[EM] Approval Strategy A- Question for Rob LeGrand

[James Gilmour]

Gervase wrote (in parts):
> Some people argue that (Plurality) PR can cause too much 
> diversity.

What is "Plurality PR"?  I thought Plurality could give acceptable PR only by chance.  Certainly the
results of UK Plurality (single-seat and multi-seat) elections at all levels of government show the
failure of Plurality to deliver PR.

 
>  This can be detrimental when the elected chamber try to vote on 
> things.  This is the reason why Italy went from proportional to a single 
> seats election. 

You need to be more specific than just "proportional".  Italy used a Party List system of PR, which
can have a tendency to encourage party splitting.  However, Italy also had many parties before 1919
when it used a majoritarian voting system, so it is doubtful whether the voting system used was a
relevant factor in that case.

With STV-PR (Choice Voting) we can see examples where the system gave representation to diversity
and that diversity has been maintained, eg Northern Ireland, and examples where diversity has
reduced from a multi-party parliament to a two-party parliament, eg Malta.


> So, there could still be room for Approval and Condorcet.  
> Nevertheless, I 
> did (and still do?) agree with you that if you want PR, why 
> not just stick 
> with Plurality.  Plurality is simple, which is a bonus.

Plurality may be simple, but it has little to do with anything I would recognise as "PR".


> Immediately below that would be Borda as it is the "next 
> step" down from 
> Cardinal Ratings.  Borda would be followed by Approval then Condorcet.

I am surprised that Borda should receive any serious consideration at all.  The defects of this
voting system are well known, so why would anyone want to use it?


>  Meanwhile, Plurality is only proportional 
> with respect to the top most voted candidate.

What does this statement mean?  How has "proportional" being interpreted here?

James