This series is part of the Politics and the Election series
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.
The most common system, used in Canada, India, the UK, and the USA, is first past the post or winner-takes-all, a voting system in which a single winner is chosen in a given constituency by having the most votes, regardless of whether or not he or she has a majority of votes.
In some countries such as France a similar system is used, but there are two rounds: the "two-round" or "two-ballot" plurality system. The two highest-voted candidates of the first round compete in a two-candidate second round or all candidates above a certain threshold in the first round compete in a two-, three- or four-candidate second round. If one candidate has a majority of votes in the first round, there is no second round.
In political science, the use of the plurality voting system alongside multiple, single-winner constituencies to elect a multi-member body is often referred to as single-member district plurality or SMDP. Plurality voting is also variously referred to as winner-takes-all or relative/simple majority voting; however, these terms can also refer to elections for multiple winners in a particular constituency using bloc voting.
The famous works of Arend Lijphart use the term "majoritarian" systems, which is used almost synonymously with "plurality" systems.

Single member

• Plurality (first-past-the-post)
  Preferential systems
  
  
  
  • Satisfy Condorcet criterion
    
    
    
    • Condorcet method
      Copeland's method
      Kemeny-Young method
      Minimax Condorcet
      Nanson's method
      Ranked Pairs
      Schulze method
      Runoff voting
      
      
      
      • Bucklin voting
        Coombs' method
        Instant-runoff
        Two-round system
        Non-rank methods
        
        
        
        • Approval voting
          Range voting
          Multi-member
          
          
          
          • Proportional representation
            
            
            
            • Cumulative voting
              Mixed-member
              Party-list
              
              
              
              • D'Hondt method
                Highest averages method
                Largest remainder method
                Sainte-Laguë method
                Proportional approval voting
                Single transferable vote
                Semi-proportional representation
                
                
                
                • Cumulative voting
                  Parallel voting
                  Single non-transferable vote
                  Non-proportional multi-member representation
                  
                  
                  
                  • Bloc voting
                    Limited voting
                    Random Selection
                    
                    
                    
                    • Sortition Voting
                      Generally plurality ballots can be categorised into two forms. The simplest form is a blank ballot where the name of a candidate is written in by hand. A more structured ballot will list all the candidates and allow a mark to be made by a single candidate, however a structured ballot can also include space for a write-in candidate as well.
                      Plurality voting is based on minimal information — a person's vote can be entirely represented by a binary choice, so anything can be used to signify a vote — the ancient Greeks would vote on ostracising someone by scratching the name of the person to be ostracised on a piece of pottery. Votes cast as physical objects can also create a realistic display of the election results, such as an array of candidates with jars filled with differently coloured beans, with the winner being the most-filled.
                      
                      Ballot types
                      
                      Examples of plurality voting
                      The election of a Member of Parliament in the UK is a well known example of the First Past the Post electoral system. But the system is also used on a smaller scale.
                      
                      Simple example
                      For this example, consider the election for the president of a school class. Each class has a president, who sits on a school council. Further assume that, in this imaginary school, male and female students disagree with each other on most issues, and students prefer to vote for others of the same sex as themselves.
                      In our hypothetical election, there are three candidates: Amy, Brian and Cathy. Each class member gets a ballot, with these three names on it. Each voter must put an "X" by one of the names on their ballot.
                      After the election finishes, the papers are sorted into three piles--one for votes for Amy, one for votes for Brian, and one for votes for Cathy.
                      The largest pile decides the winner. If Amy's pile has 11 votes, Brian's has 16, and Cathy's has 13, Brian wins.
                      Notice that there were a total of 40 votes cast, and the winner had only 16 of them — only 40%.
                      Note that the class members (the "electors") only vote once, and their votes help to choose both a class president and a member of the school council (the same person).
                      
                      The election for class president
                      Suppose that all the other classes hold similar elections. Across all the classes, 8 of the class presidents that were elected were girls, and 9 were boys. That makes the boys the overall winner. The only influence that the pupils in this particular class had was to vote for Amy, Brian or Cathy to represent themselves.
                      Some might argue that a boy won for this class because there were two girls, who "split the vote": some of the girls in the class voted for Amy and others for Cathy. Perhaps if Amy had not been a candidate, all the girls would have voted for Cathy and she would have won this class; this in turn would make the girls the winners of the whole council. This is known as the spoiler effect.
                      
                      The election for school council
                      Imagine that the population of Tennessee, a state in the United States, is voting on the location of its capital. The population of Tennessee is concentrated around its four major cities, which are spread throughout the state. For this example, suppose that the entire electorate lives in these four cities, and that everyone wants to live as near the capital as possible.
                      The candidates for the capital are:
                      The preferences of the voters would be divided like this:
                      Voting is accomplished whereby each voter in each city selects one city on the ballot (Memphis voters select Memphis, Nashville voters select Nashville, etc.) Votes are tabulated; Memphis is selected with the most votes (42%). Note that this system does not require that the winner have a majority, but only a plurality. Memphis wins because it has the most votes, even though 58% of the voters in this example preferred Memphis least.
                      
