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{{Wikipedia}}
 
In all non-dictatorial [[electoral system]]s, some form of '''tactical voting''' (or '''strategic voting''') occurs when a voter misrepresents their ''sincere preferences'' in order to gain a more favorable outcome. Any minimally useful voting system has some form of tactical voting, as shown by the [[Arrow's theorem]], [[Gibbard's theorem]], and the [[Gibbard-Satterthwaite theorem]]. However, the type of tactical voting and the extent to which it affects the timbre of the campaign and the results of the election vary dramatically from one voting system to another.
 
== Types of tactical voting ==
 
There are different types of tactical voting. Many of these can be summarized as involving "order-reversal" (you indicate you prefer Y over X though you prefer X to Y). Note that most ranked methods can incentivize order-reversal (though to varying degrees), while [[Scorescore voting]] doesn'tdoes so only very rarely. Avoiding order-reversal is rather weak, as a voter indicating they prefer all candidates equally would not be order-reversing; yet the fact that sono many[[ordinal voting]] methodsmethod can't even meet this test is seen as a huge argument against them by [[Cardinal method|cardinal]] advocates.
 
=== Compromising ===
'''Compromising''' (sometimes '''favorite-burying''' or '''useful vote''') is a type of tactical voting in which a voter insincerely ranks or rates an alternative higher (more generally, increases their support for that alternative) in the hope of getting it elected. For example, in the [[first-past-the-post election system|first-past-the-post]] election, a voter may vote for an option they perceive as having a greater chance of winning over an option they prefer (e.g., a left-wing voter voting for a popular moderate candidate over an unpopular leftist candidate). [[Duverger's law]] suggests that, for this reason, first-past-the-post election systems will lead to two party systems in most cases.
 
'''Compromising-compression''' is a compromising strategy that involves insincerely giving two candidates an equal ranking (or equal rating). '''Compromising-reversal''' is a compromising strategy that involves insincerely reversing the order of two candidates on the ballot.
'''Compromising-reversal''' is a compromising strategy that involves insincerely reversing the order of two candidates on the ballot.
 
A simple example with [[Approvalapproval voting]] using [[Approval threshold|approval thresholds]]: <blockquote>30 A| >B>C
 
20 B| >A>C
 
31 C| >A=B </blockquote>C has the most approvals (31), but if A-top voters decide to also approve B (vote A>B| >C), then they can make B win instead with 50 approvals, a result that they prefer. <blockquote>1 A>B>C
 
1 B>C>A
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=== Burying ===
'''Burying''' is a type of tactical voting in which a voter insincerely ranks (or rates) an alternative lower in the hopes of defeating it. For example, in the [[Borda count]], a voter may insincerely rank a perceived strong alternative last in order to help their preferred alternative beat it. A real-world analogy would be voters of one party crossing over to vote in the other party's [[primary election|primary]] against the candidate they think might beat the candidate of their party.
 
'''Burying-compression''' is a burying strategy that involves insincerely giving two candidates an equal ranking or rating (or truncating, which generally amounts to the same thing).
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There are two types of strategies referred to as '''pushover''':
 
* A narrow type, which involves encouraging voters to rank (or score) a candidate (called "B" in this example) lower than another candidate (called "A" in this example) in hopes that "B" is elected. This strategy won't work in systems that pass the [[mono-raise criterion]].
* A broader type (also known as '''turkey-raising''' or the '''pied-piper strategy''') which can happen in two-round systems.<ref>{{Cite news |last=Linskey |first=Annie |date=2022-09-13 |title=Democrats spend tens of millions amplifying far-right candidates in nine states |language=en-US |work=Washington Post |url=https://www.washingtonpost.com/politics/2022/09/12/democrats-interfere-republican-primaries/ |access-date=2023-10-02 |issn=0190-8286}}</ref><ref>{{Cite web |last=Norton |first=Ben |date=2016-11-10 |title=How the Hillary Clinton campaign deliberately "elevated" Donald Trump with its "pied piper" strategy |url=https://www.salon.com/2016/11/09/the-hillary-clinton-campaign-intentionally-created-donald-trump-with-its-pied-piper-strategy/ |access-date=2023-10-02 |website=Salon |language=en}}</ref> This broader type requires three candidates to explain: "A", "B" and "X". Let's say that voters are asked to choose (in the first round of an election) between "B" and "X". Voters who prefer "A" in the second round of the election may hope to have other voters vote for "the turkey" (candidate "X") who cannot beat "A", rather than see candidate "B" advance to the second round of the election, and may vote for "X" over "B" if they are allowed.<ref>{{Cite web |title=[EM] St. Louis and Pushover (Re: Reply to Rob regarding RCV) |last=Munsterhjelm|first=Kristofer|url=http://lists.electorama.com/pipermail/election-methods-electorama.com/2023-October/004961.html |access-date=2023-10-02 |website=lists.electorama.com}}</ref>
 
