[EM] STV - the transferrable part is OK (fair), the sequential round elimination is not

[Kristofer Munsterhjelm]

Juho wrote:
> If one really wants a two-party system and doesn't want voters to change 
> that fact then one could ban third parties and accept only two. That 
> would solve the spoiler problem :-). 
Who is this "one"? Since that one is at odds with the voters, that's not 
very democratic, is it?

I guess that one "democratic" way of doing it would be to have the 
question itself posed to the voters, but with a suitable low-pass filter 
(e.g. supermajority required to change it, or a majority over a long 
time); though then I think it'd be better just to have the filter on the 
decision process itself.

> From this point of view e.g. the US system is not really intended to
> be a two-party system but just a system (target state unspecified)
> that has some problems with third parties.

That's most likely the case. AFAIK, the founding fathers just copied 
Britain's election methods (first past the post, etc.), and by the time 
parts of the US noticed this wasn't really optimal, those who benefitted 
from said methods' unfairness had acquired enough power to block the 
adoption of better methods (e.g. the red scare campaign leading to STV's 
repeal in New York).

There are some exceptions. To my knowledge, some state governors are 
elected by runoff rather than just "winner takes it all". FPTP runoff 
may fail (such as with Le Pen in France, or more relevant - the "better 
a lizard than a wizard" second round in Louisiana), but at least it 
can't elect the Condorcet loser, which plain old FPTP has no problem doing.

> On  the other hand the option of third parties could be left in the rules
> intentionally. The voters are given a chance to change one of the two 
> parties to some third party if they want that so much that despite of 
> the associated spoiler problems they will eventually give the third 
> party enough votes to beat one of the leading parties. Actually 
> two-party systems need not be based on two parties only nation wide. In 
> principle each district could have its own two parties that are 
> independent of what the two parties are in other districts. There is 
> however some tendency to end up with two or small number of parties 
> nation wide.

As another reply mentioned, this has happened in Canada. With very local 
exceptions, it hasn't happened in the US - at least not recently. I 
think a key difference is that the large US parties can gerrymander, 
whereas that is not the case in Canada (since Elections Canada does the 
redistricting there). When parties can pick their constituents before 
the constituents can pick their representatives, competition suffers 
because third parties can't get off the ground.