Electoral systems matter because – in interaction with other structural and institutional factors – they influence incentives regarding government effectiveness, violence and conflict, accountability, public policy, and electoral malpractice. There are trade-offs involved in all electoral systems. For example, proportional representation systems may be more likely than majority systems to produce desirable public goods – but they also foster greater corruption.
An electoral system determines the way in which votes cast in a general election are translated into seats in the legislature. Electoral systems can be grouped into four categories based on their electoral formula:
- Plurality/majority systems: These include First Past the Post, Block Vote, Party Block Vote, Alternative Vote, and the Two-Round System. They usually involve only one seat and one candidate per electoral district. Under plurality, candidates can win a seat when they win the most votes. Majority systems try to ensure that the winning candidate receives over 50 percent of the votes, using voters’ second preferences.
- Proportional representation (PR) systems: These include List Proportional Representation and the Single Transferable Vote. They aim to equate a party’s share of parliamentary seats with its share of the national vote. This is usually done through party lists of candidates: in open lists voters rank candidates in order of preference; in closed lists, the party decides the order of the candidates.
- Mixed systems: These include Mixed Member Proportional and Parallel systems, and combine elements of the above.
- Other systems: These are the Single Non-Transferable Vote, the Limited Vote, and the Borda Count.
Electoral systems can impact governance dimensions and dynamics such as the following:
- Government effectiveness: The conventional wisdom has been that plurality systems tend to produce more effective and decisive government than PR systems because they are supposed to limit party fragmentation. However, the evidence on this remains inconclusive. It may be more useful to think about the question of government effectiveness and party systems not in terms of plurality systems vs. PR systems in the aggregate, but rather in terms of the different incentives and dynamics embedded within the different sub-categories. Research suggests that, the more candidate-centered the electoral system, and the greater the pressure for intra-party competition, the greater the level of fragmentation, irrespective of whether the system in place is a plurality. Further, contextual variables (such as the regional concentration of voters) are crucial in mediating the relationship between electoral systems and government effectiveness.
- Violence and conflict: No single conflict-managing electoral system will work in all contexts. Plurality systems may be more likely to encourage parties to make broader appeals to the population at large, but may remain less representative. PR systems, on the other hand, may be more representative but they may also be more likely to exacerbate fault lines of conflict than to generate compromise. Systems like the Alternative Vote and the Single Non-Transferable Vote may help to alleviate some of these problems, but AV is complex and SNTV may accentuate internal party fragmentation and clientelism. Two-round majority systems can promote greater cohesion of the party system, but tend to be expensive and demanding on the electorate.
- Incentives for developing candidate- or party-based reputations: The greater the ability of the party leadership to exert party discipline and the lesser the extent of intra-party competition, the greater the value of party reputation in electoral contests.
- The provision of public vs. more targeted goods: Pork barrel politics – spending that benefits a narrow group of citizens often in the politician’s ‘home district’ – is thought to be more prevalent where the electoral system is based on candidate-centred as opposed to party-centred competition.
- Corruption: Closed-list PR systems seem to be most susceptible to corrupt political rent-seeking because they weaken the link between performing well in office and re-election, and they give more power to party leaders, making monitoring difficult.
- Electoral malpractice: Recent research by Birch has suggested that elections in single member district (plurality) electoral systems are easier to manipulate reliably than those in PR systems.
Understanding how electoral systems work provides insight into the interests, opportunities and constraints that drive political actors. Further lessons are that:
- Context matters for the consequences of the choice of a particular electoral system. Relevant contextual factors include the nature of societal cleavages, federal vs. unitary systems, and the nature and quality of political parties.
- Choices of electoral design are not technical but political. Effects of changes to electoral systems are likely to take time to appear, and may produce unintended consequences in the long term.
- The influence of changes in electoral systems is likely to be incremental, but can be quite important.
- The design of constitutional structures and electoral rules is a balancing act that has produced a wide range of both problems and solutions.
