Utility: Difference between revisions
no edit summary
Psephomancy (talk | contribs) (a note from talking with Effective Altruists yesterday) |
No edit summary |
||
Line 1:
Utility broadly means satisfaction.
Though often used in voting theory to refer to cardinal utility i.e. [[Rated method|rated method]] utility, it can also be used for discussing ordinal utility i.e. ranked-preference utility. (The [[Borda count]] uses ranked ballots to find what this article would describe as rated utilities).
An example would be (using a [[preference-approval]]):
Line 26:
There are two ways to derive ranked ballots using ordinal utility. The first is for a voter to ask themselves "who are the candidates I would want to win if I could choose the winner myself?" This is equivalent to asking who you would honestly vote for in [[FPTP]], and it shows who your 1st choice(s) are. If you then remove them from consideration and repeat the question, you find your 2nd choices, etc. The second way is for a voter to ask themselves, for every possible [[head-to-head matchup]], who they'd prefer. The [[Copeland]] ranking shows the voter's ranking of the candidates. This is arguably one way to justify [[Smith-efficient]] [[Condorcet methods]]: if, for an individual voter, the best candidate(s) are the ones from the smallest group that win all head-to-head matchups against all other candidates based only on that voter's judgment, then why not for society? Similar reasoning shows why [[Score voting]] can be justified using rated utilities in head-to-head matchups to quantify harm or benefit done to the voter.
One notable contrast between ordinal and cardinal utility is that with ordinal, one voter can shift their preference to make a good majority-preferred candidate become a bad minority-preferred candidate, whereas with cardinal utility, there is a degree of damage i.e. it is not too bad a thing to elect a candidate with slightly less utility than the utilitarian winner.
== Utility vs utility ==
| |||