Sunday, July 18, 2010

Duopoly Must Go: An Appeal for Score Voting

Matt Gonzalez has graciously used his blog to host an essay from the folks at the Center for Range Voting/Election Science Foundation. For those that aren’t familiar with Matt Gonzalez, here’s a background:

Matt was the head of the Board of Supervisors in San Fransisco as a member of the Green Party. He also ran for mayor of San Fransisco as a Green. Despite being outspent 5-1 and having the likes of Al Gore come to rally for his opponent, Matt was within 6% of the runoff winner, Gavin Newsome. Matt was also the VP running mate of presidential candidate Ralph Nader in 2008.

The following essay can be found at Matt Gonzalez's blog, As It Ought to Be:

Duopoly Must Go: An Appeal for Score Voting

by Andrew Jennings, Clay Shentrup, Warren D. Smith

Progressive thinkers on all sides of the political spectrum often wonder why the United States seems incapable of escaping a two-party political system. Is it a result of an extreme demographic situation, an urban and a rural America so large and obstinate that they are incapable of cooperation? Does it somehow come from the unique American spirit, a tradition steeped in individualism and adventure? Are the third parties being silently stifled because of their opposition to our incessant march toward rule by large corporations? The answer, in fact, may be so simple that it is right at our fingertips at least once a year. Every time we vote, in fact.

Fifty years ago, French sociologist Maurice Duverger observed that the plurality voting method tends to favor a two-party system, whereas “the double ballot majority system [a.k.a. 'top-two runoff'] and proportional representation tend to multipartism.” Observations in the social sciences are never absolute, but this tendency for plurality voting to maintain two-party domination is so reliable that it has become known as Duverger’s Law.

Plurality voting (a.k.a. “first past the post”), by far the most common system in the United States, is where each voter votes for one candidate and the candidate with the most votes wins, even if he receives fewer than 50% of the votes. Top-two runoff (a.k.a. “TTR” or “delayed runoff”) is just like plurality voting, except that if no candidate receives a majority of the votes, then a subsequent election is held between the top two finishers.
Few would expect the way we count our votes to be the primary factor determining the layout of our political landscape, but the evidence is overwhelming. Beyond the empirical trends to which Duverger referred, mathematical analysis of these voting methods suggests a causal relationship. For instance, a plurality voter who prefers a Green Party candidate will often take the tactical route, casting an insincere vote for the Democrat in order to prevent the Republican from winning. This costs the voter very little, since a minor party candidate is by definition unlikely to win anyway. It seems clear that such tactics keep us locked in a two-party system.

A top-two runoff system differs considerably. To echo Duverger, most of the approximately 30 countries which use this system have escaped two-party domination, even in single-seat non-proportional elections. And as with plurality voting, analysis of the runoff system strongly suggests that this is not a coincidence, but in fact a result of voter psychology and the different tactical incentives at play. For instance, voters in the runoff have no incentive to cast an insincere vote, as there are only two choices. And once the options are narrowed down to two candidates, voters often have a better chance to get to know an otherwise unknown challenger. These factors may largely explain how Green Party candidate Matt Gonzalez was able to come within striking distance of Democrat Gavin Newsom for mayor of San Francisco in 2003 (the margin was less than 6%) despite being outspent five to one, and despite Newsom’s being endorsed by a host of powerful beltway politicians.

Opinions vary as to the relative merits of TTR versus other systems, and the above is not meant as an endorsement of TTR per se. Rather, it is a testament to the extent to which the voting method determines the party composition of a government. It seems clear that if we want to escape the two-party stranglehold, we must adopt a different voting method; specifically one which is not known to also maintain two-party domination.

Many of the modern efforts for voting reform promote an alternative form of runoff, called instant runoff voting (“IRV”), which allows voters to rank the candidates and appears to offer us a way out of our electoral difficulties. Unfortunately, communities and scholars are discovering that the hope IRV offers us for escaping our two-party system is only illusory.

Like TTR, IRV doesn’t fix the spoiler problem: a bloc of voters may get a worse result by supporting their sincere favorite candidate. For instance, in the 2009 mayoral election in Burlington, Vermont, a group of voters who preferred Republican over Democrat over Progressive could have gotten the Democrat instead of the Progressive by insincerely top-ranking the Democrat instead of the Republican. It may seem strange to think of the GOP candidate as the spoiler, but the ballot data shows that a majority of voters in left-leaning Burlington would have taken the Progressive or the Democrat over the Republican in a runoff election, making the GOP more akin to a third party in this particular circumstance — albeit a strong third party.
And therein lies the rub. See, most voters picture runoffs in the context of weak third parties. The thinking goes that if you prefer, say, Green over Democrat over Republican, then you can safely support the Green. If the Green doesn’t make it to the runoff, then your support will simply go to the Democrat. But that is only the first phase of a third party’s growth. Next imagine that the Green Party, freed from the fear of “wasted votes,” grows to encompass more and more of the electorate until it can outlast the Democrats and make it to the runoff. Finally, imagine a third phase in which the Greens have grown enough to not only defeat the Democrats, but to win against the Republicans in the runoff. This third phase represents the greatest hopes for those who see IRV as a way to end the stifling two-party stranglehold on government.

