[EM] Plurality == FPTP right?

[Closed Limelike Curves]

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 argued here
> <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
>> ----
>> Election-Methods mailing list - see https://electorama.com/em for list
>> info
>>
>
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