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SODA voting (Simple Optionally-Delegated Approval): Difference between revisions

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'''Vote for as many candidates as you approve, or vote for one candidate to delegate your vote:'''<br>
&#9634;▢ Adams (Prefers Churchill, then Bachelet, then Deakin)<br>
&#9634;▢ Bachelet (Prefers Deakin and Churchill)<br>
&#9634;▢ Churchill (Prefers Adams)<br>
&#9634;▢ Deakin (No preferences declared)<br>
&#9634;▢ ____(write-in)____<br>
&#9634;▢ ____(write-in)____
 
'''If you only vote for one candidate, your vote is delegated to that candidate, unless you check the box below.''' A delegated vote means that, if your favorite candidate shows preferences above, he or she may use your vote to approve of one or more of the most-preferred of them. For instance, if he or she can not win, he or she might approve of some other "compromise" candidate(s) who can.<br>
&#9634;▢ Do not delegate. Do not let the candidate I voted for add approvals to my vote.<br><br>
 
 
''Note: If you vote for more than one candidate, or if you vote for a write-in or other candidate with no declared preferences, your vote is not delegated. In that case, no-one can add approvals to your vote, and it does not matter whether you check the box above.''
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:a) '''Before the election, all candidates must strictly rank theall other official candidates in order of preference. Equal rankings are not allowed.''' ''These pre-announced preferences allow voters to make informed decisions in step 2; and prevent corrupt vote-selling in step 3, where candidates may only approve others in a way that is consistent with their preferences.''
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:b) '''Voters may approve one or more candidates, and also have the option to mark "Do not delegate". <u>Delegated votes</u> and initial <u>total approvals</u> are tallied and announced for each candidate.''' ''Announcing full tallies makes step 3 predictable and fair.''
<br>
<big>3. Candidates take turns to publicly use their delegated votes, startingin fromdescending theorder candidateof withdelegated most approvalsvotes.</big>
<br>
:a) ''(optional)'' There is a one-week period for candidates to analyze and negotiate based on these preliminary results. ''Actually, the optimal strategies for all candidates and the resulting winner will already be obvious. Usually, all candidates except this winner would concede as soon as preliminary results are announced. However, for the occasional candidate inclined to act irrationally in a way that matters - say, by not delegating to an ally, even though the alternative is to see an enemy elected - this interim period would give them a chance to rethink things and come into reason.''
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:b) '''As long as noEach candidate, hasin approvalsdescending equalorder toof over 50%number of votersdelegated votes, each candidate in turn mustmay <u>use some or all of their delegated ballots</u> to approve zero or more other candidates., Atconsistent eachwith steptheir predeclared preferences. That is, thethey candidatemay withadd thea highestnumber currentup approvalto totaltheir whodelegated hasvote nottally yetto usedthe theirother ballotscandidates' hasapproval theirtallies, turnas tolong as they do sonot give more to a less-preferred candidate.''' ''If, considering the votes, a candidate can win, they will probably prefer not to approve other candidates. If there are two allied candidates who need to cooperate to win, the one with more approvals has first chance not to approve the other. That way, when it's the weaker candidate's turn, they will no longer have the possibility of winning, so the weaker will approve the stronger.''
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<small><u>'''Use their delegated ballots'''</u>: The process by which a candidate effectively adds approvals to the votes delegated to him or her. When, for example, candidate A uses their delegated ballots to approve of B and C, then B and C's approval totals are each increased by A's delegated vote total. When it is a candidate's turn, they may choose to approve of nobody else, for instance if they believe they will win; but this counts as using their delegated votes, and they will not be given another chance to change that decision. When all candidates have used their votes, the election is over.</small>
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::i. If the candidate using their delegated votes has more than 5% approval, '''they may choose which candidates approve on their delegated ballots, <u>consistent with preferences</u>,''' with equally preferred ties ''(optionally)'' broken by current approval totals. ''This tie-breaking by approval totals resolves the "chicken dilemma", as explained below.''
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<small>'''<u>Consistent with preferences</u>, with equally preferred ties broken by current approval totals''': For example, candidate A may not approve B and not C unless ''either'' A predeclared a preference for B over C, ''or'' A predeclared B and C equal and B currently has more approvals than C.</small>
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::ii. ''(optional)'' If the candidate using their delegated votes has 5% approvals or less, their delegated ballots are used to <u>automatically approve</u> their preference between the frontrunners. ''Automatic approvals respect predeclared preferences but prevent minor candidates from having discretionary kingmaker power.''
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::iii. ''(optional)'' If the candidate is a write-in or got less than 1% direct approvals from voters, they may not use their delegated votes. However, any candidate may approve a write-in, regardless of the predeclared preferences. ''Write-ins do not have a chance to declare or figure in the pre-declared preferences. Candidates with less than 1% are not allowed to use delegated votes to discourage a frivolous proliferation of candidates.''
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<small>'''<u>Automatic approvals</u>''': When approvals are assigned automatically for candidate X, they are set to approve as many of their pre-declared preferences as possible without approving both of the two candidates with the highest current approval totals that they prefer differently. (For example, say that X's preferences were for (A and >B), then >C, then (>D and >E), and the approval totals are 4010, 30, 10, 20, and 15 alphabetically. A has the highest total; B has the next-highest, but does not count, because they are preferred equally to A; and D hashave the next-highest totals. So X's delegated ballots will be assigned to approve as many candidates as possible without approving both AB and D; that is, they will approve A, B, and C.)</small>
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=== Notes on rules ===
(technical issues; moved to talk page)
==== Finish resolving the "Chicken Dilemma" ====
Rationale for breaking equal-ranked ties using approvals in step 3.b)i.: One of the toughest situations for any voting system is the "Chicken Dilemma" between two near-clones. Say there are 60% "Blue" voters and 40% "Orange" voters; but the Blue voters are split between two candidates, say 35% for Navy and 25% for Sky. Any good voting system will allow one of the Blue candidates to win, if all the Blue voters support both of their candidates. But under many systems, there is a temptation for the Sky voters not to support Navy, so as to make sure that Sky, rather than Navy, is the winner. But if the Navy voters respond in kind, then Orange could defeat them both.
 
