How it works, precisely
First round: everyone votes for one option. If one clears the threshold (50 % by default in Placet, adjustable), it is over.
Otherwise a second round pits the top two against each other — the usual rule. French parliamentary elections use a different criterion: every candidate reaching 12.5 % of registered voters qualifies, which is how three-way runoffs happen.
In the second round an absolute majority is mechanically guaranteed: with two options, the plurality IS the majority. That is an arithmetic guarantee, not a guarantee of consensus.
A worked example
The same hundred people, this time over two rounds.
| Option | Round 1 | Round 2 |
|---|---|---|
| Lyon | 40 | 45 |
| Bordeaux | 35 | 55 |
| Lille | 25 | eliminated |
- Nobody reaches 50 %: Lyon and Bordeaux go through.
- Lille's 25 votes transfer: 20 to Bordeaux, 5 to Lyon.
- Bordeaux wins 55 to 45.
The runoff did correct the first round. But note what it did not do: had Lille been everyone's compromise second choice, it would have been eliminated in round one, never tested in a duel.
Where it comes from
The two-round system took hold in France during the nineteenth century and became general under the Third Republic. The Fifth Republic adopted it in 1958 for parliamentary elections, then in 1962 for the direct presidential election — first used in 1965.
The idea is a political compromise: keep the clarity of majority voting while fixing its most visible flaw, the minority winner. The runoff forces an explicit choice between two options only.
It spread far beyond France: Austria, Portugal, Brazil, Poland, most Latin American presidential elections, and a large share of French-speaking association ballots.
Where it is used
- The French presidential election and many other republics.
- French parliamentary and departmental elections.
- Association and union ballots, where an absolute majority is often required by statute.
- Weighty group decisions, when a clear mandate matters more than speed.
Limits and pitfalls
- The winner clears 50%
- You can vote with your heart in round one
- A familiar system
- Two ballots to run
- The third-placed could be a better consensus
- Unpredictable vote transfers
Frequently asked questions
Does the runoff guarantee real consensus?
No: it guarantees an absolute majority against ONE given opponent. If the duel on offer is the wrong one — because the compromise was eliminated in round one — the majority obtained is arithmetic, not political.
How can a candidate lose by gaining votes?
By changing their runoff opponent. Suppose you narrowly beat A but lose to B: a few extra first-round votes can eliminate A in favour of B and cost you the election. That is the monotonicity failure, and it is entirely demonstrable.
Two rounds or Condorcet?
Condorcet tests EVERY duel in a single vote, where the runoff tests just one, chosen by the first round. If your group can rank the options, Condorcet answers the same question more completely.
Sources
The primary references this page relies on.
- Constitution du 4 octobre 1958, article 7 (élection du président de la République, rédaction issue de la loi constitutionnelle n° 62-1292 du 6 novembre 1962), Légifrance, 1958, révisé en 1962. ↗
- Code électoral, article L. 162 (second tour des élections législatives, seuil de 12,5 % des inscrits), Légifrance, en vigueur. ↗
- Fishburn, Peter C. et Brams, Steven J., Paradoxes of Preferential Voting, Mathematics Magazine, 56(4), 207-214, 1983. DOI ↗