In response to a blog conversation on Planet Debian, Wouter Verhelst writes about voting tactics in which he claims that Instant-Runoff (wikipedia) (the method used in Australia to elect members of the house of representatives) is broken.
I have read the Wikipedia review and neither it nor my previous understanding of Instant-Runoff leads me to believe that it is broken or prone to tactical voting problems.
The main tactical voting issue in Australian elections is to give first preference to a small party (such as The Greens) in a seat where there is almost no chance of the small party winning. The idea is to have the vote effectively be a vote for whichever of the two major parties the voter prefers while also sending a message (by the first-preference votes which are widely publicised) as to their desires. If a major party wins a seat while 20% of the first preferences went to the Greens then they might find it an incentive to try and get some Green policies adopted if they want to win the next election (whether this actually works is debatable but it is a fact that people try it).
There are many people who don’t understand how the Australian voting system works and believe that they have to vote for one of the major parties to avoid a “wasted vote”. This is not due to the voting system but due to American media – and ill-educated Australians who can’t work out which parts of the news apply to them. Wouter has an advantage in living in a country where English is not the primary language – English news does not directly concern him and his country-men can probably work out that English-language voting instructions should not be followed!
The condorcet.org site has a useful analysis which demonstrates one theoretical flaw in IR, but realistically getting the average voter to use Condorcet would essentially be an IQ test as a pre-requisite to voting (numbering all the candidates in order for IR is difficult enough).
The fact that an election system is not theoretically fair is not a valid criticism unless there is a viable alternative which is better. If the lower house is to actually represent the people of each electorate (which is rarely the case nowadays) then IR seems to be the best option. If members of the lower house are not expected to represent geographic regions then Wouter’s advocacy of proportional representation makes sense.
As for the Australian Senate, the voting system for that is far too complex and I think that as a matter of principle any voting system which can not be understood by the majority of voters is wrong. A good case could be made for proportional representation in the senate.
Update: In response to Wouter’s post – tactical voting that doesn’t change the outcome of the election and merely sends a message to a political party is OK IMHO. But if you convince enough people that tactical voting is the only option in the US then the result may change.