Voting System Criteria
Scholars rate voting systems using mathematically derived voting system criteria, which describe desirable features of a system. No ranked preference method can meet all of the criteria, because some of them are mutually exclusive, as shown by statements such as Arrow's impossibility theorem and the Gibbard-Satterthwaite theorem.
Many of the mathematical criteria by which voting systems are compared were formulated for voters with ordinal preferences. If voters vote according to the same ordinal preferences in both rounds, criteria can be applied to two-round systems of runoffs, and in that case, each of the criteria failed by IRV is also failed by the two-round system as they relate to automatic elimination of trailing candidates. Partial results exist for other models of voter behavior in the two-round system: see the two-round system article's criterion compliance section for more information.
The criteria that IRV meets, and those that it does not, are listed below.
Read more about this topic: Instant-runoff Voting
Famous quotes containing the words voting, system and/or criteria:
“All voting is a sort of gaming, like checkers or backgammon, with a slight moral tinge to it, a playing with right and wrong, with moral questions; and betting naturally accompanies it. The character of the voters is not staked. I cast my vote, perchance, as I think right; but I am not vitally concerned that right should prevail. I am willing to leave it to the majority.”
—Henry David Thoreau (1817–1862)
“In a universe that is all gradations of matter, from gross to fine to finer, so that we end up with everything we are composed of in a lattice, a grid, a mesh, a mist, where particles or movements so small we cannot observe them are held in a strict and accurate web, that is nevertheless nonexistent to the eyes we use for ordinary living—in this system of fine and finer, where then is the substance of a thought?”
—Doris Lessing (b. 1919)
“We should have learnt by now that laws and court decisions can only point the way. They can establish criteria of right and wrong. And they can provide a basis for rooting out the evils of bigotry and racism. But they cannot wipe away centuries of oppression and injustice—however much we might desire it.”
—Hubert H. Humphrey (1911–1978)