![]() * HOME (NEWS UPDATES) * WHAT IS IRV? * BENEFITS OF IRV * IRV VOTE COUNTING SYSTEMS * HISTORY OF IRV * REPLIES TO ARGUMENTS * MORE INFORMATION * LOCAL CONTACTS: --IRV-Ashland --IRV-Lane County --IRV-Portland Area | Benefits of IRV The adoption of Instant Runoff Voting (IRV) can:
THE SPOILER DYNAMIC Most U.S. elections require a candidate to receive only a plurality of the votes, rather than a majority, to win an office. This means that whoever gets the most votes wins, even if that candidate receives less than half the votes. When there are only two candidates for an office one of them will have a majority (unless there is a tie), but when there are more than two candidates the votes may split between them in such a way that none of the candidates have a majority. For example, assume there are two candidates for an election and the percentage of voter support for each of them is this: Candidate X: 55% of voters support <would win if election held Candidate Y: 45% of voters support If the election were held with only the two of them, candidate X would win with majority support. But suppose a third candidate Z enters the race and draws 20% of the voters away from candidate X and 5% away from candidate Y. The percentages of voter support would change to this: Candidate X: 35% of voters support Candidate Y: 40% of voters support <would win if election held Candidate Z: 25% of voters support Now if the election were held, candidate Y would win, even though a majority of voters do not support that candidate (40% is less than half). Candidate Z has fallen into the role of the "spoiler" by splitting candidate X's supporters and allowing candidate Y to win instead. NEGATIVE EFFECTS OF THE SPOILER DYNAMIC There are several negative effects of the spoiler dynamic:
IRV eliminates the spoiler dynamic because the splitting of voter support when more than two candidates enter a race does not affect the production of a majority winner. In the above example, under IRV candidate Z would be eliminated after the first round of counting and the ballots of the voters who chose candidate Z as their first choice would transfer to each of those voters' second choice, bringing the result back to where it was in the first part of the example: candidate X wins with 55% of the voters to candidate Y's 45%. By elminating the spoiler dynamic, IRV reduces its negative effects:
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