[EM] Condorcet/Score

[robert bristow-johnson]

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Subject: [EM] Condorcet/Score

From: "Curt" <accounts at museworld.com>

Date: Fri, January 4, 2019 2:47 pm

To: "EM" <election-methods at lists.electorama.com>

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>

> Hi, I was wondering what you all thought of the following reasoning.

>

> 1) Start with the assumption that for a single-winner election, if one candidate would defeat all others head-to-head, that candidate must be the winner. This requires the method to be Condorcet-compliant, and, I believe, disregards the later-no-harm criterion.

>

> 2) Acknowledge the “one-person one-vote” principle that means that if, in a two-candidate election, candidate A has 50 votes and candidate B has 49 votes, then candidate A *must* win, even if B’s voters are wildly more enthusiastic.

>

> 3) Acknowledge that score or range voting *does* have an advantage in recognizing overall utility society when taking into account voter enthusiasm - *if* the enthusiasm is scored/recorded honestly.

>

> 4) Acknowledge the occasional (and probably rare) phenomenon of A->B->C->A loops in Condorcet-style voting, which must be resolved somehow.

>

> 5) Accept that the presence of such loops is not a “bug”, but instead the measurement of some level of indecisiveness among the electorate, such that further voter data is required.

>

> And end up with the following:

>

> 1) Present the ballots as score/range ballots

> 2) When tabulating, use the scores/ranges to deduce an ordinal (ranked-choice) ranking for each ballot, ignoring the scores/ranges otherwise

> 3) Use the rankings to determine if there is a Condorcet Winner. If so, STOP HERE. This makes the voting method Condorcet-Compliant.

> 4) If not, determine the Smith Set

> 5) Use the scores/ranges to determine the winner from within the Smith Set. This makes the method Smith-compliant.

>

> I am not well-versed in voting criteria, but it seems to me this bypasses the worst criticisms of score/range voting, while also taking in account some of their advantage. While score/range voting is susceptible to strategic voting, there should be little incentive for a voter to strategically
adjust their scores *to the point of changing their ordinal ranking*, due to the emphasis on finding the Condorcet Winner first. And so then, since people will be scoring/rating relatively honestly, greater social utility is met in the case where there is not a Condorcet Winner. Finally, we know
that the winner is (ordinally) preferred over all other candidates outside of the Smith Set, making it Smith-compliant. Score/Range/Star voting are not Condorcet-compliant (nor Smith-compliant, I think), but this voting method is.
>
it's not a bad idea.  i had, some time ago, thought of simply deriving ordinal ranking from the score ballot.
doing what you suggest (using Score Voting to resolve a Condorcet paradox or cycle) would require two passes over the voting data or, if it's a single pass, maintaining
both the defeat matrix for ranked-choice/Condorcet and for Scoring later if necessary.
i think the Score ballot imposes a burden of tactical voting on the voter.  How much should a voter score their second choice?  (Approval Voting has a similar problem, when should a voter approve
their second choice?)
Approval Voting (as well as FPTP) gets too little information from the voter, while Score Voting requires too much.  Voters aren't the same as Olympic judges at a skating competition.

--



r b-j                         rbj at audioimagination.com



"Imagination is more important than knowledge."

 
 
 
 
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