Approval Voting vs.
Instant Runoff Voting
Plurality voting suffers from two serious flaws. The first is lack of majority rule. The second is the “spoiler” problem: many voters have incentive not to vote for their favorite candidate because doing so might lead to the election of their least favorite candidate. As a result, many voters choose not to vote for their favorite candidate and instead vote for a less preferred candidate who has a chance of winning.
Many voting systems improve upon plurality voting. Click for brief descriptions of some of these systems.
Approval voting is one such system. In approval voting, voters vote for all candidates they approve of. The candidate with the highest number of votes wins the election. Benefits of this system are that it is extremely simple to explain to the voter – instructions simply state, “Vote for 1 or more candidates” – and all existing voting equipment can accommodate this system.
The Center for Voting and Democracy believes that both approval voting and instant runoff voting improve upon plurality elections and two-round runoff elections, but we prefer instant runoff voting.
Dr. Kenneth Arrow won a Nobel Prize for proving that no perfect voting system exists. This means that all systems have flaws, and all systems sometimes lead to outcomes that violate our common sense notions of fairness. For example, in plurality voting if two similar candidates split a majority of the vote, in a plurality election, a candidate strongly opposed by a majority of the voters can be elected. This violates the important criteria of majority rule.
Bearing in mind that no system is perfect and that all systems have their advantages and disadvantages, we believe that instant runoff voting is superior to approval voting for public elections for several reasons.
These reasons help explain why instant runoff voting is used for national elections in several elections and why legislation to adopt instant runoff voting is gaining such widespread support in the United States. As far as we know, approval voting is not used in any public elections in the United States or elsewhere, although in the former Soviet Union a form of "disapproval voting" was used: voters crossed out all candidates they disapproved of.
For more information, read a letter in Science magazine from Rob Richie, Terry Bouricius, and Philip Macklin on Approval Voting versus Instant Runoff Voting.