Exhaustive Ballot - Tactical Voting

Tactical Voting

Like instant-runoff voting, the exhaustive ballot is intended to improve upon the simpler 'first-past-the-post' (plurality) system by reducing the potential for tactical voting by avoiding 'wasted' votes. Under the plurality system, which involves only one round, voters are encouraged to vote tactically by voting for only one of the two leading candidates, because a vote for any other candidate will not affect the result. Under the exhaustive ballot this tactic, known as 'compromising', is sometimes unnecessary because, even if the voter's first choice is unlikely to be elected, she will still have the opportunity to influence the outcome of the election by voting for more popular candidates once her favourite has been eliminated. However the exhaustive ballot is still vulnerable to tactical voting under some circumstances. Because of the similarity between the two systems it is open to the same forms of tactical voting as IRV.

Although the exhaustive ballot is designed to avoid 'compromising' the tactic is still effective in some elections. Compromising is where a voter votes for a certain candidate, not because they necessarily support them, but as a way of avoiding the election of a candidate whom they dislike even more. The compromising tactic is sometimes effective because the exhaustive ballot eliminates candidates who are unpopular in early rounds, who might have had sufficient support to win the election had they survived a little longer. This can create strong incentives for voters to vote tactically.

Like IRV, the exhaustive ballot is also vulnerable to the tactic of 'push over'. 'Push over' is a tactic by which voters vote tactically for an unpopular 'push over' candidate in one round as a way of helping their true favourite candidate win in a later round. The purpose of voting for the 'push over' is to ensure that it is this weak candidate, rather than a stronger rival, who remains to challenge a voter's preferred candidate in later rounds. By supporting a 'push over' candidate it is hoped to eliminate a stronger candidate who might have gone on to win the election. The 'push over' tactic requires voters to be able to reliably predict how others will vote. It runs the risk of backfiring, because if the tactical voter miscalculates then the candidate intended as a 'push over' might end up actually beating the voter's preferred candidate.