Monotonicity
The monotonicity is a Voting Theory criterion/principle that characterizes voting methods for choosing the winner.
Monotonicity is satisfied when:
- if
- an alternative $x$ rises or does not fall in the individual ordering and
- $x$ was preferred to another alternative $y$ before the change in the individual orderings
- then
- (1) $x$ should still remain at least at the same position
- (2) if $x$ is a winner, it should remain the winner
- (note that (1) $\Rightarrow$ (2))
Theorems
This principle is used in two important Voting Theory theorems:
Methods
Methods that respect Monotonicity:
Methods that don't respect Monotonicity
Sources