In an election under first-past-the-post, a third party consistently wins 20% of the national vote but only 3% of parliamentary seats. A supporter concludes the system is broken and switches to voting for their second-choice major party. According to Duverger's Law, what does this individual's behavior illustrate?
ARational ignorance — the voter doesn't understand how many seats the third party actually holds
BStrategic voting — the voter abandons their sincere preference to avoid wasting their vote on a party that cannot win the local plurality
CExpressive voting — the voter is making a symbolic statement rather than trying to influence the outcome
DProportional defection — a normal feature of all electoral systems that corrects for overrepresentation
Duverger's Law explains why FPTP tends to produce two-party systems: voters who prefer a third party that cannot win the local plurality face a strategic incentive to defect. Their vote for the third party doesn't help elect anyone — it's 'wasted.' Over many elections, this strategic pressure squeezes third parties out and consolidates support around two major parties. The voter in this scenario is acting exactly as Duverger's Law predicts: rational strategic behavior aggregates into a two-party equilibrium.
Question 2 Multiple Choice
Germany's mixed-member proportional system includes a 5% electoral threshold. What is the primary purpose of this threshold?
ATo ensure that every party wins at least 5% of seats, preventing tiny parties from being shut out entirely
BTo prevent extreme fragmentation by excluding very small parties from seat allocation, while still allowing proportionality among parties above the threshold
CTo limit the number of parties to exactly 20, since 100% ÷ 5% = 20
DTo require candidates to win at least 5% of their local district vote before they qualify for list seats
Electoral thresholds are a deliberate correction to the fragmentation risk in PR systems. Without a threshold, even a party with 0.5% of the vote could win seats in a large parliament, leading to dozens of parties with minimal coherence. Germany's 5% threshold excludes parties below that level from proportional seat distribution, concentrating representation among parties with meaningful support. The tradeoff is reduced proportionality for small parties — but the intent is governability and stability rather than maximal proportionality.
Question 3 True / False
Under first-past-the-post, a party that wins 40% of the national vote can win a majority of parliamentary seats.
TTrue
FFalse
Answer: True
This is one of FPTP's defining features — and a major source of controversy about its democratic legitimacy. Because each seat is won by the local plurality, a party whose support is efficiently distributed across many districts can win far more seats than its national vote share suggests. In the UK, parties have repeatedly won large parliamentary majorities with 35–43% of the national vote. The flip side is that a party with 20% of votes spread evenly across all districts may win very few seats. This disproportionality is why FPTP is criticized as unrepresentative even as it is praised for producing clear governing mandates.
Question 4 True / False
Proportional representation systems tend to produce stronger, more accountable single-party governments than first-past-the-post systems.
TTrue
FFalse
Answer: False
This has it backwards. PR systems typically produce multiparty coalition governments, not single-party governments, precisely because no party wins a majority of seats when votes are translated proportionally. Coalition governments involve multiple parties sharing executive power, which can make accountability harder — voters struggle to assign credit or blame among coalition partners. FPTP tends to produce single-party majority governments, which are more directly accountable (voters know exactly who to reward or punish). The tradeoff is that this accountability in FPTP comes with severe disproportionality in representation.
Question 5 Short Answer
Why does first-past-the-post tend to produce two-party systems while proportional representation tends to produce multiparty systems? Explain the mechanism, not just the outcome.
Think about your answer, then reveal below.
Model answer: In FPTP, each district has one winner — whoever gets the most votes. A voter who prefers a third party that cannot win the local plurality accomplishes nothing by voting for it; their vote is 'wasted.' Rational voters therefore defect to whichever major party they dislike less. Over many election cycles, this strategic pressure drains support from third parties and concentrates it in two. In PR, even a party with 10% of the vote wins roughly 10% of seats, so voters face no strategic incentive to abandon sincere preferences. Small parties can survive and grow, producing stable multiparty systems.
The mechanism is strategic voting under FPTP (the 'wasted vote' logic) versus sincere voting under PR. Duverger's Law identifies this as a sociological regularity, not a logical necessity — there can be exceptions. But the incentive structure is clear: FPTP punishes voters for supporting parties that cannot win locally, while PR rewards any party with broad enough support to clear a threshold. District magnitude amplifies this: larger multi-member districts behave more like PR even within formally plurality systems.