Instant Runoff Voting
and why you should support it
Peter A. Taylor
April, 2000 (last modified 12-25-2009)
I am writing this essay partly in self-defense so that people don't think I'm crazy for circulating a ballot access petition for (a) any minor party, (b) a minor party whose policies I generally disagree with more than most, and (c) a minor party that is prone to acting as a spoiler for the major party that I consider to be the lesser of two evils. The reason I am doing this is because the Green Party is promoting fundamental electoral reform, particularly Instant Runoff Voting (IRV) (#glossary). My interest in electoral reform is largely that I find the two-party system to be an "electoral straightjacket," as evidenced by the very narrow and poorly centered range of debate over such issues as drug policy and health care reform. As Arend Lijphart (1984, p. 114) put it,
If partisan conflict is multidimensional, a two-party system must be regarded as an electoral straightjacket that can hardly be regarded as democratically superior to a multiparty system reflecting all the major issue dimensions.
Richard McKenzie and Gordon Tullock (1981, ch. 10) present a graphical illustration of this point in their discussion of the "median voter model." I have taken some liberties with their chart, but it looks something like Figure 1, where the "top" vs. "bottom" dimension represents some set of issues that doesn't lie neatly on the left-right spectrum. With multiple issue dimensions, it's possible for two parties to look like they're competing for the median voter when they really aren't sure where the median voter is, or when there are institutional or agreed-upon limits to the positions they can take to compete.
There are other advantages to IRV as well, such as less sensitivity to campaign spending and more pressure on political parties to nominate centrists. As Polsby and Wildavsky (p. 115) lament regarding the dynamics of modern Presidential primaries,
Where once it was useful to be the second choice of 90% of all delegates, today first choices--even of as few as 30%--are far preferable.
With IRV, second choices are often decisive. In addition to advocating IRV, I will also discuss Proportional Representation (PR), followed by a discussion of the mechanics of IRV and several similar systems.
Instant Runoff Voting
I want to clarify the difference between Instant Runoff Voting (IRV, #glossary) (aka the Australian ballot, aka the Alternative Vote, aka Hare's Method) and Proportional Representation (PR, #discussed below). They are being advocated by a lot of the same people (ie. John Anderson's Center for Voting and Democracy (CVD), and several minor political parties), and some of the ballots look similar, but the arguments pro and con are different.
PR implies diversity in the legislature, with the representatives representing factions that don't necessarily have to cooperate to get their candidates elected. I have seen economists (Buchanan and Tullock, 1962) write about this in terms of "explicit bargaining," and the idea is that legislative deals are made between the various representatives after the election.
IRV produces results more like the Westminster system, aka Single Member Plurality (SMP), aka First Past The Post (FPTP). SMP is the most familiar system in the US, the one used to elect Congress (#example). Here you get "implicit bargaining," where the trade-offs are made in the candidates' platforms, and the voters presumably pick the candidates who make more attractive compromises. If you envision people's views as laid out along a left-right spectrum, the candidates closest to the median voter are supposed to get elected (centrists). The deals are supposed to be made before the election, with the resulting legislature being more or less a rubber stamp for the median voter.
I have two main arguments for IRV. The first is that IRV does a better job than SMP of electing centrist candidates. (I'm a "centrist" in the sense that I want government policies to reflect public opinion as a whole, and not to bounce back and forth between extremes.) In the mid 1980s, Britain used to have large non-centrist Labour and Conservative parties each supported by about 40% of the voters, and a centrist Liberal Alliance supported by about 20%. (The Liberal Alliance are now the Liberal Democrats, and have moved to the left.) The big parties could try to appeal to centrist voters, but it's hard to get voters from another party to switch their support, and it hurts the big parties because of the loss of turnout from their more extremist supporters. The British Parliament, elected by SMP, thus tended to bounce back and forth between the extremes rather than staying in the center. In the US, the comparatively centrist parties are the two large ones, with fringe parties like the Greens and Libertarians (I'm not sure what to say about the Reform Party) that act as "spoilers," tending to self-destructively throw elections away from the median voter in the opposite direction. My second argument for IRV is avoiding oligarchy and the "electoral straightjacket." The worst thing about SMP from my perspective is that it severely undermines any attempt to have more than two viable parties, and so politics under SMP tends to be very oligarchic.
