[EM] Smith, FPP fails Minimal Defense and Clone-Winner

Juho juho4880 at yahoo.co.uk
Wed Mar 10 14:12:15 PST 2010

On Mar 10, 2010, at 11:35 PM, Raph Frank wrote:

> On Wed, Mar 10, 2010 at 9:24 PM, Juho <juho4880 at yahoo.co.uk> wrote:
>> Another approach to systems between proportional representation and  
>> the
>> two-party approach could be to have a proportional method but use  
>> districts
>> with only very few representatives (2, 3,...). That would provide  
>> rough but
>> in principle accurate proportionality and still give space only to  
>> few major
>> parties. (Obviously my definition of full proportionality must be  
>> "with 1/n
>> of the votes you will get one seat (where n = number of  
>> representatives)".)
> You mean a hybrid of multi-constituency PR and party list PR, or just
> PR at the district level?

I didn't quite understand your question. The method could also be non- 
party-list-based (like STV).

> If the legislature was elected using 2 seat constituencies, then
> balance of power in the legislature would be decided by the few
> districts where one or other party is near to 2/3 majority.
> If both parties were roughtly 1/2 each, then most districts would end
> up electing one from each party.

Actually we have a continuum from single member constituencies to full  
proportionality. Use of 2 seat constituencies provides a really rough  
system, but still one step smoother than single seat constituencies.

In this kind of systems (1 or 2 seats) one must maybe include also  
time in the model to understand how the system works. If voters are  
not satisfied with the biggest (ruling / most dominating) party then  
it will lose some seats in some constituencies (2/2->1/2, 1/2->0/2,  
1/1->0/1). The fairness of the system is thus not really guaranteed in  
one single election but voters can change the system still in time. If  
the system still gives most seats to the big party that voters were  
not happy with (thanks to appropriate allocation of its supporters to  
the constituencies and resulting bias in the results) then voters may  
wait for the next election and be even less satisfied with the party  
and vote more against it and finally get the result that they wanted.  
In this sense two-party systems are actually based on alternating  
dominance and some approximate proportionality is offered in time when  
one party stays in power longer than the other.


More information about the Election-Methods mailing list