[EM] Research on IRV and multiparty-ism

[Rob Lanphier]

Hi all,

I've been reading through a very interesting paper:

http://www.jstor.org/cgi-bin/jstor/printpage/00030554/di961007/96p0002q/0.pdf?userID=9803f96d@duke.edu/01cc99331a00503f125f&backcontext=results&config=jstor&dowhat=Acrobat&0.pdf
"The Two-party System and Duverger's Law: An Essay on the History of
Political Science" American Political Science Review, 76  (December,
1982), pp. 753-766. 

(Note: this link is only accessible on universities with JSTOR access)

The main point of this paper is to discuss the history of Duverger's Law,
which is explained here:
http://www.wikipedia.com/wiki/Duverger%27s_Law

At any rate, he goes into some detail on the distinction between
"Duverger's Law" and "Duverger's Hypothesis".  The "law" states that
plurality voting leads to the two-party system.  The "hypothesis" states
that majority voting and proportional representation favor multiparty
systems.  The latter is a dubious claim that Duverger himself was much
less sure of.

As it turns out, there's been research to back up the idea that Duverger's
hypothesis is false.  Specifically, it points out that IRV (referred to as
Hare voting), has lead to the reduction of parties in Ireland.  To quote:

   "Finally, Ireland provides a devastating counterexample.  Despite the
    use of the Hare system, its parties have decreased sharply in number
    since a high point in 1927, when there were seven parties plus
    fourteen independents.  In 1969 there were three parties, one of them
    very small and one independent.  This result was substantially
    reproduced in 1973 and in 1977, when one party obtained an absoute
    majority of the votes.  Not unreasonably, one student of Irish
    elections who seemed to accept Duverger's hypothesis (O'Leary, 1961),
    has now specifically rejected it (O'Leary 1979, pp. 112-13). "

The references Riker makes are to these two entries:

  O'Leary, C. 1961. /The Irish Republic and its experiment with
    proportional representation/.  Notre Dame, Ind.: University of Notre
    Dame Press.

  O'Leary, C. 1979. /Irish elections 1918-77: parties, voters and
    proportional representation/.  New York: St. Martin's Press.

I'm still reading though this, but this jumped out of the page at me given
the recent conversation regarding Australia's use of IRV, and questions
about whether IRV still reinforces the two-party system.  There's evidence
to suggest that it does.

Rob
----
Rob Lanphier
robla at eskimo.com
http://www.eskimo.com/~robla