[EM] SODA might be the method we've been looking for.

[Jameson Quinn]

Thanks, Andy, for the SODA endorsement. I agree with the advantages you
list, but I would add the avoidance of the chicken dilemma (that is, the
lack of either a self-reinforcing truncation incentive or hard-to-defend
"mindreading"results that give a burial incentive) as an important
advantage. Compromising favorite betrayal, truncation, and burial are the
basic forms of strategy; and I don't know of any other system which is so
resistant (and yet also resiliant) to all of these.

Jameson

ps. I realize I'm repeating myself a bit, but as Andy said, an occasional
plug for SODA is worthwhile.

2011/12/14 Andy Jennings <elections at jenningsstory.com>

> Jameson,
>
> Believe me, I'm on board with SODA.  I think I, too, like it better than
> LRV, but I'm still trying to get a handle on LRV to make sure.
>
> In my opinion (and my wording), SODA's advantages are:
>
> 1. The laziest possible voter, who just bullet votes for his favorite, is
> still casting a (nearly?) optimal vote that is fair to him and to the rest
> of society.
>
> 2. Voters can vote approval style, instead, if they want.
>
> 3. The only people who have to rank all the candidates are the candidates
> themselves, who should be willing to do the work to come up with a full
> honest ranking.  Their ratings are public, so we can call them out if they
> try to use turkey-raising or other dishonest strategies.
>
> 4. There is a "delegation" phase after the election where the candidates
> can negotiate an outcome, but their ability to negotiate back-room deals is
> severely limited because they have to use their pre-declared rankings and
> they have to play in an order determined by the votes.  In fact, there will
> be a game-theory dominant equilibrium and the candidates will probably have
> very little power to change the outcome.  Chicken scenarios are avoided
> because they know the play order, the other candidates' rankings, and
> exactly how much voting weight each one has.
>
> 5. If there is some super-weak Condorcet winner that is totally unfit to
> govern, then the others can indeed block him in the delegation phase.
>
> I don't see any huge theoretical downsides.  Do others still have
> reservations about SODA?  I realize that some people may be opposed to
> delegation, in principle.  And others think delegable systems just don't
> have a chance of getting implemented.  So I think these debates about which
> is the best voting system in the standard (non-delegable) model are still
> useful.  I also think it's useful for Jameson to inject a plug about SODA
> every now and then.
>
> My main reservation about SODA at this point is that I see no practical
> path to adoption.  It would be perfect for a large primary, like the
> current Republican presidential field, but there's no way to start at that
> level.  We have to start small.  But for small political elections,
> professional societies, open source decisions, elementary school elections
> etc. it seems too complicated.  I had a long discussion with a party
> district chairman here.  He's interested in alternative voting systems to
> fill his party positions but skeptical of complexity.  I don't even think
> I've pitched him on SODA because he's still thinking about Approval Voting.
>
> And with SODA, you can't just run a straw poll to show it off like you can
> with so many other voting systems.  You need the participation of the
> actual candidates to choose their rankings beforehand and to do their
> delegation afterwards.
>
> I know we haven't traditionally discussed implementation strategy on this
> list (though that has changed some recently), but if you see a good
> strategy for SODA adoption, please tell.
>
> ~ Andy
>
>
>
> On Tue, Dec 13, 2011 at 6:55 PM, Jameson Quinn <jameson.quinn at gmail.com>wrote:
>
>> I believe that LRV (Least Resentment Voting) is indeed quite a clever
>> solution to the chicken dilemma. But once more, I'd like to remind people
>> that there is a way to solve the chicken dilemma without risking a victory
>> by the plurality winner/condorcet loser. I'm speaking of course of SODA.
>>
>> First, SODA meets the FBC. In fact, in any 3-candidate scenario, and I
>> believe in any 4-candidate one, it is strategically optimal to bullet vote
>> for a candidate if you agree with their declared preferences. This ability,
>> not just to vote your favorite equal-top, but unique-top, is not shared by
>> any other method I know of. (Perhaps we could call this UFBC3, unique FBC
>> for 3 candidates.)
>>
>> How does it do with chicken dilemma scenarios? For the following, I'll
