Mathematical Paradigm of Electoral Consent
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@brozai I think it depends on your perspective. Just as a rough example, one could create a formal model of voters and candidates as having "investment" distributed over "interests," i.e. a set of "interests" and letting each voter be essentially a probability distribution over those interests. Then one could take the sum total of those interest distributions and create an "electoral interest" distribution.
If each candidate is also a probability distribution over those interests, choosing a candidate can be seen as more or less projecting/compressing the electoral distribution into the set of distributions determined by the candidate pool. With this conception a voting system functions exactly as a compression algorithm.
Real life is more complicated than that but I hope that illustrates my thinking better---a candidate's platform can be seen as a (high quality or lousy) compression of electoral interests.
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@cfrank You seem very intent on reformulating all the language, definitions, and algorithms used for voting in terms of probability measures and random variables. Out of curiosity, and I hope this doesn't come off as confrontational, why is that?
It is not less rigorous to just use the conventional definitions used in social choice theory where ballots are weak orders and so on. Similarly, I do not see the use in considering generalizations of the voter / candidate sets to be of arbitrary (infinite) cardinality.
It could possibly be of interest to study limiting behavior of voting rules as the number of candidates or voters grow---for example, studying the probability of a tie or of a Condorcet cycle in the limit of these quantities---but I don't think that's what's happening here.
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@brozai said in Mathematical Paradigm of Electoral Consent:
You seem very intent on reformulating all the language, definitions, and algorithms used for voting in terms of probability measures and random variables.
Hopefully this won't come off as a pile-on, but this was something I was confused about as well (regarding a previous paper), it seems way more complex than it needs to be. I compared it to saying that a "randomly selected point in a glass had a 75% chance of being occupied by liquid," as opposed to simply saying that "the glass is 75% full." It strikes me as a very roundabout way of expressing a simple concept.
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@brozai I am not trying to reformulate all of the language, definitions, and algorithms for voting in terms of probability measures and random variables. I am proposing a specific paradigm that happens to include an intimate incorporation of probability theory, along with a few specific voting systems that fit nicely within that paradigm. Connecting with a larger mathematical framework allows use of the powerful tools that belong to that framework, and probability theory seems appropriate to me.
I agree that it is not less rigorous, it's equally rigorous. It's just the way I think and express myself, probably because my background is in pure math. If you see a more apt way to describe the concepts I am proposing I would definitely like to hear that. I want to find a higher level of abstraction that can maybe unify some of the things we're looking at in voting theory, if I could find a good theoretical foothold I would be using category theory, but I don't want to go too far off into abstract nonsense that nobody wants to look into.
I don't actually agree that it is very much more complex than it needs to be. As I mentioned in the introduction of the pamphlet, connecting voting theory with probability theory is nothing new. Condorcet was one of the pioneers of voting theory and his Jury Theorem is a direct application of probability theory to voting theory. As another example, Nash's equilibrium theorem is a direct application of probability theory and topology to game theory.
The use of generalization is just that it is more general, and might be more amenable to application in other areas. I mentioned machine learning as one such area. And I want to point out that ordinal scores are different from weak orderings.
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@cfrank I have a pure math background as well, so trust me I'm no stranger to painful detail & abstraction
I agree that there can be interesting connections to probability theory. The Jury Theorem is a great example.
In this case, I am not convinced it is necessary or instructive to introduce any additional tools or definitions beyond what is already commonplace in voting algorithms.
In the words of Dijkstra
The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise
And I believe we already have the tools to be absolutely precise with regular old ranked ballots over finitely many candidates. Sticking with conventional nomenclature and concepts will help people understand your proposal much more easily, and will also help contextualize it and compare to other methods.
In particular, I believe SP dominance is in fact equivalent to Borda dominance, and I believe your weighted PFPP scheme is in fact equivalent (edit: not equivalent since we have to allow skipped rankings, but very closely related) to a positional scoring rule, but these connections are very hard to see underneath all the new definitions and unnecessary framework.
It's possible I am misinterpreting something and that the equivalence I suggest above is invalid, but if this is the case I would find it very helpful to my understanding if you could provide an example where they differ !
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@brozai I want to look into that Borda dominance scheme and see if it is different from my proposal. (EDIT: I totally do have access)
PFPP may be equivalent to a positional scoring rule at each election, but the prescription of the particular scoring rule and how it is allowed to change from one election to the next according to informative distributions is what makes PFPP different. For example, a thought I had earlier today was actually that if the distributions are allowed to update, then as fewer people over-use the higher score values, they become more potent when they are used. This can give voters an even stronger incentive against strategic bullet voting, since it will weaken their vote in the future when they may actually feel strongly about a candidate.
I'll read the PDF paper you linked and see if they coincide, if they do then I'll be happy because that means probably more analysis has been done on this system! Otherwise I'll try to illustrate points where I find that they differ. I think already the fact that the winner is called "generalized Condorcet" points to something different, since the methods I am proposing (at least on the surface, I could be wrong) have nothing to do with the Condorcet criterion.
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PFPP may be equivalent to a positional scoring rule at each election, but the prescription of the particular scoring rule and how it is allowed to change from one election to the next according to informative distributions is what makes PFPP different
Ok, fair enough, but I can't comment on whether or not this is a good thing. It certainly would be a radical reform to current elections.
