[EM] 28 years of progress and a wakeup call

[Kristofer Munsterhjelm]

On 2024-05-23 04:24, robert bristow-johnson wrote:
> 
> 
>> On 05/22/2024 5:00 PM EDT Kristofer Munsterhjelm <km_elmet at t-online.de> wrote:
>>
> ...
>>
>> A very simple modification to IRV would be Condorcet//IRV. Do you think
>> that could work? Benham is better but needs more explanation.
>>
> 
> As I have said, I have sorta soured on the "modify IRV language to
> make it Condorcet consistent" approach.  The simplest
> Condorcet-consistent modification to Hare IRV is BTR-IRV.  I'm pretty
> sure that is.

I see your point, and I'd say that "modify IRV language" is mainly good 
for two things:
	- If the jurisdiction is already used to IRV, it might be easier to 
pass, and
	- If you really need strategy resistance, Condorcet-IRV hybrids will 
provide. (Not applicable to BTR-IRV.)

> Okay, I will try to stick with the semantics from Wikipedia:
> 
> * Condorcet methods fit within two categories:
> 
> ** Two-method systems, which use a separate method to handle cases
> in  which there is no Condorcet winner.
> ** One-method systems, which use a single method that, without any
> special handling, always identifies the winner to be the Condorcet winner.
> 
> I think that they call that "separate method" a "completion method".
> At least this Canadian MP does: https://condorcet.ca/ .

The election methods area of Wikipedia has been pretty heavily edited 
lately, but that seems reasonable enough.

> No the advantage of a One-method Condorcet system is that it doesn't
> need a completion method in the legislative language and we're done with
> it.  If there is no CW, we just take what we get.  I think that BTR-IRV
> might be the simplest One-method Condorcet system to encode into law
> with words.  Probably the One-method system I would prefer most, if I
> were king of the world, would be Ranked-Pairs.  (Still agnostic about
> Working Votes vs. Margins.)  But I am not sure we can get Ranked Pairs
> passed into law.

How about Minmax as an approximation to RP?

The difficult part would be to explain its underlying reasoning: that in 
the absence of someone who wins every pairwise matchup, we take the one 
who loses the least no matter who he's paired up with.

It's the two level quantifier that makes it hard to understand: find the 
candidate whose worst defeat is the least. If seen from the right 
perspective (someone who beats everybody handily is better than someone 
who beats by just a little), it seems kinda obvious, but it's hard to 
phrase it in a way that makes this perspective evident.

It's pretty easy to find the winner once you have the Condorcet matrix, 
though.

I guess that's the thing. You can't easily pass an outright 
pairwise-based method unless the people understand the logic to 
considering things pairwise. The *language* is secondary in that sense.

> But I think that transparency in marketing is important, because this
> is one of my biggest criticisms of FairVote.  So I see some value in
> the Two-method Condorcet systems because the first method is the
> simple application of the Condorcet criterion to examination of every
> single pairing of candidates:

> 1. Begin with every candidate not labeled as a loser.
> 
> 2. For every possible pairing of candidates; if more voters mark 
> their ballots ranking Candidate A higher than Candidate B than the 
> number of voters marking their ballots ranking Candidate B higher
> than Candidate  A, then Candidate B is labeled a loser.
> 
> 3. After examination of every pairing of candidates, the candidate
> left not labeled a loser is the candidate elected.
> 
> 4. If, after examination of every pairing of candidates, no candidate
> is not labeled a loser then the following Completion Method
> determines  which candidate is elected:
> 
> (Condorcet-Plurality --- 5. Completion method: The candidate with
> the  Plurality of first-choice rankings is elected
> 
> (Or Condorcet-TTR --- 5. Completion method: The two candidates with
> the most first-choice rankings shall face each other in a runoff in
> which the candidate that has more voters ranking that candidate higher
> than the other candidate is elected.)
> 
> Now this Condorcet-TTR is going to work very much like
> Condorcet-IRV, but it doesn't refer to all of the IRV semantics, just
> for the sake of a  completion method.  Can't that be good enough?

This is comparable to my fpA-fpC method except simpler to understand but 
not monotone. Its main problem, I think, is that if irrelevant 
candidates hog the first preferences, then first preferences are not a 
good measure of strength. E.g. in the 2021 City Council Ward 2 
Minneapolis election results, Smith//fpA-fpC (and presumably Smith//TTR) 
gave a result that agreed with minmax, whereas plain Condorcet// 
wouldn't have. This could also have clone independence implications if 
there's no CW.

If, on the other hand, cycles (dishonest or honest) are rare, then 
there's no problem, and we just need something that doesn't horribly 
break the few times cycles exist.

It might be good enough. I'm just saying where its limits are :-)


Here's an attempt to define the Smith set operationally. It doesn't seem 
too complex - as I mentioned above, the sticking point seems rather to 
be whether policy makers and the public understand that the Condorcet 
way of doing things is sensible to begin with.

1. If more voters prefer a candidate A to another candidate B, we say 
that A beats B.

2. The method first finds the admissible candidates, then performs a 
calculation as if only the admissible candidates had run.

3. Start by admitting the candidate who beats the most other candidates. 
If there is a tie by that measure, admit all of the tied candidates.

4. Check if there is another candidate who beats an admissible 
candidate. If so, admit that candidate and check again.

5. Repeat the checking and admitting process for as long as there exists 
a candidate who beats an admissible candidate.

6. Once there are no more non-admissible candidates who beat admissible 
candidates, eliminate the candidates who have not been admitted.

7. Count the ballots again, ignoring preferences for candidates who have 
not been admitted.

8. Of the two candidates with the most first preferences in this second 
count, elect the one who beats the other. If there is a tie, break the 
tie randomly.

(Smith//TTR)

Of course, this might be overengineering. If it *is*, then Condorcet// 
would be good enough.

> So Condorcet expresses a better, clearer principle of democracy than
> does Hare.  Or Borda.  Or FPTP.  Or STAR.  Or Approval.  What is needed
> is legislative language that doesn't scare the policy makers nor the
> public away.  And IRV and STAR have also scared away some people because
> of the perceived complexity of the method in legislation.  I don't want
> Condorcet language to be unnecessarily complex and not opaque at all.
> (Like Schulze and some of these other ideas of your, Kristofer, would be
> opaque.  They are not sufficiently concise.)  I want people to know
> exactly what they are getting with the language defining the method
> encoded in law.

I'm under no illusion that my methods are simple. I'm definitely more of 
a research type, trying to figure out what's possible rather than what's 
implementable.

If someday the public places as much trust in Condorcet methods as the 
NZ voters do in Meek's method, or the Norwegian voters do in the (pretty 
complex) top-up seat algorithm, *then* point them in my direction. Or 
Schulze's :-)

-km