[EM] Score Voting and Approval Voting not practically substantially different from Plurality?
benn at 4efix.com
Mon Jun 24 06:06:53 PDT 2013
Hi guys, I'm still here, still pondering, but now I have another question.
I've been thinking about score voting, approval voting, and plurality (FPTP)
voting, and I have a concern.
Say we have a situation where we have three candidates, say Gore, Nader, and
Bush. Say we have a voter, Abe whose greatest concern is that Bush NOT win.
His second priority is that Nader win over Gore - but this priority is a
distant second. He *really* doesn't want Bush to win. He would prefer Nader
over Gore, but he *hates* Bush.
Let's also say that Abe is intelligent, and he is committed to using his
vote to maximize his happiness - in other words, rather than vote sincerely
and cause his preferences harm, he will always vote strategically where it
is to his benefit to do so.
If Score Voting was in place, and he were to vote sincerely, Abe probably
would vote something like 'Gore:75, Nader: 100, Bush: 0'. However, he's no
fool, and he knows that while it is theoretically possibly that Nader
*might* win, Gore is his best chance to stopping Bush, and that withholding
score from Gore might (if all Nader supporters did it) result in Gore not
getting enough of a score, therefor Bush could win.
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 voting.
The only people who would bother to vote sincerely are:
1) Those who truly prefer Gore highest and Bush lowest (or vice versa),
because there's no strategic downside.
2) People who would rather feel more "sincere" about their vote than
feel good about the outcome of their vote.
3) People who aren't intelligent to realize that by voting sincerely
they may be helping elect their least preferred candidate.
And say what you want about intelligence being a bar to entry, you can bet
that the smart people behind ALL candidates will make sure that everyone
gets the message, so we can largely ignore #3. Most people I imagine would
be pragmatic enough to worry more about the end result and less about
sincere vs. strategic, so we ignore #2. And #1 people are going to vote the
same way anways, so they may as well use Approval voting.
OK, so let's throw out Score Voting and use Approval voting. Gore v Nader V
Bush. Abe (who hates Bush but prefers Nader) gives an approval vote to
Nader, his top-most preference, but knowing that withholding approval from
Gore could elect Bush (and not wanting to play the spoiler) he also gives an
approval vote to Gore. Since Gore in this example is far and away receiving
much more support than Nader, Gore now beats Bush.
Let's call the party that put Nader on the ballot the Green party, and that
they continue to field candidates in further elections that use the Approval
voting system. Abe notices the following pattern: when the Green party
fields a candidate that doesn't even have a glimmer of hope winning the
election (like the Gore/Nader/Bush one) that people that support the Green
party candidate also approve the Democrat candidate as a bulwark against the
Republican. And since in those elections the Green party never really had a
hope of winning, the Green approval vote is ultimately irrelevant - those
elections would have proceeded no differently than if the Green supporters
had simply voted Democrat.
But much worse yet, Abe notices that in *some* election, the Green party
actually gets a chunk of people thinking that Green could actually win. And
emboldened by their hopes, many Green supporters decide to go for it,
approve of the Green candidate, but *not* the Democrat one. Result: in
elections where more voters think more favorably towards Green's chances,
their least preferred choice (the Republican) tends to win more!
This are my two thoughts:
a) Intelligent use of Score Voting becomes Approval Voting, and the
harm in unwise use of Score voting means that Approval Voting is superior to
(and simpler than) Score voting pragmatically.
b) Approval Voting tends to result in irrelevant approval votes being
given to weak candidates - which is pointless, or slightly stronger (but
still losing) candidates can once again present a spoiler effect where a
person's least preferred choice is elected because they cast their approval
only toward their most preferred choice, who was nowhere near supported
enough to stop their least preferred choice.
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?
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. :(
eFix Computer Consulting
<mailto:benn at 4efix.com> benn at 4efix.com
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