1st by a slim faction.
• Vulnerable to strategic voting: voters may rank strong competitors last regardless of their true preferences, artificially lowering a frontrunner's point total. This is a well-known weakness of the system.

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Semi-Proportional Systems: Partial Solutions

These systems fall between majoritarian and proportional extremes, producing some proportionality without full PR mechanisms. They often create strategic dilemmas for parties and voters that can fragment or consolidate party systems in unpredictable ways.

Single Non-Transferable Vote (SNTV)

• One vote per person in multi-member districts: the top vote-getters win seats, but votes don't transfer.
• Creates intra-party competition because parties must carefully manage how many candidates to run and how to distribute supporter votes among them. If a party runs too many candidates, its vote splits and all of them lose. If it runs too few, it leaves winnable seats on the table. This nomination strategy problem is unique to SNTV and doesn't arise under FPTP (where there's only one seat per district).
• Historically used in Japan (before 1994) and Taiwan: can produce either fragmentation or factional politics within dominant parties.

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Quick Reference Table

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Self-Check Questions

1. Which two systems both use ranked ballots but produce different types of winners? What explains the difference in outcomes?

2. A country wants to maintain local district representation while ensuring overall proportionality in parliament. Which system should they adopt, and how does its mechanism achieve both goals?

3. Compare FPTP and Party-List PR: How does each system affect the number of parties, the likelihood of coalition governments, and the representation of minority viewpoints?

4. Why might SNTV create strategic dilemmas for political parties that FPTP does not? What must parties calculate when deciding how many candidates to nominate?

5. If an FRQ asks you to explain why France uses a Two-Round System for presidential elections rather than FPTP, what argument about democratic legitimacy should you make?