[EM] Anyone got a good analysis on limitations of approval and range voting? (long)

[Matthew Welland]

On Tuesday 10 November 2009 03:37:56 am Kristofer Munsterhjelm wrote:
> Matthew Welland wrote:
> > So, to re-frame my question. What is the fatal flaw with approval? I'm
> > not interested in subtle flaws that result in imperfect results. I'm
> > interested in flaws that result in big problems such as those we see
> > with plurality and IRV.
>
> IMHO, it is that you need concurrent polling in order to consistently
> elect a good winner. If you don't have polling and thus don't know where
> to put the cutoff (between approve and not-approve), you'll face the
> Burr dilemma: If you prefer A > B > C, if you "approve" both A and B,
> you might get B instead of A, but if you "approve" only A, you might get
> C!

This seems to me to be a minor, not major, flaw.  Having to vote A & B to 
hedge your bets is not ideal but you might even be able to argue some 
benefits to it. A will see B as a serious threat and vice versa. They may 
make adjustments to their stands on issues to accommodate voters like you. 
Approval voting is enough to bring competition for votes back into the arena 
and I think it makes negative campaigning a very risky strategy. 

Also, again, your single vote is irrelevant. It is the aggregate of 
thousands or millions of votes that will make or break A vs. B. How many 
feel so strongly against A that they cannot vote for him or her?

The binary nature of approval is washed out by large numbers just as a class 
D amplifier can directly produce smooth analog waveforms out of a pure 1 or 0 
signal.

> Thus the kind of Approval that homes in on a good winner employs
> feedback. The method is no longer Approval alone, but Approval plus
> polling. That /can/ work (people approve {Nader, Gore} if Nader has
> fewer votes than Gore, so that Bush doesn't win from the split, but only
> approve either Nader or Gore if both are large), but why should we need
> to be burdened with the feedback?

Sure, in any real election there will be many dynamics at work. Feedback 
polls, debates etc. will all improve an election. Approval might benefit from 
feedback but I don't see why it becomes fatally flawed without it, only 
mildly flawed.

> Some, like Abd, argue that we always reason based on others' positions
> to know how much we can demand, and so that this is a feature rather
> than a bug. That doesn't quite sound right to me. In any event, if you
> want Approval + bargaining (which the feedback resolves to), make that
> claim. Approval alone, without feedback, will be subject to the flaws
> mentioned earlier, however.