An electoral system is a set of institutional formulas producing a collective choice through voting. The main elements of an electoral system are: assembly size or total number of seats; district magnitude or number of seats to be elected in a district; the electoral rule to allocate seats from votes; and the ballot permitting the voter different choices. Different rules and procedures have combined these elements in many ways to produce a variety of electoral systems in the real world.
In late medieval and early modern assembly elections in local communities with homogeneous electorates, relatively simple electoral systems prevailed. A typical system until the nineteenth century was composed of: (1) multi-member districts; (2) plurality or majority rule; and (3) an open ballot. Essentially, voters could vote for their preferred individual candidates, and those with the higher numbers of votes were elected. This type of electoral system can produce a consensual individual representation of the community, especially in contexts of high economic and ethnic homogeneity in which it is relatively easy to identify common interests and select collective goods. Such systems have survived at the local level in some countries, and they are still typically used in meetings and assemblies of modern housing condominiums, neighborhood associations, school and university boards, professional organizations, corporation boards, and students’ and workers’ unions.
However, in contexts of relatively complex and heterogeneous electorates, simple electoral rules create incentives for the coordination of candidacies and voting. Forming a list of candidates, a faction, or, in more modern terms, a party, may move voters to vote en bloc rather than for individuals weighed separately. In multimember districts using plurality rule, voting en bloc (or the general ticket) may produce a party sweep or overrepresentation by a single party. Once partisan candidacies and partisan voting emerged in a number of countries by the mid-nineteenth century, some political leaders, activists, and politically motivated scholars began to search for new electoral rules and procedures that could reduce single-party sweeps and exclusionary victories. The two main options were either retaining plurality or majority rule but in smaller single-member districts, or retaining multimember districts but using new proportional representation rules.
RULES AND PROCEDURES
In a small single-member district, a candidate that would have been defeated by a party sweep in a larger multimem-ber district may be elected. Thus, this type of system tends to produce more varied representation than the old system with voting en bloc. Several majoritarian rules can be applied. With simple plurality, the winner is the candidate supported by only a relative majority, that is, by a higher number of voters than any other candidate but not requiring any particular number, proportion, or threshold of votes. In practice, this makes it possible for generally binding decisions presumably decided by "majority" to actually be won by only a minority of voters. Plurality rule has traditionally been used in England and the United Kingdom and in modern times in former British colonies, including the United States, Canada, and India. Plurality-based electoral systems are also called first-past-the-post and winner-takes-all systems.
With other rules based on the majority principle, if no alternative receives an absolute majority (more than half) of the votes, further rounds of voting are implemented, these rounds either requiring a simple plurality or reducing the choice to the two candidates with the highest numbers of votes in the first round. Such majority-runoff systems have traditionally been used in France, among other countries. A variant requires voters to rank all candidates, and includes several counts of votes (instead of several rounds of voting), until a candidate obtains the most preferences, as in the majority-preferential electoral system used in Australia (also called alternative vote or instant runoff).
Proportional representation in multimember districts allocates seats to multiple parties competing in an election on the basis of the votes received. The basic mathematical formulas that make this principle operable were invented in late eighteenth century for apportioning seats in the U.S. House of Representatives among differently populated states. These formulas were reinvented in Europe in late nineteenth century for the allocation of parliamentary seats to political parties with different numbers of votes. A proportional representation formula defines a quota of inhabitants or votes worth a seat. The "simple" quota (as devised by both Alexander Hamilton [1755/57-1804] and Thomas Hare [1806-1891]) is the divisor between the total number of inhabitants or votes and the total number of seats. But it usually requires an additional criterion to allocate some of the seats, most commonly to the largest remainders after the quota is used. In contrast, the smaller highest average or distributive number (as devised by both Thomas Jefferson [1743-1826] and Victor d’Hondt [1841-1901]) is sufficient to allocate all seats. This quota can be calculated after the election by several procedures, including trial and error, a series of divisors, or by lowering the simple quota until it fits.
