fling93 loves fishies

The Factors Behind a Country's Choice of a Multi-Party or Two-Party System

This is a term paper I wrote for my Political Science night class in Comparative Governments (which was a big reason I haven’t been blogging). My wife thought this was extreme overkill for an undergraduate course at a community college (and yes, I got an A), but I was really interested in the topic, and this was the first academic paper I’ve written in a long, long time. Although note, I’ve since made some minor changes from the original paper to make it a bit more accessible and thus less academic.

There are a multitude of factors that affect whether a country becomes a multi-party democracy or a two-party democracy. They include the level of institutionalization of a country’s existing political parties, whether the government is a presidential system or a parliamentary system, the level of diversity in the country’s electorate, and the type of electoral system chosen. Comparing the importance of these factors is beyond the scope of this paper, although it appears that the last one is the most significant factor. It is, however, worth noting that the choice of electoral system itself is affected by several factors, including some of the ones already listed above.

A variety of factors (link)

The level of institutionalization of political parties is important because parties are political entities of their own, seeking power by whatever means they have available, sometimes by trying to reform the system in their favor and sometimes by cooperating with other political parties. They can also build up loyalty and name-recognition among the electorate, which means that a party with a long history is likely to be able to make use of their base of support in order to hold on to power. Thus, a stable multi-party system is likely to stay a multi-party system merely because all of the parties are strong enough to ensure their continued existence. Meanwhile, in a two-party system, the two parties typically wish to hold onto their power and exclude other parties from power, and thus have an incentive to cooperate and collude with each other to maintain the status quo (Rae, Hanby, and Loosemore 1971). So if the system has been stable, it is unlikely to change, regardless of whether it’s a two-party or a multi-party system. Of course, it’s a different situation if the political circumstances change, which I’ll discuss later.

Another factor is whether a country is presidential or parliamentary. Upon first glance, it would seem that this would have little bearing on the number of parties, since the main difference between the two systems is simply whether the executive is elected directly or appointed by the legislature. However, Stepan and Skach (1993) analyzed the number of parties in many parliamentary and presidential democracies. The used the “formula devised by Markku Laakso and Rein Taagepera to measure the ‘effective’ number of political parties in the legislatures of these forty-one political systems. Of the thirty-four parliamentary democracies, eleven had between three and seven effective political parties…. However, no pure presidential democracy had more than 2.6 effective political parties” (Stepan and Skach 1993).

One possible reason for this disparity is because presidential systems seem to exacerbate the stability issues of multi-party systems. In a multi-party system, a president is much less likely to have a majority in the legislature and thus will have a very tough time pushing through legislation, even if it is critical (Mainwaring 1992). Since there are no constitutional methods of resolving an impasse between the executive and legislative branch, this can result in presidents attempting to bypass the legislature altogether or broadening their powers, and such moves can risk retaliation via a military coup, as evidenced by several examples in Latin America (Mainwaring 1992). A similar impasse in a parliamentary system, on the other hand, can be resolved by the prime minister calling for new parliamentary elections or a legislature’s vote of no-confidence in the prime minister (indeed, in Star Wars: Episode I - The Phantom Menace, Queen Amidala — played by the hotness that is Natalie Portman — called for a vote of no confidence in Chancellor Valorum, inadvertently paving the way for the evil Palpatine).

Presidential systems also create incentives for strategic voting. Strategic (or tactical) voting is when a voter votes for a party they think has a good chance of winning even if the party is not their first choice, and this tends to hurt smaller parties. In most parliamentary systems, small parties can still play an important role in joining (or refusing to join) the coalition to select the Prime Minister, and then can also threaten to leave the coalition, bringing down the government. But in a presidential system, small parties are typically irrelevant because the president is directly elected and thus the parties in the legislature generally do not form coalitions. And even if a small party wins seats, they still play little or no role because the executive has no incentive to cooperate with them (they either already have the majority party and can pass legislation, or they do not, and there is an irresolvable impasse). Small parties are also hurt because they have no shot at winning the presidency. This creates incentives for smaller parties to unite into larger parties, reducing the number of parties in a presidential system.

