This is a cross post from here.
Remember to vote everyone, and I thought that in honor of the election today I'd talk about designing voting systems. Now that is a huge category so I'm going to narrow the focus a bit and leave out things like the electoral college, how you actually do the voting, or many people running for many open seats and just stick to voting for 1 open job slot directly.
To start out we need to state the goal of voting, which is to get everyone's opinion on who would hold this office best. Now what we want is everyone's honest opinion, and so our goal in designing a voting system is to minimize 'Meta Voting' which is where a person votes not for who they actually want to win or for who represent's their views, but to try and stop a less desirable outcome. An example of this is when ever there is a third party candidate running for office there is always a concern that person will siphon votes away from what ever side of the isle they more appeal to and that will cost the more mainstream candidate the election. So while the third party candidate might represent the voter's views better they don't vote for them because there is someone they don't want to win. Anytime you are encouraging people to not express their honest views that is a failure of the electoral system.
This is a problem with multiparty systems though, if the goal of an election is to pick the person who best represents the voter's views then you should be wary of voting systems that let people win with a plurality of votes (not the majority just the most). Plurality based systems tend to encourage extremism on account of the fact that you don't need to appeal to the majority of people but need to appeal to a smaller group a great deal. Say there are 4 people running: one on the color green, one on the color blue, one on the color purple, and one on orange. Now the green/blue/purple vote overlap a great deal, which in spite of the fact orange is not liked at all by the majority of the voters can give orange the advantage. If the green/blue/purple vote share is 70% (by which i mean 70% would like to see one of those colors win over orange) but the colors split their votes evenly orange will win with its 30% as the other colors will have only about 23% of the votes a piece. So orange wins even though 70% don't like it. So candidates don't want to appeal to 51% of the people, they want to be loved by a much smaller percentage which means extremism is likely to hold a lot of sway.
This is where people start to meta vote, vote not for who they want but to prevent and outcome they don't like. That is a problem because how can you elect people that represent your voters when you are telling your voters to lie about who they want? You can mitigate this problem by instead of having the voters choose one you have them rank all the prospects from the person you want the most to the person you want the least. Then once everyone has voted you see who got the least #1 votes and remove them from the race and distribute those votes to those voter's #2, and so on until someone has a majority. In this way you allow for as many parties as you want to run with out the system favoring extremism, because a candidate will have to at least appeal to a majority of the people.
There are problems with this system, the first being the complexity. The complexity of the voting process isn't a terrible amount (though it is more) but it isn't a kind of vote you can hand count as due to the the nature of the system it would require recount after recount and so needs to be automated at some level. The second being what if there are 3 people running: candidate 1 got 51% of the round 1 votes, candidate 2 got 49% of the round 1 votes, and candidate 3 got 0% of the round 1 votes. Now imagine that candidate 3 for 100% of the rank 2 votes, by which I mean no one wanted him the most but everyone thought he would do a good job. He is the moderate candidate, no one is excited about him but everyone thinks he would be good if their guy didn't win. How do you value that?
All voting systems have problems, but the problems are not equal. I think the complexity the ranking voting system introduces is worth the benefits of allowing for many parties with out encouraging extremism and helping to mitigate meta voting.