[EM] St. Louis and Pushover (Re: Reply to Rob regarding RCV)

Sun Oct 1 01:44:03 PDT 2023

Hi Chris,

I'm going to reply to your original email (and quote it on the bottom).
I'm going to replace "SCORE" with "[STAR]" in your email, because you
agreed in an earlier mail that's what you meant

I have a lot clearer idea of what the "pushover" strategy is now, thanks
(at least partially) to your email (thank you!).  My hunch is that the
pushover strategy may not be as well-studied, but it may be that there's
different terminology used in academic circles (perhaps "pied piper"...see
below).  I'm assuming from your email address that you're Australian.  Is
"pushover" strategy common in Australian elections, and commonly named by
that name?   My hunch is that pushover is a bigger problem in IRV/RCV/STV
than it is in more consensus-oriented election methods (like approval, any
Condorcet system, STAR).  I ask this because we don't talk about "pushover"
here in the United States, but it wouldn't surprise me if Australians talk
about it a lot.  We don't have very many places using STV/IRV/RCV, and the
politics of those places (e.g. San Francisco, Cambridge Mass) are treated
like outliers in mainstream political conversation.  San Francisco has
weird politics (which I assert from my office in San Francisco)

There are more places that use "top-two open primary" (like California and
Washington state).  "Pushover" hasn't (yet) made it into the mainstream
political lexicon in either place (that I know of), but I do know that in
2022, the Democratic Party here made a point of trying pushover against the
Republicans in regular first-past-the-post primaries :
https://www.washingtonpost.com/politics/2022/09/12/democrats-interfere-republican-primaries/

It was a risky strategy, but (I'm sad to say) it probably worked in 2022.
It failed for Hillary Clinton in 2016 though (see this 2016 article about
Clinton's "pied-piper strategy"):
https://www.salon.com/2016/11/09/the-hillary-clinton-campaign-intentionally-created-donald-trump-with-its-pied-piper-strategy/

This claim you make is interesting:
 "[STAR] somehow doesn't 'violate monotonicity' and yet [...] is more
vulnerable to Pushover than RCV (aka IRV) which does.".

Is that true?  It seems to me that RCV's series of runoffs lead to many
opportunities for weak candidates to snowball via transfers from eliminated
candidates.  The snowball effect in RCV usually snowballs to the center of
public opinion, but can sometimes roll toward the outskirts as candidates
get eliminated and their ballots get transferred to a stronger and stronger
candidate on the outskirts.  With STAR (and Score), I believe the candidate
needs to have strong support from all voters to get a high enough score to
advance (since all ballots are considered in the runoff round), but perhaps
similar polarization can occur under STAR over time.  It's truly an
interesting question which method is more susceptible to pushover.

As for the monotonicity of STAR, I'll need to leave it as an exercise for
the reader.  I'm not sure anyone has proven that STAR is monotonic, though
I suspect that an example of non-monotonic STAR would be a really weird
edge-case.

Rob
p.s. I've replaced "SCORE" with "[STAR]", but won't correct your spelling
of "maximising" nor "favourite", even though my spell checker really wants
me to.  English-speaking people are one people, separated by common
language.  :-)

On Sat, Sep 30, 2023 at 1:07 AM C.Benham <cbenham at adam.com.au> wrote:

> Rob,
>
> A question for Chris (anyone who cares to answer), what's the best
> explanation of pushover at a public URL that seems reasonably academically
> rigorous (e.g. something that seems like it would pass muster as a citation
> on English Wikipedia)?
>
>
> Blake Cretney (who used to be active here) had a web-page  ("condorcet.org"
> I think it was called)
> that is unfortunately now extinct. I regret not copying and storing the
> definitions/explanations that
> were there.
>
> That is where "Push-over" strategy was defined.  As I recall it said
> something simple like
> "the strategy of promoting a weak alternative for it to be beaten by a
> preferred stronger one".
>
> But really I think we are in the realm of common-sense and the bleeding
> obvious rather than being
> in awe of and deferring to academic authority.  Whatever it is exactly
> called, in the US political system it must be commonplace.
>
> Because (at least in some states) you have open public party primaries.
> Suppose you are a supporter of party A, and either you are happy with all
> the candidates running in A's primary election (or you are confidant that
> your favourite can win that primary without your help, or something in
> between) and so you decide to instead vote in main rival party B's primary
> to vote not for your sincere lesser evil but for the candidate you think
> would have the smallest chance of beating the A candidate in the general
> election.
>
> You would be using a Push-over strategy.
>
> Likewise suppose the method is plurality Top-Two Runoff.  If you are
> confident that your favorite can make it into the top two without your help
> then in the first round you might vote for a candidate (of course
> preferably among the other front-runners for the second spot) that you
> think most likely to lose in the runoff against your favourite. Then in the
> final you can vote sincerely.
>
> If the method is approval TTR, things are much easier for the pushover
> strategists because they don't have to rely on on other voters to get their
> favourite into the final two, and also they don't have to limit themselves
> to promoting just one weak candidate.
>
> If you only care about electing your favourite, the obvious strategy is to
> approve your favourite and all the candidates that you are confident can
> neither displace your favourite out of the top two or pairwise beat your
> favourite in the final.
>
> [STAR] is similar.  There one can choose between maximising the chance
> that a weak candidate will get in to the final two, or weakening your vote
> for the weak candidate to just below maximum (4 instead of 5) so as to help
> your favourite win the top-two pairwise comparison.
>
> In comparison with the methods I've so far mentioned in RCV (fka IRV) the
> would-be pushover strategists face the greatest problems and risks. They
> have to rely entirely on other voters to both get their sincere favourite
> into the final top two and also to overcome the strategists' own votes, for
> the strategists' sincere favourite to win the final two comparison.
>
> That electowiki entry you linked to:
>
> Pushover[edit
> <https://electowiki.org/w/index.php?title=Tactical_voting&veaction=edit&section=4>
>  | edit source
> <https://electowiki.org/w/index.php?title=Tactical_voting&action=edit&section=4>
> ]
>
> *Push-over* is a type of tactical voting that is only useful in methods
> that violate monotonicity <https://electowiki.org/wiki/Monotonicity>. It
> may involve a voter ranking or rating an alternative lower in the hope of
> getting it elected, or ranking or rating an alternative higher in the hope
> of defeating it. Also known as a *paradoxical* strategy. Note that it is
> usually very difficult to successfully pull off, and often backfires (i.e.
> elects the pushed over candidate).
>
>
> The first sentence looks like something I recall from that extinct page.
> It is correct in the universe of pure ranking methods. But according to
> apparent consensus here (and a wikipedia page you linked to)  [STAR]
> somehow doesn't "violate monotonicity" and yet (as I've discussed) is more
> vulnerable to Pushover than RCV (aka IRV) which does.
>
> Regarding the last bit, I've no idea how the author would know that it
> "often backfires", or have any idea how "often" it is attempted.
>
> Chris Benham
>
>
>
> *Rob Lanphier* roblan at gmail.com
> <election-methods%40lists.electorama.com?Subject=Re%3A%20%5BEM%5D%20St.%20Louis%20and%20Pushover%20%28Re%3A%20Reply%20to%20Rob%20regarding%20RCV%29&In-Reply-To=%3CCAK9hOYnPv5QaWnZhEhgAK6P08XyHdA1ew1p2fRn%2B0jD58DsUkA%40mail.gmail.com%3E>
> *Tue Sep 26 21:39:35 PDT 2023*
> ------------------------------
>
> Hi Chris
>
> Regarding former St. Louis resident Lewis Reed's preference of voting
> system, I'm not sure.  I suspect he was selling his preference to the
> highest bidder, and since he was still the President of the St. Louis Board
> of Aldermen, he presumably had influence in STL politics (until the bribery
> case in court made him politically radioactive).  Whatever remaining
> influence Reed may still have is waning with every day he spends in an
> Arkansas prison, where I believe he lives today. Something tells me that
> electoral reform is the least of Reed's worries in 2023.
>
> Regarding approval's potential vulnerability to pushover when used in a
> top-two primary, I'm personally not very concerned about the theoretical
> possibility.  Perhaps in the far future, we'll have really sophisticated
> voters who understand how to strategically influence the primary in a way
> that causes top-two approval to fail in a way that causes problems.  My
> sense is that St. Louis (which uses top-two approval) has bigger problems
> than sophisticated attempts at "pushover"
>
> I believe that St. Louis voters just wanted a good mayor in 2021, and
> approved many competitors to Lewis Reed (including Tishaura Jones and Cara
> Spencer).  From my analysis, it looks like the wealthier voters in the
> southern portion of St. Louis (i.e. the type that pay handsomely for
> produce at farmers' markets in mall parking lots on the weekends to assuage
> their guilt for the collapse of the independent farming in the United
> States) voted for Cara Spencer.  The voters in the northern part of the
> city (in the floodplain at the confluence of the Missouri and Mississippi
> Rivers, which USUALLY doesn't flood very much) voted for Tishaura Jones.
> Given the demographics of St. Louis (43% Black, 42.9% non-Hispanic White,
> 5.1% Hispanic, 4.1% Asian, 1.0% Hispanic White), it seems like a Tishaura
> Jones was a great choice to succeed their longtime White mayor.  Northern
> St. Louis is largely Black and Hispanic, and it's in really rough shape,
> despite having some fantastic old brick houses and lots of fantastic real
> estate that is available for very little money (see <https://youtu.be/SPyjYQALnrE>).  Jones is the first Black mayor of St.
> Louis since 2001, and third Black mayor that the city has ever had (and the
> first Black woman in the role).
>
> Based on my cursory research, I'm not sure the "pushover" phenomenon is
> well known outside of the jargon-speaking electoral reform community (and
> perhaps not even here).  Note that the electowiki section about pushover
> has no citations, and the "push over" section of a similar article on
> English Wikipedia even has the infamous "citation needed" tag:
>
>    - https://electowiki.org/wiki/Tactical_voting#Pushover
>    -
>    https://en.wikipedia.org/wiki/Tactical_manipulation_of_runoff_voting#Push_over
>
> Note: the "Push over" section appears to have had the "citation needed"
> banner on it since 2009, which means that said banner is almost old enough
> to get its driver's licence in many places.  I have a hard time taking the
> criterion too seriously given that it doesn't seem to warrant its own
> article on English Wikipedia.  It seems all of the important ones have
> articles:
>
>    -
>    https://en.wikipedia.org/wiki/Comparison_of_electoral_systems#Compliance_of_selected_single-winner_methods
>
> A question for Chris (anyone who cares to answer), what's the best
> explanation of pushover at a public URL that seems reasonably academically
> rigorous (e.g. something that seems like it would pass muster as a citation
> on English Wikipedia)?
>
> Rob
>
> p.s. having driven through St. Louis many times (and even stayed there a
> couple of nights), it's not hard to guess where the powers-that-be drew the
> red lines:https://storymaps.arcgis.com/stories/366759e8b76c46efbf6ff9e8fff3ac0b
>
>
> ----
> Election-Methods mailing list - see https://electorama.com/em for list
> info
>
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