One factor that has a pretty clear connection with multi-partyism is electorate diversity, whether it be ethnic, religious, or ideological. A diverse society is much more likely than a homogenous society to have multiple factions that will demand a multi-party system. This effect is magnified in very large countries, where an electorate fragmented along ethnic or religious lines is more likely to have a large number of voters who would not feel adequately represented in a two-party system. This effect in obvious in Iraq, where the Shiites, Kurds, and Sunnis would be ill served by a two-party system that would probably exclude the Sunnis, perhaps resulting in a civil war. Indeed, sometimes countries with only two major ethnic factions will still choose PR because they desire adequate minority representation, as was the case in South Africa after apartheid ended.

The electoral system (link)

Of course, all of these factors seem to be less significant than the type of electoral system, more specifically if a country uses plurality (also known as first-past-the-post) or proportional representation (PR). Plurality is the voting system that we use in the United States, where the one candidate with the most votes wins. Although it is very simple to understand, it has various side effects that I’ll cover shortly. PR, on the other hand, is a system where parties typically win seats according to the percentage of votes that they get.

Duverger’s law and hypothesis (link)

According to Duverger’s law, plurality voting favors the two-party system (Duverger 1963, as cited in Riker 1986). Duverger believed this was due to two reasons: a “mechanical effect” and a “psychological effect” (Riker 1986). The mechanical effect referred to the fact that plurality elections under represent losing parties much more than PR. For example, if the winner receives 51% of the vote, 49% of the electorate gets zero representation whatsoever. The psychological effect relates to the “spoiler effect,” which should be familiar to those who witnessed the 2000 presidential election in the United States. In plurality, a third party candidate will typically split the vote with one of the major parties, handing the election to the other party (I illustrated this in an earlier post). This means that voters for the third party can inadvertently hurt their second choice. To avoid this, many voters will use strategic voting and ignore third parties. Indeed, the psychological effect also applies to candidates, who don’t want to waste their time, resources, and effort running in a party that has an insignificant chance of winning.

Both of these effects hurt third parties, which is why plurality tends towards a two-party system. Neither of these effects appear nearly as strongly in Proportional Representation (PR), which is the main reason why Duverger (1963, as cited in Riker 1986) also said that PR (as well as majority voting, such as two-stage runoffs) favors multi-partyism. Riker (1986) calls this Duverger’s hypothesis. The hypothesis, however, does not seem to have very much empirical support. There are several problematic counterexamples, namely Austria, Germany, and Ireland, all of which use PR but have only two or three parties. Ireland in particular used to have seven parties, but this decreased to three, one of which is very small (Riker 1986).

The reasons for this become clearer when you examine the differences between plurality and PR in a more formal fashion. One important measure is the concept of the threshold of representation, introduced by Rokkan (1968 as cited in Rae, Hanby, and Loosemore 1971), which is the minimum number of votes required for a party to gain representation. It’s kind of a best-case scenario for a third party. A more insightful measure is the threshold of exclusion, which is more of a worst-case scenario — the maximum number of votes a party can get while still failing to win a seat. This is more meaningful because existing political parties have a strong incentive to cooperate to prevent new parties from emerging to challenge the status quo. Therefore, in order to win a seat, new parties will usually have to exceed, not just the threshold of representation, but also the higher threshold of exclusion.

Not surprisingly, PR systems with multi-member districts have much lower thresholds of exclusion than plurality, meaning that it is harder to exclude new parties. This suggests that, “It is not so much that P.R. leads directly to the formation of new parties — a complex process indeed — but that it makes it more difficult to stifle them once they have emerged and begun to contest elections” (Rae, Hanby, and Loosemore 1971). This is why the electoral system is not the only factor that determines whether a country is multi-party or two-party. It is not enough that a country uses PR. PR doesn’t actually provide an incentive for new parties but merely removes the disincentives against them. For a multi-party system to happen, new parties will still have to form, and other factors such as diversity and size will come into play to determine whether or not this happens.

Still, while there are some two-party countries with PR, there are very few multi-party countries that use plurality. The primary exceptions are Canada and India. Rae (1971, as cited in Riker 1986) explains Canada as an example of regionalism, where each local election still features two main parties, but in some regions, one of the two parties are only local, resulting in multiple parties nationwide. This happens in Canada because it is geographically large and has a very decentralized federal system. Indeed, Boix (1999) notes that, “under certain conditions, federalism operates as a (quasi-perfect) substitute for PR.”

