[EM] Criterions for party-list PR systems

[Vidar Wahlberg]

On Fri, Sep 04, 2015 at 04:51:16PM +0200, Kristofer Munsterhjelm wrote:
> Part of the reason that you'll find more discussion about candidate
> methods than party list, I think, is that there's an idea that candidate
> methods give greater freedom. In candidate methods, the voter can decide
> which candidates in a party he prefers the most, and thus not only rank
> between parties but also within them; and he can also vote for an
> independent if so inclined, or mix candidates from different parties
> (e.g. rank the candidates he thinks are particularly honest ahead of
> those he thinks are less so, irrespective of party affiliation). Thus,
> for candidate methods, there's no need to favor parties as such: a
> candidate may run with or without party support.

I'm not entirely convinced that candidate methods are superior to
party-list methods. I do agree that they give greater freedom, but
they're arguably more likely to turn the election into a popularity
contest where who the candidates are become more important than their
policies. Party-list systems won't fully remove the popularity contest
either, but they help shift the focus away from the candidates to the
policies of the party the candidates are representing.
Shifting focus away from charisma to ideology/policies I would argue is
an important goal in political elections, albeit it's not an easily
measurable goal as opposed to the voting system criterions.


> In http://www.votingmatters.org.uk/ISSUE3/P5.HTM, Douglas Woodall
> defines some clone criteria. In particular, he defines "clone-no-harm"
> as "replacing a candidate x by a set of clones should not harm another
> candidate y". He then says that this is incompatible with the Droop
> proportionality criterion.

This (clone-no-harm) is a good example. If you were to translate a
party-list method to a candidate method where candidates were simply
ordered X1>X2>X3>Y1>Y2>Y3>Z1>Z2>Z3 (and disallow voters to rearrange the
candidates, i.e. closed list), then I believe STV would pass this
criterion. It would not if you allow voters to rearrange the candidates
(i.e. open list), as the votes may end up being evenly spread for one
party, causing that party's candidate to be excluded earlier in the
election process.


-- 
Regards,
Vidar Wahlberg