>> give honest ratings, then discuss the likely strategic implications under
>> SODA.
>>
>> 40 C
>> 25 A>B
>> 35 B>A
>>
>> If this is the honest situation, then candidates A and B have every
>> reason to find a way to include each other in their predeclared preference
>> lists. These predeclared lists are made openly, and so one side cannot
>> betray the other without giving the other side a chance to retaliate. The
>> chance for retaliation will make betrayal a losing strategy.
>>
>> 40 C
>> 25 A
>> 35 B>A
>>
>> If the A camp is honestly indifferent between B and C, and candidate B
>> finds this indifference credible, then B can still decide not to retaliate,
>> that is, to ignore A's truncation and nonetheless declare a preference for
>> A. This enables A to win without B spoiling the election.
>>
>> (Any single-round method which elects A here is subject to the chicken
>> dilemma; electing B is, in my mind, crazy; and any method which elects C
>> here has been spoiled by candidate B, and so encourages shenanigans of the
>> republicans-funding-greens sort. Any method I know of except SODA fails in
>> one of these ways.)
>>
>> 40 C
>> 25 A>B
>> 35 B
>>
>> This is like the above situation, but since A had no chance of winning
>> anyway, they have even less of a motivation to retaliate against B, whether
>> or not B's truncation is honest.
>>
>> 40 C>>A
>> 25 A>>B
>> 35 B>>A
>>
>> In this situation, it's difficult to say who's the "correct" winner;
>> depending on the underlying utilities, it could easily be any of the three,
>> so I'd have no problem with a method that elected any. Still, ideally a
>> method would give similar results here as in the situations above, so that
>> candidates and voters are not motivated to be conciliatory, rather than
>> projecting an image of someone who's inclined to truncate.
>>
>> Strategically, it is in B's interest to truncate, to reduce the chance of
>> 10 C>>A voters voting CA and thus giving A the all-important second move in
>> the vote delegation stage. Then, candidate A will declare a preference for
>> B, in order to present C with a credible threat. And candidate C will
>> declare a preference for A to prevent B from winning.
>>
>> 40 C>>A???
>> 25 A>B
>> 35 B>>A???
>>
>> This is the "weak condorcet winner" situation. The question marks denote
>> a "preference" for the dark-horse candidate A which would evaporate in a
>> runoff, when people took a hard look at A without being distracted by the
>> C/B rivalry. If that is the case, A should not win. And indeed, even if C
>> predeclares a preference for A, when C is faced with the morning-after
>> reality of the choice to throw the election to A or allow it to go to B,
>> they have a chance to leave it with B if A is really such a bad candidate.
>> Sure, C may prefer a weak winner who owes them a favor to a stronger
>> opponent, and so elect A even if B would be socially-optimal; but at least
>> SODA gives B a chance in this situation. Any Condorcet method would simply
>> elect A and not look back.
>>
>> I think that the situations above show that SODA always allows honest
>> truncation without a strategic penalty, but does not encourage strategic
>> truncation.
>>
>> I know that some people on this list dislike SODA for its delegation.
>> Obviously, I disagree. Consider:
>> - SODA delegation is optional and eyes-open. Because of pre-declaration,
>> you know what kinds of result your delegated vote could and could not
>> promote, and if you don't like those results, you don't delegate.
>> - SODA delegation allows results that seem to me to be obviously better
>> than other methods in the above scenarios.
>> - SODA delegation allows for unmatched simplicity from the average
>> voter's perspective. If you like your favorite's declared preferences, just
>> vote for them, and you're done.
>> - SODA delegation allows significant minority candidates a moment of
>> personal power, which they can use to extract (non-binding) promises before
>> throwing their votes behind someone. I believe that this transitory moment
>> of minority power is a healthy compromise between the stability and
>> leadership in winner-take-all systems and the broader accommodation of
>> minority interests in parliamentary systems.
>>
>> Of course, there are cases where SODA is not ideal. For instance, for a
>> pre-election poll, SODA cannot be used unless the inter-candidate
>> preferences can be somehow known or inferred. Still, I think SODA is
>> overall a standout good method for most cases where high-stakes
>> single-winner elections are appropriate.
>>
>> Jameson
>>
>>
>
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