India, on the other hand, is harder to explain. Anckar (2001) suggests it retains a multi-party system because of its population size and ethnic heterogeneity, but I find this less than convincing because there are many other large and diverse countries using plurality that don’t have so many parties, including the United States. On the other hand, Riker (1986) suggests that the reason is because India’s strongest party, Congress, is also the Condorcet winner (i.e. the centrist party), which is only defeated when parties on the right and the left unite against it, but as those parties are ideologically far apart, their coalition never lasts very long. This is more plausible, but in response, Sartori (1986) notes that in several countries, including Britain, Australia, and New Zealand, the centrist party actually ends up getting squeezed by the two sides and losing. So India’s apparent defiance of Duverger’s law remains a mystery.

Behind the choice of an electoral system (link)

Aside from India, the vast majority of countries that use plurality have two-party systems, and Duverger’s law is widely accepted among political scientists. This indicates that plurality is a formidable obstacle to the formation of new parties, one which generally must be removed before the other factors can have an effect. The question still remains why a country chooses plurality or PR as its electoral system, and this in turn is affected by a variety of factors, some of which are surprisingly arbitrary.

One simple but important factor is the time period when a country became a democracy. Older democracies like Britain and the United States invariably chose plurality because it was the only democratic voting system known at the time, and nobody realized it would create a two-party system. PR didn’t rise to prominence until the late 1800’s, particularly after the Association Internationale pour le Progres des Sciences Sociales met in 1864 to discuss Thomas Hare’s new system of PR, also known as the Single Transferable Vote (STV). PR soon became the system of choice, since it was widely viewed as the fairest and the most representative voting system (Blais, Dobrzynska, and Indridason 2005). Therefore, most of the countries that transitioned to democracy at this time chose PR.

It wasn’t until the late 1930s when prominent critics of PR began to emerge, most notably Hermens, who linked PR and the multi-party system with the failure of the Weimar Republic in Germany (Blais, Dobrzynska, and Indridason 2005). Although many scholars believe he overstated his case (Riker 1986), the debate over the merits of two-party and multi-party systems continues today, and the choice between plurality and PR is no longer so clear for newly emerging democracies, which now take into consideration some of the previously mentioned factors, like diversity.

Another factor is, quite simply, being a former British colony. Britain was the country that originated plurality voting, and many of their colonies were often inspired by the British system when devising their own democratic system, including Canada, India, and the United States. Indeed, Blais and Massicotte (1977, as cited in Boix 1999) found that being a British colony was a strong predictor on whether a country chooses plurality.

A more complicated subject is what causes an existing democracy to change its electoral rules. Rokkan (1970, as cited in Boix 1999) suggested that a crucial factor was the widespread introduction of universal suffrage at the beginning of the twentieth century. After this change, the parties in power in many countries feared that the newly broadened electorate would sweep them out of power unless they implemented a system that made it easier for them to hang onto power, and PR, with its lower threshold of exclusion, was a prime candidate.

Boix (1999) greatly expanded upon this hypothesis, specifically on how to determine the level of threat that established parties faced. In particular, many of the countries using plurality faced the rise of the socialist movement (and thus a Socialist Party) as workers finally got the vote. Boix (1999) theorized that if that Socialist Party was positioned strongly and if the two older parties were of about equal strength, then the established parties would split the right side of the electorate, handing the election to the Socialist Party. To prevent this, the two parties would be likely to support PR so that they could still hold onto power in the new situation. If, on the other hand, the emerging Socialist Party was weak (e.g. on the very left fringe of the electorate), it wouldn’t pose much of a threat, and the two older parties would be likely to keep the existing system. Also, if one of the two older parties was much stronger than the other, the weaker party’s voters would be much more likely to defect to the stronger party in order to prevent a Socialist victory (another example of strategic voting), and would also be likely to keep plurality voting.