I sent the paper to the gmail attached to the google drive you shared, so let me know if you don't receive it. Unfortunately they don't do a ton of analysis besides introduce the concept of positional scoring dominance and then prove what types of dominance are actually constructible (what they call "Condorcet words"), but it is relevant I think nonetheless. In the language of this paper I think SP dominance corresponds to the k-Condorcet winner in the case where k = n.
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@brozai on second thought, PFPP and its weighted variants definitely are not positional score systems even without accounting for the potentially changing distributions. It is only a positional score system if the distributions used for the random SP ceiling heights are uniform. I think the explanation of the system will become clearer with visuals.
In any case it could very well be that being a k-Condorcet winner when k=n is equivalent to being a unique candidate that is not SP dominated. I’m not sure! Still working through the paper.
I tried to give an explanation of the unweighted PFPP system a while back through a video. It may help, if you were interested, but I understand if it’s not your cup of tea! This is the video:
https://app.vmaker.com/record/SGSydGYcwOW9Vf6d
It’s like 20 minutes… 10 if you do x2, potentially less if you skip around.
On a related (maybe controversial?) note I take some issue with the Condorcet criterion. I also have noticed that ElectoWiki doesn’t seem to be very objective about it. While a Condorcet winner has the majority support of the electorate over any other candidate in a pairwise face-off, the majority groups that support the winner from different face-offs can differ from each other dramatically.
In other words, I would say that there is no guaranteed stable locus of electoral consent for a Condorcet winner—it is rather like a stitching together of victories in various unrelated and somewhat gamified competitions, and to me this makes the Condorcet paradox less of a paradox. In line with the concluding remarks of the paper I think it’s not at all obvious or necessarily correct that the Condorcet winner is the ideal choice even when one exists.
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@brozai I also wanted to address your point about majority rule. If you are referring to May's Theorem, I think it's important to consider the scope of the proof. The theorem is proved assuming that voters can indicate one of only three options, -1, 0, or +1. The formal properties don't fully make sense beyond that scope.
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@cfrank well, this is true, but I think the monotonicity condition means that, with strategic agents, it has a natural extension to score ballots
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@brozai I would need to see it formally. I can see what you mean about strategic agents, but I don’t see any extensions mentioned on Wikipedia but a similar statement (whatever that means) for approval voting (fully strategic score voting), and then some for other first-preference aggregators which would have us using plurality voting. I personally doubt a useful extension to generic score voting exists, because of the nature of the preferential ambiguity between a strong majoritarian assertion and a weaker but broader consensus.
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@cfrank A function monotonic on [0,1]^n --> {0,1} must also be monotonic on {0,1}^n --> {0,1}
Strategic agents will only submit values in {0,1} since by monotonicity any other value makes the chance of electing their favorite strictly lower.
Therefore the method must coincide with majority on {0,1}^n ballots, which is the entire domain of ballots from strategic agents
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@brozai this reasoning implies that a voter only considers the outcomes “my favorite wins” and “my favorite does not win.” A voter can also consider outcomes like “my favorite doesn’t win, but my second favorite does,” or “my favorite doesn’t win, but neither does my least favorite.”
Bullet voting is maybe a good strategy for an econ voter who is not at all risk averse and are all-or-nothing for their top choice, but real people are risk averse with stratified preferences and will try to establish at least a Plan B in case Plan A doesn’t work out.
Increasing the probability that one’s favorite wins as much as possible locally does not necessarily increase the probability of a more global “acceptable outcome” as much as possible, which is what many real people try to accomplish, depending on their definition of what constitutes an acceptable outcome.
This does somewhat seem to lead to approval voting, which I don’t think is a bad system actually. I’d have to learn more about it. Obviously it has its own problems, but at least burial is quite minor..
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@cfrank I am specifically referring to the case of 2 candidates! In this case, bullet voting will always be optimal
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@brozai I see! Yes that makes more sense. I still am not sure, because there may be a minority with a strong preference against the weakly held majority preference, and this just isn't taken into account. Obviously that is the whole issue with majoritarianism. The more I consider it the more and more keen I am on multi-winner proportional representation. In that case I feel like something like quadratic voting might potentially do a very good job identifying candidates with interests that represent those of the electorate.
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@cfrank If you are interested in proportional representation I would read the following paper which gives a good overview of PR schemes for approval ballots: https://arxiv.org/pdf/2007.01795.pdf
Quadratic voting is a somewhat poor quality method (imo) unfortunately.
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@brozai Oh really, why is QV poor quality? I'm sure there are superior more sophisticated methods.
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@cfrank Afaik, it does not have very good proportionality guarantees. It's probably better suited for something like participatory budgeting than it is for elections.
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@brozai I see, yes according to what I've learned about it QV tends to incorporate the strengths of interests and not just the proportion of people with those interests. Depending on what is desired that may be a good thing or a bad thing. There has also been research on its resistance to collusion and it seems to hold up very well, which is a property that I definitely like.
I found this presentation very interesting:
One point brought up by an audience member during the Q&A was that QV seems to illuminate the relative preferences of the electorate, which show up in the presenter's data as approximate Gaussian distributions and the grouping together of different strata of right-wing and left-wing groups, which does not occur without the quadratic cost.
