[EM] My summary of the recent discussion

[James Gilmour]

> >> I think Plurality can be claimed to be the ideal method for the 
> >> single-member districts of a two-party system, but then one should 
> >> maybe also think that third parties should not be allowed  to run, and 
> >> we should stick to the same two parties forever.
> > 
> > I don't get it.
> > 
> > of course, if there are only two candidates, there is no problem with 
> > Plurality (because it's also a Majority).
> > 
> > so how is Plurality so flawed if we accept that a two-party system is 
> > fine and dandy?  if not Third parties, for Independents?
> > 
> > what is the scenario with two parties where FPTP is so flawed?
> 
> I think you already said it. If you want a system that allows 
> also third parties and independents take part in the 
> election, then Plurality is flawed. Only if you think that 
> third parties and independents should nor run, and there 
> should be only two parties, then Plurality is fine.

These contributions to this discussion take an extremely narrow view of representation of voters as it is clear this discussion is
not about a single-winner election (state governor, city mayor) but about electing representative assemblies like state legislatures
and city councils.  There can be major problems of representation if such representative assemblies are elected by FPTP from
single-member districts even when there are only two parties.

Even when the electorates of the single-member districts are as near equal as possible and even when the turnouts are near equal,
FPTP in single-member districts can deliver highly unrepresentative results if the support for the two parties is concentrated in
particular districts -  as it is in most electorates.  Thus party A that wins 51 of the 100 seats in the assembly may win those
seats by small margins (say 550 votes to 450 votes) but party B that looses the election with 49 of the 100 seats may have won its
seats by overwhelming margins (say 700 votes to 300 votes).  Thus the 51 A to 49 B result is highly unrepresentative of those who
actually voted: 42,750 for party A but 57,250 for party B.

These numbers are deliberately exaggerated to show the point, but here in the UK we see this effect in every UK General Election
since 1945, where the "win small, loose big" effect of FPTP has consistently benefited the Labour Party at the expense of the
Conservative Party.

And where such vote concentration exists  -  at is does everywhere  -  the result can be greatly influenced by where the boundaries
of the single-member districts are drawn.  "Move the boundary, change the result".

These are fundamental defects of FPTP in single-member districts that must be addressed if you want your elected assemblies to be
properly representative of those who vote.

Both of these defects has greater effect if the electorates are not so equal or if the turnouts vary with party support (as they
certainly do in the UK).

So even when there are only two parties, FPTP is very far from "fine".

James Gilmour





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