=== Free Riding ===
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It's important to differentiate between ''coordinated'' strategy, and ''uncoordinated'' strategy, as well as informed strategy vs. uninformed strategy.
 
For example, [[Approvalapproval voting]] and [[Scorescore voting]] guarantee that at least half of the voters can force their preferred candidates to tie or win, and force their dispreferred candidates to tie or lose (meaning they pass a weak form of [[mutual majority]]). However, this crucially hinges on these half of the voters of voters knowing a) that they all prefer those candidates, and b) that they all plan to use the strategy. Otherwise, those who attempt the strategy may either fail to support all of the candidates supported by the group of voters, resulting in the strategy not always working, or they may do it while not everyone else in the group does, which potentially weakens their own vote's ability to influence who wins among the candidates not maximally preferred by that half of the voters. So strategy comes in difficulty levels of execution.
 
== Strategy-free voting methods ==
 
It has been shown by the [[Gibbard-Satterthwaite theorem]] that it is impossible for a voting method to be both strategy-free and deterministic (that is, select the same outcome every time it is applied to the same set of ballots). The [[Random Ballot]] voting method, which selects the ballot of a random voter and uses this to determine the outcome, is strategy-free, but may result in different choices being selected if applied multiple times to the same set of ballots.
 
However, the extent to which tactical voting affects the timbre and results of the campaign varies dramatically from system to system: see below.
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== Examples in real elections ==
 
In [[United Kingdom]] elections, there are three main parties represented in the Parliament: the [[British Labour Party|Labour party]], the [[Conservative Party (UK)|Conservative party]] and the [[Liberal Democrats (UK)|Liberal Democrats]]. Of these three, Labour and the Liberal Democrats are most similar. Many people who prefer the Liberal Democrats vote for the Labour candidate where Labour is stronger and vice-versa where the Liberal Democrats are stronger, in order to prevent the Conservative candidate from winning.
Of these three, Labour and the Liberal Democrats are most similar. Many people who prefer the Liberal Democrats vote for the Labour candidate
where Labour is stronger and vice-versa where the Liberal Democrats are stronger, in order to prevent the Conservative candidate from winning.
 
In 2010, Liberal and Conservative governments shared the vote of the UK voters creating a hung government, it was decided that Conservatives and Liberal Democrats will perform as a power-sharing government. However this was not the first time the country has been run in a similar fashion as Liberal and Conservative governments alternated in power until World War I and Labour formed two short-lived minority governments in 1923-24 and 1929-31.
 
In the 1997 UK General Election, the [[Democratic Left (United Kingdom)|Democratic Left]] organised GROT - Get Rid Of Them - a tactical voter campaign. In 2001, the Democratic Left's successor organisation the [[New Politics Network]] organised a similar campaign [http://www.tacticalvoter.net tacticalvoter.net]. Since then tactical voting has become a real consideration in British politics as is reflected in by-elections and by the growth in sites such as www.tacticalvoting.com who encourage tactical voting as a way of defusing the two party system and empowering the individual voter.
 
== Rational voter model ==
 
Academic analysis of tactical voting is based on the rational voter model, derived from [[w:rational choice theory]]. In this model, voters are ''short-term instrumentally rational''. That is, voters are only voting in order to make an impact on one election at a time (not, say, to build the political party for next election); voters have a set of sincere preferences, or utility rankings, by which to rate candidates; voters have some knowledge of each other's preferences; and voters understand how best to use tactical voting to their advantage. The extent to which this model resembles real-life elections is the subject of considerable academic debate.
 
