SABR voting

[Jameson Quinn]

This is another voting system, very similar to PAR, but hopefully simpler to describe.

SABR stands for the ratings each voter can give to each candidate: "Support", "Accept", Blank, or "Reject". The winner is the first candidate, going in order from most to least "support" ratings, who isn't “strongly beaten”. To see whether a candidate X is "strongly beaten", give X one point for each voter who rates them “support” or “accept”, and each other candidate Y one point for each voter who rates Y above “reject” and at least as high as X. Any Y who has more points than X "strongly beats" them. If there’s no candidate who’s not strongly beaten, count all blanks as "reject" and try again; this guarantees a winner.

This method is monotonic; passes Majority, Mutual Majority, Majority Condorcet Winner, and Majority Condorcet Loser; does well in center-squeeze scenarios (by Majority Condorcet Winner); and does well in chicken dilemma scenarios, without a slippery slope. It obeys a weakened form of later-no-harm, Later-lower-no-harm (LLNH): adding an “accept” ranking for X cannot cause a candidate Y you “support” to lose, unless X is supported by more voters than Y.

This method does not meet the favorite betrayal criterion, but I believe that it has no favorite betrayal incentive in normal scenarios. (I'd like to find a way to define "normal" so that's rigorous, but I haven't yet got something I'm ready to share.)

This method does not meet participation and consistency, but it is easy to define weakened versions of these criteria which it meets.

I'm interested in making a statement of this method that's as clear and concise as possible, so I'd love to hear any criticism of, suggestions for, or questions about the definition above.

[William Waugh]

If there isn't a balancing vote for each possible vote, I'm skeptical of its worth for defeating 2PD.

On Friday, December 2, 2016 at 9:38:09 PM UTC-5, Jameson Quinn wrote https://groups.google.com/forum/?fromgroups#!topic/electionscience/fGjV04XyEwY

[Jameson Quinn]

2016-12-03 0:02 GMT-05:00 William Waugh <2knuw...@snkmail.com>:

If there isn't a balancing vote for each possible vote, I'm skeptical of its worth for defeating 2PD.

Why do you say that?

I think you could add an "anti-accept" option to SABR, to make it a balanced system. I suspect that might even restore FBC, if you did it right. But explaining the counting procedure for and the strategic implications of "anti-accept" would be hugely complicated and largely pointless; for the majority of voters in all scenarios, and for all voters in the majority of realistic scenarios, the S/A/R options would cover the strategic necessities, and Blank would be a safe way to lighten the burden of rating lesser-known candidates.

For me, any system which can handle chicken dilemma and center squeeze can end the two party monopoly. So I'm interested to hear why you don't agree. 

[William Waugh]

A voting system meets the balance constraint unless there can be a scenario where for two voters P and S and a bunch of other voters, once the other voters have voted, if the tally would give a certain outcome, P's vote can sway the outcome, and that of S cannot sway it back no matter how S votes validly within the system. If such a scenario is possible, it is also possible to have millions of voters who agree with P and millions who agree with S. Since the same number of S-agreeers as P-agreeers cannot sway back the outcome as determined by the S-agreeers, it takes more count, maybe substantially more count, of the S-agreeers to balance the effect on the election that the P-agreeers wield. Under these circumstances, the S-agreeers see that when they vote their actual opinion, they have less political power than some other voters. This may lead them to betray their favorites in search of political power, as we know happens in FPTP.