Plurality Rule, Proportional Representation, and the Mechanics of U.S. Elections

The criterion for winning is the fourth prominent feature of electoral law in the United States.
While Americans often cite majority rule as the defining trait of democracy, the actual standard for the majority of U.S. elections is plurality rule.
Plurality rule is defined as a system where the candidate who receives the most votes in a specific district or constituency wins the election, regardless of whether they achieve a majority ( $> 50\%$ ) of the total votes.
Hypothetical Scenario of Plurality Rule:
- Suppose three parties nominate candidates for a single seat.
- Party A receives $34\%$ \ of the vote.
- Party B receives $33\%$ \ of the vote.
- Party C receives $33\%$ \ of the vote.
- Under plurality rule, the candidate from Party A wins the seat because they have the most votes, even though $66\%$ \ of the voters preferred a different candidate.

"First Past the Post": This is the most common system in the United States, combining plurality rule with single-member districts.
"Winner Take All": This is a plurality system used by most states when choosing delegates for the Electoral College. The candidate receiving the most votes wins $100\%$ \ of the delegates for that state.
Majority Rule Exceptions in the U.S.:
- Both Louisiana and Georgia require candidates to receive at least $50\%$ \ of the total votes to be declared the winner in statewide elections.
- If no candidate reaches the $50\%$ \ threshold, a runoff election is held approximately one month later between the top two vote-getters from the initial round.
Multimember Districts: Some city councils utilize this system where multiple seats are filled in a single election. For example, if there are $7$ \ seats available, the top $7$ \ vote-getters each win a seat.

Lack of Preference Reflection: Critics argue that plurality rule often results in outcomes that do not accurately represent public preference because a majority of voters may have collectively preferred someone other than the individual who won.
"Wasted Votes": Votes cast for losing candidates in a plurality system are often considered "wasted" because they do not translate into any form of representation.
Aggregation Effects: In the aggregate, the combination of plurality rule and single-member districts tends to inflate the representation of the largest political party while deflating the share of seats won by smaller parties.

Geographic Context: Great Britain (U.K. Independence Party, Conservative Party, Labour Party).
Conservative Party: Won $37\%$ \ of the popular vote but secured $51\%$ \ of the seats.
Labour Party: Placed second with $30\%$ \ of the popular vote and received $36\%$ \ of the seats.
U.K. Independence Party (UKIP): Came in third with $13\%$ \ of the popular vote but secured only $1$ \ seat in the $650$ -seat House of Commons.
This example illustrates how plurality rule creates a significant disparity between the popular vote percentage and the actual legislative representation.

Definition: Competing political parties win legislative seats in direct proportion to their share of the total popular vote.
Hypothetical Scenario: In a PR system, if three parties split the vote $34\%$ \ / $33\%$ \ / $33\%$ \ , the first party receives $34\%$ \ of the seats, and the other two each receive $33\%$ \ of the seats.
Comparative Advantages of Single-Member Districts with Plurality:
- Allows voters to choose specific individuals as personal representatives rather than just voting for a party label.
- Produces a definitive winner quickly without the necessity of expensive or time-consuming runoff elections.

Proportional representation is rare in the U.S., but its most significant application is in the Democratic presidential primary elections.
Historical Context of the 1988 Primaries:
- Candidate Jesse Jackson routinely won approximately $20\%$ \ of the vote but only garnered about $5\%$ \ of the delegates.
- Jackson negotiated with party leaders to change delegate allocation rules to make the Democratic National Convention more representative.
Resulting Rule Change: Delegates within congressional districts are now assigned on a proportional basis.
- Threshold Example: If a district has $5$ \ delegates, a candidate wins $1$ \ delegate by receiving $20\%$ \ of the vote and $2$ \ delegates by receiving $40\%$ \ of the vote.
Previous System: Before this change, the Democratic Party used a plurality-based "winner take all" system for congressional districts, which created a strong majoritarian tendency.

Maurice Duverger: A political scientist who formalized the relationship between electoral rules and party systems in his 1951 book, "Party Politics".
Duverger’s Law: Plurality rule creates two-party politics, whereas proportional representation encourages the development of more than two parties.
Global Observations:
- Plurality rule countries have far fewer parties; elections usually boil down to two major parties competing for power, with one winning an outright majority of seats.
- PR systems typically have many parties, none of which usually hold a decisive majority, leading to the formation of coalition governments.

The logic of the law is based on the strategic behavior of two groups: politicians and voters.
Strategic Behavior of Politicians:
- Imagine a center-right and a center-left party. A politician on the far right may want to form a third party.
- Splitting the Vote: If the far-right politician creates a new party, they split the conservative vote, effectively helping the center-left party win.
- Because this outcome is the least desirable for the far-right politician, they have no incentive to leave the center-right party.
- Centrist constraints: If the existing parties remain moderate, there is very little segment of "true centrists" left for a third party to capture.
Strategic Behavior of Voters:
- Voters engage in "sophisticated voting" to avoid wasting their votes.
- If an extremist candidate cannot win, the voter will support the "second best" moderate choice because that moderate has a better chance of winning than the extremist.
- This deprives extremist candidates of the votes they need to be viable.

2012 Republican Primary: Mitt Romney was more moderate than typical primary voters and other candidates. Voters coordinated on Romney because they recognized him as the strongest candidate for the general election.
2016 Republican Primary: A large field of moderate candidates made it difficult for voters to coordinate around a single individual.
Comparison of Nominating Seasons in 2016:
- Democratic Party: Because of proportional representation, the contest between Hillary Clinton and Bernie Sanders remained close and was not decided until the final day of the primaries.
- Republican Party: Plurality rule and winner-take-all contests allowed the primary to be decided much faster.
- Donald Trump Statistics (2016): By early May, Trump had won less than $47\%$ \ of the popular vote but secured $62\%$ \ of the delegates, leading CNN to declare him the presumptive nominee with over a month of voting remaining.
Conclusion: Plurality rule with single-member districts creates powerful structural pressure toward two-party politics and majority control in legislatures.