[EM] Consociational PR

Raph Frank raphfrk at gmail.com
Wed Sep 5 09:35:46 PDT 2012

On Wed, Sep 5, 2012 at 5:17 PM, Kristofer Munsterhjelm
<km_elmet at lavabit.com> wrote:
> You fill the body using PR, but each body is assigned a set of voters, or
> rather ballots, so that the discrepancy between (say) Schulze and Schulze
> STV is minimized. I think Hamming distance would make the most sense for the
> discrepancy measure. If body X has 50 seats, then you take the 50 candidates
> first ranked on Schulze. Call the set of these candidates X1. Then you take
> the 50 candidates first ranked on Schulze STV, and call that set X2. The
> discrepancy measure for body X is the Hamming distance (number of candidates
> in one set but not the other) for X1 wrt X2.

That is kind of what I mean, you look at the PR assembly and compare
it to the standard condorcet ordering.

> Do you mean measuring the dissimilarity between a Condorcet ranking for the
> whole electorate and each body's PR result?

I mean measure the dissimilarity between each house and its PR
version.  However, the total dissimilarity is the sum of the house's

>> It also breaks the secret ballot.
> Not really. The apportionment is done after the election. So the method
> would provide the same result whether the ballots were:

I mean you have to match Mr. A between the 2 votes, or would you use
the same ballots for both stages?

> How would that work in practice? If you have three House of Reps buildings
> (or floors in the same building), each of which houses 100, it would be
> somewhat difficult to house 300 representatives in one of them. I suppose
> you could have 300 seats in each, but then most of the bodies' seats would
> be vacant.

There are clustering algorithms that will give an estimate of the
number of clusters in the data.

Basically, as you add more clusters, the average match gets better and
better, but then it levels off.  You could have a rule that the number
of clusters is equal to the smallest number that has a match that is
at least 75% of the match if you assumed 10 (or some large number)

> So the party composition of the executive is not decided by negotiations,
> but rather ahead of time as the parties are given seats?

There are no negotiations.

Basically, after the election, each elected member of the assembly
declares which community they are from (they can say none).

Also, they have to say which party, but that might have to be the one
they ran for.

There is a meeting with all the party leaders, and the executive seats
are assigned.

The leader of the party with highest (assembly seats) / (cabinet seats
held so far + 1) gets to nominate a member of cabinet and pick which
department of the ones remaining.  The means the number of seats is
d'Hondt, but each seat has responsibility for a different department.

Finance is not included and is handled separately (don't know exactly).

> PR systems may also, in certain situations, become majoritarian through
> mutual strategy. The strategy goes like this: First the governing coalition
> decides to move closer to one another in order to be effective (and all the
> positive properties ascribed to majoritarian systems). They construct a sort
> of "unified exterior" where they in private agree among themselves on the
> position to take and then stick to it in public. The opposition then moves
> closer in order not to stand divided against the united majority. After a
> while of this, you get one majority bloc and one minority bloc.

Right.  That is worst if each sub-party has a solid ethnic support
base, so the majority coalition stays solid at just above 50%.

> However, while PR may have de facto majoritarian rule in this manner some of
> the time, majoritarian systems have it all the time, so I still favor PR
> over majoritarian systems.

Ideally, you want many parties that are willing to go into government
with each other, but don't end up merging.

> Also, I think that candidate-focused methods
> would, all other things equal, be less susceptible to producing this kind of
> strategy than would party lists.

Right.  Anything with moves power to the centre doesn't help.

Ideally, you want balance of power to be held by "floating voters",
i.e. voters who will vote based on how well the parties perform in

> In something like STV, the voters can elect
> candidates that prefer to negotiate out in the open rather than in private.
> The voters can do so while still supporting parties whose leaders think the
> strategy is a good idea.

Right, negotiations happen after the election rather than an agreement
decades ago being crystalised.

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