The Copeland method
The simplest Condorcet method: count the duels won and lost. Easy to tally by hand, but often tied on a cycle. It has no real advantage over Schulze.
When to choose it: if your bylaws require it, or if everyone must be able to redo the calculation in their head. In that case, plan a rule for ties.
- Origin
- Arthur H. Copeland, 1951; the idea goes back to Ramon Llull in the 13th century
- Variants offered
- Copeland
- Computation
- Polynomial, in n² for n options
Counting the duels won.
Each option gets one point per duel won and loses one per duel lost; the ranking follows that score. The Condorcet winner, which wins all its duels, is always elected.
But Copeland ignores the size of the victories: on a cycle, each option wins as many duels as it loses, and they all end up tied, whatever the number of voters.
The same cycle, counted duel by duel.
- Camille , then Adèle , then Sophie 40 voters
- Adèle , then Sophie , then Camille 35 voters
- Sophie , then Camille , then Adèle 25 voters
- 1 Camille. Wins against Adèle, loses against Sophie: score 0.
- 2 Adèle. Wins against Sophie, loses against Camille: score 0.
- 3 Sophie. Wins against Camille, loses against Adèle: score 0.
- Camille 1 won, 1 lost 0
- Adèle 1 won, 1 lost 0
- Sophie 1 won, 1 lost 0
What the method guarantees, compared with first-past-the-post.
The whole family of majority and Condorcet criteria, but neither independence of clones nor ties that fade as the number of voters grows.
| Criterion | Copeland | First-past-the-post |
|---|---|---|
| Majority An option ranked first by more than half of the voters wins. | Yes | Yes |
| Majority loser An option ranked last by more than half of the voters never wins. | Yes | No |
| Mutual majority If a majority ranks a group of options ahead of all the others, the winner belongs to that group. | Yes | No |
| Condorcet winner The option that beats each of the others in a duel is always elected. | Yes | No |
| Condorcet loser The option beaten by each of the others in a duel is never elected. | Yes | No |
| Smith criterion The winner belongs to the smallest group of options that beat every option outside it. | Yes | No |
| Independence of clones Adding an option very similar to another does not change the outcome among the others. | No | No |
| Monotonicity Ranking the winner higher can never make them lose. | Yes | Yes |
| Local independence Removing the option that finished last (or first) in the result does not change the order of the others. | No | No |
| Reversal symmetry If every ballot is reversed, the former winner no longer wins. | Yes Note 1 | No |
| Participation Voting sincerely can never leave a voter worse off than abstaining. | No | Yes |
| Consistency If an option wins in two separate groups, it wins when they are combined. | No | Yes |
| Later-no-harm Ranking an additional choice can never hurt those already ranked ahead of it. | No | Yes Note 2 |
| Resolvability A final tie becomes unlikely as the number of voters grows. | No | Yes |
| Fast computation The result is computed in polynomial time, even with many options. | Yes | Yes |
- ✓ always satisfied
- ✕ can be violated in some votes
- ? no published source establishes it
- 1 Blank cell in Wikipedia’s general table; “yes” in its table of Condorcet methods and in the legacy condorcet.vote table.
- 2 Trivially: first-past-the-post never looks beyond the first choice.
Our implementation choices.
- Wins minus losses. Each duel won adds a point, each duel lost takes one away, and a tied duel counts for nothing.
- No added tie-breaker. Neither Borda nor a drawing of lots: options with the same score share the rank.
- A complete ranking. Options are ordered by decreasing score.
Further reading.
| Type | Reference |
|---|---|
| Encyclopedia | Copeland’s method Wikipedia |
| Documentation | Voting Methods CondorcetPHP · docs.condorcet.io |
| Paper | The Copeland method: I. Relationships and the dictionary Donald G. Saari, Vincent R. Merlin (1996) · Economic Theory 8(1) |
The other methods
- The Schulze method The strongest paths of victories between each pair of options. Our default method.
- The Ranked Pairs method Duels locked in one by one, from the most decisive to the closest, skipping any that would create a cycle.
- The Dodgson Quick method The option closest to beating everyone, following Lewis Carroll’s idea.
- Method comparison Each method’s properties, criterion by criterion, set against first-past-the-post.