[EM] Approval Voting and Long-term effects of voting systems

[robert bristow-johnson]

there is some truth mixed in with this, but some hooey mixed in also.



---------------------------- Original Message ----------------------------

Subject: [EM] Approval Voting and Long-term effects of voting systems

From: "Daniel LaLiberte" <daniel.laliberte at gmail.com>

Date: Mon, November 21, 2016 1:08 am

To: election-methods at lists.electorama.com

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> This message is about two related subjects:

>

> 1. Factoring in the long-term emergent effects of each voting system.

> 2. An example of how Approval Voting results in better long-term effects.

>

> Among the many criteria for evaluating voting systems (

> https://en.wikipedia.org/wiki/Voting_system#Evaluating_voting_systems_using_criteria)

> I don't see any that address the long-term effects of using each voting

> system. In other words, the effect on one election is certainly important,

> regarding the satisfaction of the election results by voters and

> candidates. But I would argue that it is even more important to consider

> the long-term effects that emerge when applying a voting system repeatedly

> over many elections. A small bias one way or another may not be very

> apparent if you only look at one election, but over may elections, they can

> add up and perhaps compound the bias exponentially.

>

> There are many long-term effects to consider, but in particular, I am

> thinking of one pernicious problem: the tendency for two major parties to

> emerge and dominate all politics which results from the repeated

> application of plurality voting.
This is called "Duverger's Law" and it comes out because of the regret that voters for a third-party or independent candidate feels after finding out that the major-party candidate they hated most defeated the other major-party candidate they
disliked less.  Then voters start thinking that their 3rd-party vote is wasted.
>This problem is fairly easy for most
> people to understand, although I am surprised to see that there seems to be

> a lot of denial about this effect as well. Some would even defend having

> only two major parties, or very few parties. That is an interesting

> subject to discuss, but regardless, I believe we should be aware of how our

> choice of a voting system will affect things over time, how society is

> likely to evolve based on the rules we lay down, and in fact, how it is

> actually very likely that the dominant forces in society will quickly and

> vociferously defend whatever rules resulted in their rise to dominance.

>

> But back to this one question, studies and long-term experience have shown

> that other voting systems besides plurality, in particular IRV, also result

> in the dominance of two major parties.
I don't see any reason why IRV results in the dominance of the two major parties.  The problem that IRV suffers is that sometimes IRV does not elect the Condorcet Winner and then voters feel that the election failed when a candidate is elected
despite that more voters marked their ballots that they preferred a specific different candidate.  Then this cascades into other problems like spoiler and later harm.
Setting aside the Condorcet cycle, none of this would occur with Ranked-Choice Voting with a Condorcet-compliant
tabulation of votes.
> This may be more surprising to
> people, but looking at the underlying cause, it seems we can make a rather

> important simplifying argument about most voting systems regarding this

> problem. I would assert that the underlying cause of this problem of

> two-party dominance in any voting system is that it gives voters the

> ability to rank or order at least one candidate higher than the rest.

>

> The reason this ability to rank candidates becomes a problem is the spoiler

> effect, where voters will have a strong motivation to give their highest

> rank to one of the leading candidates. If they don't, then they weaken the

> chance of that candidate winning and therefore strengthen the chance of the

> less preferred leading candidate. Because one of the leading candidates is

> likely to win, all the rest of the rankings of non-leading candidates

> hardly matter at all.
Again, this is a demonstrated problem with IRV, but not so much with Condorcet (sans cycle).
> In any election, there will be two candidates who are the strongest in

> terms of popular support, and thus the most likely to win.
Not true.  In Burlington 2009, we had three candidates who where all seen as approximately equally strong.  One was the IRV winner, another was the Plurality winner, and yet another was the Condorcet
winner.
>Consequently (to
> grossly over-simplify the process) with any voting system that permits

> ranking, groups of voters will tend to coalesce around support for these

> two leading candidates to encourage everyone to support their preferred

> leading candidate.
That's not true.  There is no intrinsic reason for this with Ranked-Choice Voting.
>Eventually two major parties arise, and everyone who

