In the world of electoral reform, all of the terms and statistics that get thrown around can seem a little daunting. One good way to lose someone's interest in a topic is to insist that your favorite voting system has very low monotonicity. So let's take a step back and try to get a quick handle on some of the concepts that we at FairVote deal with all the time, but might be a little off the beaten path for the average blog reader.
First off, we use the term "plurality" a lot when we talk about voting systems, and it's not a word that comes up very often in everyday parlance. So what do we mean by "plurality systems"? Quite simply, a plurality system, also called the "first past the post" system, rewards the candidate who receives the most votes. Plurality systems are used in instances where there is just one position that needs to be filled. There is no minimum threshold percentage wise of the vote that any candidate needs to reach in order to win. On one hand, this makes plurality systems easy to use. Anybody is capable of counting up ballots and determining which number is the biggest.
The trade-off is that plurality voting can lead to some odd results. In a plurality system, if you are in a 99-person race for in which everybody else gets 1% of the vote and you manage to get 2%, you win the election, even if the other 98% of people all think you are woefully unqualified. While this scenario is obviously implausible in the real world, there have been myriad incidences in actual elections in which the winner of a plurality election has received far less than 50% of the vote. Take for example the primary race to fill White House Chief-of-Staff Rahm Emanuel's former congressional seat. The district leans heavily towards Democrats, so effectively the winner of the Democratic primary was all but assured the seat come the general election. However, the election being on such short notice led to a wide-open primary that drew twelve Democratic candidates. Michael Quigley won with a mere 22% of the vote and he now serves in the U.S. House. And thanks to gerrymandering, there is a good chance that the 22% he won in a poorly attended primary will ensure him a seat in the House for as long as he chooses to remain.
To further exemplify how plurality systems can lead to skewed results, we'll look at a hypothetical situation involving France's 2002 Presidential Elections:
Jean-Marie Le Pen was (and still is) the leader of the far-right National Front Party. He has been accused of being xenophobic and anti-Semitic, he has repeatedly belittled the Holocaust as trivial, and has made several racist remarks over his long life span as a politician. Despite this, Le Pen has a sizeable following in France, though clearly in the minority. 13% of French citizens in 2002 had an unfavorable view of him and 61% had a highly unfavorable view. Those approval ratings make either of the last two Governors of New York look popular. That being said, in the 2002 French presidential elections, Le Pen managed to narrowly come in second place out of a field of over 15 candidates with 16.86% of the vote, only about 3% shy of incumbent President Jacques Chirac who had the most votes with 19.88%.
Hypothetically, if France used a plurality system instead of a two-round runoff, Le Pen would have been within 3 percentage points of winning the presidency of France, president, even though three quarters of the country was, to put it lightly, adamantly against him. Luckily, France has a majority system that required a second round run-off between Chirac and Le Pen. Ultimately, Chirac won in one of the most lopsided run-offs of all time, winning with over 78% of the vote. However, this vote was not so much a mandate for Chirac as much as a severe reprimanding of LePen by the French public (a group of French political activists held up signs in protest prior to the election that said, "Vote for the Crook, not the Fascist"). So while this example never could have led to a LePen presidency in France, it beautifully illustrates how plurality systems can distort the public's preferences. Had France been using a ranked voting system like instant runoff voting, in which voters could have ranked the candidates in order of preference, the results would have better reflected the opinions of the voters, and no second election would have been necessary.
Another unfortunate effect that plurality systems can have is that they tend to under-represent minorities and less mainstream groups, leading in many cases to a virtual two-party state. For instance, parties in the U.S. such as the Green or Libertarian parties rarely get representation in government, even in areas where they have a sizeable amount of support. Furthermore, people who may have supported smaller parties under a system where they know they have a viable voice are often forced to sell out to one of the two large parties in order to ensure that the "lesser of two evils" (as I've heard many small party supporters call the two big tent parties in America) gets more representation. Since smaller parties rarely have a chance to get a plurality of the vote in any single member district, they serve predominantly as spoilers ("google Bush Gore Nader Florida 2000) for an example) rather than as representatives in government who actually get to directly influence policy. Thus, plurality systems tend to limit the number of plates around the dinner table as fewer voices are heard in the political world.
Thus, after analyzing plurality systems, it is evident that although they are simple to use and are good for holding politicians accountable to a geographic location, they often fail to truly represent the intentions and interests of its constituents. Considering democracy is supposed to be about majority rule, it seems odd to use a system in which majority consensus is not required and in some cases not even sought. Plurality systems are widely accepted here in the U.S. partly because they are so familiar and seemingly straightforward, but it is important to have an honest, analytical discussion today about the merits of any system by which we facilitate our democracy.