[EM] PR for ethnically polarized electorates

[Forest Simmons]

Thanks to Juho and Toby for their insights.

It is true, as they suggest, that question 2 is the harder one.

The simplest answer to question one that I know of is based on an idea that
Martin Harper came up with 12 years ago as a way of showing that ordinary
Approval satisfies "one voter one vote" in the same strict sense that IRV
does (through vote transfer):

First list the candidates in order of most approval to least approval.
Then on each ballot transfer the entire support of the voter to the highest
candidate on the list that is approved on the ballot.  In other words, the
voter's one and only vote is for the candidate she approves that is most
approved by other voters.  As Martin pointed out, this assignment of votes
still elects the ordinary Approval winner in the single winner case.  (Half
a dozen years later Jobst pointed out that this same idea can be used to
assign probabilities in a single winner lottery method.)

I am now pointing out that Martin Harper's vote transfer scheme is a simple
way of designing a PR method (based on approval ballots) that solves
problem one. In the given example let us assume that the truncations are
reliable indicators of disapproval.  Then the approval ballots are

10 A
30 A, M
45 B, M
15 B

The approval order is M>B>A

The first faction ballots all count for A.  The last faction ballots all
count for B, and the other 75 ballots all count for M, yielding the desired
quotas of 10, 15, and 75 respectively.

Toby asks the question of why this M heavy proportion is so desirable.

One answer is that in these polarized countries (the ones that inspired
this thread in the first place) the fewer extremists in power the better.
But in my next post, the one addressing question two, I will give a more
dispassionate answer to that question.

Forest



On Wed, Jun 25, 2014 at 12:23 PM, Toby Pereira <tdp201b at yahoo.co.uk> wrote:

> At first glance it seems that 10, 15 and 75 for A, B, M respectively seems
> a little optimistic from a voting system. It's not just that party list PR
> would shut out M - I can't see any system calling itself PR could award the
> seats in those proportions. Something like reweighted range voting or the
> score PR system I detailed a couple of weeks ago would stop M being shut
> out with honest voting, but they would go nowhere near as far as you are
> suggesting.
>
> Regarding voter honesty, it may be difficult to ensure it anyway with a
> normal score-based PR method, but I can't see how you could get it to work
> given that you would want the middle two factions' support for A and B to
> be effectively ignored. To be clear, 10, 15, 75 are the proportions
> you'd expect if the 75 people who gave a positive score to M completely
> lost all their support for A/B and raised M to from 80 to 100.
>
>    *From:* Forest Simmons <fsimmons at pcc.edu>
> *To:* EM <election-methods at lists.electorama.com>
> *Sent:* Wednesday, 25 June 2014, 1:21
> *Subject:* [EM] PR for ethnically polarized electorates
>
> In Rwanda it was the Hutu and the Tutsi tribal division.  In Iraq the
> Sunni, Shia, and Kurds.  In the former Yugoslavia it was the Serbs Croats
> and Bosnians.  There are similar divisions today in the Ukraine, Israel,
> Syria, Bolivia, etc.
>
> What do they have in common?  A need for electing a representative body
> that has as many moderates and as much consensus as possible so that
> minorities are not so desperate for separation, i.e. to prevent the scourge
> of Balkanization that seems to be spreading like a plague.
>
> Suppose that there are two extreme groups A and B supported by two
> individual ethnicities, as well as a more moderate group M with preferences
> like
>
> 10 A(100)
> 30 A(100)>M(80)
> 45 B(100)>M(80)
> 15 B(100)
>
> (The numbers in parentheses represent voter expectations of relative
> benefits.)
>
> In ordinary party list PR methods the parliament would be formed by 40
> representatives from A and 60 representatives from B.  The moderate party
> would be shut out entirely.
>
> Here are my questions:
>
> 1. What method(s) would take this information and elect a parliament with
> respective party strengths of  10, 15, and 75  for A, B, and M?
>
> 2.  What election method could possibly get the two middle factions to
> honestly convey this information via their ballots?  In other words, how to
> keep the two middle factions from defecting from their common interest?
>
> Forest
>
>
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