First-past-the-post voting

In a first-past-the-post (FPTP or FPP; sometimes formally called single-member plurality voting or SMP) electoral system, voters cast their vote for a candidate of their choice, and the candidate who receives the most votes wins (irrespective of vote share). FPTP is a plurality voting method, and is primarily used in systems that use single-member electoral divisions. FPTP is used as the primary form of allocating seats for legislative elections in about a third of the world's countries, mostly in the English-speaking world.
Many countries use FPTP alongside proportional representation, for example, in a parallel voting system or as part of a mixed-member proportional representation system. In some countries that elect their legislatures by proportional representation, FPTP is used to elect their head of state.
FPTP can be used for single- and multiple-member electoral divisions. In a single-member election, the candidate with the highest number (but not necessarily a majority) of votes is elected. In a multiple-member election (or multiple-selection ballot), each voter casts (up to) the same number of votes as there are positions to be filled, and those elected are the highest-placed candidates corresponding to that number of positions. For example, if there are three vacancies, then voters cast up to three votes and the three candidates with the greatest number of votes are elected.
The multiple-round election (runoff) voting method uses the FPTP voting method in each of two rounds. The first round, held according to block voting rules, determines which candidates may progress to the second and final round.
Illustration.
Under a first-past-the-post voting method, the highest polling candidate is elected. In this real-life illustration from the 2011 Singaporean presidential election, presidential candidate Tony Tan obtained a greater number of votes than any of the other candidates. Therefore, he was declared the winner, although the second-placed candidate had an inferior margin of only 0.35% and a majority of voters (64.8%) did not vote for Tony Tan:
Effects.
The effect of a system based on plurality voting spread over a number of separate districts is that the larger parties, and parties with more geographically concentrated support, gain a disproportionately large share of seats, while smaller parties with more evenly distributed support gain a disproportionately small share. It is more likely that a single party will hold a majority of legislative seats. In the United Kingdom, 19 of the 24 general elections since 1922 have produced a single-party majority government; for example, the 2005 general election results were as follows:
In this example, Labour took a majority of the seats with only 36% of the vote. The largest "two" parties took 69% of the vote and 88% of the seats. In contrast, the Liberal Democrats took more than 20% of the vote but only about 10% of the seats.
FPTP wastes fewer votes when it is used in two-party contests.
Waste of votes and minority governments are more likely when large groups of voters vote for three, four or more parties as in Canadian elections. Canada uses FPTP and only two of the last six federal Canadian elections produced single-party majority governments.
Advantages.
Supporters of FPTP argue that its concept is easy to understand, and ballots can more easily be counted and processed than those in preferential voting systems. 
FPTP often produces governments which have legislative voting majorities, thus providing such governments the legislative power necessary to implement their electoral manifesto commitments during their term in office. This may be beneficial for the country in question in circumstances where the government's legislative agenda has broad public support (albeit potentially divided across party lines), or at least benefits society as a whole. However handing a legislative voting majority to a government which lacks popular support can be problematic where said government's policies favour only that fraction of the electorate that supported it (particularly if the electorate divides on tribal, religious or urban/rural lines).
Supporters of FPTP also argue that the use of proportional representation (PR) may enable smaller parties to become decisive in the country's legislature and gain leverage they wouldn't otherwise enjoy (although this can be somewhat mitigated by a large enough electoral threshold). They argue that FPTP generally reduces this possibility, except where parties have a strong regional basis. A journalist at "Haaretz" noted that Israel's highly proportional Knesset "affords great power to relatively small parties, forcing the government to give in to political blackmail and to reach compromises;" Tony Blair, defending FPTP, argued that other systems give small parties the balance of power, and influence disproportionate to their votes. 
Allowing people into parliament who did not finish first in their district was described by David Cameron as creating a "Parliament full of second-choices who no one really wanted but didn't really object to either." Winston Churchill criticized the alternative vote system as "determined by the most worthless votes given for the most worthless candidates."
Disadvantages.
Unrepresentative.
