[EM] FBC, center squeeze, and CD

[C.Benham]

On 11/7/2016 6:07 AM, Michael Ossipoff wrote:
> ...someone could say. "You didn't just favor X. You added a ballot, 
> thereby spoiling a majority. It has nothing to do with the fact that 
> you voted for X. You could have plumped for any of various candidates, 
> and the effect would have been exacsly the same."

"Someone" could /say/ that, but it wouldn't make any sense.

> But you can't say anything like that to to explain why X lost when I 
> raised hir in my ranking. In that instance, making the ballot-set more 
> favorable to X is the _only_ thing that I'm doing.

Increasing the turnout is generally regarded as a good thing.  If the 
method used was one of the mono-raise failing methods I like (such as 
IRV and Benham), I would say:

"Unfortunately it isn't possible for voting methods to have every 
desirable property (because some of those properties are mutually 
incompatible), and this method economises
by not meeting mono-raise. You were unlucky to be stung by that failure."

But generally speaking people care most about their favourites, and IRV 
meets not only mono-add-plump but also mono-add-top. It's true that 
after the election
some of losing candidate X's supporters could complain "If we hadn't 
top-ranked X, then X would have won" but that is unlikely to be noticed 
and of course isn't
true of all (or anything like all) of X's supporters.  So the X 
supporters as a whole could complain "If we had been well informed and 
coordinated we could have
used a mixed strategy (with not all of us voting the same way) and 
elected X."

But if voters accept the method as fair and legitimate then that 
"complaint" won't be taken seriously or get much sympathy.

Just as no quasi-intelligent device should be so "stupid" as to be 
confused by the very simple and spectacular MMPO failure example, 
neither should it be
confused by the very very simple mono-add-plump scenario.

What (arguably) desirable properties (or criterion compliances) are 
incompatible with meeting Mono-add-Plump?

Chris Benham


> Ok, thanks, Chris, for settling that matter. I guess we have to 
> reluctantly give up Conditional Bucklin.
>
> But it would have been strategically great!
>
> Now, here's a question on a related topic:
>
> Say I arrive at the polling-place late. Before I arrive X is winning. 
> I show up & plump for X, and that causes X to lose.
>
>
> ...is that worse than if I raise X in my ranking, and that causes X to 
> lose?
>
> If so, why?
>
> It seems to me that the latter is worse than the former.
>
> I if show up late and plump for X, I'm doing two things: I'm adding a 
> ballot, and I'm voting that ballot in a way that clearly should favor X.
>
> If i angrily complain, "Hey, how come, when I arrived and plumped for 
> X, that made X lose??!"
>
> ...someone could say. "You didn't just favor X. You added a ballot, 
> thereby spoiling a majority. It has nothing to do with the fact that 
> you voted for X. You could have plumped for any of various candidates, 
> and the effect would have been exacsly the same."
>
> But you can't say anything like that to to explain why X lost when I 
> raised hir in my ranking. In that instance, making the ballot-set more 
> favorable to X is the _only_ thing that I'm doing.
>
> So plainly violating Mono-Raise is worse than violating Mono-Add-Plump.
>
> Michael Ossipoff
>
>
>
> On Sun, Nov 6, 2016 at 10:27 AM, C.Benham <cbenham at adam.com.au 
> <mailto:cbenham at adam.com.au>> wrote:
>
>     The example I just posted of  "IBIFA with an anti-defection
>     device"  failing FBC I'm afraid also works for both Mike's suggested
>     "Conditional Bucklin" and Forest's suggested "TopMiddleBottom".
>
>     20: F=C >>B
>     07: F > C=B   (or, for the sake of Forest's method suggestion, F
>     >> C=B)
>     25: B
>     48: W
>
>     All three of these methods elect W, but if the 20 F=C >> B voters
>     change their rating of F from Top to Middle or Bottom
>     then the winner changes to B.
>
>     Chris Benham
>
>
>

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