On Sat, Jan 31, 2009 at 6:47 PM, Kathy Dopp <[email protected]> wrote: > On Sat, Jan 31, 2009 at 5:41 AM, Raph Frank <[email protected]> wrote: > >> That isn't the case in plurality. Lots of people vote for one of the >> top-2 rather than their favourite. > > That is called Strategizing. In plurality it is ALWAYS TRUE that if I > choose to vote for a candidate in any election, my vote will increase > that candidate's chances of winning, not decrease it.
That is likely true in IRV too. Unless you know the exact probabilities, giving a candidate a higher ranking is more likely to help than hurt the candidate. I think the likely situation with IRV is that there will be 2 major candidates. Voting for anyone else will have little effect. It doesn't elect a condorcet winner. Again what is your view on condorcet methods and approval? > Clearly IRV/STV never allows me to vote for a candidate first and know > that it will help that candidate win, whereas in plurality I always > know that if I vote for a candidate it increases that candidate's > chance to win. I am not sure chance to win is the right term here. If ranking a candidate first has a 70% of helping and 30% chance of hurting, then it also increases the candidate's chance to win. I would disagree that absolute monotonicity is required for a voting system to be considered fair. As long as the chances of participation failure/non-monotonicity is low enough, then that is acceptable. The fact that plurality is monotonic doesn't outweigh the tendency of the system to 2 party domination. ---- Election-Methods mailing list - see http://electorama.com/em for list info