First past the post is most often criticized for its failure to reflect the popular vote in the number of parliamentary/legislative seats awarded to competing parties. Critics argue that a fundamental requirement of an election system is to accurately represent the views of voters, but FPTP often fails in this respect. It often creates "false majorities" by over-representing larger parties (giving a majority of the parliamentary/legislative seats to a party that did not receive a majority of the votes) while under-representing smaller ones. The diagram here, summarizing Canada's 2015 federal election, demonstrates how FPTP can misrepresent the popular vote.
Majority reversals.
A party that nationally wins the most votes is not certain it will win a plurality of seats. Famous examples of the second placed party (in votes nationally) winning a majority of seats include the elections in Canada in 2019, in Ghana in 2012, in New Zealand in 1978 and in 1981 and in the United Kingdom in 1951.
Even when a party wins more than half the votes in an almost purely two-party-competition, it is possible for the runner-up to win a majority of seats. This happened in Saint Vincent and the Grenadines in 1966, 1998 and 2020 and in Belize in 1993.
This need not be a result of malapportionment. Even if all seats represent the same number of votes, the second placed party (in votes nationally) can win a majority of seats by efficient vote distribution. Winning seats narrowly and losing elsewhere by big margins is more efficient than winning seats by big margins and losing elsewhere narrowly. For a majority in seats, it is enough to win a plurality of votes in a majority of constituencies. Even with only two parties and equal constituencies, this means just over a quarter of the votes of the whole.
Geographical problems.
Geographical favouritism.
Generally FPTP favours parties who can concentrate their vote into certain voting districts (or in a wider sense in specific geographic areas). This is because in doing this they win many seats and don't 'waste' many votes in other areas.
The British Electoral Reform Society (ERS) says that regional parties benefit from this system. "With a geographical base, parties that are small UK-wide can still do very well".
On the other hand, minor parties that do not concentrate their vote usually end up getting a much lower proportion of seats than votes, as they lose most of the seats they contest and 'waste' most of their votes.
The ERS also says that in FPTP elections using many separate districts "small parties without a geographical base find it hard to win seats".
Make Votes Matter said that in the 2017 UK general election, "the Green Party, Liberal Democrats and UKIP (minor, non-regional parties) received 11% of votes between them, yet they "shared" just 2% of seats", and in the 2015 UK general election, "[t]he same three parties received almost a quarter of all the votes cast, yet these parties "shared" just 1.5% of seats."
According to Make Votes Matter, and shown in the chart below, in the 2015 UK general election UKIP came in third in terms of number of votes (3.9 million/12.6%), but gained only one seat in Parliament, resulting in one seat per 3.9 million votes. The Conservatives on the other hand received one seat per 34,000 votes.
Distorted geographical representation.
The winner-takes-all nature of FPTP leads to distorted patterns of representation, since it exaggerates the correlation between party support and geography.
For example, in the UK the Conservative Party represents most of the rural seats in England, and most of the south of England, while the Labour Party represents most of the English cities and most of the north of England. This pattern hides the large number of votes for the non-dominant party. Parties can find themselves without elected politicians in significant parts of the country, heightening feelings of regionalism. Party supporters (who may nevertheless be a significant minority) in those sections of the country are unrepresented.
In the 2019 Canadian election Conservatives won 98 percent of the seats in Alberta/Saskatchewan with only 68 percent of the vote. All but Conservatives are pretty much unrepresented; the general appearance is that all residents of those two provinces are Conservative, which is an exaggeration.
Tactical voting.
To a greater extent than many others, the first-past-the-post method encourages "tactical voting". Voters have an incentive to vote for a candidate who they predict is more likely to win, as opposed to their preferred candidate who may be unlikely to win and for whom a vote could be considered as wasted.
The position is sometimes summarised, in an extreme form, as "all votes for anyone other than the runner-up are votes for the winner." This is because votes for these other candidates deny potential support from the second-placed candidate, who might otherwise have won. Following the extremely close 2000 U.S. presidential election, some supporters of Democratic candidate Al Gore believed one reason he lost to Republican George W. Bush is that a portion of the electorate (2.7%) voted for Ralph Nader of the Green Party, and exit polls indicated that more of them would have preferred Gore (45%) to Bush (27%). This election was ultimately determined by the results from Florida, where Bush prevailed over Gore by a margin of only 537 votes (0.009%), which was far exceeded by the 97488 (1.635%) votes cast for Nader in that state.
