[EM] Plurality == FPTP right?

[Richard Lung]

While in accord with the sentiments of this post, John Stuart Mill MP 
when in Parliament pointed out that "majoritarianism" isn't 
majoritarian, a majoriity of a majority in Parliament may be a minority, 
a half of a half is a quarter. He was advocating "Mr Hare's system" of 
"Personal Representation" so grotesquely misrepresented, here, as IRV.



On 07/05/2024 18:27, Closed Limelike Curves wrote:
> This is great, thank you so much! No objections from me to political 
> scientists, especially not any on this list. Definitely not any who 
> are interested in social choice. :)
>
> This left me a bit confused, though—
> 1. Would you think of the terms "First-past-the-post" and "Plurality 
> voting" as interchangeable in a paper, when used without qualification?
> 2. What do you mean by "Categorical ballots"? I haven't heard that 
> term. Most social choice theorists think of FPTP as a ranked ballot 
> rule (one that just happens to ignore everything after the first rank).
>
> With regards to the paper, I don't think ballot exhaustion is a 
> problem for majoritarianism; exhausted ballots still produce 
> simple/relative majorities in the last step. No method can guarantee 
> an absolute majority (>50%) for one candidate over another, except by 
> forcing voters to express opinions they don't really hold (e.g. rank 
> candidates they know nothing about). The same problem is true of 
> two-round systems as well—the apparent absolute majority is created by 
> ignoring the voters who don't turn out in the second round.
>
> The main reason IRV and two-round aren't majoritarian is they can 
> override the will of a majority of voters, even when there's no need 
> to do so (i.e. no cycle). People who hear John won because he had 
> "majority support" naturally take that to mean most voters preferred 
> John to his opponent Jack; most would be surprised if the opposite 
> were true (as can be the case in non-Condorcet systems). Social choice 
> theorists use the term "majority-rule" the same way (it means if most 
> voters support A over B, then A wins, unless someone else beats A).
>
> In other words, simply having a majority of voters in the final round 
> isn't enough: if most voters preferred someone else, you're not really 
> the majority choice/. /(Was Chirac really the majority choice because 
> he had a majority against Le Pen? That seems like a low bar, given a 
> soggy baguette could've beat Le Pen as well!)
>
> This is what most of us on this list mean when we say IRV is 
> plurality-like: the eliminated candidate is determined by the loser of 
> a plurality vote at each step, so majority support isn't enough to 
> win. You need to have several pluralities as well (one for each round).
>
> On Mon, May 6, 2024 at 12:39 PM Jack Santucci <jms346 at georgetown.edu> 
> wrote:
>
>     Political scientist here. Please don't pelt me with rotten fruit.
>
>     We generally use three categories to differentiate
>     electoral systems. The number of categories depends on who's
>     writing, but everyone pretty much agrees on three: district
>     magnitude (1 in your case), ballot type (categorical in your
>     case), and then allocation rule (plurality in your case).
>
>     Shugart, Latner, and I arguedhere
>     <https://protectdemocracy.org/work/toward-a-different-kind-of-party-government/>that
>     'FPFP' did not really exist in the US due to the widespread use of
>     primaries, some of which have been replaced with nonpartisan
>     winnowing rounds (AK, CA, etc). FWIW, Burnett and Kogan (2015)
>     noted
>     <https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2519723> this
>     elision in their conclusion nearly a decade ago.
>
>     Other examples of plurality allocation with categorical ballots
>     /and multi-seat districts/:
>     - multiple non-transferable vote (incl. as limited voting)
>     - single non-transferable vote (incl. as limited voting)
>     - cumulative voting
>     - etc...
>
>     I generally stay quiet, but this issue is fundamental enough, I
>     think, to merit the above contribution. FPTP often comes across as
>     an imaginary target.
>
>     A purist might insist on calling IRV 'plurality' as well, so long
>     as it does not require the voter to rank all choices.
>
>     Jack
>
>
>     On Mon, May 6, 2024 at 3:10 PM Closed Limelike Curves
>     <closed.limelike.curves at gmail.com> wrote:
>
>         I just need to double-check I haven't gone completely insane
>         and both of these terms really are synonyms. Comments on the
>         talk page would be helpful:
>         https://en.wikipedia.org/wiki/Talk:Plurality_voting#Merge_from_FPTP
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