[EM] Amnon Rubinstein's Proposal for Electoral Reform in Israel
watermark0n at yahoo.com
Tue Apr 25 14:03:58 PDT 2006
James Gilmour <jgilmour at globalnet.co.uk> wrote: > Antonio Oneala> Sent: Tuesday, April 25, 2006 12:08 AM
> I've never really been a fan of STV-PR. It's still a system
> that's not independent of irrelevant alternatives, so in most
> states it squeezes out third parties and moderates, unless
> you expand the districts to an enormous size
On what evidence do you base this assertion?
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Besides that fact that practically every country that has used STV has boiled down to a more or less two-party system?
Well, I doubt you're going to find many people in the world who will say that STV is indepndent of irrelevant alternatives. It still has the same problem that plurality and IRV have: you have 1 vote for 2 choices, and you have the same abount of power for 10 choices. Obviously, people are going to vote tactically and pick one out of the two. It's a system not designed to aggregate preferences of large numbers of choices. The transfer of votes doesn't make a bit of difference, as seen by the fact that there are only 3 people not affiliated with the two party system in all of the Australian house, which uses IRV. What IRV is is basically a complicated version of plurality that almost always spits out the same results.
Since STV is a multi-winner PR version of IRV, and the 1 vote basically acts as a quota here, obviously you're going to get more variety in there, but this does not make it independent of irrelevant alternatives. The main thing that makes STV more proportional than SNTV is transfer of surplus votes, which creates great potential for tactical voting in that system. But this does not make STV perfect. The system, like SNTV, will be limited to about as many parties as there are seats, and it will usually have a "center squeeze" effect, whereby moderates are eliminated first. There's fewer opportunities for strategic nomination than in SNTV, but still, a party can improve their outcome by running fewer candidates than there are seats, and vote-splitting. There's also the problem of non-monotonicity, and quite a few other things. If you ran party list votes through STV, you would get far less proportional results the normal quota methods.
STV was a half-hearted attempt to fix a broken system, SNTV. PAV is a completely new system, one that isn't broken, and has the same amount of tactical voting problems as normal AV voting, unlike STV, which introduces more tactical problems than normal plurality in single-member districts. IRV was a stupid importation of the further broken system into single-member districts. PAV is the only proportional system I've yet to see, besides party-list, that's satisfies the FBC, and is mostly independent of irrelevant alternatives.
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