First Past the Post electoral system: Difference between revisions
Removed "winner-take-all" because that describes *all* single-member methods. Moved plurality voting to the top of the list because it is used more often than the others.
(Copying the current summary from w:First-past-the-post voting (oldid=927483757), and prepending it to this article. Will delete irrelevant portions next...) |
(Removed "winner-take-all" because that describes *all* single-member methods. Moved plurality voting to the top of the list because it is used more often than the others.) |
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{{Wikipedia|First-past-the-post voting}}A '''first-past-the-post''' ('''FPTP'''; sometimes '''FPP''')<ref>{{cite web|url=https://www.dia.govt.nz/diawebsite.nsf/wpg_URL/Resource-material-STV-Information-More-about-FPP?OpenDocument|title=More about FPP|author=The Department of Internal Affairs, Government of New Zealand|website=dia.govt.nz|language=en-NZ|access-date=2019-02-17}}</ref> [
First-past-the-post is often referred to with the following terms:
* '''plurality voting'''
* '''most votes wins'''
* '''relative majority'''
* '''choose-one voting'''
* '''single-member plurality (SMP)'''
The term "first past the post" is borrowed from the sport of [[wikipedia:horse racing|horse racing]].
== Background ==
{{see also|choose-one ballot}}
[[File:Muybridge_race_horse_animated.gif|thumb|The term "first past the post" comes from horse racing. The winner of a horse race is the horse whose nose (or other body part) crosses in front of the post before all of the other horse noses.]]
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.
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").▼
=== History ===
{{Wikipedia|horse racing}}
▲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 ==
{{Wikipedia|Plurality}}
{{main|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 system | regional systems]] for electing parliaments with [[Single-member district | Single-member districts]], and is practised in close to one third of countries. Notable examples include the [[w:United States|United States]], the [[w:United Kingdom|United Kingdom]], as well as some of the latter's former [[w:colony|colonies]] and [[w:protectorate|protectorate]]s, such as [[w:Canada|Canada]] or [[w:India|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 district | 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|Category:FPTP-based voting methods]].
== Criteria ==
In the single-winner context, Approval is almost a [[Pareto criterion|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 vote|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-efficient]][[Condorcet 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|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.
== Comparison ==
=== Notes ===
[[Cumulative voting]] is an extension of FPTP in the sense that it also restricts a voter to putting their maximal vote weight or support behind at most one candidate, but also allows a voter to distribute their vote weight to multiple candidates.
FPTP can be thought of as a [[Condorcet method]] where only a voter's 1st choice candidate among all candidates can receive votes in [[Head-to-head matchup|head-to-head matchups]]; in this formulation, the [[Smith set]] always contains the candidates who are tied for having the most votes.
Many voting reform advocates would prefer to replace FPTP with a [[Proportional representation]] voting method.
Note that [[Asset voting]] can be thought of as a way to modify FPTP to better reflect voters' wishes, because it allows voters who are unrepresented by the FPTP winner to form majority coalitions for their preferred candidate among the losers. In effect, instead of voters being forced to group behind only two candidates whatsoever, Asset allows voters to do this, and then if they dislike the winner of the top two, they can recombine behind other candidates in new [[Head-to-head matchup]]<nowiki/>s.
==References==
<references/>
{{fromwikipedia}}
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[[Category:Binary voting methods]]
[[Category:Single-mark ballot voting methods]]
[[Category:FPTP-based voting methods]]
[[Category:Monotonic electoral systems]]
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