But this rosy picture starts to darken the moment we take account of two crucial factors. First, it must be noted that each of these three phases is generally a prerequisite for the next. This is explained concisely as follows: as a third party grows, it will become powerful enough to defeat its most similar major party before it will become powerful enough to defeat both major parties. Second, the middle phase is effectively a barrier to the third. It is precisely the scenario experienced in Burlington. In this phase, the Greens defeat their most similar opponent, only to lose in the runoff. For Greens who prefer the Democrat to the Republican, the announced ballot totals will make clear to them that their honesty caused them to get the Republican instead of the Democrat. If even a mere 10% of them decide to cast a tactical vote for the Democrat in the next election, then even a prodigious 10% increase in their popularity by that time will be completely nullified. More realistically, their popularity would increase by less than 10%, in which case the tactical behavior would bring them down faster than they could increase their membership.

Many IRV proponents have argued that such strategy is infeasible and/or inadvisable, since it is likely to “backfire.” We address this theoretical argument in detail elsewhere, but for now let’s put aside contentious theorizing, and turn our attention to empirical reality. Australia uses instant runoff voting to fill each of the 150 seats in its House (has used IRV since 1918). It also uses other methods for other elections, e.g. its Senate is elected with a multiwinner method called PR-STV (proportional single-transferable vote). Australia’s House is two-party dominated; in the elections of 2001, 2004, and 2007 combined, not a single house seat was won by a third-party member. In contrast, quite a few seats in their Senate (e.g. 9 out of 76 in their 2005-2008 Senate and 6 in the 2008-2011 Senate) were/are occupied by third parties, mainly the Greens.

The same trend has been observed with IRV elsewhere, such as the Irish presidency (a near monopoly despite being mostly ceremonial), and in Malta and Fiji (before it was a dictatorship). And it is interesting that San Francisco supervisor Ross Mirkarimi (who helped found the California Green Party) switched from Green to Democrat in early 2010, despite the fact San Francisco now uses IRV, instead of the delayed runoff system it used when Matt Gonzalez made his impressive mayoral bid.

Of all these examples, Australia may be the most pertinent. We noted that their Senate uses STV, while their House uses IRV. STV is a multiwinner proportional system, and it so happens that IRV is actually the single-winner form of STV, so both systems use the same ranked ballot. Thus it is not too surprising that many American election activists see the adoption of IRV as a crucial “stepping stone” to proportional representation via the adoption of STV. IRV gets voters accustomed to ranking the candidates, and puts the basic machinery in place to tabulate those ranked ballots in the specific manner that STV entails. Even IRV proponents who are aware of its tendency for duopoly often support it for this very reason; they want proportional representation. In fact FairVote, the organization most often associated with the push for IRV, was founded in 1992 as “Citizens for Proportional Representation” (and later the “Center for Voting and Democracy”), and it seems that behind the scenes, their pursuit of IRV is a long-term play for proportional representation in America.

The stepping stone strategy might actually make sense were it not for the USA’s rigid impediments to proportional representation, which was made illegal at the federal level via a 1967 law which outlawed multi-member districts. In 1996, congresswoman Cynthia McKinney (who later ran as the Green Party candidate for US President) wrote, but failed to pass, bill HR 2545, which would have overridden that previous 1967 law. She re-introduced a similar bill, HR 1189, in 2001. It failed again. Then she tried again with HR 2690 in 2005. It failed yet again.

This leads us to believe that PR will be federally unobtainable in the USA as long as we are two-party dominated (a Congress dominated by two parties will continue to block anti-duopoly legislation such as McKinney’s). We therefore believe that proponents of PR must find a single-winner voting method which doesn’t maintain duopoly, as a prerequisite to PR. As has been noted, ordinary top-two runoffs fit that description, but they have their own problems, both in terms of voter turnout and the cost and fatigue associated with extra elections. And they can still leave voters justifiably fearful of supporting candidates they sincerely prefer to the apparent frontrunners, in the first round. (As a reminder, voters have no incentive to be insincere in the runoff.)

There are other voting systems that work with a ranked ballot and have several advantages over instant runoff voting (e.g. Condorcet methods), but even more exciting is a simpler class of voting systems discovered in the past few decades, based on an entirely different paradigm: ratings rather than rankings. These systems let each voter consider each candidate separately and assign to each a score or grade.

In his 2008 book Gaming the Vote, author William Poundstone (an MIT physics grad) suggests a voting method called range voting (a.k.a. score voting), in which voters rate the candidates on a scale such as 0-10 or 1-5. When the scale is reduced to 0-1, we effectively have approval voting, which is identical to plurality voting except that there is no limit on the number of candidates a voter may support. A third method, the Majority Judgement, asks the voters to use a few natural-language terms (Excellent/Good/Acceptable/Unacceptable, for example) to grade the candidates and chooses the winner by finding the candidate who was given the highest grade by a majority of voters (the median grade).