                      Memphis, the state's largest city, with 42% of the voters, but located far from the other cities
                      Nashville, with 26% of the voters
                      Knoxville, with 17% of the voters
                      Chattanooga, with 15% of the voters
                      Memphis
                      Nashville
                      Chattanooga
                      Knoxville
                      Nashville
                      Chattanooga
                      Knoxville
                      Memphis
                      Chattanooga
                      Knoxville
                      Nashville
                      Memphis
                      Knoxville
                      Chattanooga
                      Nashville
                      Memphis More complex example
                      Plurality is often conflated with Single-winner voting systems in general, in order to contrast it with Proportional Representation. See the advantages there for other advantages of plurality in this context, such as regionalism and accountability.
                      
                      Advantages
                      Plurality may well be the simplest of all voting systems. This implies specific advantages. It is likely to be quicker, and easier to administer; this may also imply that an election costs less to run. It may also have an effect on voters, because it is easy to explain and understand. Alternative voting systems may alienate some voters who find the systems hard to understand, and who therefore feel detached from the direct effect of their own vote.
                      
                      Simplicity
                      The arguments for a plurality voting system rely heavily on the preservation of the "one person, one vote" principle (often shortened to OMOV for "one man, one vote" or more recently "one member, one vote"), as cited by the Supreme Court of the United States, wherein each voter is only able to cast one vote in a given election, where that vote can only go to one candidate. Plurality voting systems elect the candidate who is preferred first by the largest number of voters. Other voting systems, such as Instant-runoff voting or Single Transferable Vote also preserve OMOV, but rely on lower voter preference to arrive at a candidate earning either absolute majority or droop quota, respectively.
                      However, proponents of other systems, such as approval voting, point out that the OMOV principle was made to control the magnitude of districts; that each district must be relatively in proportion to one another in population. Approval voting does not actually represent some voters more than others, so the OMOV principle would be a weak one to discount it on. In any case, it could be argued approval voting grants one vote for each candidate to each voter - which they may choose not to cast, and cannot vote cumulate on one candidate.
                      
                      Preservation of One Person One Vote principle
                      See single-winner voting systems for other disadvantages commonly associated with plurality, such as diminished representation, sweepout and other skewed results, and "safe seats".
                      
                      Disadvantages
                      To a much greater extent than many other electoral methods, plurality electoral systems encourage tactical voting techniques, like "compromising". Voters are pressured to vote for one of the two candidates they predict are most likely to win, even if their true preference is neither, because a vote for any other candidate will be likely to be wasted and have no impact on the final result. This is known as Duverger's Law.
                      In the Tennessee example, if all the voters for Chattanooga and Knoxville had instead voted for Nashville, then Nashville would have won (with 58% of the vote); this would only have been the 3rd choice for those voters, but voting for their respective 1st choices (their own cities) actually results in their 4th choice (Memphis) being elected.
                      The difficulty is sometimes summed up, in an extreme form, as "All votes for anyone other than the second place are votes for the winner", because by voting for other candidates, they have denied those votes to the second place candidate who could have won had they received them. It is often claimed by United States Democrats that Democrat Al Gore lost the 2000 Presidential Election to Republican George W. Bush because some voters on the left voted for Ralph Nader of the Green Party, who presumably would have preferred Gore to Bush. Conversely, Republicans can claim that Ross Perot was a spoiler who enabled Bill Clinton to win the 1992 and 1996 presidential elections with a minority of the popular vote, because Perot had split the conservative vote, winning 8.4 percent of the vote, far better than Nader did, with less than 0.5 percent of the vote.
                      Such a mentality is reflected by elections in Puerto Rico and its three principal voter groups: the Independentistas (pro-independence), the Populares (pro-commonwealth), and the Estadistas (pro-statehood). Historically, there has been a tendency for Independentista voters to elect Popular candidates and policies. This phenomenon is responsible for some Popular victories, even though the Estadistas have the most voters on the island. It is so widely recognised that the Puertoricans sometimes call the Independentistas who vote for the Populares "melons", because the fruit is green on the outside but red on the inside (in reference to the party colours).
                      Because voters have to predict in advance who the top two candidates will be, this can cause significant perturbation to the system:
                      A feature of the FPTP system is that invariably, voters can select only one candidate in a single-member district, whilst in multi-member districts they can never select more candidates than the number of seats in the district. Some argue that FPTP would work better if electors could cast votes for as many candidates as they wish. This would allow voters to "vote against" a certain despised candidate if they choose, without being forced to guess who they should vote for to defeat that candidate, thus eliminating the need for tactical voting. Such a system would also serve to reduce the spoiler effect. This system is called approval voting.
                      