=== Predisposition to sincerity ===
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Blais and Nadeau use a two-step analysis procedure to argue that 30% of the voters who would have benefited from strategic voting in the 1988 Canadian election actually did vote strategically.<ref name="Blais Nadeau 1996 pp. 39–52">{{cite journal | last=Blais | first=André | last2=Nadeau | first2=Richard | title=Measuring strategic voting: A two-step procedure | journal=Electoral Studies | publisher=Elsevier BV | volume=15 | issue=1 | year=1996 | issn=0261-3794 | doi=10.1016/0261-3794(94)00014-x | pages=39–52}}</ref> They furthermore reason that tactical voting is more prevalent if the voters have only a weak intensity of preference for their first choice over their second, or if the election is a close race between their second and third choice.
 
However, the dominance of the two major parties in the United States (typically pulling well over 90% of the vote) suggest this predisposition can be overwhelmed when the incentives for strategy become too large.
 
=== Myerson-Weber strategy ===
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The model assumes that the voter's utility depends only on who wins, not (for instance) whether a losing candidate the voter supports is seen to have put up a good fight.
 
For a [[weighted positionalpoint-summing system]], the strategy can be formally described as follows. Let there be ''k'' candidates and define
 
: ''v''<sub>''i''</sub> = the number of points to be voted for candidate ''i''
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== Pre-election influence ==
 
Because tactical voting relies heavily on voters' perception of how other voters intend to vote, campaigns in electoral systems that promote compromise frequently focus on affecting voters' perception of campaign viability. Most campaigns craft refined media strategies to shape the way voters see their candidacy. During this phase, there can be an analogous effect where campaign donors and activists may decide whether or not to support candidates tactically with their money and labor.
 
In [[rolling election]]s, or [[runoff voting|runoff votes]], where some voters have information about previous voters' preferences (e.g. presidential [[primary election|primaries]] in the [[United States]], [[France|French]] presidential elections), candidates put disproportionate resources into competing strongly in the first few stages, because those stages affect the reaction of latter stages.
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Some people view tactical voting as providing misleading information. In this view, a ballot paper is asking the question "which of these candidates is the best?". This means that if one votes for a candidate who one does not believe is the best, then one is lying. Labour Party politician [[Anne Begg]] considers tactical voting dangerous: [http://news.bbc.co.uk/1/hi/uk_politics/1091208.stm]
 
: "Tactical voting is fine in theory and as an intellectual discussion in the drawing room or living rooms around the country, but when you actually get to polling day and you have to vote against your principles, then it is much harder to do".
 
While most agree that tactical voting is generally a problem, there are some cases when a strictly limited amount of it may bring about an more democratic result. Since the [[Gibbard-Satterthwaite theorem]] shows that all systems are vulnerable to tactical voting it become a question of which kinds of tactical voting are encouraged by each system more than the existence of it at all. For [[Rankedranked voting]] systems, [[Arrow's impossibility theorem]] proves that any voting system is arguably undemocratic in at least some case. However, tactical voting may be used to mitigate the issues of such systems. For instance, under purely honest voting, [[Condorcet method]]-like systems tend to settle on consensus candidates, while [[Instant-Runoff Voting]] favors those candidates which have a stronger polarizing faction - who may often be more fringe in beliefs. An electorate using one of these two systems but which (in the general or the specific case) preferred the characteristics of the other system could consciously use strategy to achieve a result more characteristic of the other system. Under Condorcet, they may be able to win by "burying" the consensus candidate (although this risks throwing the election to the opposing faction); while under IRV, they could always compromise and vote for the consensus above their true favorite.
 
The problem is that such tactical voting would tend to overshoot and give undesired results. This greatly complicates the comparative analysis of voting systems. If tactical voting were to become significant, the perceived "advantages" of a given voting system could turn into disadvantages - and, more surprisingly, vice versa.
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Finally, any voting system that relies on a particular strategy to produce good results can be replaced by another voting system that executes that strategy on behalf of the voters - a so-called declared strategy voting method. This is a consequence of the [[w:revelation principle]]. It is thus not possible to get around impossibility results by relying on tactical voting.
 
