A simple guide to electoral systems-Majoritarian systems

In my writing, I use terms that not all of my readers will understand. While I use them habitually, some of the people who read this may not have the grasp on electoral systems required to get a full understanding of the point I am trying to make. This post, which hopefully will be followed up with one on proportional systems, will attempt to rectify this.

What are majoritarian systems?

Electoral systems can mostly be divided into two families, although there are a number of systems that cannot be easily divided into these groups that I will cover in a later post. There are the majoritarian systems, which tend to be designed to give parliamentary governments stable majorities, and the proportional systems, which tend to be designed to closely match seat and vote shares. Majoritarian single-seat systems are exclusively used for presidential election.

Majoritarian systems are the oldest type of electoral system. They were used to elect the first parliaments. Proportional systems were only invented around the 1900s, and only came into common use after World War 1.

The main systems

First past the post/single member plurality

The first past the post (hereafter referred to as the single-member plurality system) electoral system is the oldest electoral system. It is very simple. Areas are divided into constituencies or electorates, each electing one member of Parliament. Voters vote for one candidate, and the candidate with the most votes win. The system is also used for presidential elections, where the whole country is treated as one constituency. 

The system can be modified to elect more than one member. Under this system, known as the 'block vote' or 'multiple non-transferable vote', voters have as many votes as members of parliament to be elected. The candidates with the most votes are elected.

Another modification, known as the 'party block vote', also elects more than one member. Under this system, parties put up list of candidates, and voters vote for a list. The list with the most votes elects all of the candidates on that list as members of parliament. This system, considered fairly undemocratic, is used in (surprise!) Singapore.

These systems tend to favour parties that have popularity nationwide, or high popularity in a certain area. Duverger's Law, a series of 'rules' written by political scientist Maurice Duverger, states that single-member plurality tends to create a two-party system.  The system is used in many countries, most of which use it due to British colonial practice. Single-member plurality used in the United Kingdom for national and local elections, India for all direct elections, the United States, and Canada.

Two-round system

The two-round system is another majoritarian electoral system with some variations. Under the two-round system, one election is held, in which any candidate may participate. If any candidate wins a majority, the election is over. Otherwise, another round is held. The criteria for entering this round differs amongst systems; some only permit the top two finishers in the second round, others set a numerical threshold, and others allow any candidate to compete in the second round. At the second round, the highest polling candidate wins.

This system can be modified to elect multiple members. In one method, used in French local government, voters have as many votes as there are seats. Any candidates with 50% of the votes cast (not ballot paper votes) are elected. A second round is held, at which twice the candidates left to be elected are permitted to participate. In this election, the number of candidates not elected in the first round are elected as the highest polling candidates.

Another method is basically the party block vote, except if no list wins 50% in the first round, a second round is held, in which the highest polling list wins, and the list candidates are elected.

The basic system is used in France to elect the President and National Assembly, as well as in many French colonies. It is used more commonly for Presidential elections than to elect parliaments. Duverger's Law states that the two-round system will tend to lead to two broad coalitions of parties opposing each other. The system tends to be very majoritarian, and it is often used to remove representation from unpopular parties, such as the National Front in France.

Alternative vote/Instant runoff voting/Preferential voting

This electoral system, known mainly by three names, but which I will refer to as instant runoff voting, is a preferential system of voting. Voters use a preferential ballot (example below).

Australian ballot paper. Credit:Antony Green

Under this system, voters vote 1 for their most preferred candidate, 2 for their next most preferred, and so on. Under some systems, voters must number every box, while some systems require just a 1.

At the start of the count, all the 1 votes are counted up. Any candidate with 50% of the 1 votes is elected. If no candidate has 50%+1, the candidate with the fewest 1 votes is excluded. Their preferences (next numbers) are distributed to candidates still in the count. If any candidate now has a majority, they are elected. If not, the lowest polling candidate has their preferences distributed. This process is repeated until one candidate gets 50%+1.

This system is relatively rare. It is used for all elections in single-member electorates in Australia, for all elections in Papua New Guinea, and for by- and presidential elections in the Republic of Ireland. It is also used for presidential elections in Sri Lanka.

A modification of this system,, called the 'supplementary vote' is used for English mayoral elections. Under the supplementary vote, voters may give a first preference to one candidate, and a second preference to another. No further preferences may be given. At the first count, all first preferences are counted. If no candidate wins a majority, all candidates but the top two are excluded, and any of their second preferences that were cast for the top two are transferred to the second preference. The candidate with the most votes in the top two after preferences is elected.