Plurality voting

Plurality voting refers to electoral systems in which a candidate in an electoral district who polls more than any other (that is, receives a plurality) is elected. Used for elections of representative bodies, it competes with the proportional representation^[1] (where the composition of the body reflects the percentage of the votes received across all districts). In systems based on single-member districts, the plurality system elects just one member per district and is then frequently called a "first-past-the-post" (FPTP), sometimes "single-member [district] plurality" (SMP/SMDP).^[2] A system that elects multiple winners elected at once with the plurality rule and where each voter casts multiple X votes in a multi-seat district is referred to as plurality block voting. A semi-proportional system that elects multiple winners elected at once with the plurality rule and where each voter casts just one vote in a multi-seat district is known as single non-transferable voting.

Plurality voting is distinguished from majority voting, in which a winning candidate must receive an absolute majority of votes: more than half of all votes (more than all other candidates combined if each voter has one vote). Under single-winner plurality voting, the leading candidate, whether or not they have a majority of votes, is elected.^[3]

Plurality voting is widely used throughout the English-speaking world as a result of its spread by the British Empire, including in most of the United States. Outside of the English-speaking world, it is slightly less popular than its close cousin, the runoff family of methods.

Social choice theorists and electoral reform advocates are generally opposed to plurality voting and its variants, citing major issues such as a high vulnerability to spoilers, a tendency towards duopoly and lesser of two evils voting, and their bias toward extremist candidates (as a result of failing the median voter theorem).

the largest city, but far from the others (42% of voters)

Memphis

near the center of the state (26% of voters)

Nashville

somewhat east (15% of voters)

Chattanooga

far to the northeast (17% of voters)

Knoxville

Substantial power is given to the . Some voters will tend to believe the media's assertions as to who the leading contenders are likely to be in the election. Even voters who distrust the media know that other voters believe the media, and so those candidates who receive the most media attention will nonetheless be the most popular, and thus most likely to be one of the top two.

news media

A new candidate, who is in principle supported by the majority of voters, may be considered unlikely to become one of the top two candidates, because of the lack of a track record. The candidate will thus receive fewer votes, which will then give them a reputation as a low poller in future elections, which perpetuates the problem.

The system may promote votes against than for a candidate. In the UK, entire campaigns have been organised with the aim of voting against the by voting either Labour or Liberal Democrat. For example, in a constituency held by the Conservatives, with the Liberal Democrats as the second-placed party and the Labour Party in third, Labour supporters might be urged to vote for the Liberal Democrat candidate, who has a smaller hurdle to overcome and more support in the constituency than their own party candidate, on the basis that Labour supporters would prefer an MP from a competing leftist or liberal party than a Conservative one. Similarly, in Labour/Liberal Democrat marginals in which the Conservatives are third, Conservative voters may be encouraged or tempted to vote Liberal Democrat to help defeat Labour.

Conservative Party

If enough voters use this tactic, the first-past-the-post system becomes, effectively, , a completely different system, in which the first round is held in the court of public opinion. A good example was the 1997 Winchester by-election.

runoff voting

Voting system attributes and comparison to non-plurality systems[edit]

Attributes and criteria[edit]

Majority criterion: Will a candidate always win who is ranked as the unique favorite by a majority of voters?

– Example of an incumbent governor, Rick Perry, winning re-election despite gaining less than 40 per cent of the vote

2006 Texas gubernatorial election

Cube rule

Deviation from proportionality

Plurality-at-large voting

Anti-plurality voting

List of democracy and elections-related topics

Instant-runoff voting

Approval Voting

Score voting

Single non-transferable vote

Single transferable vote

Runoff voting

Mudambi, Ram; Navarra, Pietro; Nicosia, Carmela (1996). . Public Choice. 86 (3/4). Springer: 341–357. ISSN 1573-7101. JSTOR 30027122. Retrieved 19 April 2024.