== Definitions ==▼
== Tactical voting in particular systems ==▼
{{seealso|Bullet voting}}▼
}}
 
'''Frontrunner/viable candidate''': A candidate expected to have a significant chance of winning.▼
[[Steven Brams]] and [[Dudley R. Herschbach]] argued in a paper in ''[[Science (journal)|Science]]'' magazine in [[2000]] that [[approval voting]] was the system least amenable to tactical perturbations. This may be related to the fact that approval voting does not permit preferences ('likes' or 'dislikes') to be stated at all, permitting only a statement of [[tolerances versus preferences|tolerances]], that is, "which candidate could you stand to see win", as opposed to "which candidate would you ''like'' to see win".▼
 
'''Truncation:''' When a voter doesn't show support for some of their less-preferred candidates (i.e. an A>B>C voter truncates and only votes A>B or A).▼
Due to the especially deep impact of tactical voting in [[first past the post]] electoral systems, some argue that systems with three or more strong or persistent parties become in effect forms of [[disapproval voting]], where the expression of disapproval, to keep an opponent out of office overwhelms the expression of approval, to approve a desirable candidate. [[Ralph Nader]] refers to this as the "least worst" choice, and argues that the similarity of parties and the candidates grows stronger due to the need to avoid this disapproval.▼
 
'''Bullet voting:''' When a voter only supports one candidate (usually defined as also maximally supporting them in [[rated method]]<nowiki/>s). It is a special case of truncation.▼
Some common terms:
 
'''Min-maxing:''' When a voter gives maximal support to some candidates (usually defined here as ranking or rating them all equally) and no support to all other candidates.▼
There are arguments about the best voting strategy to take in different systems, but the general consensus is:▼
 
▲== Tactical voting in particular systems ==
[[Approval voting]] and [[Score voting]]: Give the highest score to your favorite frontrunner and all candidates you prefer equally or more than that frontrunner, and the lowest score to all other candidates (known as the threshold strategy or min-max-ing i.e. giving some candidates the '''min'''imum score and others the '''max'''imum score).
 
▲[[Steven Brams]] and [[Dudley R. Herschbach]] argued in a paper in ''[[Science (journal)|Science]]'' magazine in [[2000]] that [[approval voting]] was the system least amenable to tactical perturbations. This may be related to the fact that approval voting does not permit preferences ('likes' or 'dislikes') to be stated at all, permitting only a statement of [[tolerances versus preferences|tolerances]], that is, "which candidate could you stand to see win", as opposed to "which candidate would you ''like'' to see win".
▲== Definitions ==
▲{{seealso|Bullet voting}}
▲'''Frontrunner/viable candidate''': A candidate expected to have a significant chance of winning.
 
▲Due to the especially deep impact of tactical voting in [[first past the post]] electoral systems, some argue that systems with three or more strong or persistent parties become in effect forms of [[disapproval voting]], where the expression of disapproval, to keep an opponent out of office overwhelms the expression of approval, to approve a desirable candidate. [[Ralph Nader]] refers to this as the "least worst" choice, and argues that the similarity of parties and the candidates grows stronger due to the need to avoid this disapproval.
▲'''Truncation:''' When a voter doesn't show support for some of their less-preferred candidates (i.e. an A>B>C voter truncates and only votes A>B or A).
 
▲There are arguments about the best voting strategy to take in different systems, but the general consensus is:
▲'''Bullet voting:''' When a voter only supports one candidate (usually defined as also maximally supporting them in [[rated method]]<nowiki/>s). It is a special case of truncation.
 
* [[Score voting]] (including approval): Give the highest score to all candidates better than the expected value of the winner (or better than the frontrunner, if you don't know the expected values). Give the lowest score to all the other candidates. This is known as the threshold strategy or min-max-ing.
▲'''Min-maxing:''' When a voter gives maximal support to some candidates (usually defined here as ranking or rating them all equally) and no support to all other candidates.
* Methods failing [[No Favorite Betrayal]]: Rank your favorite frontrunner first and your least-favorite frontrunner last.
 
== Notes ==
 
=== Voting for the lesser of two evils ===
{{seealso|Lesser of two evils}}
}}
Much voting strategy revolves around a voter deciding whether to back one of the frontrunners or not; this often reduces further to deciding which of 2 frontrunners to back, which results in essentially a [[head-to-head matchup]] between the two. This is often referred to as deciding whether to "vote for the lesser of two evils or waste your vote". One of the goals of voting reform is to allow voters to be able to be as sincere as possible in expressing their preference for nonviable candidates.
 
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