[EM] Score Voting and Approval Voting not practically substantially different from Plurality?
panjakrejn at gmail.com
Mon Jun 24 15:53:21 PDT 2013
On Mon, Jun 24, 2013 at 6:06 PM, Kristofer Munsterhjelm <
km_elmet at lavabit.com> wrote:
> On 06/24/2013 03:06 PM, Benjamin Grant wrote:
>> So strategically speaking, Abe reasons that although he supports a less
>> likely candidate more, he strategically should score the front-runner
>> Gore at full strength, so long as keeping Bush out is the greatest need
>> – and so long as Nader’s win is unlikely.
>> So, as far as *I* can see, this converts Score Voting into Approval
> You're generally right. There are some very particular situations with
> incomplete information where it makes the most sense to use partial
> ballots, but those happen way too rarely to make a difference.
Excellent, that makes me feel like I am not utterly in left field wondering
where everyone went.
> You can see this from the other end, too: say you're in an Approval
> election and want to vote 0-10-range style. You want to give X a rating of
> 4, but it's an Approval election. To do this, you generate a random number
> on 0...10. If it is lower or equal to the rating (in this case 4), you
> approve of X, otherwise, you don't. If everybody did that, the Range and
> Approval results would give the same winner (with high probability). So in
> a real sense, Range is Approval with fractional votes permitted.
> Also, Range could possibly give different results than Approval voting.
> Consider an election where 99% of the voters are strategic. The vote comes
> out to a tie between Nader and Gore, according to these 99%. Then the
> remaining 1%, voting sincerely, vote something like [Nader: 90%, Gore: 70%,
> Bush: 10%] (strategic would be [Nader: 100%, Gore: 100%, Bush: 0%]). Then
> those votes break the tie and Nader wins.
> For reasons like this, a mix of strategic and honest voters give better
> results than just having strategic ones.
Of course, there are (in the circumstance where Gore is the better chance
to beat Bush than Nader) likely more Gore:100 Nader:0 Bush) votes than
Nader: 90 Gore:70 Bush 10 ones.
In fact, given that we *are* talking about an election with two strong
front running candidates and one "spoiler" weaker one, isn't it *far* more
likely that Gore is far in front of Nader and the only real unknown is if
Gore will beat Bush or not? Which leads right back to the entire scenario
of issues I began with.
The thing is, whenever we have more than two parties running, I think we
will always have weaker "spoiler" parties that cannot really win, but that
can, if the system allows or encourages people to vote against their best
interest, cause people to get a much lower ranked choice, possibly their
least preferred choice - this is my whole concern.
Am I substantially wrong about any of this? Ultimately, in real and
>> practical terms, it seems that done intelligently, Score Voting devolves
>> into Approval Voting, and Approval Voting devolves into Plurality Voting.
>> How is this not so?
> I would much prefer a good ranked balloting system to Approval, but let me
> try to explain the other side as well.
> Your observation is right in that there's obvious tension between
> approving of only Nader (so Nader will win) and of both Nader and Gore (so
> Bush won't win). This is one of the reasons I dont like Approval all that
> much: I think it burdens the voter with having to convert an internal
> preference into an Approval-style ballot in what I call "manual DSV". DSV
> is Designated Strategy Voting, a meta-system where one has a computer find
> out the optimal strategic vote for some given honest vote. The implication
> of having to engage in manual DSV is rather like having to do a
> mathematical task in your head before voting: we'd rather not and it makes
> the system more unwieldy.
> So there are really three stages to a prospective new party or candidate
> (like the Greens or Nader):
> 1. the candidate is not competitive (e.g. fringe candidate).
> 2. the candidate is competitive but either not strong enough to win, or
> there's been a miscalculation by the voters.
> 3. the candidate has taken over the position that would belong to a
> competitor (e.g. Nader becomes the new Gore).
> I think Approval advocates argue that the relative share of approvals will
> inform the voters of where they are. So the progression goes something like:
> In stage one, everybody who approves of Nader also approves of Gore.
> In stage three, the tables are turned: everybody who approves of Gore also
> approves of Nader, but Nader still wins.
> Stage two and the transition to three is the tricky part. In rounds of
> repeated polling, the voters start off cautious (approving both Nader and
> Gore). Then they see that Nader has approval close to Gore's level, so some
> start approving of Nader alone. This then reinforces the perception that
> Nader is winning, so more voters approve of Nader alone. And so it goes
> until Nader is slightly ahead of Gore and wins.
Aha! But what if what is likely happens in stage two: People get ahead of
themselves and give their full support to Nader and less support to Gore
*before* Nader is strong enough to beat Bush? Then Bush wins, both the
Nader and Gore voters freak out, and now Nader people go back to voting
Gore with full support, because now they've been burned!
The only way to avoid this, I *think*, is with a system in which expressing
a preference of A over B doesn't let C win - and such a system may well
have worse flaws, possibly.
So, the way I see it: Approval is very simple on the front end. It's just
> "count all the votes". Back end is a completely different matter, as you
> see above. I think Approval pushes a lot of the oddities of voting into the
> "back-end" - the space in which the elections happen, as it were. The
> method itself appears to be very good (pass FBC, etc), but that's because
> the calculations happen in the minds of the voters before they submit their
> ballots and the criterion failures are therefore "hidden". If one were to
> make a computerized system that took preferences as inputs and then
> directly produced the output that the voters would be thought to reach
> through repeated polling, that system would probably fail quite a number of
> But it is better than Plurality. It is nowhere as complex as IRV, it is
> just "count all the votes". As a compromise, it's better than not reaching
> any compromise at all.
Well, to be fair, just about anything is better than plurality. However,
what I meant is that functionally Approval (when each voter acts to their
best (or least bad) outcome) seems not that different from Plurality
Voting. We still top vote the front runner that has the best chance to
defeat our abhorred candidate. If we have a candidate we prefer more than
the palatable front runner, we can top vote him too, but that won't help
Nader beat Gore. It seems irreconcilable in this context.
> If it *is* so, then as much as I abhor Plurality Voting, I must now
>> likewise abhor Score and Approval Voting. But that shoves me back at
>> the Bucklin, IRV, and other system that have one of my least favorite
>> flaws – that ranking X higher than Y can cause Y to beat X.
>> It’s days like these that I feel that there *is* no way to elect people
>> that is fair and right.
> Remember that criterion compliances are absolute. So a method may fail a
> criterion yet be perfectly acceptable in real elections. Being able to say
> that a method passes a criterion, though, helps a lot in that you now don't
> have to consider the possibility that the criterion might actually intrude
> upon real settings.
> Still, there are results that are valid within certain domains. For
> instance, Black's single-peakedness theorem says that if all voters have
> preference functions that are highest at some point on a line and decrease
> from there (without increasing again), and the voters rank the candidates
> in order of preference, then any Condorcet method picks the candidate
> closest to the median voter. Also, IIA holds in such a situation because
> there are never any Condorcet cycles.
Yup, that's where I will begin making charts! ;) (Seriously.)
I just have to find the time and focus to bring my endeavor with this to
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