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SODA voting (Simple Optionally-Delegated Approval) (view source)

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Simple Optional Delegated Approval (SODA) is a single-winner system inspired by [[approval voting]] and [[asset voting]]. It is arguably [[Pareto dominant]] over these systems (at least, as used for occasional elections), which in turn are both (separately) pareto dominant over plurality; that is, it offers only advantages, and no disadvantages, when compared to approval, occasional asset, or plurality. This makes it an excellent choice as a practical voting reform proposal, as you can easily and honestly refute any argument against it. (There are many systems which are arguably better than SODA in some way, but all are also arguably worse in some other way.)
 
== Procedure ==
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# Approval totals for each candidate are also tallied. These preliminary results are announced, along with the number of "delegable votes" each candidate has.
# If any candidate has an absolute majority at this point, or cannot possibly be beaten by any other candidate using the delegable votes and candidate rankings available, then they win immediately.
# There is a brief period - perhaps a week or two - for candidates to analyse and negotiate based on these preliminary results. (Actually, in the broad majority of cases, the correct 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.)
# All candidates publicly delegate their votes, in descending order of the number of delegable votes they have, publicly delegate their votes; that is, they choose ana number N, and add their "delegable vote" total is added to the approval totals of their top N favorites as announced in step one. They may choose N=0 - that is, not delegate their vote to anyone. They may not choose N=(number of candidates) - that is, delegate their votes to everyone. If they declared a tie in their preferences, they must either delegate to all candidates whom they included in that tie (as well as anyone they ranked above that), or none of them. (Note: TheDoing this in descending order prevents a weaker candidate from givingmaking an ultimatum to a stronger candidate, and thus strengthens the strategic equilibrium of any pairwise champion there is.)
# The highest total wins.
 
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==== Prevent sliver candidates from having kingmaker power ====
 
Optional rulestep 4.5 (betweenapplied 4after andstep 54 above): If any candidate has less than 5% (of the total votes) as delegable votes, and is not one of the top two in total votes, then those votes are automatically delegated down their preference list as far as the Condorcet winner (considering known ballots and preference orders) among the candidates on their preference list, or, in case of elections with a cycle, as far as the second member of the Smith set (correct CPNE strategy for a Smith set of size 3; larger Smith sets, with over two members included in the minor candidate's preference list, are hit-by-lightning unlikely).
 
This rule would help 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 [not] delegate those votes. That's unjust, and this rule would prevent it. So this rule is recommended whenever people will tolerate the complexity.
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# SODA is extremely easy for the voters; in fact, no voting system is simpler to vote. (Plurality, by restricting you to only one vote, also makes it possible to mistakenly "overvote", spoiling your ballot. There is no such way to accidentally invalidate your ballot under SODA. Also, both Plurality and Approval require a conscientious voter to consider strategy and polling status; SODA allows a simple bullet vote to still be strategically as strong as possible, regardless of the candidate standings.)
# All the steps of SODA have a clear purpose. Instead of relying on complicated rules to give a good outcome, SODA gives simple tools to the people involved, so that a good outcome is simply the rational result.
# There is no motivation for dishonesty from individual voters. A voter can safely vote for any candidate that they honestly agree with, without fear of that vote being wasted; or safely vote an honest approval-style ballot, if they do not agree with any candidate's preference order.
# Any vote delegation is entirely optional. Any voter who dislikes the idea of their vote being delegated in a "smoke-filled room", need not allow that to happen.
# SODA is far more likely to arrive at a majority result than Plurality (or even IRV). It may even be more likely to give a Condorcet winner than a Condorcet system.
# Assuming that all voters who choose to delegate their vote agree with the declared preference order of their candidate, and assuming that approval ballots are enough to express the relevant preferences of all voters who do not cast a delegable ballot, then any pairwise champion (Condorcet winner) will be a known, strong equilibrium winner. That means that, if all candidates delegate their votes rationally, no coalition of candidates can elect anybody they all prefer to the natural winner, the candidate who could beat all others one-on-one. (This is simply due to the well-known result that a CW is a [[Strong Nash equilibrium]] winner under Approval.)
# Leaders of minority factions would have an appropriate voice for their concerns, although power would ultimately reside with any majority coalition which exists.
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Simple response to a ''candidate'' who makes this argument: "He just wants the only smoke-filled room to be the one inside his skull." That is, minority factions '''should''' have a seat at the table, as long as everything is done transparently. In SODA, all vote totals, preference orders, and final delegation decisions 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.
 
 
=== "Why go to the trouble of pre-announced rankings and a second round? Why not just have candidates pre-announce their delegated approvals?" ===
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OK, maybe I went a little overboard. So here's the pitch I'd make to a third-party supporter to balance it out.
 
"What do you want, in the end? People like you are in a minority, and I'm sure you realize that you won't take over the world overnight. So you want a fair hearing, you want a seat at the table. Most voting systems are just selling you dreams. One day, they say, you're going to convince a majority to join your team, and on that glorious day your team's gonna be in charge. How well has that worked for the Republicans and the Democrats? How much important change do you see when the pendulum swings back and forth between the two of them? Not enough. The truth is, by the time you sway a majority, your big ideas are going to be watered down.
 
"But there's another option. You can keep having big ideas, and just have a system that doesn't shut you out of the room. There are a lot, a lot of people who aren't fully satisfied with 'their' party, who are looking for another option. Take off their two-party shackles, let them safely vote for someone else, and they'll jump at the chance. And there you will be, with 10, 15, 25% of the vote. No, that won't be enough to win, but it will darn well be enough to get some respect, to get your ideas a fair hearing, get some of them tried, which is what you need in order to grow. And if the major party supposedly on 'your' side doesn't listen, you will have the power to take those votes and go home. You know and I know that major party politicians, they call themselves leaders, but what they really are is cowards. When you're sitting on a double-digit pile of votes, they will listen to you, trust me."
 
[[Category:Single-winner voting systems]]
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