Condorcet//Approval

From Electowiki
(Redirected from C/A)
Jump to navigation Jump to search

Condorcet//Approval is an election method by which the Condorcet winner is elected if one exists, otherwise the approval winner is elected. Also see Smith//Approval below.

Explicit/Implicit Approval[edit | edit source]

Approval can be designated by a cutoff ranked among alternatives (explicit approval). Alternatively, if truncation is allowed, all explicitly ranked candidates could be considered to be approved (implicit approval).

Burial resistance[edit | edit source]

Condorcet methods are generally vulnerable to burying strategy. One faction buries a candidate by ranking him insincerely below other candidates. This is an attempt to give this candidate new or stronger pairwise defeats.

When all explicitly ranked candidates are considered approved, Condorcet//Approval makes burying strategy more risky than in other Condorcet methods. Burying is only effective when it prevents the targeted candidate from being the Condorcet winner. But a faction can't succeed in this task without then being counted as approving the candidate(s) beneath which the targeted candidate was insincerely ranked. This makes it quite likely that burying strategy will backfire, and cause a candidate to be elected who is actually liked less than the targeted candidate.

One drawback in proposing implicit approval of all explicitly ranked alternatives is that, in general elections, many "sincere" (naive) voters will feel entitled to rank all alternatives. Many may then bristle at the assertion that they approve of unsavory candidates by exercising their franchise to distinguish between lesser and greater "evils". This perception may be mitigated somewhat by a change in terminology. Even so, voters or legislators may balk at reform if they anticipate voter frustration.

Favorite Betrayal criterion compliance[edit | edit source]

Approval voting's satisfaction of the Favorite Betrayal criterion can be preserved in Condorcet//Approval by using the tied at the top rule. This results in the Improved Condorcet Approval method. However, this variant technically isn't Condorcet-compliant.

Satisfied Criteria[edit | edit source]

Condorcet//Approval satisfies Condorcet and always elects a majority favorite, but doesn't satisfy Smith or the Majority criterion for solid coalitions. It satisfies monotonicity and, when truncation is permitted, Minimal Defense (and the Strong Defensive Strategy criterion) and the Plurality criterion.

It fails Clone-Winner, Participation, and Later-no-harm.

Smith//Approval[edit | edit source]

The approval winner may be limited to the Smith set. This variation perforce satisfies the Smith criterion and the Majority criterion for solid coalitions. It satisfies clone independence at least when clones are defined such that every voter approves either all or no members of a clone set.

Explicit, Fully Ranked Smith//Approval[edit | edit source]

If this deserves a concise name, then use mine -- Jrfisher
Voters must rank all but one alternative, (disallow ties or truncation).
Therefore, use an approval cutoff (explicit approval).
Pick the Condorcet Winner (CW) if there is one. Otherwise...
Find the smallest set of alternatives having no defeats outside the set (Smith set).
Within that set, the alternative with the most winning votes against the approval bar is the winner.

See also[edit | edit source]

Definite Majority Choice (DMC)