This would explain why the U.S., which only faced a weak Socialist threat, kept plurality voting while Germany embraced PR. To bolster his claim further, Boix (1999) introduces a dependent variable, the effective electoral threshold, which is basically the average between the threshold of representation (he calls it inclusion) and the threshold of exclusion. He then measures how this variable correlates with the strength of the Socialist threat as well as other variables (such as size and diversity), and finds that the threat variable is the most significant, followed by geographical size.

However, Blais, Dobrzynska, and Indridason (2005) find this explanation less than compelling, believing that strong Socialist parties were actually more of an effect of the existing voting system than an actual cause themselves. They believe the underlying cause to be majority voting systems, typically the two-stage majority runoff, which were already more amenable to multi-party systems than plurality voting. A two-stage runoff election is similar to plurality except that the first runoff narrows the field to the top two finishers, who then run against each other in the second runoff. This allows multiple parties to enter the race, knowing that they can move their support to one of the finalists. Recall that majority voting was included in Duverger’s hypothesis as tending towards multi-partyism.

However, although majority voting provides less of an obstacle to new parties, it is not very proportional and, perhaps more importantly, it gives political parties more uncertainty than PR systems (sometimes a party or candidate that loses in the first runoff doesn’t throw their support behind anybody). And since there was a time period (1865-1938) where PR was widely considered to be the most democratic system that existed, there was already considerable public pressure to move to PR, so merely having less resistance from the political parties in power was often the difference between a country switching or not. Like Boix, they back up this hypothesis with numbers that are beyond my level of expertise to evaluate, but it seems to be a compelling case.

In conclusion, there are a variety of intertwined factors that determine whether a country ends up with a two-party or multi-party system. The choice of electoral system appears to be the most important factor in the sense that plurality tends to a two-party system (via Duverger’s law) and PR removes this tendency. But this choice is itself affected by the size and diversity of the country, as well as more arbitrary factors such as the year the system was chosen and whether the country was a former British colony. Furthermore, whether a country moves to PR is a complicated issue that depends on the existing electoral system and/or whether the existing parties in power view the change as being to their political benefit. It is perhaps not very comforting to find that the particulars of a country’s political system sometimes depends as much upon luck as anything else, but perhaps this understanding will help open more debate on deciding the most suitable political and electoral system to implement.

References (link)

Anckar, Carsten. (2001). Effects of electoral systems: A study of 80 countries. Paper presented at the SNS Seminar in Stockholm, September 28-29, 2001.

Blais, Andre and Massicotte, Louis. (1997). Electoral Formulas: A macroscopic perspective. European Journal of Political Research, 32. 107-29.

Blais, Andre, Dobrzynska, Agnieszka , and Indridason, Indridi H. (2005). To adopt or not to adopt proportional representation: the politics of institutional choice. British Journal of Political Science, 35. 182-190.

Boix, Carles. (1999). Setting the rules of the game: The choice of electoral systems in advanced democracies. American Political Science Review, 93. 609-624.

Duverger, Maurice. (1963). Political Parties: Their organization and activity in the modern state. 3rd edition. (B. North and R. North, Trans.). London: Metheun. New York: Wiley.

Mainwaring, Scott. (1992). Presidentialism in Latin America. In Arend Lijphart [ed]. Parliamentary versus Presidential Government. New York: Oxford. p. 111-117.

Rae, Douglas. (1971). The Political Consequences of Electoral Laws. 2nd edition. New Haven: Yale.

Rae, Douglas, Hanby, Victor, and Loosemore, John. (1971). Thresholds of representation and thresholds of exclusion. Comparative Political Studies, 3. 479-488.

Riker, William H. (1986). Duverger’s Law Revisited. In Bernard Grofman and Arend Lijphart [eds]. Electoral Laws and Their Political Consequences. New York: Agathon. p. 19-42.

Sartori, Giovanni. (1986). The influence of electoral systems: Faulty laws or faulty method? In Bernard Grofman and Arend Lijphart [eds]. Electoral Laws and Their Political Consequences. New York: Agathon. p. 43-68.

Stepan, Alfred and Skach, Cindy. (1993). Constitutional frameworks and democratic consolidation: Parliamentarianism versus presidentialism. World Politics, 46, (1). 1-22.