[EM] Majority Criterion, hidden contradictions

[Chris Benham]

Abd ul-Rahman Lomax wrote:

>If a method allows voters to express a "strict preference," and 
>Approval does, but it also allows voters to do something else, does 
>this mean that voters who *have* expressed a strict preference, in 
>the manner that the election method permits, are to be considered as 
>not having expressed this preference merely because the method did 
>not allow them to take the alternate path without expressing a strict 
>preference?
>
Typically completely stupid question.

>How can a voter express a "strict preference" in Approval.
>
>Is there a means to do it?
>
>That voters may do something else, which is express a "group 
>preference" *is irrelevant*. Or is it relevant? How?
>
Suppose we have a lot of hampers of food to give away. We have larger 
ones that contain more
than one type of food, and smaller ones that contain only one type. We 
then invite recipients to
each choose one only hamper to take home.  So yes, some of these people 
could have expressed
a "strict preference" for a certain type of food and a few might have, 
but we never asked them to
and those that did paid the price of getting less food.

>What in the 
>criterion covers this contingency?
>
For especially obtuse morons, it comes under the heading of  "criteria 
that apply to ranked ballot
methods". Approval isn't a ranked ballot method, so we ask "if the 
voters each have a candidate they mean
to rank alone in first place on a ranked ballot, can we (reasonably, 
reliably, consistently) infer from the ballots
they submit who those candidates are?"

The answer for FPP is obviously "Yes". For this purpose an FPP ballot 
can properly be considered to be
simply a ranked ballot that doesn't allow equal-ranking at the top. The 
fact that the "lower preferences"
are ignored or invisible or don't exist is irrelevant.

>I'm not sure that Benham said exactly what he intended to say..
>
I did. I'm normally careful to do that.

>We assume that voters intend to do what they did.
>
For criteria that apply to ranked ballots, we assume that the voters 
mean to submit a
ranked ballot. Venzke and Woodall interpret Approval ballots as ranked 
ballots
with all the ranked candidates approved and the numbers indicating the 
order in
which they are ranked  obscured.

I think Abd's real-world propaganda concerns are misplaced. In 
situations where
FPP elects a majority winner, supporters of that candidate will usually 
have enough
pre-poll information to know to use the "exclusively approve your 
favourite" strategy.
In fact usually it will be known in advance who the two front-runners 
are, and if the
voters in general adopt the sensible "approve the front-runner I prefer 
to the other
plus all the candidates I prefer to both of them" strategy then of 
course in practice
Approval will always elect a majority favourite.

Approval is in much bigger trouble in comparison to IRV, which *does* 
have it all
over Approval in terms of  majority-related guarantees (except perhaps 
for Minimal
Defense).

Promoting Approval versus IRV requires continually hammering  Favourite 
Betrayal
Criterion, ultimate simplicity and huge "bang for buck", and Minimal 
Defense.


Chris Benham





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