[EM] Proposed bullet-voting prohibition criterion

[Peter Gustafsson]

Kristoffer:

Thanks for pointing out those possibilities for how a big party can instruct its voters on how to thwart the intent of this proposed criterion. Obviously, BVP is not sufficient to ensure the transition from a two-party environment to a multiparty environment. What are your ideas on how make a stronger set of criteria to that end?

As to your note about range voting: If the rule allows a vote in which one candidate gets 99 points, another 1 point, and all others get 0 points - then that is so close to bullet voting so that it should for all intents and purposes be considered such. I want the voting system to be designed so that valid votes are significantly different from a bullet vote.

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> Date: Tue, 29 Jan 2013 23:23:04 +0100
> From: km_elmet at lavabit.com
> To: miningphd at hotmail.com
> CC: election-methods at electorama.com
> Subject: Re: [EM] Proposed bullet-voting prohibition criterion
>
> On 01/27/2013 03:45 PM, Peter Gustafsson wrote:
> >
> > There are lots of voting system criteria that have been described,
> > but I have not seen this one - or any one like it - described
> > before.
> >
> > Bullet-voting prohibition Criterion: "A voting system should not be
> > constructed in such a way so that it is both legal and rational for a
> > voter to fill in a ballot with only one party or candidate name, so
> > that the voter refuses to order by preference all candidates that are
> > not his first preference."
>
> This criterion seems to be two combined. These are:
>
> - It should not be possible to submit a ballot listing only one party
> ("legal")
> - For any ballot that includes only one party, there should exist at
> least one other ballot that lists more than one party and which doesn't
> make the voter worse off if he were to vote that ballot instead
> ("rational").
>
> I think the second here is pretty much Later-no-harm, though I share
> Benham's opinion regarding methods that only pass LNHarm or LNHelp (and
> not both or neither). That is, a method that passes only LNHarm
> encourages random-fill (the voter adding more parties or candidates in a
> random order because it can't hurt), and a method that passes only
> LNHelp encourages bullet-voting.
>
> As for the first criterion, that's reasonable enough, but I think the
> intent can be thwarted.
>
> > Since FPTP enforces bullet voting, it obviously fails the BVP
> > criterion. In Approval voting, it is legal to vote for only one
> > candidate, so it fails also. In score voting, it is legal to give 99
> > points to one candidate and 0 points to all others, so it also fails.
> > All other voting systems (that I can think of right now) can be made
> > compatible with this proposed BVP criterion by adding a rule that the
> > voter must supply at least 4 (or whatever number sufficiently high)
> > most preferred candidates, otherwise the vote is spoiled.
>
> It's easy to modify Approval and Range/score to pass the "legal" part of
> the criterion, though. Just say that the Approval ballot is only valid
> if at least two candidates are approved, or that the Range ballot is
> only valid if, after removing a candidate given max score, there are
> candidates with non-min score left.
>
> > So, what would happen if a voting system with a BVP-criterion
> > enforcement would be introduced? I see two possible scenarios:
> >
> > 1. The big parties split into several very similar parties, so that
> > hidebound voters of that party can vote a complete list of only party
> > members.
> > 2. The big parties do not split, and the voters of those
> > parties engage in mutual burying. Their voters vote their party #1,
> > then supply a long list of minor parties, so that they do not have to
> > give any help to the hated other big party. Meanwhile, many 3rd party
> > voters will vote one big party at the bottom, and several will
> > tactically vote both big parties at #1 and #2 from the bottom.
>
> There's a third possibility. The parties may produce "decoy lists" that
> aren't expected to get much support at all and are thus easily
> controlled by the parent parties. Party voters could then vote for a
> party and a randomly picked decoy list to get around the BVP limitation.
>
> For instance, say that party X introduces 12 pseudoparties (one for each
> month) and instructs their voters to vote for X and the pseudoparty
> corresponding to the voter's birth month. Then, in a majoritarian
> system, the pseudoparties won't get their candidates elected (because
> the parent party will always have significantly more support); and in a
> proportional representation system, the method would give seats to the
> parent parties and these parties' voters would be considered represented
> by them, thus again giving the pseudoparties few seats.
>