Update (10-31-2010): Daniel Hannan, author of The New Road to Serfdom, argues that US-style primary elections are the main difference between the US and Europe. Bear this in mind when comparing US and other political arrangements. Perhaps I should quit whining and just be grateful for primary elections.
Maurice Duverger said that the tendency for SMP to produce two-party elections is so strong that it comes as close as anything does in the field of sociology to being a natural law. The "mechanical" effect of underrepresenting minor parties in Parliament is reinforced by the "psychological" effect that people don't like giving their support to a party that consistently gets screwed. Another quasi-natural law is that political parties are oligarchal. It is normal for there to be a lot of conflict between party leaders and political candidates, but one thing that makes the US weird is the use of primary elections, which tends to severely undermine party discipline. In Britain, the party leaders usually win these fights. In the US, the candidates usually do.
With Instant Runoff Voting (IRV), there are single-seat districts, as with Single Member Plurality (SMP), but the voters rank their preferences in order (1,2,3,4,5). The ballots are distributed to the candidate ranked first. If no one has a majority, the candidate with the fewest ballots is eliminated, those ballots are redistributed to whomever is next on each ballot, and they are recounted. The process repeats until someone has a majority (#mechanics). If Britain had used this system in the 1980s, the Liberal Alliance would still not have won many elections, given its level of first place support, but its supporters, who were relative centrists, would have determined the outcome between Labour and Conservative. This would have forced the big parties towards the center, to compete for "second preferences" from the centrist party's voters, which tendency is so tragically lacking in politics in Papua New Guinea (PNG) since PNG switched to SMP (see I-IDEA Handbook in #references). There is also no "spoiler" effect with IRV, so it is possible to have several viable parties. This in turn gives minor parties incentives to field reasonable candidates, something that I find sadly lacking in the US.
My point is that if you like the Westminster model, you should like IRV, because IRV implements it better than SMP does. The most serious objection I have heard to IRV is that it is more complicated, requiring voters to be able to count to five (a reasonable ballot size). I tend to dismiss this argument as partisan, but perhaps I am being ungenerous.
Update, 12-25-2009: In Australia, where voting is mandatory and ballots
are complicated, there seems to be a problem with
"donkey voting," where
voters mindlessly write "1,2,3..." and leave as quickly as possible.
Other single-member district election systems
There are other single-seat systems that I also like, and discuss below in the #mechanics and #glossary sections. Condorcet's pairwise comparison method and Nanson's point-based elimination method are like IRV (the 1,2,3... ballots are identical), except that a small centrist party like the old Liberal Alliance would usually win. Instead of eliminating the candidate with the least first-place support, Condorcet goes through the list of candidates two at a time trying to find one candidate who would beat each and every one of the others in one-on-one elections. Sometimes you get a rock-paper-scissors result, and need a tiebreaker. Nanson is more elegant because the tiebreaking process is automatic. The two problems with these are that you need a computer to count the ballots even for a classroom-sized demonstration, which probably makes IRV a significantly easier sell to a skeptical audience, and you may have trouble getting people to sit still long enough to explain these other systems. Approval voting is simpler (SMP ballots, but more than one candidate may be checked) and is a good system if the number of candidates is large.
