[EM] Why does IRV but not delayed top-two runoff lead to 2-party domination?

[raphfrk at netscape.net]

 Just forwarding my reply:
 
 
 > --- In RangeVoting at yahoogroups.com, "Jan Kok" <jan.kok.5y@> wrote:
 > >
 > > 1. Different strategy calculations by voters under the two systems.
 > > Voters who like a "third party" candidate seem more willing to vote
 > > for their favorite in the first round of TTR, than corresponding
 > > voters under IRV are willing to rank their favorite 1st. Why, why?!?
 > > Most IRV supporters in the US have no clue that voting their favorite
 > > 1st can ever hurt them. 
 > 
 There was an arguement that top 2 run-off is easier to understand, so
 voters are more capable of using the system to get their desired
 candidate.
 
 
 In IRV elections, I assume pollsters still ask "who is your first
 choice?", so voters should be able to use the same strategy.
 
 > 
 > > From my limited discussions with Australians,
 > > it seems most of them have no idea either. So why aren't Australians
 > > voting for third party candidates as their first choices, enough that
 > > they might occasionally win? While at the same time, voters in TTR
 > > countries feel free to vote for whoever they want, often enough that
 > > TTR countries tend to have flourishing multiparty systems?
 > > 
 > 
 Is there any country that uses condorcet as an election method for a
 single office like the President ?
 
 A centerist/compromise candidate should win the office when there is
 one office with considerable power. However, this maintain stability
 of what faction the candidate comes from.
 
 In the 3 candidate case, IRV and top 2 run-off are identical in
 theory. However, when there is 4 or more candidates, they are
 different. If there are enough candidates, it goes (semi) random. 
 Most of the horror file for top 2 run-off is that the (probable)
 condorcet winner doesn't make it past the first round. 
 
 Also, the more candidates there are running the more incentive there
 is for smaller parties to run a candidate, so more candidates run. 
 (This is balanced by not splitting the vote to much)
 
 I think that some of top 2 run-off's multi-party credentials come from
 the fact that it is sorta a cross between condorcet and random ballot.
    Raphfrk
 --------------------
 Interesting site
 "what if anyone could modify the laws"
 
 www.wikocracy.com   
   
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