Why preferential voting is superior to first past the post

The South Australian state election will be held on March 21. Preferential voting will be used to elect members for all 47 single-member lower house seats. This is the same system as used for federal House of Representatives elections.

Some Australian conservatives are advocating Australia return to first past the post (FPTP), but a conservative government introduced preferential voting in 1918 to stop vote splitting between two conservative parties. Right-wing preferences helped the Coalition maintain its grip on power from 1949 to 1972. Preferential voting is far superior to FPTP.

After Labor’s landslide at the May 2025 federal election, some right-wingers have complained that preferential voting gave Labor too many seats. They want Australia to revert to FPTP, where there are no preferences. In FPTP, the candidate with the most votes wins the seat.

National primary votes at the election were 34.6% Labor, 31.8% Coalition, 12.2% Greens, 6.4% One Nation and 15.0% for all Others. After preferences, Labor defeated the Coalition by 55.2–44.8 and won 94 of the 150 House of Representatives seats (63% of seats). In both two-party and seat share, this was Labor’s biggest win since 1943.

While Labor’s margin expanded after preferences, they won the national primary vote by 2.8%. Analyst Kevin Bonham said that on primary votes, Labor would have won 86 seats to 57 for the Coalition (actual 94 to 43). Labor’s primary votes were much more efficiently distributed than the Coalition’s.

Labor won a disproportionate seat share at the election, but this occurs with single-member systems, particularly with a blowout result. Those complaining about Labor’s big majority should advocate switching to proportional representation, not FPTP.

The United Kingdom 2024 election was held using FPTP. Labour won 411 of the 650 seats (63% of seats) on 33.7% of the national vote. This occurred primarily because Labour’s vote share was ten points ahead of the second placed Conservatives.

A brief history of preferential voting in Australia

Prior to 1918, federal elections used FPTP. In 1918, there was a byelection for Swan that was contested by the Nationalists (a predecessor of the Liberals), the Country Party (a predecessor of the Nationals) and Labor.

Labor won this byelection with 34.4%, to 31.4% for the Country Party and 29.6% for the Nationalists. With the combined vote for the two conservative options adding to 61.0%, it was clear a different system would have given the Country Party the win.

After this byelection, the Nationalist government introduced preferential voting, resulting in Labor losing the Corangamite byelection in 1918 to a Victorian Farmers candidate by 56.3–43.7, despite Labor winning the primary vote by 42.5–26.4 with 22.9% for the Nationalists.

Originally preferential voting was introduced to allow the two conservative parties (now Liberals and Nationals) to compete against each other without splitting the conservative vote and giving Labor wins it didn’t deserve. There are still “three-cornered” contests now where the Liberals, Nationals and Labor all contest the same seat.

This Wikipedia page gives national primary votes for Labor, the Coalition and all Others, the Labor and Coalition estimated two-party share and House seats won by Labor, Coalition and others at elections from 1910 to 2022.

Until the 1990s, the combined primary votes for the major parties was around 90% in most elections. This means that other than in three-cornered contests, preferences had limited impact. There were high Other votes in 1931, ‘34, '40 and '43, with the first three cases due to a Labor split (New South Wales Lang Labor).

In the first two of these cases, Labor was far behind on primary votes and made up some ground on preferences, but the Coalition still won easily. In 1940, Labor trailed by 3.7% on primary votes but won the two-party vote by 50.3–49.7. However, the Coalition formed government with the support of two independents until those independents sided with Labor in 1941.

In 1943, there was a split within the Coalition, and other preferences favoured the Coalition, reducing Labor’s primary vote lead of 26.9 points to 16.4 points after preferences.

In 1955, a Labor faction split from Labor and became the Democratic Labor Party (DLP), directing preferences to the Coalition. From 1955 until the DLP’s demise in 1974, it dominated the third party vote, and so overall preferences in this period assisted the Coalition.

The DLP helped the Coalition to have the longest period of one-party government from 1949 to 1972. Labor was estimated to have won the two-party vote in 1954, 1961 and 1969, but the Coalition won a majority of House seats.

Since 1987, preferences have favoured Labor, allowing it to overturn primary vote deficits to win the two-party vote in 1987, 2010 and 2022. First the Democrats and then the Greens assisted Labor after preferences. One Nation’s first rise at the 1998 election didn’t stop overall preferences from favouring Labor.

The only time Labor formed government while losing the two-party vote occurred in 1990, when they won a majority of seats despite losing by 50.1–49.9. Labor lost the election in 1998, even though it won the two-party vote by 51.0–49.0.

Some recent polls have One Nation surging into second place behind Labor, ahead of the Coalition. On current polling, there are more right-wing sources of preferences than left-wing sources, so overall preference flows could favour the right at the next federal election, whether it’s One Nation or the Coalition that benefits most.

In early elections, some seats were often uncontested, meaning only one candidate nominated for that seat. No votes were counted in such seats, so national primary votes will be distorted by the exclusion of these seats.

Why preferential voting is superior to FPTP

At the 2025 election, Labor’s Ali France defeated Liberal leader Peter Dutton in his seat of Dickson by 56.0–44.0. But Dutton had more primary votes than France, winning 34.7% of the primary vote to 33.6% for France, with 12.2% for a teal independent, 7.6% for the Greens and 4.2% for One Nation.

FPTP gives a massive benefit to the side of politics (left or right) that has its vote more concentrated with one party or candidate. In the two 1918 byelections, the left vote was concentrated with Labor, and in Dickson 2025 the right vote was concentrated with Dutton. Preferential voting is far fairer by allowing all candidates’ votes to eventually count.

In FPTP, many voters need to choose between supporting the candidate they most prefer even if that candidate is uncompetitive, and voting for the candidate best placed to keep someone they dislike out. Votes for uncompetitive candidates are effectively wasted in FPTP.

Labor may have won Dickson under FPTP as some of the teal and Greens voters would probably have voted for Labor tactically to beat Dutton. But voters shouldn’t need to make these choices.

Parliaments require majorities to function. The party winning the most seats does not necessarily form government, for example Labour formed government after the 2017 New Zealand election even though the conservative National won the most seats.

In the UK, the Conservatives needed to form alliances with other parties after winning the most seats but not a majority at the 2010 and 2017 elections. Preferential voting is closer to parliamentary systems than FPTP.