There are several different Proportional Representation (PR, #glossary) systems. There's the Single Transferable Vote (STV) system that Ireland uses, which closely resembles Instant Runoff Voting (IRV), except that there is more than one seat per district. The other main type is Party List, which is what Israel and Italy use. Party List comes in several flavors. Germany uses a "mixed member" system with both SMP and Party List seats. Most Party List systems seem to have multi-seat thresholds (1% for Israel, 5% for Germany) for how much support a party has to have in order to win any seats. There are also some "semi-proportional" systems such as Cumulative Voting. Most democracies have some form of PR. (See Douglas Amy or the CVD website #links below.)
The worst horror story I heard about PR was that in Weimar Germany, extremist parties would agree to sack the Chancellor, then be unable to agree on a replacement. Modern Germany has a rule that you have to agree on a replacement first. Obviously, this is not an issue with a Presidential system. On the other hand, I've heard it argued that some Latin American countries have problems because of the combination of PR with a Presidential system, resulting in #gridlock (see Cox, below). My impression is that SMP systems (ie. Westminster) are more sensitive to the way things work in the proverbial "smoke-filled back rooms," whereas PR systems are more sensitive to the way legislatures work. Amateur reformers like me tend to get upset about smoke-filled back rooms, whereas my impression is that political scientists tend to get more upset about mob rule, military coups, and quirks in the way legislatures work. The "explicit bargaining" of PR is more sensitive to foibles in the ways legislatures work than the "implicit bargaining" of single member districts. While I like PR in principle, whether or not I buy the arguments for it will depend on the details of the particular government it's being proposed for, and what reforms it's bundled with.
Here are some arguments for Proportional Representation (PR):First, there are some standard arguments you're likely to get from the Center for Voting and Democracy. Perhaps the single most important argument for PR in the US is that #Single Member Plurality (SMP, aka First Past The Post, FPTP, Winner Take All) is unjust because of minority vote dilution, and PR (unlike Instant Runoff Voting) is seen as an alternative to racial gerrymandering. (All single-seat election systems are necessarily "winner take all.") Minorities are highly underrepresented in the legislature under SMP (so are women). This promotes alienation and ill-will between minorities and the overrepresented groups. Low voter turnout in the US is sometimes blamed on SMP because of alienation, lack of clear choices between the major parties, and the low probability of many people's votes contributing to the victory of their candidates ("wasted votes"). SMP typically results in a two-party system that rewards mudslinging and issueless campaigns. The quality of political debate and legislative deliberation suffers from lack of diverse viewpoints (See the Arend Lijphart quote above, and my remarks below about Joycelyn Elders.). SMP rewards gerrymandering, which is impossible under PR (it is almost a contradiction in terms). There are too many "safe" districts where the major political parties do not even have effective competition from each other. US politics often invite the complaint that the major parties aren't different enough to provide a clear choice, whereas British politics often invite complaints about the major parties not being moderate enough. It is possible to make both complaints simultaneously if one regards both parties as being dominated by the same special interests or if one doesn't regard the left-right spectrum as an adequate representation of the issues. Also, money is too important in US politics, due partly to the self-fulfilling prophecy effects of SMP, and it's hard to attack this problem with campaign finance reform without trashing the 1st Amendment. (Front-runner status can be more or less bought in the beginning of a campaign for a party nomination, and SMP punishes voters for supporting any candidate who is not either the front runner or his leading opponent.) Winner Take All also produces a lot of false mandates: a razor-thin advantage that is spread evenly geographically gives "landslide" victories. (This is how I view the "Reagan revolution.")
Objections to Proportional Representation:Obviously, there are partisan objections to PR. I suspect that the religious right are overrepresented, and that many of them know it, and want the situation to stay that way. I gather that the "liberal" (social democrat) wing of the Democratic Party is in a similar position with respect to labor and other groups within the party, and all of them are advantaged relative to the groups like the drug policy reform movement that are effectively outside both parties. Joycelyn Elders, President Clinton's former Surgeon General, got sacked for even suggesting that the US study the British "harm reduction" approach to drug policy, despite widespread popular sentiment that the US "War On Drugs" has gone way too far in many respects (ie. persecuting medical marijuana users). I see this sacking as a major victory for the mafia. My perception is that there are significant elements of the Democratic liberal wing who prefer being disproportionately powerful, even though this means that their archrivals in the religious right are also disproportionately powerful.
