andrewducker | My general feeling on the by election result

Strictly speaking, this ends up with 50% of the people who voted thinking that the elected candidate was better than at least one alternative. Not necessarily better than the alternatives, plural.

(Also, 50% of the people who voted, not 50% of the electorate. But surely no voting system can guarantee anything about the latter without making voting mandatory, and I don't think anyone literally does that – even in countries where it's mandatory to show up and do something with a ballot paper, I've not heard of one where spoiling it isn't still an option.)

I disagree about your first point there. 50% of people must have made ranked that person higher than all of the other remaining options. If they'd only ranked them above one other person then they'd currently have assigned their vote to a different option.

Higher than all the other remaining options, after the algorithm started eliminating people, sure. But that's an internal detail of the voting system – if my favourite candidate was eliminated early, I won't consider that I got a candidate I preferred to all the alternatives!

If 1/3 of voters think A > B > C, another 1/3 think B > C > A, and the remaining 1/3 think C > A > B, then, for each of the three candidates, 2/3 of voters would prefer someone else. There's no candidate that 50% or more of voters prefer to the alternatives.

After one candidate is eliminated (say C, because those thirds weren't quite exact), the remaining vote between A and B goes heavily in favour of A, because all the people who had C as first choice preferred A to B. Fine, we have a result, and it's true that 2/3 of people preferred A to B in the notional second-round vote. But that was notional!

The only way you can say that more than half the voters preferred A to the alternatives is if you pretend C wasn't one of the alternatives, because of their elimination in the first round. And since the rounds are instant and happen entirely in the imagination of the algorithm, that hardly seems like a particularly interesting property, especially because you can't use it to compare with other preference-voting systems (like Condorcet-type things) that don't even have internal rounds.

If the winning candidate A pursues a policy that B was dead against, claiming their 2/3 of the vote as a huge mandate of popular support, then maybe they have a point. But if they pursue a policy that C was dead against, on the same grounds, it would clearly be untrue.

Oh yes, 50% of the remaining options.

But that's the point, of the options that *could* be elected 50% of the voters preferred one option more than the other. The fact that some people had a strong preference for a person that could never be elected doesn't change that.

Which doesn't mean they loved them wholeheartedly, just that they thought that they were better than the other option.

And I can agree that you occasionally end up in awful cycles, but I understand that in real life that is unusual. Plus, of course, a Labour candidate elected only because the Greens and Lib Dems gave them a higher preference now has to remember that if they piss off those voters too much next time then those preferences can just vanish. So they're beholden across more of the political spectrum.

But that's the point, of the options that *could* be elected 50% of the voters preferred one option more than the other.

Which is why I said that you do end up with 50% of the voters preferring the winner to somebody – namely, to whoever survived until the last notional round and then lost it.

It's true that if the elimination process doesn't need to go the full distance then this might look more sensible. And of course I'm not arguing that bloody FPTP is better – when we had the choice to switch to this kind of system I voted in favour. But I don't like to see overstated arguments even for my own position (perhaps especially not for my own position), and I think it's disingenuous to describe it as "50% preferred A to all the alternatives" when what you really mean is "all the alternatives except the ones that my own algorithm decided didn't count".

But it's not to *somebody* it's to *everyone who might plausibly win*.

And I don't think it's fair to say "the ones that my own algorithm didn't win". We're talking about a single seat here. If we were talking about multi-member constituencies then which algorithm you use, how you divide up the seats between multiple parties, etc. makes a big difference. But when it comes to a single winner situation I don't think I've seen many alternatives seriously discussed which would leave the party that 7% of the voters had as their first choice in active competition. Are you thinking of an algorithm which wouldn't do that?

(I'm ignoring things like Approval Voting, because it doesn't have very wide support, and seems to leave itself open to strategic voting in a way that looks complex and unpleasant if it becomes common.)

Ah, so when you said "preferred to the alternatives", your idea of which alternatives to consider was derived from some first-principles idea other than "the set of candidates eliminated during the IRV process"? That would make more sense, but in that case, was definitely unclear in your original statement of "any voting system that doesn't do this isn't fit for purpose".

Also, I think there are several plausible ways to define the set of not-hopeless candidates. The one that sprang to my mind was the Smith set. But apparently IRV can elect a candidate outside that set, by sometimes eliminating the Condorcet winner if there is one!

My idea is very basically - that nobody should be considered voted in, in a single seat, unless they are preferred by at least 50% of voters over the other options. I gave an example of how you might do that, but I am totally open to alternative methods of finding out what people prefer.

(Also, did you see people being nice about you over here: https://andrewducker.dreamwidth.org/4560569.html?thread=32304313#cmt32304313 ?)

Looking at some stats from Australia, where voting is compulsory, (AEC stats on informal voting), the number varies by state and over time, but is typically from 2-10% "informal voting" (which includes people who failed to understand the instructions as well as those who deliberately "spoiled" their ballot or just handed in a blank ballot paper).
Coincidentally, we have a Federal election today, will be interesting to see how our RWNJ parties do ("Trumpet of Patriots", and "Pauline Hanson's One Nation", for example).

My general feeling on the by election result

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