Vote splitting: Difference between revisions

The major advantage of such a system is to eliminate the standard forms of vote splitting which are present in [[Single-mark ballot]] systems. This effectivelycan eliminateslargely eliminate issues that give rise to the [[wasted vote]], orthough most ranked methods do still fail the [[Favoritefavorite betrayal criterion|favorite betrayal]] problems.

Unfortunately, it can be proven mathematically that ranked ballots cannot produce a communal preference without serious issues. There are no non-dictatorial rank voting systems that satisfy both [[Pareto Criterion]] and [[Independence of irrelevant alternatives]] in a way that can produce such a communal preference. This is known as [[Arrow's impossibility theorem]] and states that when voters have three or more candidates, no ranked voting electoral system can convert the ranked preferences of individuals into a community-wide (complete and transitive) ranking while also meeting [[Pareto Criterion]] and [[Independence of irrelevant alternatives]].{{redundant}} Both [[Pareto Criterion]] and [[Independence of irrelevant alternatives]] are well-supported requirements by experts and the general public, though note that [[IIA]] is incompatible with [[majority rule]]. The main reason that ranked ballots are still proposed as a solution to vote splitting is that the general public is not aware of the [[Arrow's impossibility theorem]]. It is mathematically complex and somewhat counter-intuitive in many systems so is easily ignored. There is a large discrepancy between what the voter impact is perceived to be and what occurs in implementation.

Cardinal voting systems do not have vote splitting. However, some [[Multi-Member System]] can still fail criteria related to Vote splitting such as [[Independence of irrelevant alternatives]]. Note that in practice, because it is expected that at least some voters will [[Strategic voting|strategically vote]] or [[normalize]] their ballots, that all cardinal methods will fail [[IIA]].