First Past the Post electoral system

A first-past-the-post (FPTP; sometimes FPP) electoral system is one in which voters indicate on a ballot the candidate of their choice (their 1st choice), and the candidate who receives the most votes wins.

First-past-the-post is often referred to with the following terms:


 * winner-take-all
 * most votes wins
 * plurality voting
 * relative majority
 * choose-one voting
 * single-member plurality (SMP)

The term "first past the post" is borrowed from the sport of horse racing.

Background


FPTP is generally done with a choose-one ballot. Note that the FPTP-relevant information can also be captured with a ranked ballot (by only looking at a voter's 1st choice candidate; if the voter has several first choices, it is recommended to split their vote equally between each of those candidates, similar to cumulative voting), or with a rated ballot (by identifying the candidates given the highest rating on the ballot as the voter's 1st choice(s)). By extension, runoff voting and other Category:FPTP-based voting methods can also be done using more expressive ballot types.

History
The term "first past the post" refers to a now seldom-used analogy with horse racing, where the winner is the first to pass a particular point (in this case a plurality of votes), upon which all other runners automatically and completely lose ("winner take all"). It is a useful term in advocacy opposed to it because the term "first" implies that there is some temporal aspect to who win when in fact the ballots all counted before a winner is determine.

Plurality
First-past-the-post elections only require winning candidates to receive a plurality of the total number of votes. FPTP is a common feature of regional systems for electing parliaments with  Single-member districts, and is practised in close to one third of countries. Notable examples include the United States, the United Kingdom, as well as some of the latter's former colonies and protectorates, such as Canada or India.

Activism around FPTP
Much electoral activism has centered around providing alternatives to FPTP voting.

As a multi-winner method
The system itself can directly be used as a multi-winner method when implemented as a Regional system with Single-member districts. In this scenario it is often referred to as single member plurality. However, there are extensions to Multi-Member Districts.

The two most common extentions to the multi-winner case are Single non-transferable vote and Plurality-at-large voting. An intermediate form is limited voting, which gives a voter the ability to choose fewer candidates than the number of seats to be filled, but usually lets voters pick more than one candidate. The general principle in any multi-winner extension of FPTP is that a voter can support at most as many candidates as there are seats to be filled.

While the single non-transferable vote is not in itself a proportional method, coordinated strategy by parties can make it behave like party list, which is proportional. However, the strategy needs to be carefully executed, and thus SNTV may encourage patron-client relationships in which a powerful legislator can apportion votes to his or her supporters.

Preferences
FPTP is notable among voting methods for offering a voter no way to express a preference for more than one candidate; see the ballot article for examples of other ballot types. It passes monotonicity, meaning that a candidate can never be hurt if voters vote for that candidate, which is a notable property. In terms of voter behavior, it has been widely observed that FPTP tends to result in elections with at most two sharply opposed major candidates. Duverger's law and the center squeeze effect offer insight into this; essentially, voters are encouraged to group up to ensure their candidate can get the most votes, yet this prevents some voters from supporting their favorite candidate. Runoff voting and Instant runoff voting are two voting methods highly based on FPTP-like principles; see Category:FPTP-based voting methods.

Criteria
In the single-winner context, Approval is almost a Pareto improvement (pun) over FPTP; it preserves its simplicity and good qualities while adding in others, such as passing Favorite Betrayal. In the multiwinner context, SNTV is more proportional than Bloc Approval voting, so a Cardinal PR method using Approval ballots may work better.

One of the biggest complaints against FPTP is that it has a spoiler effect. This is most easily visualized by observing that FPTP passes the majority criterion but not the mutual majority criterion:

26 A>B

25 B>A

49 C

C has the most 1st choices and wins here with 49 votes. Yet if one of A or B drops out, then the remaining candidate of the two will be a majority's 1st choice and thus win with 51 votes. IRV/RCV guarantees such scenarios don't occur, with ￼￼Smith-efficientCondorcet methods giving an even stronger guarantee: if C's voters had a preference between A or B, they'd have the power to ensure their preference between the majority's candidates wins. This is also an example of FPTP failing the majority loser criterion.

FPTP can be done by allowing each voter to cross out the names of all of the candidates they don't support. In this formulation, a voter must cross out all but one candidate's name or have their ballot thrown out. Approval voting is where a voter may cross out only as many names as they desire.