                      Substantial power is given to the media. 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 will know that other voters do believe the media, and therefore those candidates who receive the most media attention will nonetheless be the most popular and thus most likely to be in one of the top two.
                      A newly appointed candidate, who is in fact supported by the majority of voters, may be considered (due to the lack of a track record) to not be likely to become one of the top two candidates; thus, they will receive a reduced number of votes, which will then give them a reputation as a low poller in future elections, compounding the problem.
                      The system may promote votes against more so than votes for. In the UK, entire campaigns have been organised with the aim of voting against the Conservative party by voting for either Labour or Liberal Democrats based on which is most popular in each constituency, regardless of the voters' opinions of the policies of these parties.
                      If enough voters use this tactic, the first-past-the-post system becomes, effectively, runoff voting - a completely different system - where the first round is held in the court of public opinion. Tactical voting
                      Duverger's law is a principle of political science which predicts that constituencies that use first-past-the-post systems will become two-party systems, given enough time.
                      First-past-the-post tends to reduce the number of political parties to a greater extent than most other methods, thus making it more likely that a single party will hold a majority of legislative seats. (In the United Kingdom, 18 out of 22 General Elections since 1922 have produced a majority government.) Single party rule enables quicker decision-making with less need for back and forth negotiation; some argue that this is an advantage.
                      Multi-party coalitions, on the other hand, require consent among all coalition partners to pass legislation, which some argue gives small parties a disproportionate amount of power. In the UK, arguments for plurality often look to Italy where the frequent government changeovers are presented as undesirable. (This problem could be solved with separation of powers, in which the entire government didn't have to turn over just because it lost a vote.)
                      FPTP's tendency toward fewer parties and more frequent one-party rule can also produce disadvantages. One such disadvantage is that the government may not consider as wide a range of perspectives and concerns. It is entirely possible that a voter will find that all major parties agree on a particular issue. In this case, the voter will not have any meaningful way of expressing a dissenting opinion through his or her vote.
                      Another disadvantage is that fewer choices are offered to the voters, often pressuring voters to vote for a candidate with whom they largely disagree so as to oppose a candidate with whom they disagree even more (See tactical voting above); this feature pressures candidates to appeal to the extremes in order to avoid being undercut. This appeal-to-extremes operates by giving those voters who are more centrist no choice but to vote for them. The likely result of this is that candidates will less closely reflect the viewpoints of those who vote for them.
                      It may also be argued that one-party rule is more likely to lead to radical changes in government policy that are only favoured by a plurality or bare majority of the voters, whereas multi-party systems usually require greater consensus in order to make dramatic changes.
                      
                      Effect on political parties
                      Wasted votes are votes cast for losing candidates or votes cast for winning candidates in excess of the number required for victory. For example, in the UK General Election of 2005, 52% of votes were cast for losing candidates and 18% were excess votes - a total of 70% wasted votes. This is perhaps the most fundamental criticism of FPTP, that a large majority of votes may play no part in determining the outcome. Alternative electoral systems attempt to ensure that almost all votes are effective in influencing the result and the number of wasted votes is consequently minimised.
                      
                      Wasted votes
                      Smaller parties can disproportionately change the outcome of a FPTP election by swinging what is called the 50-50% balance of two party systems, by creating a faction within one or both ends of the political spectrum which shifts the winner of the election from an absolute majority outcome to a simple majority outcome favouring the previously less favoured party. In comparison, for electoral systems using proportional representation small groups win only their proportional share of representation. In the United States, this mechanism falls within one major reasoning (USA, Voting act, 1970s) favoring two-party, First-past-the-post (FPTP) electoral systems.
                      
                      Disproportionate influence of smaller parties
                      The United Kingdom continues to use the first-past-the-post electoral system for general elections, and for local government elections in England and Wales. Changes to the UK system have been proposed, and alternatives were examined by the Jenkins Commission in the late 1990s but no major changes have been implemented. Canada also uses this system for national and provincial elections. In May 2005 the Canadian province of British Columbia had a referendum on abolishing single-member district plurality in favour of multi-member districts with the Single Transferable Vote system after the Citizens' Assembly on Electoral Reform made a recommendation for the reform. The referendum obtained 57% of the vote, but failed to meet the 60% requirement for passing. The Canadian province of Ontario is in the midst of a referendum on a Mixed Member Proportional proposal, also requiring 60% approval; the referendum will take place Oct 10, 2007. See http://www.yourbigdecision.ca, established by Elections Ontario, for more information.
                      Wales, Scotland, Northern Ireland, the Republic of Ireland and Australia are notable examples of countries within the UK, or with previous links to it, that use non-FPTP electoral systems.
                      Recent examples of nations which have undergone democratic reforms but have not adopted the FPTP system include South Africa, almost all of the former Eastern bloc nations, Russia, Afghanistan and Iraq.
                      
                      Where plurality voting is used
                      
                      Cube rule
                      List of democracy and elections-related topics
                      Proportional representation
                      Runoff voting
                      Single non-transferable vote
                      Single transferable vote
                      Voting system