In Puerto Rico, there has been a tendency for Independentista voters to support Populares candidates. This phenomenon is responsible for some Popular victories, even though the Estadistas have the most voters on the island, and is so widely recognised that Puerto Ricans sometimes call the Independentistas who vote for the Populares "melons", because that fruit is green on the outside but red on the inside (in reference to the party colors).
Because voters have to predict who the top two candidates will be, results can be significantly distorted:
Proponents of other voting methods in single-member districts argue that these would reduce the need for tactical voting and reduce the spoiler effect. Examples include preferential voting systems, such as instant runoff voting, as well as the two-round system of runoffs and less tested methods such as approval voting and Condorcet methods.
Effect on political parties.
Duverger's law is an idea in political science which says that constituencies that use first-past-the-post methods will lead to two-party systems, given enough time. Economist Jeffrey Sachs explains:
However, most countries with first-past-the-post elections have multiparty legislatures, the United States being the major exception.
There is a counter-argument to Duverger's Law, that while on the national level a plurality system may encourage two parties, in the individual constituencies supermajorities will lead to the vote fracturing.
It has been suggested that the distortions in geographical representation provide incentives for parties to ignore the interests of areas in which they are too weak to stand much chance of gaining representation, leading to governments that do not govern in the national interest. Further, during election campaigns the campaigning activity of parties tends to focus on marginal seats where there is a prospect of a change in representation, leaving safer areas excluded from participation in an active campaign. Political parties operate by targeting districts, directing their activists and policy proposals toward those areas considered to be marginal, where each additional vote has more value.
Wasted votes.
Wasted votes are seen as those cast for losing candidates, and 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. On this basis a large majority of votes may play no part in determining the outcome. This winner-takes-all system may be one of the reasons why "voter participation tends to be lower in countries with FPTP than elsewhere."
Gerrymandering.
Because FPTP permits many wasted votes, an election under FPTP is more easily gerrymandered. Through gerrymandering, electoral areas are designed deliberately to unfairly increase the number of seats won by one party by redrawing the map such that one party has a small number of districts in which it has an overwhelming majority of votes (whether due to policy, demographics which tend to favour one party, or other reasons), and many districts where it is at a smaller disadvantage.
Manipulation charges.
The presence of spoilers often gives rise to suspicions that manipulation of the slate has taken place. A spoiler may have received incentives to run. A spoiler may also drop out at the last moment, inducing charges that dropping out had been intended from the beginning.
Smaller parties may reduce the success of the largest similar party.
Under first-past-the-post, a small party may draw votes and seats away from a larger party that it is "more" similar to, and therefore give an advantage to one it is "less" similar to.
Safe seats.
First-past-the-post within geographical areas tends to deliver (particularly to larger parties) a significant number of safe seats, where a representative is sheltered from any but the most dramatic change in voting behaviour. In the UK, the Electoral Reform Society estimates that more than half the seats can be considered as safe. It has been claimed that members involved in the 2009 expenses scandal were significantly more likely to hold a safe seat.
However, other voting systems, notably the party-list system, can also create politicians who are relatively immune from electoral pressure.
May abet extreme politics.
The Constitution Society published a report in April 2019 stating that, "[in certain circumstances] FPTP can ... abet extreme politics, since should a radical faction gain control of one of the major political parties, FPTP works to preserve that party's position. ...This is because the psychological effect of the plurality system disincentivises a major party's supporters from voting for a minor party in protest at its policies, since to do so would likely only help the major party's main rival. Rather than curtailing extreme voices, FPTP today empowers the (relatively) extreme voices of the Labour and Conservative party memberships."
Electoral reform campaigners have argued that the use of FPTP in South Africa was a contributory factor in the country adopting the apartheid system after the 1948 general election in that country.
Suppression of political diversity.
According to the political pressure group Make Votes Matter, FPTP creates a powerful electoral incentive for large parties to all target similar segments of voters with similar policies. The effect of this reduces political diversity in a country because the larger parties are incentivised to coalesce around similar policies. The ACE Electoral Knowledge Network describes India's use of FPTP as a "legacy of British colonialism".
