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

C.Benham cbenham at adam.com.au
Sat Sep 30 01:07:09 PDT 2023


> 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.

SCORE 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 violatemonotonicity <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)  SCORE 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 
> <mailto: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
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