Technical Evaluation of Election Methods

An election method is a voting procedure and a set of mathematical rules for determining the winner(s). The best election method gives the electorate, to the maximum extent possible, the leaders they sincerely prefer, and it minimizes their need to vote strategically (e.g., for the "lesser of two evils"). The choice of an election method should not be based on subjective notions, nor should it be designed to advance any particular social, political or ideological agenda (other than fair elections, of course). It should be based, rather, on a set of strictly objective technical criteria. The criteria we choose are listed below, followed by a compliance table. Of those criteria, we consider monotonicity mandatory, and we consider compliance with Condorcet and other criteria highly desirable.

  • Monotonicity Criterion (MC)
  • Condorcet Criterion (CC)
  • Generalized Condorcet Criterion (GCC)
  • Strategy-Free Criterion (SFC)
  • Generalized Strategy-Free Criterion (GSFC)
  • Strong Defensive Strategy Criterion (SDSC)
  • Weak Defensive Strategy Criterion (WDSC)
  • Favorite Betrayal Criterion (FBC)
  • Summability Criterion (SC)
Table 1: Election method criteria compliance (X=complies)
 
 
 
M
C
 
 
C
C
 
G
C
C
 
S
F
C
G
S
F
C
S
D
S
C
W
D
S
C
 
F
B
C
 
 
S
C
Condorcet X X X X X X X ? X
Approval X - - - - - X X X
Cardinal X - - - - - X X X
Plurality X - - - - - - - X
Borda X - - - - - - - X
IRV - - - - - - - - -

The election methods considered here are far from a complete list of all methods that have ever been seriously proposed, but they are the methods we consider most important. We consider Condorcet the best choice, because it is the only method that complies with both the monotonicity and Condorcet criteria, as well as several others. We consider Approval a good second choice, with the advantage of extreme simplicity. Unlike Condorcet, Approval Voting has a realistic chance of being adopted in the near term. Cardinal Ratings are strategically equivalent to Approval but more difficult to implement, hence they are not worth pursuing.

Plurality is important only because it is the current election method. We consider Instant Runoff Voting (IRV) the worst choice, but it is important because it is currently popular among electoral reform organizations, unfortunately. IRV does have one point in its favor: it requires the same voting equipment and voting procedures (ranking candidates) as Condorcet voting, so it could possibly be a step toward Condorcet voting. Borda is not a serious contender but is included here because it is relatively well known.

Note that the Condorcet method has several possible variations for resolving cyclical ambiguities, but Table 1 applies to the SSD (Schwartz Sequential Dropping) method, which is explained elsewhere at this website.