Talk:Australian electoral system: Difference between revisions
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Why two-party domination? Added multiple reasons
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:: Agreed. This was written poorly and with a lot of bias. I have added some links and tried to remove bias. Would be nice if somebody could add some more details on the reasons why STV is causing two party domination. It should spell out why such issues are not expected in cardinal systems. --[[User:Dr. Edmonds|Dr. Edmonds]] ([[User talk:Dr. Edmonds|talk]]) 16:57, 2 July 2022 (UTC)
::: That would be IRV. STV, being a proportional representation method, doesn't seem to cause two-party domination unless limited by something else. In Australia's case, it seems that IRV's pull is greater than STV's push (as it were). As far as I know, neither academic research nor EM gives any definite answer to why two-party domination occurs with IRV, and whether it can be generalized to all majoritarian single-winner methods. Possible reasons for two-party domination are:
:::: * Center squeeze (unstable IRV outcomes when there are three strong contenders, e.g. Burlington). Condorcet doesn't have that.
:::: * Favorite betrayal (IRV has this, Condorcet does too, usual cardinal methods don't)
:::: * District magnitude (SNTV with s seats seems to produce s+1-party rule in Japan, https://www.jstor.org/stable/193914, but on the other hand, France with single-member district [[top-two runoff]] has four or so party rule)
:::: * Natural packing/cracking effects (a party that has 10% support everywhere being given only a few seats because it's the outright favorite few places, e.g. the Liberal Democrats in the UK). This affects all single-member district methods unless they have top-up seats.
:::: * Too few dimensions to issue space (analogous to Malta, and Taagepera and Grofman's https://doi.org/10.1111/j.1475-6765.1985.tb00130.x)
:::: * Some interplay of these effects (e.g. low dimensionality issue space kept low by center squeeze effects)
::: The only things that seem definite are: IRV can tether STV's otherwise multiparty rule, and single-member districts don't force two-party rule (counterexamples being runoff voting in France, approval in Greece). Even Plurality's two-party rule may sometimes be limited to a local scope (Canada, India). [[User:Kristomun|Kristomun]] ([[User talk:Kristomun|talk]]) 17:41, 3 July 2022 (UTC)
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