[EM] Consociational PR

[Kristofer Munsterhjelm]

Here's a system I thought about some days ago. It's a bit interesting on 
its own, but I haven't found out if it has any practical uses, or is 
good enough to use in the situations that spring most readily to mind.

Say you have a divided society. In this society, disparate groups of 
people vote for "their" parties or candidates, and there's little 
overlap between each group's candidates. In ordinary PR, you might get 
kingmaker scenarios that provide instability; in majoritarian systems, 
the lesser groups might not get any representation at all.

What if one divided the different groups' candidates into different 
chambers? Then one could provide each with mutual blocking rules to get 
closer to a consensus system rather than a majority system, without 
having the system be as brittle as an actual supermajority system.

So here's the system. Say you have k different legislative bodies (n 
doesn't matter, but should probably be small, and if possible highly 
composite, so something like 2, 3, or if you're really pushing it, 6). 
Furthermore, say there are n voters. After the election, associate to 
each body, n/k voters so that the difference between the seat allocation 
to each were one to run a majoritarian election for that body accordng 
to the associated voters, and were one to run a proportional election 
for that body, is minimized. Then run the actual elections - one PR 
election for each body - and you're done.

If society is divided, then the proportional result becomes like the 
majoritarian one (or less different) if each group gets its own body -- 
and we don't have to set ahead of time or have any preconception about 
what those groups actually are.

The system is not perfect, of course. By enshrining a division into n 
groups, it may polarize those groups. Mutual veto or double majority 
rules could help counter this, but that doesn't make the system elect 
more compromise candidates. Furthermore, for the same reason, it could 
slow the merging of divided groups, because the existence of n bodies 
would reinforce the notion that there are exactly n groups "that matter".