Instant-runoff voting controversies

Instant Runoff Voting (IRV) is the name commonly used in the United States for Preferential Voting. There are campaigns for IRV in a number of states and local jurisdictions in the U.S. which have been largely promoted and supported, in recent years, by a non-profit educational and advocacy organization called FairVote.

Opposition to this campaign can be classified into two broad categories:
#Those who prefer to maintain the status quo, which is generally Plurality voting, or two-round runoff elections.
#Those who prefer reforms other than Instant Runoff Voting.

The arguments of these two groups are different, and sometimes the same argument is used on both sides; for example, some IRV advocates claim that IRV will help third parties to gain a toehold and, if they can eventually muster majority support, to win elections. This argument has been summarized as "IRV will allow third parties to grow without being spoilers." In seeming agreement with this, some opponents of IRV argue that IRV will indeed damage the two-party system, which these critics consider important to American democracy.

On the other hand, critics of IRV who prefer other reformed methods have claimed that IRV will help preserve the two-party system, pointing to the countries that use single-winner STV, which have long maintained strong two-party systems with little exception. Further, some support for IRV comes from major-party supporters who want to eliminate the spoiler effect caused by vote-splitting, as with the Ralph Nader vote in Florida in the 2000 U.S. Presidential election, which presumably came largely from voters who would prefer Al Gore over George W. Bush, and which vote was more than enough to turn that election. These supporters of IRV expect that it will help maintain the two-party system by preventing spoiled elections.

Controversies over Instant Runoff Voting can be broken down into a series of specific issues. These may be defined by arguments being made, Pro or Con;

Arguments in favor of IRV and the debate over them
Pro: IRV allows one ballot to determine a majority winner

Rank ballots allow a runoff process to eliminate candidates without asking voters again for their top remaining choice. The process logically must ends in a majority winner (or a tie) when two final candidates remain.

It is possible for a winner to be chosen without a majority of the total ballots in some cases where enough voters have all their ranked candidates eliminated.

There are two sources of this failure of incomplete ranking:
# Some IRV implementations don't allow complete ranking, either due to voting machine limitations or other reasons; for example, in San Francisco, only three ranks are available on the ballot.
# Voters who don't rank enough of the candidates to express a preference between the final two candidates.

In both cases such ballots, with all choices eliminated, are considered exhausted and don't count for or against the winner.

In order to avoid this issue, some jurisdictions using IRV have required that voters rank all candidates, which, by definition, creates a majority winner, because ballots not ranking all candidates are eliminated, but this has not been proposed for the United States.

In comparison, a two round system (with a majority requirement) will always allow interested voters to participate in the runoff round. However, typically there is a significant drop-off in voter turnout in the second round and it is possible for the nominally majority winner to receive fewer votes than the loser received in the first round of voting.

Pro: IRV will eliminate the Spoiler effect

If a third party candidate draws sufficient votes away from what would otherwise be a majority winner, causing a candidate to win with only minority support, the election has been "spoiled."

Historically, IRV has reduced the spoiler effect, as in Ann Arbor, Michigan, where IRV was implemented by referendum and which then resulted in the election of the city's first African-American mayor, a Democrat. Prior to this, the mayor of Ann Arbor had been Republican, due to vote splitting between the Democratic Party and the Human Rights Party. A new referendum to rescind the reform was then placed on the ballot for a special election, with low turnout, which reversed the reform.

However, critics of IRV point out that there are other reforms which could also reduce the spoiler effect, including Condorcet methods, and the commonly used Runoff voting. Bucklin voting, as actually used for a time in some jurisdictions in the United States, did allow apparently sincere preferences to be expressed without spoiling elections.

Thus addressing the Spoiler effect is an argument for election reform, not necessarily specifically for Instant-runoff voting; which reform is most appropriate would depend upon other characteristics of the voting systems being considered.

Pro: IRV will encourage sincere voting

All election reforms known to be under serious consideration do encourage increased sincerity in voting, and there is no controversy over the necessity of compromise under Plurality voting.

IRV advocates can make a strong claim that it encourages sincere voting, particularly in a two-party system or other elections where there are only two strong candidates. In such conditions, sincere ranking at the top entails no risk and insincere ranking in lower ranks offers no incentive.

However when there is a strong third candidate, situations can arise where there is an incentive for a voter to abandon a favorite for a compromise who looks like a stronger competitor to win.

