Which Method is Fair?
Learning Outcomes
- Determine the winner of an election using preference ballots
- Evaluate the fairness of an election using preference ballots
- Determine the winner of an election using the Instant Runoff method
- Evaluate the fairness of an Instant Runoff election
- Determine the winner of an election using a Borda count
- Evaluate the fairness of an election determined using a Borda count
- Determine the winner of en election using Copeland's method
- Evaluate the fairness of an election determined by Copeland's method
So Where’s the Fair Method?
At this point, you’re probably asking why we keep looking at method after method just to point out that they are not fully fair. We must be holding out on the perfect method, right? Unfortunately, no. A mathematical economist, Kenneth Arrow, was able to prove in 1949 that there is no voting method that will satisfy all the fairness criteria we have discussed.Arrow’s Impossibility Theorem
Arrow’s Impossibility Theorem states, roughly, that it is not possible for a voting method to satisfy every fairness criteria that we’ve discussed. To see a very simple example of how difficult voting can be, consider the election below:5 | 5 | 5 | |
1st choice | A | C | B |
2nd choice | B | A | C |
3rd choice | C | B | A |
Licenses & Attributions
CC licensed content, Original
- Which Method is Fair?. Authored by: Lumen Learning. License: CC BY: Attribution.