I have a number of reactions to these objections:
The dynamics of a large group, such as a nation full of independent voters or a legislature with hundreds of relatively independent members, are different from those of a small group, such as a "smoke filled back room" committee composed of the leaders of five cohesive political parties, where the legislature can be counted on to rubber stamp anything the committee decides. Ferejohn discusses this in terms of the "logic of coalition forming" on p. 45 of Reflecting, and Proportional Representation potentially being "too stable," with the same coalition forming despite major changes in public opinion. By the same token, coalitions can be "unstable," shifting frequently despite little or no change in public opinion. The influence wielded by religious zealots in Israel suggests that if conflict is multidimensional, the logic of coalition forming may result in a fringe party's influence being far out of proportion to its numerical strength (see Figure 2).
These differences in group dynamics have several implications. For one thing, the arguments for and against PR may depend on whether US-style primary elections are used or if the political parties are disciplined, British-style. The major US political parties are relatively amorphous.
Another implication is that it matters how the chief executive is chosen. I want executive functions to be uninterrupted and dominated by centrists. Ideally, I would like to see a Constitutional Amendment to abolish the Electoral College, and elect the President by popular vote using #^Nanson's method. I don't like the Westminster system of having the legislature choose the Prime Minister, especially if the political parties are large and cohesive. Israel made a strange compromise, by having the Prime Minister elected by popular vote (SMP, unfortunately), but still requiring him to get the legislature's approval to "form a government." This seems to me to defeat the whole purpose of a popular election for the Prime Minister.
A third implication is that, since US legislative "agenda setters" such as the Speaker of the House and Senate Majority Leader are chosen the same way as the British Prime Minister, I have similar objections to the way these officers are chosen. Currently, these officers are chosen by majority vote in elections that are internal to the respective legislatures. Ideally, I would like to see these officers elected by popular national vote using Nanson's method. (I am also concerned that power within Congress is not uniformly distributed, with the seniority and committee systems. If everyone is more or less a centrist, this may not be such a big deal, but with PR, it may be a bigger problem.) Since PR systems are more sensitive to quirks such as "agenda manipulation" (see Mueller) in the way legislatures work, great care should be taken to minimize these quirks.
A fourth implication is that if you have cohesive political parties, especially using Party List PR, you may need some mechanism to ensure that there is a substantial centrist block or a substantial number of independent centrists. A mixed member system such as Germany's is one way to do this. There is also a method by Robert Loring (Loring Ensemble Rule A, LERa) that does this by combining #STV with #^Condorcet (the Condorcet winner is identified and made exempt from the elimination process). You might consider setting upper bounds as well as lower bounds on the number of seats that can be held by any one party. My prejudices run towards US-style incohesive parties with primary elections, but I am concerned that these do not do as good a job of keeping the voters informed. I also agree with Mosch Virshup that the procedures that the political parties use in choosing candidates are at least as important as the procedures for the general election.
Figure 2 suggests how a pure PR system with cohesive parties could produce a legislature with little influence from centrists, creating problems relating to the "logic of coalition forming."
Relative Benefits and RisksThe Single Transferable Vote (STV, #glossary) PR system used in Ireland and the Australian Senate seems to me to be much less risky than Party List PR. STV is like IRV, except that the districts may have as many as 5 seats. Party List more or less means voting for a party rather than a candidate. STV doesn't represent very small political minorities (<20%) very well, but it allows considerable minority representation and offers an escape from the "electoral straightjacket" while still rewarding the parties for being moderate and for courting voters from other parties for their "second preferences." (Ferejohn talks about the "politics of persuation" versus the "politics of mobilization.") Instant Runoff Voting (IRV) would give me maybe 60% of the benefits that I think are possible with an ideal Party List PR system, with essentially no disadvantages as long as the number of candidates on the ballot is kept reasonable (ie. 5 or so). STV would give me maybe 90% of the benefits of Party List, with maybe 20% of the disadvantages. But even in advocating STV, I would want to combine it with IRV, #^Condorcet, or Nanson's method for any single-seat elections, including ones that are internal to the legislature. I note that the US already has a gridlock problem at times, as with the Clinton/Gingrich follies of 1995, so I would advocate one of these single-seat reforms regardless of any movement towards PR.