This compromise incentive occurs with all single-vote runoff (actual or "instant") methods because compromise candidates may be dropped before the final round. Voters who want to maximize their influence must consider two questions: "Whom would I prefer to win?" and "Who can win the final round?" and may find these differ.

Studying whether or not this incentive to compromise occurs in practice is difficult because IRV elections depend on individual ballot data. Complete ballot by ballot ranking data was made public following San Francisco, CA and Burlington, VT, IRV elections, which may allow for further analysis on this point.

Theoretical studies of the relative likelihood of election "pathologies" have been done, particularly through simulations; however, they have not been published in peer-reviewed journals or other reliable sources.

Based on the similarity in some respects between IRV and Runoff voting, though, there are election examples showing, most notably, failure to find the best compromise, and some elections in San Francisco have been won with only minority support expressed; in such a situation, it is possible that the winner would have lost in a direct contest with another candidate.

Other methods may be monotonic, i.e., raising a candidate in preference can never cause that candidate to lose. In Approval voting, for example, it never hurts to vote for the favorite; on the other hand, with Approval, voting additionally for another candidate can, under some conditions, cause the favorite to lose to that other candidate. Advocates for Approval argue that these conditions are, in a two-party system, rare or nonexistent, just as IRV advocates argue that the Voting criterion "failures" of IRV would not commonly occur.

To put it simply, it would seem a rare thing that a voter would vote, in the United States, for both the Democratic and Republican candidates. For similar reasons, in major partisan elections in the United States, IRV is unlikely to run into problem election scenarios that would encourage insincere voting; however, they may occur in non-partisan elections with more than two viable candidates.

Pro: IRV gives voters a wider range of choices

Like the two round system, IRV tends to give voters a wider range of choice among candidates than plurality. More independent and third party candidates are likely to run because the spoiler problems are less severe.

Pro: IRV will reduce negative campaigning

This argument is commonly advanced based on a theory that candidates will want to seek second-rank votes from supporters of other candidates, hence they would presumably be less likely to attack such candidates. However, critics allege there is a lack of evidence that such an effect actually occurs. No formal studies are known to have been conducted. In any event, any reduction in negative campaigning would likely only be between those candidates nearest to each other politically. Candidates who are far apart politically would have little incentive to refrain from attacking each other, as they would be unlikely to win second preferences from voters at the other end of a political spectrum.

Pro: Like plurality, IRV requires the winner to have core support.
FairVote has asserted, "We believe a winner should be at least one voter’s first choice, meaning they would receive more than 0% in current rules." Essentially, if a candidate is dropped in the first round, even if this candidate is everyone's second choice, that candidate cannot win, and, of course, a candidate with no votes would be immediately dropped.

Other reformers, such as Range voting and Condorcet method advocates, don't consider "core support" a meaningful criterion. "Core support" would be connected to having a party working for the candidate, and may be related to an ability to govern if elected, but the likelihood of a candidate being relevant to a real election with no first place support would be low, and harm from electing such a candidate, should it occur, has not been shown.

Arguments against IRV and the debate over them
Opposition to instant-runoff voting consists of those who favor plurality or other systems over this particular preferential voting system. The organized opposition to IRV has sometimes taken the form of newspaper editorials opposing local and state IRV initiatives.

Con: With IRV, voting for a candidate can cause the candidate to lose

Instant runoff voting, like the two-round runoff election method, is non-monotonic, which means that voting for a candidate can cause the candidate to lose the election, by altering which candidates make it into the final runoff tally. Visualizations of this are available from multiple independent sources. The extent to which this can occur in real-world elections is disputed. In cases where there is a Condorcet Winner, and where IRV does not choose it, a majority would by definition prefer the Condorcet Winner to the IRV winner.

For instance, consider 3 candidates, A, B and C. A is well ahead in first preference votes but doesn't have 50%; all votes for B have A as second preference; and all votes for C have B as second preference. So for A to win, s/he needs B, rather than C, to be eliminated (so that A can receive B's preferences). So it is possible to have a situation where a supporter of A needs to vote for C as first preference in order for A to win. If the voter, instead, votes for A, C could be eliminated first and then B wins. By raising the rank of A, from second rank to first rank, the A supporter causes A to lose.

