[EM] MAV on electowiki

Jameson Quinn jameson.quinn at gmail.com
Fri Jun 28 09:19:30 PDT 2013

2013/6/28 Chris Benham <cbenhamau at yahoo.com.au>
> Jameson,
> "...But I don't think it's realistic..."
> I don't think any of the "multiple majorities" scenarios are very
realistic. Irrespective of how they are resolved,
> all voters who regard one or more of the viable candidates as
unacceptable will have a strong incentive to top-rate all the candidates
they regard as acceptable, out of fear that an unacceptable candidate gets
a majority before their vote can help all the acceptable ones.

There are three possibilities in this case:

-1D spectrum L-C-R. There is no need for the marginal voters to top-rate C,
because C will naturally get a majority first.
-Chicken dilemma. I think the strategic incentives in this case are the
opposite of what you claim. The two frontrunners who could get simultaneous
majorities are similar ideologically, so the incentive is to drop their
rating to second-to-bottom or even bottom, not to elevate them to top.
-Ideology-free, personal charisma: It would take an extreme amount of
asymmetric strategy to sway the result in such cases, so I suspect most
voters will not bother to try, and just be honest.

> I still say that your suggestion only increases that incentive (even
though maybe more psychologically than likely to cause extra actual
post-election regret).
> Forget about using the mechanism for resolving the (probably very rare)
multiple-majorities scenario to try to gain some whiff of "later-no-harm".
> BTW, the "Majority Choice Approval" Bucklin-like method using ratings (or
grading) ballots, simply elected the candidate whose majority tally was the
biggest. I also prefer that to your suggestion. It and yours are simpler to
count than the Mike Ossipoff idea I support.
> I'm very glad to hear you think IBIFA is a great method.
> I'll stop quibbling about how you classify it.

It's got great results, but is problematic for its counting complexity.

> "Condorcet is too complex."
> Does that mean that you don't care that it fails FBC?
> Condorcet//Approval is pretty simple (and IMO quite good).

I do care about FBC to some degree, but I think that all serious Condorcet
systems come close enough to meeting it for my purposes. That is, very few
voters would use a favorite betrayal strategy.

I do have strategic concerns with Condorcet though: with burial. Probably
the best (closest to later-no-help) Condorcet systems are OK in this
regard, but I'm afraid I don't know which those are.

I also think complexity is a real concern. Anything that is only N²
summable is certain to have complex scenarios where it's not particularly
easy to explain why candidate X is the winner. I much prefer N-summable
systems where you can assign a single number to each candidate and the best
one wins, because I think those are easier for an average voter to
intuitively grasp. That intuitive grasp has to do with how many words it
takes to define the rules, but I think the bandwidth of the summability is
also a factor. A simple three-viable-candidate scenario which can be
reduced to 3 numbers fits in the average persons head; one which requires 6
numbers is too complicated.

> Am I right in assuming that you only like methods that meet FBC or
Condorcet and maybe Mono-raise? And/or are biased towards electing
centrists?  And for some or all of these reasons you don't like IRV?

FBC is negotiable, if a method comes close enough. I'd give a similar
weight to near-later-no-help, and some lesser weight to near-later-no-harm.

If by "biased to centrists" you mean "with honest votes, nearly always
elects a CW or utility winner", then yes. Note that I think that Bucklin
methods (including the limiting case of approval) meet this criterion, but
I wouldn't necessarily say that they're biased towards centrists; it really
depends on how the voters act, and there are plausible scenarios for
centrists losing in such systems. But I don't think IRV meets this bar.
That is, center-squeeze is one of my main problems with IRV, along with its
problems with summability/fraud-poofing.

> Chris Benham
> Jameson Quinn wrote (27 June 2013):
> 2013/6/27 Chris Benham <cbenhamau at yahoo.com.au>
> Jameson,
> "I don't see it..."
> Say on an ABCD grading ballot you give your Lesser Evil X a B, and then
in the second round both X and  your Greater Evil Y reach the majority
threshold. In that case you obviously might have cause to regret that you
didn't give X an A.
> OK, I see what you're saying now.
> But I don't think it's realistic. If X and Y both reach a majority at B,
then there are some voters giving both of them a B or above. This looks a
lot more like a chicken dilemma situation between two similar frontrunners,
than like a situation where X versus Y is a gaping difference which
justifies the use of a just-in-case strategy for a low-probability
occurrence. Especially because, in a chicken dilemma situation, multiple
majorities would tend to slide down towards the second-to-bottom rating,
not up at the second-to-top one.
> That is why your suggestion makes it (even) less safe to not simply give
all the acceptable candidates an A.
> "I think that's [IBIFA] a great method, but I would classify it as
"improved Condorcet" rather than "Bucklin-like".
> No. There isn't any pairwise component in the algorithm, and unlike the
"Improved Condorcet" methods it doesn't directly aim to come as close as
possible to meeting Condorcet without violating Favorite Betrayal.
> There is no pairwise component in the narrowest sense, but it still is
only summable at (R-1)*(N²), which is actually worse than a regular
Condorcet method.
> Again, I think this method would deliver excellent results, and I see why
it is in certain ways akin to a Bucklin or median method. But its
quasi-pairwise counting complexity still makes me see it as more similar to
improved Condorcet methods than to Bucklin ones.
> But another method I support is in that category, "TTPBA//TR".  Mike
Ossipoff  promoted it as "Improved Condorcet, Top"  (or ICT).
> Right, there's a lot of good methods out there. Any of these would
satisfy me as more resistant to strategy than either Condorcet or Score.
And those two in turn are quite satisfactory as being at least as good as
approval with more expressivity, and approval is satisfactory as being a
giant and strict improvement over plurality. Great.
> And I like to talk about the relative merits of each proposal here on the
> But if we talk like this in front of non-mathematical voters, we'll only
turn them off. We need simple proposals. Approval is step one; most of us
agree on that. But some voters, like Bruce Gilson, will never be satisfied
with approval because it doesn't feel expressive enough.
> So I think it's worth having a second option to offer. To me, pitching
Score feels dishonest: "Look at this great system! Amazing great things it
can do! (But watch out, if you vote other than approval-style, you'll
probably regret it.)" Condorcet is too complex. I want a simple, good
system. MAV would fit the bill. If you have another proposal that would,
then the way to get me onto your side is to demonstrate that it has more
supporters than just you. That goes for you, Chris, and also for you, Abd.
> Jameson
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