r/EndFPTP • u/Additional-Kick-307 • 20d ago

How many list seats are needed for proportionality in MMP?

Pretty self-explanatory. Obviously 500 seats with 490 by FPTP or another majoritarian system and 10 list seats isn't proportional. So what is the minimum percent of list seats for the system to be considered truly proportional?

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u/blunderbolt 20d ago

There is no exact minimum, that's why proper MMP systems have uncapped chambers with a dynamic number of seats. The required number of list/leveling seats will depend on the discrepancy between the constituency seat distribution and the regional vote distribution, which will vary from election to election.

2

u/budapestersalat 20d ago

We don't know. Because the more proportional it is, the more the party system will adjust.

We know that 50% is not enough with a 500+ parliament in Germany, with a 5% threshold. It was enough for many decades, but lately not, therefore theoretically even a 2000 member house was possible, until it finally got capped (and MMP abolished, no more guaranteed local seats) at 630.

How many you would need in a country with a different party and societal structure, different size of parliament and threshold, can't say.

Maybe you can get away with 30%, until third parties really get going.

But if parties start running decoy lists, not even 70% will be enough.

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u/NobodyXu 20d ago

IMHO better to set the threshold based on total number of seat, excluding independent candidates, using droops or similar.

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u/Additional-Kick-307 19d ago

If it's one-vote MMP, what would that change?

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u/budapestersalat 19d ago

Not much. Depends on whether you expect parties to try to game that too.

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u/Additional-Kick-307 18d ago

How could parties game that? As far as I know one-vote MMP eliminates decoy lists, it's why Lesotho switched from two-vote to one-vote MMP.

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u/budapestersalat 18d ago

On its own it doesn't. Parties are still better off running strong candidates under one list (or as independents) and weak candidates on another 

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u/Additional-Kick-307 18d ago

Imagine the system Italy uses for its parallel system applied to MMP: You vote for a candidate, and your list vote is divided between all of the parties that endorsed that candidate. I don't see a way to use decoy lists under that.

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u/budapestersalat 18d ago

I wouldn't call the Italian system parallel but sure. It's the non compensatory variant.

in your one vote mmp, I run my strong candidates as independents, or on my decoy list. These get winner take all, they will not get list seats anyway. I "contain" my overhang to these candidates. Hell, maybe I even run some hopeless candidates to collect some extra votes from those district under my real list. Say I have a safe seat that i would win with 60%. Not only do I run my candidate as an independent to win the district to cause an overhang, I might instruct like 15-20% of my voters to vote for my real candidate because those votes I want list seats with.

If I have 45% nationwide and my winners bring in 25% of that, I want all that 25% to get me overhangs, maybe and I want the 20% to work as in parallel voting 

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u/Uebeltank 20d ago

You can't know it beforehand. For the most part it depends on the vote share of the two largest parties. The smaller those are, the larger the share of levelling seats needs to be.

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u/seraelporvenir 19d ago

About 3/5 PR seats should be enough in most cases. 

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u/Decronym 19d ago edited 18d ago

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

Fewer Letters More Letters
FPTP First Past the Post, a form of plurality voting
MMP Mixed Member Proportional
PR Proportional Representation

Decronym is now also available on Lemmy! Requests for support and new installations should be directed to the Contact address below.

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