[EM] Challenge: two-party methods

[Juho Laatu]

On 9.7.2011, at 14.23, Kristofer Munsterhjelm wrote:

> Juho Laatu wrote:
>> After some recent discussions and thoughts around two-party systems I
>> thought it would be interesting to discuss two-party systems also in
>> a more positive spirit. The assumption is thus that we want the
>> system to be two-party oriented. We want to have two strong parties,
>> and one of them should rule. We want to allow only well established
>> parties with wide support to rule. The first obvious approach is to
>> ban all other parties than the two leading parties. But maybe we
>> don't want  to be so brutal. Let's not ban the possibly already
>> existing, much liked and hopeful third parties. It is also good to
>> have some competition in the system. Let's not allow the two leading
>> parties think that they don't have to care about the voters and they
>> can do whatever they want, and stay in power forever.
>> What would be a good such method? In addition to what was already
>> said we surely want e.g. to avoid the classical spoiler problems.
> 
> I can think of two simple PR-based methods.
> 
> In the first, you use ordinary divisor-based PR, but set the divisors so that they have a great large-party bias (even worse than D'Hondt).

It seems that this method would favour large parties so that they would get lots of seats, and it would make sense to generally vote for them. One problem with respect to the targets might be that small parties may have problems to grow since votes to them have less weight than votes to large parties. If left wing gets 50% of the votes, and in the right wing there are two parties, 35% and 15%, then left wing gets majority. The small party was a spoiler to the right wing.

> 
> In the second, you also use ordinary divisor-based PR, but top up the list of the largest party so that it always gets 50%+1 of the seats if it would otherwise get below that.

It seems that also here we may have a spoiler problem. In situation 40: L1, 10: L2, 40: R1, 10: R2 any additional voters moving from a 40% group to the 10% group of the same wing would be spoilers.

> 
> But I think that any two-party system will discourage smaller parties. If only the two major parties can rule, voters will strategically think that "either I can use my vote to grant the lesser evil more seats/power so it can defeat the greater evil, or I can use my vote to vote for a small party that hasn't got a chance beyond being the opposition anyway. I'll do the former". That sort of thinking will create an invisible barrier to third parties, because as long as the third parties aren't large enough that they might win (become one of the top two) with a small amount of additional votes, voters won't vote for them, and if they don't vote for them, they'll never get close enough to the threshold.

There might be irrational fears, that may be based on how the old methods have worked. The target is anyway to make such fears irrational. The intention is that although my favourite small party can not win this election, it is quite possible that it will win in the next election, or one after that.

Even If the votes are now 50: A, 45: B>C>A, 5: C>B>A, next time they could be 50: A, 35: B>C>A, 15: C>B>A, and next time 50: A, 24: B>C>A, 26: C>B>A. C should thus be able to grow without disturbing the balance between A and {B, C}. (These votes should work in the method that I proposed.)

> 
> I can think of two ways to get around that, but both would bend the definition of a two-party system.
> 
> Let's call the first an "explicit coalition system". The election process itself is party list PR. After the election is done, a group of parties with a total vote share greater than a majority must form a coalition; they do so by an internal supermajority vote, after which this group gets the government and the rest becomes the opposition.
> After that is done, they rule until at least one of the parties (or some fraction of the whole group), plus the opposition (or supermajority thereof), agrees to dissolve the current coalition. After that is done, there are new elections. The current coalition rules until the next coalition can organize itself.

Are you saying that actually many multi-party systems (that work pretty much in the described way) are actually single-party governments, and therefore the system is essentially a government vs. opposition system, and that would make it effectively a two-party system? It is true that governments typically have a unified policy, and the opposition takes the opposite position. Technically this approach meets the two targets that I set, but I was thinking of somewhat more stable parties, not ones that would be redesigned after every election based on the results that the numerous smaller parties that participate in the election do get :-).

(Note that I wrote the targets for a single-winner election (they talk about electing one of the candidates) and we have now expanded the discussion also to multi-winner elections. They are interchangeable though, since many single seats van be summed up to multiple seats, and multiple representatives can elect a single winner, maybe a government coalition or a president.)

> 
> The second, I'd call "PR by credit". Again, votes are counted as in party list. Each party also has an "account". After the election, the number of votes for each party is added to the relevant party's account. Then the parties allocate votes to gain seats in a continuous bidding process. That is, call parties 1...n's current bids, B_1...B_n. Then the tentative seats allocation is according to some major-party biased divisor method that considers B_1...B_n the number of votes each party got. The seats count is updated continuously until the timeout, then each party's bid is withdrawn from its account. While it is unfair in any given election, the smaller parties can accumulate votes in their accounts and later use this to take the throne of government, if for only a term.
> However, I think this kind of hybrid monetary system would have some adverse results. First, it would cause great oscillations. The composition of the parliament could swing hard left, with lots of, say, environmental bills, then swing hard right, with the new government scrambling to undo those bills and to impose their own, then swing hard left again, each sweep of the pendulum causing chaos. Second, differences in turnout could add more noise: if there's less turnout, there's less of an impact to each party's account.

I think two-party countries typically oscillate between two extremes. Or actually they are not extremes since both major parties tend to move close to each others in the hope of making some of the voters of the other party to move on their side. But oscillation of one-party governments tends to be the rule. Although in multi-party systems governments tend to be "compromise based combined governments" we need not follow that rule in our two-party system.

This kind of oscillation and also credit based methods typically offer proportionality in time (instead of "proportionality now" as multi-party parliaments or governments). I'll propose one additional method to explain what I mean and how this relates to the interest of letting only the major parties rule.

Let's say that the votes are approval votes. All parties have credit accounts that contain unused ballots from the previous elections. The votes of this election will be added to the credit accounts. The winner is the party with most credit ballots. We will delete as many ballots from that party as there are voters (total number of voters) (some fine-tuning may be needed because the number of voters may change between elections). Note that we deleted actual ballots, i.e. also those other parties that were approved in some of these ballots lost some ballots from their account. Maybe we will subtract votes proportionally so that ballots with different approval patterns will be reduced in same proportion (some fine-tuning maybe here too, maybe all ballots to this party only will be eliminated).

Now we have a system that puts one party at a time in power. It is fully proportional in time in the sense that all parties will get their time in office one day. But if we want to stop small parties winning the election unless they grow into large parties we need some additional rules. One could for example allow only parties that have reached some predetermined number of votes in this election to win (or...). We could also eliminate votes that are older than five elections. There are also other tricks (fine-tuning and more coarse tuning possible again).

My point was anyway that this kind of credit based systems could indeed be one solution to the challenge (only large parties rule, one at a time, and small parties may grow into large parties).

Juho


> 
>> P.S. Could there be also three-party or n-party systems? Limiting the
>> number of parties to n would be an alternative to thresholds. This
>> approach could be used also in a two-party system, i.e. set the
>> threshold e.g. to 33% (or lower, or higher). Does the proposed method
>> work better than such thresholds or simply picking two largest
>> parties?
> 
> The approaches above could be adjusted to n-party systems, yes.
>