How Instant Runoff Voting Compares to Alternative Reforms
Evaluating Alternatives to IRV
This chart compares the most widely discussed voting methods for electing a single winner (and thus does not deal with multi-seat or proportional representation methods). There are countless possible evaluation criteria. The criteria at the top of the list are those we believe are most important to U.S. voters.
We evaluate other single-winner election methods on these standards, but initially through three criteria that we see as essential in measuring a method's political viability in the United States:
- Does the method violate the most basic principle of majority rule? In an election with two candidates, we believe the candidate preferred by a majority should always win.
- Does the method require the winner to have core support? We believe a winner should be at least one voter’s first choice, meaning they would receive more than 0% in current rules.
- Does the method promote insincere voting? Voters should be likely to vote sincerely, according to the method’s rules, and not lose out to tactical voters who vote insincerely.
Alternative 1: Range Voting
With range voting, voters score each candidate: for example, they could award between 0 and 99 points to each candidate. The candidate with the most points wins. As of early 2007, range voting has not been used in any public election in the world and by very few, if any, private associations.
Bottom-line: Range voting violates all three of our common sense principles of preserving majority rule, requiring a minimum level of core support and rewarding sincere voters.
Example: Consider a range voting election in which 100 voters have the power to assign a score between zero and 99. There are two mediocre candidates. Of the 100 voters, 98 greatly dislike Candidate B, but decide to express their distaste for both candidates by giving one point to Candidate A and none to Candidate B. The remaining two voters prefer Candidate B and are more tactical. They award 99 points to Candidate B and 0 points to Candidate A. The election ends with B beating A by a landslide of 198 to 98 despite the fact that fully 98% of voters preferred Candidate A.
Explanation: This example illustrates how a tactical fringe can overrule a vast majority of voters when the majority votes sincerely and the minority votes tactically. Tactical calculations rise exponentially with the entry of more candidates, at which point winners also do not need to have been any voter’s first choice.
Alternative 2: Approval Voting
Approval voting is a form of range voting, with voters limited to awarding candidates a one or zero. As of early 2007, it has not been used in a public election in the United States. The largest association to use it, the Institute of Electrical and Electronic Engineers, abandoned it in 2002 after most voters started to simply cast plurality voting-type ballots.
Bottom-line: Approval voting violates all three of our common sense principles of preserving majority rule, requiring a minimum level of core support and rewarding sincere voters.
Example: To illustrate how approval voting violates majority rule, consider a primary with 100 voters and two candidates liked by all voters. 99 voters choose to approve of both candidates even though slightly preferring the first candidate to the second. The 100th voter is a tactical voter and chooses to support only the second candidate. As a result, the second candidate wins by one vote, even though 99% of voters prefer the first candidate.
Explanation: This example shows how voting sincerely in an approval voting election will count against your first choice – e.g., if you approve of a lesser choice, you are giving that candidate support equal to your first choice, and that support could cause your first choice to lose. Voters must always be aware of which candidates might win, and candidates have every incentive to ask supporters privately to vote only for them while publicly pretending otherwise. Many voters will bullet vote (e.g., cast one vote for their first choice and no votes for anyone else), thereby reducing even further voters’ ability to express their range of views about candidates. In a three-candidate race, a candidate also can win despite not being even a single voter’s first choice.
Alternative 3: Condorcet-Type Rules
Condorcet-type voting rules are such that voters rank candidates in order of choice, and each candidate is compared with every other in terms of how many voters rank one ahead of the other. If there is a candidate who beats all others in these comparisons he or she is the winner. Condorcet-type voting rules have not been used in any public election in the world as of early 2007, but are used to elect the leadership of some private associations.
Bottom-line: Condorcet-type voting violates the principle of requiring a minimum level of core support by permitting a candidate to win who would not win a single vote in a plurality election.
Problem 1: With these rules, a candidate can win without being a single voter’s first choice. By putting such heavy emphasis on breadth of support, Condorcet-type systems, like approval voting, encourage candidates to be seen as the “least offensive” candidate rather than leaders who take strong positions that might alienate some voters.
Problem 2: Condorcet comparisons can yield a situation where, in an election among Candidates A, B and C, Candidate A is preferred to B, B preferred to C, and C preferred to A. In this situation, there is no winner, and a “fallback” method must break the cycle. When this fallback is needed, sincere voters can be punished. Finally, Condorcet-type rules are difficult to count by hand in big elections. Hand-counting is important if problems emerge with voting machines or software.
- For an expanded argument for Instant Runoff Voting over Condorcet-type voting, read Greg Dennis's commentary available here.
Scholarly Assessment of IRV
Advocates of range voting, approval voting and Condorcet voting sometimes criticize instant runoff voting for (1) being “non-monotonic” (theoretical situations exist in which improving the ranking of a particular candidate can hurt that candidate’s chance of winning because it can change the order of which candidates lose for being in last place) and (2) not always electing the Condorcet winner.
IRV advocates dismiss these criticisms. Potential non-monotonicity with IRV is irrelevant in practice and will not affect voter strategy. We also believe that there are times when the Condorcet winner should not win if that candidate is so lacking in core support that he or she would never win even one vote in a plurality or runoff system. To us, being able to lead and represent people effectively makes it important that a significant number of voters rank the ultimate winner as their first choice.
Leading scholars provide scholarly grounding for our views. Here are two of many examples:
- In The Burr Dilemma in Approval Voting (Journal of Politics, February 2007, pgs. 35-36), University of Pennsylvania’s Jack H. Nagel explains persuasively why potential non-monotonicity is not a serious flaw for IRV.
- Virginia Polytechnic Institute Professor Nicolaus Tideman downplays the Condorcet critique by noting “that in 87 elections in the sample [a sample focused on particularly large fields of candidates being elected by a proportional voting system that relies on ranked ballots] there were just three in which there was a dominant option [i.e. Condorcet winner] that was not chosen” (Collective Decisions and Voting: The Potential for Public Choice, Ashgate Publishing, 2006, pgs. 194-195).