The plurality voting system is a single-winner voting system often used to elect executive officers or to elect members of a legislative assembly which is based on single-member constituencies. This voting method is also used in multi-member constituencies in what is referred to as an exhaustive counting system.
Plurality electoral systems tend to encourage the growth of relatively stable political systems dominated by two major parties (a phenomenon known as “Duverger’s Law”). Such an electoral system, though, does not represent the interests of all (or even most) voters. In fact, since a candidate need have only a plurality of votes to be elected, most voters may actually have voted against the winner.
Single Round Plurality Voting: With a single round, citizens only get to vote once, for only one candidate. Two Rounds Plurality Voting: In order to compensate for the single round voting drawbacks, a second round has been devised in some places to give small parties a better chance to have their voice heard.
Since all the candidates compete with each other and the voters only have one vote, it makes sense for the political parties to put forward only one candidate, to increase their chance of being elected. An inner-party primary election is however only a tactical necessity in Plurality Voting. Using other election methods, the primary would be an unnecessary step.
Since the early 1990s the trend has been away from plurality systems and toward proportional systems although in population terms SMP (single member plurality - candidate with most votes win) remains the most commonly used system. Some countries like New Zealand have, since the 1990s, replaced SMP by a mixed system of proportional representation and plurality systems.
The first-past-the-post system is widely seen to be unfair and many attempts have been made to improve or replace it in countries where it is in use. However, the system does have a number of advantages. First it provides for a direct relationship between the member of the legislature and the local constituency; second, there can be a degree of local control over the party's choice of candidate and parties must take some account of the constituency's wishes when selecting a candidate; third, the system elects the candidate who receives the largest number of votes; fourth, the system is straightforward and easy to understand; fifth, the system allows electors to directly choose the government; sixth, there is less opportunity for minority parties to be given power disproportionate to their electoral support; seventh, there is less likelihood of a proliferation of minor parties which may make the formation of stable governments difficult.
Plurality electoral systems are most commonly associated with single-member districts and "first past the post" allocation rules. The use of single-member districts creates a strong link between representatives and their constituencies. A few plurality systems use multimember districts and different rules for allocating seats in the legislature.
The plurality electoral system is the oldest and the most frequently used voting system. It is used for legislative elections in the United States and India, the world's two largest liberal democracies, as well as the United Kingdom and many former British colonies. Because of their tendency to produce a disproportionately large number of seats for the majority party, plurality systems usually produce strong single-party governments which produces a stable political system because there is no need to form coalition governments.
It is used in Britain, Canada, India, the USA, and other countries associated with British colonialism. It is also known as the (single ballot, single member) simple plurality electoral system. Sometimes it is referred to as a majoritarian or as the simple majority system, which is misleading since a candidate only has to win a plurality (i.e. the most votes), not a majority.
Electoral process in which the candidate who polls more votes than any other candidate is elected. It is distinguished from the majority system, in which, to win, a candidate must receive more votes than all other candidates combined. Election by a plurality is the most common method of selecting candidates for public office.
Duverger’s law suggests that when voters learn that plurality elections give an advantage to the major
parties, they tend to concentrate their votes on the two largest parties. The disproportional seat allocation and the tendency to vote for the largest parties are referred to as ‘the mechanical and the psychological effect of
plurality systems’ (Duverger 1964).