[[File:Chickendilemma.png]]
 
This is called the "Chicken Dilemma" because it resembles a [http://en.wikipedia.org/wiki/Chicken_(game) game of chicken], in that both blue factions benefit from being the only one to deny support, but both lose if both deny support. In fact, since no single blue voter can reliably know exactly how other voters in the two blue factions will behave, it resembles a blindfolded game of chicken.
 
This dilemma can be a problem for many voting systems. Approval voting, Range voting, Majority Judgment, and many Condorcet systems such as Schulze voting — all of them good systems — all can have some version of this problem. There are a few voting systems, such as IRV and some versions of Condorcet, which correctly elect Navy no matter what the Sky voters do. But these systems go too far in fixing the problem, and thus get bad results in some situations that superficially resemble the true "chicken" scenario in some way. For instance, if Orange voters strongly prefer Sky to Navy, IRV pushes them to dishonestly vote the "lesser evil" Sky over their true favorite Orange.
 
SODA already does better than most systems in resolving the chicken dilemma. The two blue candidates can each make sure that the other one includes them in the predeclared preference order. Then, if all votes are delegated, Navy, starting with more approvals, will add approvals to those delegated votes first (after Orange), and not approve Sky. Sky will be forced to approve Navy, or see the orange candidate win. Thus, Navy will win — the correct result.
 
But if the Sky voters are especially strategically-inclined, they could give Sky non-delegable approvals instead of delegable votes. If Sky did not have enough delegable votes to help Navy defeat Orange, then Navy would be forced to approve Sky, and Sky would win. Of course, the Navy voters could do the same thing; either "defensively" or "in retaliation", it doesn't matter. And so, while SODA resolved the game of chicken for the candidates, it is still a possibility if the voters are ruthless and engaged enough.
 
This rule would allow Orange to give the win to Navy (the correct winner) if Orange wished to; in the case where the Sky voters had attempted the strategy in the previous paragraph. Remember, if Orange had cared to, they could have declared a preference between Navy and Sky to start out with. This thus resolves the chicken dilemma completely, without causing other bad scenarios; something no other serious voting reform proposal can claim.
 
Unfortunately, while the rule itself is simple, it's taken 6 paragraphs to explain the rationale. Thus it's probably better not to raise this issue with most voters.
 
==== Prevent weak minor candidates from having kingmaker power ====
 
Step 3.b)ii.
This rule helps make this system more attractive to major-party politicians. But it's a principled rule, not just a sop to the major parties. Consider the "kingmaker" case: in a basically 50/50 split, some tiny party has the balance of votes, and manages to extract concessions far bigger than their base of support justifies, just in order to delegate those votes or not. That's unjust, and this rule would prevent it.
 
5% is a good cutoff here; for instance, nationally in the US, that's tens of millions of voters, and enough to deserve a voice. It shouldn't be too high, because this rule is effectively taking power away from voters; that's only justified if the faction is so small that the power is not legitimate, and so it's better to err a bit on the small side if anything. But under 5% - that is, under 10% of the winning coalition - doesn't deserve kingmaker power.
 
== Example ==
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{{Tenn_voting_example}}
 
In this simplified example, all the residents of each city agree on the rankings of all the other cities, so there would be no reason for anybody to do anything but bullet vote. Memphis has the first option to choose approvals for its delegated votes, and, as the leader, decides to approve noone but itself. Nashville goes second; it is the pairwise champion (Condorcet winner), so it also declines to approve any others. ChatanoogaChattanooga and Knoxville would approve each other and Nashville, to prevent Memphis from winning. Nashville would then be the winner, with 58% approval after delegation.
 
