if the candidate is the 1st choice of a majority of voters, then that candidate should be selected.
Total # of votes + 1
Borda Count Method
Calculate votes by votes and ranking. (can violate majority if majority exists)
Head to Head Criterion (condorcet criterion)
If a candidate is favored when compared seperately with each of the other candidates, then the favored candidate should be elected.
Who is the condorcet candidate?
the candidate who wins each head to head match up.
The monotonicity criterion
Have an election x wins. Some changes are made, all of which favor x. Conduct the election again. X should still be the winner.
Irrelevant- alternatives criterion
Have an election x wins. One of the other candidates drops out. Recalculate the winner. X should still win.
Arrow Impossibility Theorem
States that no system of voting will always satisfy all of the 4 fairness criteria.
Who proved the Arrow Impossibility Theorem? When?
Kenneth Arrow in 1951.
count the # of approvals each candidate received.
Most 1st place votes