Different forms of ballots may either force a categorical vote or permit some choice of individual candidates. Categorical ballots are used in single-member districts where voters can vote for only one candidate, as well as in multimember districts where voters can vote for only a closed list of candidates or en bloc. In contrast, open lists permit voters to select one or several candidates from a party list. With the double vote, voters choose both a closed party list and one individual candidate. The open ballot permits voters to vote for individual candidates from different parties. The majority-preferential vote and the single-transferable vote require voters to rank individual candidates.
ELECTORAL SYSTEM CONSEQUENCES
Elections in single-member districts by plurality or majority rule always produce a single absolute winner, who may have the support of only a minority of voters as a first preference. A winner by plurality or by second-round majority might be defeated by a losing candidate by absolute majority if a choice between the two were available. Majoritarian rules may thus induce nonsincere or "strategic" voting that favors the voter’s second-best or less-rejected candidate, so as to prevent the victory of a least-preferred one. In contrast, proportional representation electoral systems are more inclusive of several groups. Since most votes count to elect seats, they promote a more sincere revelation of preferences by voters.
In parliamentary elections with multiple single-member districts, plurality rule typically gives overrepresentation to one or two parties at the expense of others and fabricates a single party’s absolute majority of seats, thus permitting the formation of a single-party cabinet. In contrast, multiparty parliaments based on proportional representation tend to produce multiparty coalition governments based on a majority of seats and popular votes. In practice, there is a paradox: "majoritarian" electoral systems often create governments with minority electoral support, while proportional representation rules, which were initially devised to include minorities, tend to produce governments with majority electoral support. In plurality-rule electoral systems, a small change in the total number of popular votes can provoke a complete alternation of the party in government. Proportional representation systems, where parties may have opportunities to share power with different partners, produce more policy stability in the long term.
THE CHOICE OF ELECTORAL SYSTEMS
In general, the Micro-mega rule applies: the large prefer the small and the small prefer the large. Specifically, dominant and large parties prefer small assemblies and single-member districts that are able to exclude others from competition. In contrast, multiple small parties prefer large assemblies and large districts with proportional representation that can include them. Existing parties tend, thus, to choose electoral systems that are able to crystallize or consolidate the previously existing party configurations and systems.
However, the size of the assembly is a structural variable positively correlated to the country’s population and difficult to change dramatically. In large countries, such as Australia, Canada, France, India, the United Kingdom, and the United States, a large assembly can be sufficiently inclusive, even if it is elected in small, single-member districts, due to the territorial variety of the representatives. In small countries, by contrast, the size of the assembly is small and, as a consequence, the development of multiple parties favors more strongly the adoption of inclusive, large multimember districts with proportional representation rules. Proportional representation was first adopted for parliamentary elections in relatively small countries such as Belgium, Denmark, Finland, Netherlands, Norway, Switzerland, and other western European democracies in early twentieth century. In the long term, both the number of countries and the number of democracies in the world increase, while large countries decentralize, leading to an overall decrease in the size of democratic assemblies. This induces the adoption of more inclusive, proportional representation electoral rules.
In addition, the number of parties tends to increase under any electoral system as a consequence of the broadening of suffrage rights, as well as initiatives to politicize new issues and change the public agenda by groups seeking power or new policy decisions. Indeed, plurality rule provides incentives to form only a few viable large candidacies or parties. But coordination fails with relative frequency, due to the costs of information transmission, bargaining, and the implementation of agreements among previously separate organizations. Lack of coordination may produce defeats and no representation for candidates, groups, and parties that have significant support among voters. Parties unable to coordinate themselves into a small number of candidacies to compete successfully under plurality rule tend to choose electoral systems that can reduce the risks of competing, giving all participants greater opportunities to obtain or share power.
There is, thus, a general trend toward proportional representation over time. Nowadays, most democratic countries in the world use electoral systems with proportional representation rules. Likewise, for presidential elections, plurality rule tends to be replaced with second-round majority rules permitting multiparty competition in the first round. Many countries have also introduced a greater element of individual candidate voting. In fact, none of the new democracies established in countries with more than one million inhabitants in the "third wave" of democratization (since 1974) has adopted the old British model of a parliamentary regime with elections in single-member districts by plurality rule.
