Electoral Systems
- Distinguish first-past-the-post, proportional representation, and mixed systems
- Explain how electoral rules shape the number of parties
- Identify the electoral systems used across the core countries
Three families of electoral system
Electoral systems translate votes into seats. In first-past-the-post (FPTP) — also called single-member-district plurality — the country is divided into districts, and the candidate with the most votes in each wins the one seat; the UK and Nigeria use it for their legislatures. In proportional representation (PR), parties win seats in proportion to their share of the vote, so a party with 30% of votes gets roughly 30% of seats. In a mixed (mixed-member) system, voters elect some representatives by district and others by party list — Mexico and Russia use mixed systems for their lower houses, combining district and proportional seats.
How rules shape party numbers
Electoral rules powerfully influence how many parties thrive — an insight known as Duverger’s law. FPTP tends to produce two dominant parties, because votes for smaller parties are "wasted" when only the top finisher wins, pushing voters and elites toward two broad camps. PR tends to produce multiparty systems, because even small parties can win seats with a modest vote share, encouraging many parties to compete and often requiring coalition governments. Mixed systems fall in between. This is why the UK’s FPTP long favored two big parties while PR systems abroad host many.
Elections under authoritarian rule
Elections happen even where power is not genuinely contested. China holds no competitive national elections; only local people’s congresses have limited voting, and the Communist Party controls candidacies. Iran holds real elections for president and parliament, but the Guardian Council vets candidates first, so competition occurs only within a pre-approved field. Russia’s elections are managed to favor the ruling party. Comparing these to the UK’s and Mexico’s competitive elections shows that the rules and freedom of competition, not just the act of voting, determine whether an election is meaningful.
A country switches from a proportional-representation system to first-past-the-post. Predict how this is likely to change the number of viable parties and why, using Duverger’s law.
- 1.Recall the starting point: PR awards seats in proportion to vote share, so many small parties can win representation, producing a multiparty system.
- 2.Recall the effect of FPTP: only the top vote-getter in each district wins, so votes for small parties yield no seats and are "wasted."
- 3.Apply Duverger’s law: rational voters and elites abandon uncompetitive small parties and consolidate behind two major ones to avoid wasting votes.
- 4.Predict the outcome: the number of viable parties should shrink toward two, as seen in FPTP systems like the UK.
According to Duverger’s law, a first-past-the-post (single-member-district plurality) electoral system tends to produce:
Memorize the pairing: FPTP → two parties (UK), PR → many parties + coalitions, mixed → in between (Mexico, Russia). When a prompt changes the electoral rules, predict the party-system effect through Duverger’s law for full credit.
Iran holds genuine elections for its president and parliament, yet competition is limited because:
Match each core country to its lower-house electoral system: UK/Nigeria = FPTP; Mexico/Russia = mixed; China = no competitive national elections; Iran = elections with Guardian Council vetting. This map answers many electoral-system questions directly.
Answer the 2 checkpoints as you read.
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