Afterthoughts (5-18-2009):The case study of PNG seems to me to be a compelling argument against FPTP in multi-tribal societies like PNG, but Australia seems to be a different story. When I read about Australian politics, or exchange email with Australians, I am disappointed by how familiar the controversies seem. Australia uses two of my favorite election systems (IRV for the lower house, STV for the Senate), and has considerable representation by minor political parties, but the parties tend to form two semi-permanent coalitions, and the issues seem to be condensed onto pretty much the same left-right political axis as in the US, Canada, and Great Britain.
Mechanics of several single-seat voting systemsConsider 1980s British politics, where there was a strong left (Labour) party, and strong right (Conservative), and a weak center (Liberal Alliance). Suppose that Labour has 39% of the vote, Conservative 41%, and Alliance 20% in some electoral district. For sake of keeping the examples simple, suppose that the voters are in three blocks, with their preferences ordered as in Figure 3.
39% of voters
20% of voters
|Conservative Party |
41% of voters
|Labour candidate||1st||2nd (?)||3rd|
|Conservative candidate||3rd||3rd (?)||1st|
Under Instant Runoff Voting (IRV, aka Australian ballot, aka Alternative Vote), the Alliance candidate is eliminated, but the centrist voters who supported it may then determine the outcome of the contest between Labour and Conservative. If the Alliance voters second preferences favor Labour by more than 2% of the total vote, Labour wins. The election tends to go to whichever major party is more successful at wooing the center. Minor parties do no harm to major parties that resemble them and minor parties can hope to gradually grow and become major parties if they appeal to the center. (Apart from being biased in favor of large parties, IRV can sometimes produce "perverse" results where a shift in support from candidate X to Y can cause X to be eliminated instead of Z, which can result in Z winning instead of Y. This is not important in practice because the voters' behavior isn't predictable enough for this to be a basis for "insincere" or "strategic" voting. As "Arrow's Impossibility Theorem" shows, all election systems have some quirks like this; it is nowhere near as perverse as SMP. See Nielsen and de Villiers or Mueller.)
|Candidate||1st Count||2nd Count||Result|
Nanson's "Borda elimination" method superficially resembles the "Borda count," which is a point system. Candidates are ranked in order of preference on each ballot, like IRV. Candidates are awarded points according to how highly they are ranked on each ballot. Under Borda count, the most points wins. Under Nanson, the candidate with the fewest points is eliminated, and the ballots are iteratively recounted as if the loser had never existed (lower-ranked candidates on each ballot are promoted). This goes on until there is only one candidate left. If the Alliance party gets second preferences of both the Labour and Conservative voters (which presumably it would, as the center party), the Alliance would score enough points to survive the first iteration, and the candidate who is eliminated first would be determined by the Alliance voters. If the Alliance voters' second preferences are predominantly Labour, the Conservative candidate is eliminated first, and then the Conservative ballots help give the election to the Alliance. Under Nanson's method (or Condorcet or Approval), centrist minor parties can win.
First count (3 points for first preference, 2 for second, 1 for third):
(4 points for first preference, 3 for second, 2 for third, 1 for last)
Voters rank candidates as with IRV
No circular tiebreaker needed in this case.
GlossaryApproval Voting: Like SMP, but you can vote for as many candidates as you like.
References (in no particular order)For information about electoral reform in general, visit The Center for Voting and Democracy (CVD).