VOTING.WIKI

01

First past the post.

The simplest counting method — and the most consequential. Whoever has the most votes wins. The ballot is short, the rules fit on a postcard, and the math is grade school.

It rewards being the first preference of the largest minority. It punishes splits among allies. In a three-way race with one consensus candidate, plurality can hand the seat to whoever everyone agrees should be second.

• 1791first U.S. House under plurality
• ~58countries that use it for legislatures
• 35.9%winning share with the lowest plurality (UK 2005)

02

Ranked-choice voting.

Voters list candidates in order of preference. The lowest-ranked candidate is eliminated round by round, and their ballots are redistributed to the next preference still standing.

RCV (also called instant-runoff) reduces the spoiler effect and lets voters express nuance without throwing their ballot away. The math is heavier; the user experience is — with a good ballot — not noticeably harder.

1. round 1 No one clears 50%.
2. round 2 Last-place candidate eliminated; ballots redistributed.
3. round 3 Repeat until a majority winner emerges.

03

Approval voting.

Vote for as many candidates as you approve of. The candidate approved by the most voters wins. No ranking, no rounds.

Approval is unusually robust to the spoiler effect because adding a candidate cannot hurt the candidates a voter already approves of. Critics note it asks voters to pre-decide a personal threshold — what counts, for them, as “acceptable”?

04

Single transferable vote.

A multi-winner generalization of ranked choice. Used to elect a body, not a person. Surplus votes from winners transfer to next-preferences; losers are eliminated and theirs do too.

STV is the closest practical thing to proportional representation while keeping local geographic representation intact. Ireland and Malta have used it for nearly a century; the Australian Senate uses it now.

quota   = floor(votes / (seats + 1)) + 1
elected = candidates with first-prefs ≥ quota
surplus = (elected_votes − quota) * weight

05

The threshold question.

Every system asks the voter for some unit of preference. Plurality asks for one favorite. Approval asks for a set. Ranked methods ask for an order. Score systems ask for a number.

There is no neutral choice. The shape of the ballot shapes the politics that follow. Choosing a voting system is not a technical question with a hidden right answer — it is itself a vote, cast at the level of the rules.

“Every electoral system creates the electorate it claims to measure.”