[EM] Duverger's Law

[Forest Simmons]

I read the interesting paper referenced below, but couldn't tell which of
Duverger's observations is supposed to be "Duverger's Law."

Is it just that a first past the post lone mark single ballot system tends
to keep a two party system entrenched?

Here in the USA the two party system has degenerated into more of a one
party system, with superficial cosmetic differences.  Is this also a
natural consequence of the voting system?  Has anybody written on the
dynamics that lead to one party systems?

It seems to be a corollary to Duverger's Law.  The two parties that
survive Duverger's Law compete for the perceived median voter position on
superficial matters while both strive to maximize satisfaction for their
capitalist backers.  [The same big money donors support both parties in
order to hedge their bets when the races are close.]

In other words, it's no accident that Gore and Bush were running neck and
neck in the last presidential race.  The big money wants to reinforce
Duverger's Law to make sure that whichever of the two parties wins, it's
going to support corporate welfare.

Forest

On Mon, 24 Feb 2003, Bart Ingles wrote:

>
> Just to further muddy the waters on the definition of "majority", note
> Duverger's use of the term as apparently synonymous with "plurality":
> http://www.janda.org/c24/Readings/Duverger/Duverger.htm
>
> (BTW the "two-ballot majority system" Duverger discusses is NOT the
> Runoff method, since there is no fixed elimination rule.
>
>
>
> Alex Small wrote:
> >
> > On the subject of majorities and Margins vs. Winning Votes, my
> > understanding of the matter (which I will deliver without prejudice, since
> > I have no strong opinion on the matter) is this:
> >
> > Say that two of our pairwise contests in an election are:
> >
> > A>B  51-49
> > B>C  45-40
> >
> > (Assume there are 100 people casting ballots, at least 3 candidates, and a
> > cyclic ambiguity to resolve.)
> >
> > A majority of the people casting ballots have said "We prefer A to B."  A
> > plurality of the people casting ballots have said "We prefer B to C", with
> > 15 voters abstaining.
> >
> > A winning votes advocate can say "A has majority support relative to B.
> > That's a stronger defeat for B than C's defeat, since B only beat C with a
> > minority (plurality) of the people casting ballots."
> >
> > A margins advocate can say "Yes, A beats B with a majority of the people
> > casting ballots.  But, B beats C with a _majority of the people
> > participating in the B vs. C contest_.  Since the other people voluntarily
> > abstained from that contest, we shouldn't consider them, we should only
> > consider who got a larger percentage of the people participating in each
> > contest."
> >
> > I hope that clears some air on the debate over the word "majority."  It
> > all comes down to "majority of whom?  People casting ballots or people
> > expressing preferences with respect to a particular pairwise contest?"
> >
> > I don't claim to resolve any normative issues of which provides a more
> > socially desirable criteria, or technical issues of which method provides
> > more perverse strategic incentives.
> >
> > Alex
> >
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