Likelihood of involvement in war.
Leblang and Chan found that a country's electoral system is the most important predictor of a country's involvement in war, according to three different measures: (1) when a country was the first to enter a war; (2) when it joined a multinational coalition in an ongoing war; and (3) how long it stayed in a war after becoming a party to it.
When the people are fairly represented in parliament, more of those groups who may object to any potential war have access to the political power necessary to prevent it. In a proportional democracy, war - and other major decisions - generally requires the consent of the majority.
The British human rights campaigner Peter Tatchell, and others, have argued that Britain entered the Iraq War primarily because of the political effects of FPTP and that proportional representation would have prevented Britain's involvement in the war.
Campaigns to replace FPTP.
Many countries which use FPTP have active campaigns to switch to proportional representation (e.g. UK and Canada). Most modern democracies use forms of proportional representation (PR). In the case of the UK, the campaign to scrap FPTP has been ongoing since at least the 1970s. However, in both these countries, reform campaigners face the obstacle of large incumbent parties who control the legislature and who are incentivised to resist any attempts to replace the FPTP system that elected them on a minority vote this is summed up by the idiom "turkeys don't vote for Christmas".
In the UK, the campaign to scrap FPTP is further complicated by the laws regarding state funding of political parties (including short money rules). The Labour Party, for example, receives significant funds from the UK state by virtue of it retaining its status as the Official Opposition party: in the 2018/19 financial year, the Labour Party received £7.88m, equivalent to 79% of total state funding, despite receiving only 40% of the popular vote in the prior general election. Under proportional representation, Labour's status as the Official Opposition party would potentially be vulnerable, and therefore its level of state funding would also be at risk, thus providing a financial incentive for Labour to retain FPTP. However, the Conservative Party benefits considerably from the same effect when in Opposition.
Voting method criteria.
Scholars rate voting methods using mathematically derived voting method criteria, which describe desirable features of a method. No ranked preference method can meet all the criteria, because some of them are mutually exclusive, as shown by results such as Arrow's impossibility theorem and the Gibbard–Satterthwaite theorem.
Majority criterion.
The majority criterion states that "if one candidate is preferred by a majority (more than 50%) of voters, then that candidate must win". First-past-the-post meets this criterion (though not the converse: a candidate does not need 50% of the votes in order to win). Although the criterion is met for each constituency vote, it is not met when adding up the total votes for a winning party in a parliament.
Mutual majority criterion.
The mutual majority criterion states that "if a majority (more than 50%) of voters top-rank some k candidates, then one of those k candidates must win". First-past-the-post does not meet this criterion.
Condorcet winner criterion.
The Condorcet winner criterion states that "if a candidate would win a head-to-head competition against every other candidate, then that candidate must win the overall election". First-past-the-post does not meet this criterion.
Condorcet loser criterion.
The Condorcet loser criterion states that "if a candidate would lose a head-to-head competition against every other candidate, then that candidate must not win the overall election". First-past-the-post does not meet this criterion.
Independence of irrelevant alternatives criterion.
The independence of irrelevant alternatives criterion states that "the election outcome remains the same even if a candidate who cannot win decides to run." First-past-the-post does not meet this criterion.
Independence of clones criterion.
The independence of clones criterion states that "the election outcome remains the same even if an identical candidate who is equally-preferred decides to run." First-past-the-post does not meet this criterion.
List of current FPTP countries.
The following is a list of countries currently following the first-past-the-post voting system for their national legislatures.
Prior to the 2020 election, the US states of Alaska and Maine completely abandoned FPTP in favor of ranked-choice voting or RCV. In the US, 48 of the 50 states and the District of Columbia use FPTP to choose the electors of the Electoral College (which in turn elects the president); Maine and Nebraska use a variation where the electoral vote of each congressional district is awarded by FPTP, and the statewide winner is awarded an additional two electoral votes. In states that employ FPTP, the presidential candidate gaining the greatest number of votes wins all the state's available electors (seats), regardless of the number or share of votes won, or the difference separating the leading candidate and the first runner-up.