ChatanoogaChattanooga could, before the election, not include Nashville in its preference list, hoping to force Nashville to approve it. But in that case Memphis would approve Nashville to prevent Nashville from being forced to hand the election to ChatanoogaChattanooga, and so Nashville would win with an even larger majority. Therefore, ChatanoogaChattanooga will not attempt this.
 
== Advantages ==
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Simple response to a ''politician'' who makes this argument: "You just want the only smoke-filled room to be the one inside your skull." That is, minority factions '''should''' have a seat at the table, as long as everything is done transparently. The two-party system stifles some of the valid concerns of the members of the party coalitions. In SODA, all vote totals, preference orders, and final approvals added to delegated ballots are known; in the end, that's not a smoke-filled room, it's a transparent seat at the table, with a just degree of power which is derived from the people.
 
=== "There are other systems which are better in some ways"? Yes, but unlike them, SODA is better than plurality in otherALL ways. ===
 
This is true. [[Condorcet]], [[Range Voting]], and Median systems like [[Majority Approval Voting]] (or others: [[Majority Judgment]], [[MCA]], or [[Bucklin]]) each have some claim to be the "best voting system". But SODA is the best system which has no downsides versus plurality. All those other systems require more-complicated ballots. All of them require more-complicated, or even dishonest, strategic decisions from the voter, to get the most effective vote.
 
So in the end, while any of those other systems would be, in my opinion, a clear net benefit versus plurality, with SODA you don't need any qualifications like "'''net''' benefit" or "in my opinion". It is simply better, in every way.
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=== "Sounds too much like a parliamentary system, which has caused problems in [Italy / Israel / wherever]"? No, SODA still leaves "buck stops here" responsibility. ===
 
SODA does involve some parliamentary-style negotiation for about a weekshort period after each election. But then it's done, and the winner is in power until the next election. Unstable parliamentary countries, or ones where minority parties have inordinate power, are that way because minority parties can leave the governing coalition at anywill, triggering new timeelections. SODA does not have that problem; in many ways, it's really the best of both worlds between a 3-branch system and a parliamentary system.
 
=== "Why go to the trouble of pre-announced rankings and a second round? Why not just have candidates pre-announce the approvals they will add to their delegated votes?" Because the best compromise is only clear after the votes are tallied. ===
 
This sounds appealing, but would not work if two similar candidates were in a close race to see which had more first-choice votes, while an opponent stood ready to take advantage if they split the vote (that is, in the Chicken Dilemma, also discussed aboveon the talk page). The system as it stands allows the similar candidates to see, after the votes are counted, which of them deserves to win: the one with the higher approval total. That one will go first and not delegate their votes, and then other one (of necessity) will.
 
In general, this system, because it provides perfect information on voting totals at the time when delegation is happening, will make strategy obvious. This has the paradoxical result that, as long as most voters agree with their favored candidate's chosen ranking order, this system will in practice be '''more Condorcet compliant than a Condorcet method''' (because strategy could confound a true Condorcet method more often than SODA).
 
== Criteria Compliance ==
SODA itself does not satisfy [[monotonicity]] due to a complicated and implausible scenario involving 5 or more candidates. However, a slightly-modified version in which, before the delegated assignments, candidates can self-assign a penalty to be assessed at the end of the delegated assignment round, does. This modified version, MODA, is effectively identical to SODA for any plausible real-world election.
 
SODAMODA satisfies [[monotonicity]], the [[favorite betrayal criterion]], the [[majority criterion]], and the [[mutual majority criterion]]. Depending on assumptions and definitions, it can pass the [[Condorcet loser criterion]].
 
It does not satisfy the [[independence of irrelevant alternatives]] criterion in general, but it does if the "irrelevant alternative" is assumed to delegate votes in the same way as any candidate whose delegable votes they supplant. Similarly, it can only pass the [[participation]] and [[consistency]] criteria if it is assumed that candidate delegations do not change. These assumptions are ''not'' realistic, but they do show that the method is in some sense "close to" passing these criteria.
 
In any case where honest delegation could show a majority Condorcet winner, such delegation forms a strong Nash equilibrium. This shows that in general, strategic refusal to delegate is likely to fail.
 
=== Condorcet criterion (includes highly technical discussion) ===
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Each "undelegated approval elector" would know the statewide non-delegated approval total, and the total of number of affiliated electors throughout the EC, for each candidate. Other "approval electors" would count as fractionally affiliated based on their known approval totals. These electors would be sworn to vote for whichever of the two candidates with the most nationwide electors had the highest statewide undelegated approval total. They would be chosen by the candidate for whom they were sworn to vote.
[[Category:Single-winner voting systemsmethods]]
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