If you and your dining partner rank the kind of restaurants you'd like to go to tonight.

You rank 1) Indian 2) Chinese and 3) Italian

Your partner ranks 1) Gastropub 2) Chinese and 3) Steakhouse

you're going to get Chinese food, not because it exists on a line between each of your first choices, but because it is acceptable to each of you, if not preferred. It is a compromise by definition.

That's a compromise by the numbers, not by the nature of the food.

Chinese food isn't a compromise, a blend between Italian, Indian, Gatropub and Steakhouse food.

In Chinese food there isn't a little bit from every other choices. A candidate being chosen on virtue of a compromise by the numbers doesn't mean s/he aggregates some ideas from other candidates.

Hence my remark about that candidate being on a different spectrum from the others.

I am not saying he shouldn't be chosen or that people wouldn't be happy about it, I am saying that his ideas aren't a compromise from the other candidates' ideas.

Right. And I'm saying that political positions don't have to fall on a single line either.

How many axes can you chart a poltician's positions on?

Authoritarian<>Libertarian

Traditional Values <> Social Relational Values

Survival Values<>Self Expression Values

Interventionalist <> isolationist

That's just a few from https://en.wikipedia.org/wiki/Political_spectrum

Say in the US 2016 election Sanders had run as a 3rd party. He was a liberal populist. He might well have been the second choice of both the Trump and Clinton voters, despite not being positioned between the two. He'd still have been the compromise candidate.

Not a great example, because neither you nor your friend probably despise any of those 5 choices, and even if you do, it’s no big deal to just decide to get dinner separately tonight. Remember, political elections are about choosing the candidate or policy that exerts power over everyone in the jurisdiction.

Wow. So literal.

So let's talk 2016 presidential election

I'd imagine that a Trump Voter's ballot would look like the following if Sanders had run as an independent.

1) Trump 2) Sanders 3) Gary Johnson (Maybe with a flip on 2/3)

Clinton voters would be

1) Clinton 2) Sanders

Neither primary choice would be acceptable to the other. There would be some voters who preferred Sanders first.

... while still being everyone's second choice out of several?

Edit: As much as everyone's trashing IRV as "horrible" I don't see a simple, worrisome case where it violates monotonicity; those seem limited to really pathological electorates where nothing will make them happy anyway.

Yeah, I'm not sure where the qualms about monotonicity are coming from. In an IRV the lower-ranked preferences do not count until the higher-ranked preferences have already been eliminated for not reaching majority

https://rangevoting.org/Burlington.html here's a real life election with a Condorcet winner in which IRV elected some other candidate.

The reason there are not more examples like this one is that most governments don't release enough information about ballots in IRV elections.

As soon as I can find some time to work through that, I'll give my thoughts.

But ... is there maybe a truncated explanation of the general dynamic there?

Basically, imagine you have three candidates: A, B, and C, and there are 50 voters, and the votes come in like this:

  100 - A > C > B
  100 - B > C > A
  40 - C > A > B
  10 - C > B > A

After round 1 of IRV, candidates A and B each have 100 votes, C has 50. C gets knocked out, 40 votes move to A, 10 votes move to B. A now has 140 votes, and B has 110, and A is declared the winner.

The problem is that the B > C > A don't get their second choice considered. Why does this matter? Look at it when you put the votes into pairs.

  A vs B: 140 people think A > B.  110 think B > A.
  A vs C: 100 people think A > C.  150 think C > A.
  B vs C: 110 people think B > C.  140 think C > B.

C is actually the more popular candidate, but C LOSES using IRV!

> Edit: As much as everyone's trashing IRV as "horrible" I don't see a simple, worrisome case where it violates monotonicity;

It's terrible because the loser-elimination step that makes non-monotonicity an issue also makes it less straightforward to tabulate, not because non-monotonicity is an issue outside of edge cases.

Yeah I guess I’m just not really invigorated by fears of “difficulty of tabulation” and “bad behavior on edge cases”. Maybe I react differently from the typical voting system enthusiast?

> Yeah I guess I’m just not really invigorated by fears of “difficulty of tabulation” and “bad behavior on edge cases”.

Difficulty in tabulation affects speed of, certainty of, and confidence in results, as well as cost of implementation.

> Maybe I react differently from the typical voting system enthusiast?

Nope, especially on neglecting pragmatics like tabulation; that's practically a hallmark of voting system enthusiasts.

>Difficulty in tabulation affects speed of, certainty of, and confidence in results, as well as cost of implementation.

Which doesn't rise to the level of "that is so bad it must be stopped".

>> Maybe I react differently from the typical voting system enthusiast?

>Nope,

Kind of strange, since the entire reason for my confusion and joining this thread is because of enthusiasts' doom-and-gloom about the quality of the results themselves, and how they worry about the edge cases and I don't.

Are you invigorated by the cost fears? Because they seem like a sliver compared to the cost of Gore vs Bush.

I guess I can't comprehend how someone doesn't view non-montonicity as a fatalflaw in a voting system.

If I can hurt my preferred candidates chances of winning by ranking them higher on my ballot then the voting system is broken.

Non-monotonicity is a problem.

Non-monotonicity solely on a few pathological edge cases where voter preferences are a nigh-intransitive clusterf—- is not a problem.

I think that the Burlington example that has been cited a lot in this thread shows that non monotonicity is a problem for IRV in not just pathological edge cases.

The problem with difficulty to understand isn't a simple logistical fear. It's fear that voters won't understand what their vote means.

I never expressed mystification at comments that expressed that fear, because it actually makes sense.

Also, it's that they won't have a basis for respecting the result when their candidate loses.

What does political spectrum/agenda even have to do with it?

The theoretical candidate was everyone's second preference. That sounds like quite a good compromise.

What I often see in my local election is that 3rd-party candidates are often (not always, but often) very inexperienced, and might have platforms that don't make sense or aren't coherent. I've frequently got serious doubts about their ability to function competently - let alone effectively - in the position they're applying for.

With IRV, though, I could see a situation where they are much more likely to win simply because, nowadays, Republicans' and Democrats' general level of mutual disdain is such that I wouldn't be surprised if it ends up being common for people who identify with one major party to rank the candidate from the other major party below every other candidate more-or-less out of spite.

>What I often see in my local election is that 3rd-party candidates are often (not always, but often) very inexperienced, and might have platforms that don't make sense or aren't coherent

This is a symptom of our current system. Anybody who has any ambition in politics will modify some of their positions to fit one of the major two parties. If running for another party wasn't a death sentence, you would see more competent candidates in those parties.

Yep. Just trying to think through plausible practical scenarios where IRV might produce a bad outcome.

Which is worth doing because, regardless of what the ideal situation is, if it's associated with a spectacularly bad outcome in one of the earlier elections that uses it, that's going to be a big impediment to wider adoption.

Even in a sharply polarized contest, it's usually the case that most of the "third party" candidates receive fewer first-preference votes than those from the major parties.

So the minor parties (and independents) are eliminated first, and their preferences are distributed. Which usually means than one of the major party candidates scrapes over 50%, reflecting the minor party voters' basic preference for one of the major parties over the other.

In this (common) situation, I think IRV actually works really well.

The major parties still end up in government, but they see the first-preference percentages for the minor parties, and understand what policy positions are important to the electorate.