User:Psephomancy/CW vs UW: Difference between revisions

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Here are 3 voters (X, Y, Z), and three candidates (A, B, C) in a two-dimensional [[Political spectrum|political space]]. The faint circles show the distance from each voter to each candidate, so you can see that B is slightly closer to Z than C is, for instance.
 
Candidate C is the Utilitarian Winner.: They are the best representative of the entire population (X, Y, Z), and makesmake the population happiest overall.
 
Candidate A is the Condorcet Winner and the Majority Winner.: They are a (slightly) better representative of a majority faction (X, Y), even though they make the minority faction (Z) very unhappy.
 
Condorcet and majoritarian systems choose A, because 2 voters slightly prefer A over C, but C is the best match for ''all'' voters. The fundamental problem with ranked-choice ballots is that they can't capture ''intensity'' of preference, so X/Y's slight preference for A over C is given equal weight to Z's strong preference for C over A.
 
(Borda also chooses A, since it weights all relative preferences equally, even though the preference strengths are not equal. Borda results in A getting 4 points, C 3 points, and B 2 points.)
 
See also [https://leastevil.blogspot.com/2012/03/tyranny-of-majority-weak-preferences.html The Tyranny of Weak Preferences]