Proposition - Yes/No/Abstain
UN General Assembly
Description: A proposition needs to have a "yes" vote of greater than 50% to be accepted.
This ballot allows a voter to abstain from a central Yes / No style of proposition.
Abstension are not used in the calculation of the result, which means that for the proposition to pass there still needs to be more "yes" votes than "no" votes.
As with the basic yes/no proposition, the inclusion of the choice to abstain means that the "yes" vote needs to be more than 50% of the combined "yes" and "no" vote. Abstensions are therefor used effectively opt out of the decision making process.
Commentary: Ahhh the good ole 'Fence Sitter' !
This allows for one of the simplist forms of voting tactics. The advantage is that it allows a voter to remain distanced from the outcome of one decision in order to better position themselves for another (later) decision, which is more important to them.
When two rival camps are diametrically opposed on an issue, if a third camp decides to abstain from the vote, then it may work that on any subseqent issue, the third camp will have neither of the two other camps as enemies, thus enhancing their position.
Political manouvering aside, it could be argued that the impetus to abstain from a vote may be based on the idea of acting from a "higher" set of principles. There is a tendency to view an abstension as though to say, "I am not going to drop down to your level in order to debate this."
History: Like the agree/disagree proposition, this one is as old as democracy itself.
In more modern forms, the abstension could be argued to be the equivalent of a "no" vote in a "yes/no" decision that uses concensus rules.
Examples: The abstension is often used in meetings. The UN General Assembly, for instance, will allow for countries to abstain from a proposition vote. Often this will signify that the country neither accepts or rejects a decision, but is more concerned with not getting either the proponents or detractors off side.