Score voting has historically been overlooked, based on the assumption that it would succumb to pervasive tactical exaggeration. But that view was debunked back in 2000, when a Princeton math Ph.D. named Warren D. Smith performed an extensive set of computer calculations which showed the system working extremely well, even with high rates of tactical voting. This is based on an objective “economic” indicator of voter satisfaction with (or “representativeness of”) election outcomes, called Bayesian regret.

This can be understood if we think for a moment about a voter whose preferences are Nader=10, Gore=6, Bush=0. If this voter is sincere, he casts those very scores. But if he is a tactical voter, like those who voted for Gore instead of Nader under plurality voting, how should he vote under score voting? For starters he wants to give Gore a 10, and Bush a 0, to maintain the tactical advantage he sought under plurality voting. But he can additionally give a 10 to Nader, and any other candidates he prefers to both frontrunners, with no fear of negative consequences. (In election theory parlance, we say that score voting passes the Favorite Betrayal Criterion.) Whereas you will recall that with IRV, tactically placing the Democrat in first place absolutely requires a Green voter to place the Green lower than first place. But with score voting, giving Gore a maximum score in no way prevents a voter from still giving Nader a maximum score too. So third parties face no artificial barrier to growth, as they do with IRV.

A simple way to think of it is that a tactical score voter should support the same candidate as he would with a plurality ballot, and then also support all the candidates he likes better. This means that the appearance of being “unelectable” need not become a self-fulfilling prophecy, like with plurality, IRV, and so many other methods. If it turns out that enough voters prefer a minor party or independent candidate to the presumed frontrunners, then he can actually win, even if the voters are highly tactical! Empirical evidence strongly suggests election outcomes will then be vastly more representative of the actual relative support for the candidates.

We believe this has enormous consequences, beyond the obvious opportunity to escape from two-party domination. For instance, the inordinate importance of cash in elections is largely a product of the need to prove electability. Consider exit polling from 2000 in which 90% of Nader supporters claimed to have voted for someone other than Nader. This shows that the number of votes Nader could have received by convincing voters he could be elected (e.g. by having an enormous campaign “warchest” and/or getting the nomination of a major party) was nine times as large as the number of votes he won by trying his best to convince voters he should be elected. Also consider that in the 2008 US presidential election, Mitt Romney spent large amounts of cash from his personal fortune to bus in voters to straw polls with no legal consequence whatsoever, apparently in order to be seen early on as a frontrunner, so as not to be abandoned by tactical voters, who fear wasting their vote on candidates who can’t win.

These may seem like anecdotes, but their prevalence amounts to something greater. Money matters far too much in today’s political process. And efforts to curb that with typical campaign finance reform are inherently unstable, as cheaters will be more likely to win elections, and then just make their cheating retroactively legal, and/or intimidate government officials who dare to try to prosecute them. We believe it may be more effective to try to reduce the inherent importance of cash, than to wage a potentially futile battle to level the playing field. With score and approval voting, a candidate need not prove his electability in order to earn your vote.
In summary, we would be wise to realize that the lack of alternative choices in American politics is unlikely to be repaired without changing to a better voting system, and that instant runoff voting is probably not the answer. We should give serious consideration to voting systems based on ratings, where voters can evaluate each candidate independently, and never fear giving their full support to the candidates they prefer to the frontrunners. While it’s impossible to predict exactly how these systems will play out in practice, the theory and a great deal of empirical evidence make them seem promising, and it’s clear that the systems we have now are not working and it’s time to look outside the box for a voting system that will truly support smaller parties and encourage alternative ideas in our political discourse.


  1. No comments on the dialogue between me and BL?

    I agree wholly with the view that the lack of satisfactory choices in the US is due to our election rules and that fairvote's IRV3 is unlikely to change that adequately.

    But I believe that a mix of 3-seated American Proportional Representation and some form of single-seated elections(I 'm less picky about single-seated elections) in city council or AmPR in state house and single-seated in state senate wd change our political dynamics signicantly, even if the system still tended to have two major parties.

    The point is that they'd be two rather different major parties as a result of local third party options and their inabiility to dominate a state's political system.


  2. This essay was about single-seat election systems. You're referring to multi-seat election systems. Proportional/multi-seat systems are referenced here to demonstrate IRV as a failed tactic for reform.

    I'm sure I'll do a post on multi-seat systems in the future. But you should know that as a general rule, the fewer seats you're voting on, the less proportional the outcome will be. David Farrell in his book Electoral Systems suggested this number should be at least five. In most systems, this gives a threshold of about 17%. Suggesting districts of three would lead to more proportional outcomes, but it's a bit too small. Though this is what Illinois did when it used a cumulative voting system.

    It is my opinion that any time one can make a position multi-seat, they should so that proportional methods can be used. Single seat elections should be used as sparingly as possible for seats such as president, governor, mayor, et cetera. Minus some anomalous consensus, single-seat positions will ignore much of the voters. And by the way collective decisions are done in government with legislation, single-seat elections should not be trivial.

  3. Thanks for following up on this line of questioning over at anewkindofparty.

    I think 3 is actually not bad, so long as it's 3-seated Hare LR, which is biased in favor of the bigger smaller parties.

    I think that we need to focus more on moving from what is the case in our political system and less on the ways it ideally should work...



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