Voters may try to exploit this weakness in any forced elimination runoff using a "." This strategy is relatively easy to attempt within a traditional runoff where a bluff vote can be made and reversed in later rounds. IRV makes this strategy riskier because a single ballot doesn't allow the push-over to be changed back to the true preference in the final round.

There is disagreement on the significance of using the monotonicity criterion to evaluate IRV. For example, Austan-Smith and Banks argue that "monotonicity/nonmonotonicity in electoral systems is a nonissue." Moreover, "depending on the behavioral model governing individual decision making, either everything is monotonic or nothing is monotonic."

Con: IRV suffers from the spoiler effect

IRV stops the '3rd-party spoiler effect' as long as the 3rd party clearly does not have a chance to win. However, if third parties become competitive, tactical voting may re-emerge, as in plurality elections. If voters believe a compromise choice has a better chance of winning in the final runoff tally than their true favorite, they may decide to rank this compromise candidate first, to avoid electing their least preferred candidate. This is not the case with Condorcet methods.

IRV advocates note that this effect will be much more rare than in plurality and less rare than a two round system. Within any runoff process (with forced elimination) voters supporting the final runner up candidate can always second-guess the results and wonder if another candidate could have won with a strategic compromise of their preferences. Advocates argue that IRV's elimination process allows weak parties and candidates to compete fairly without affecting the winner. When a third party reaches a level of core support for a chance to win, then it's up to voters to consider strategic compromise in their rankings, if they are concerned whether a favored candidate (third party or not) has enough compromise support to win the final round.

Con: IRV violates the one person one vote mandate

Since some voters have their ballot counted for their first choice, while other voters have their ballot counted for a later choice, some argue that it violates the one man, one vote mandate of the U.S. constitution. IRV was challenged in court on these grounds in a Michigan case, Stephenson vs. the Ann Arbor Board of City Canvassers in 1975. In that case, IRV (called Majority Preferential Voting or M.P.V.) was upheld as in compliance with this constitutional standard. In his decision Judge James Fleming wrote that
:"Under the 'M.P.V. System', however, no one person or voter has more than one effective vote for one office. No voter's vote can be counted more than once for the same candidate. In the final analysis, no voter is given greater weight in his or her vote over the vote of another voter, although to understand this does require a conceptual understanding of how the effect of a 'M.P.V. System' is like that of a run-off election. The form of majority preferential voting employed in the City of Ann Arbor's election of its Mayor does not violate the one-man, one-vote mandate nor does it deprive anyone of equal protection rights under the Michigan or United States Constitutions."

On the other hand, in Minnesota, there is the precedent of Brown v. Smallwood, a case which addressed the constitutionality under Minnesota law of Bucklin Voting. Bucklin also involves, like IRV, alternative votes, coming from lower ranks, but it amalgamates them in a different manner, bringing them in as additional votes instead of through substitution. Focusing on an alleged one-person, one-vote violation in this, advocates of IRV have claimed that Brown v. Smallwood will not apply, in any challenge, to IRV. However, the majority argued in Brown v. Smallwood, most strongly, against the principle of any kind of alternative vote, so some legal advisors have given the opinion that Brown v. Smallwood does indeed apply to other alternative voting systems. There was a dissent in Brown v. Smallwood which specifically attempted to refute the one-person, one-vote argument, and there is evidence in the record of this case that predominant legal opinion of the time, as well as other precedent in U.S. law, was reversed by the court, and the judgment in Brown v. Smallwood was not replicated elsewhere.

===Con: "if it ain't broke don't fix it" or "plurality voting is good enough" ===
Plurality supporters point to the fact that most elections in the U.S. use plurality voting, and voters seem to accept plurality winners as legitimate. The fact that some revered leaders, such as Abraham Lincoln, did not receive a majority of the vote is sometimes mentioned.

It can be claimed that the spoiler effect is not a weakness but a strength because it encourages and rewards like-minded candidates and voters to work together before the election. This encourages the formation of strong coalitions or parties, who attempt to best represent a collective position to the largest set of voters they can. Thus once an election is held, all compromising work has been completed and it's up to the voters to decide a first choice and accept the results as best.

Con: IRV will help preserve the two-party system
In a country such as the UK where a third party already has some representation, IRV has been rejected because, rather than giving voters more choices, it could actually disfavour the third party. The Independent Commission on the Voting System known as the found that, far from doing much to relieve disproportionality, it is capable of substantially adding to it, and its effects are disturbingly unpredictable.
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