Idea
Voters number candidates in order of preference. If no candidate has a majority of first preferences, the last-placed candidate is eliminated and those ballots move to their next choice, repeating until someone holds a majority of the remaining ballots. The single-winner form is called instant-runoff voting, the alternative vote, or in Australia preferential voting. Its multi-winner form is the single transferable vote.
Theory
The method aims to give a majority winner without a separate runoff and to reduce vote-splitting among similar candidates. It is not Condorcet-consistent and can be non-monotonic: Doron and Kronick (1977) showed that more support for a candidate can cause that candidate to lose.
Real examples
- Australia: preferential voting for the House of Representatives since the 1918 Electoral Act; first used at the Corangamite by-election, 14 December 1918.
- Maine: Question 5 passed in November 2016; first used in June 2018 primaries; in the November 2018 Second District race Jared Golden beat Bruce Poliquin after transfers.
- New York City: approved in 2019, first used in the 22 June 2021 primaries.
- Alaska: adopted by Measure 2 in 2020.
Critique
Ballots can be exhausted if voters rank few candidates, counting can be slow and harder to explain, and some US states have banned the method.
Results
Claims about reduced polarisation, higher civility or higher turnout are contested; studies differ by place, design and measure.
Claims
Australia's House of Representatives has used preferential voting since the Commonwealth Electoral Act 1918. At the Corangamite by-election on 14 December 1918 William Gibson overtook James Scullin, who led on first preferences, after preferences were distributed.[1][2]
Maine adopted ranked-choice voting by initiative in November 2016 (52.1% yes). In the November 2018 Second District race Jared Golden defeated Bruce Poliquin 142,440 to 138,931 after transfers. New York City approved it for primaries in 2019 and first used it on 22 June 2021.[1][2][3][4]
Evidence that ranked-choice voting reduces polarisation or negative campaigning is mixed: survey work reports more civil campaigns under preferential voting, while studies of exhausted ballots and non-monotonic outcomes qualify claims of broader benefits.[1][2][3]
Revision history
- 2026-10-23rev 1 — Seed import