> doesn't join one of these two major parties is excluded.
Just not true.  And little evidence to support the claim.
> So once voters and candidates figure this out, any such voting system ends

> up devolving into the dominance of two major parties that we get with

> simple plurality voting.
Again, a claim made with no justification.
> In fact, one might argue that plurality voting is

> better just because it is simpler.
THAT does happen.
> But Approval Voting avoids this problem.
No, it just creates more trouble.  It's Approval Voting that devolves into Plurality Voting once voters start wondering whether or not they should Approve their
second-choice candidate (or whether they should Approve their third-choice).  Voters don't want their second-choice to beat their first-choice.  How do they stop that from happening?  (By bullet-voting their first choice, and that devolves Approval into Plurality.)
>
Equal-rank approval votes mean
> voters don't get the option to express their preferred ranking, but because

> of that, they aren't at all motivated to bias their ranking dishonestly.
That's baloney.  They may very-well not Approve of their second-choice candidate (whom they do actually approve of) to protect their first-choice candidate.


> They only have to decide which candidates to approve, or where the cut-off

> is between approval and disapproval.
No. That is a falsehood.
They have to consider whether or not their second-choice candidate has a chance of beating their first-choice.  And they have to consider whether or not their third-choice has a chance of beating either their
second-choice or their first-choice.  And then they have to decide if that risk is worth it to Approve their second or third choices.

> Given that there are, as before, two leading candidates,
That's a "given" that I do not accept as axiomatic.
> how does Approval

> Voting affect whether one of those two leading candidates will win? One of

> the two leading candidates is likely to win even with Approval Voting, so

> it would appear there is no benefit, but that would be a short-sighted way

> to judge a voting system. In subsequent elections, it would seem likely

> that more candidates will run who have broader appeal to ALL voters, not

> just a majority or plurality. Because the winning candidates will be those

> who are most approved of by the most voters, there will be no value in

> parties that typically focus on appealing to no more than half of the

> voters.

>

> So I suspect the long-term use of Approval Voting would be self-correcting

> toward better and better representation of ALL voters, not just half the

> voters, because in each election, almost all of the voters contribute to

> choosing the winning candidates, and that only gets better over time as the

> candidates who decide to run get closer to receiving the approval of all

> voters.

>

> Can any other voting system claim a similar long-term effect? Even a

> voting system with three ranks, e.g. Approve, Neutral, Disapprove, would

> encourage voters to approve one of the leading candidates, and give neutral

> or disapprove votes to the rest. I wonder if Approval Voting might be the

> ONLY system that has this long-term effect.

>

> What I am aiming for is a voting system that self-corrects over time. No

> matter what voting system we choose, there is probably always going to be

> at least some small bias, some inequities or incompleteness. So we need to

> understand this and deal with it.

>

> But one important question should not be overlooked: What do we want to

> self-correct toward? That is, what is the long-term goal? I believe we

> should want to move toward a closer or better representation of society as

> a whole, but there are other ways to look at that.

>

> Looking forward to reading your feedback.
I think most of your gushing for Approval voting is not well-founded.  What if the voter prefers Candidate A as their favorite, but suspects that Candidate B and Candidate C are the leading candidates?  How should that voter vote with an
Approval ballot? Please answer that question with specifics.
Approval Voting (and also Score Voting) requires *more* voter strategy than does Ranked-Choice Voting decided in a Condorcet-compliant manner.  IRV has problems (like a spoiler).  Of course Borda and Bucklin have weird
problems that also motivate tactical voting.  But when there is no cycle, Condorcet Voting expresses exactly the will of the majority voters over all combinations because it satisfies one simple to understand property:
"If more voters mark their ballots that they prefer Candidate A
over Candidate B than the number of voters who mark their ballots to the contrary, then Candidate B is not elected."
I still don't know how or why anyone would argue with that democratic value.
 
Sorry, you Approval advocates have *never* made your case persuasive.
 (And that includes Warren, whom I have a lot of respect for.)




--
r b-j                  rbj at audioimagination.com
"Imagination is more important than knowledge."
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