Wednesday, June 5, 2013

Everyday range voting

Negotiating preferences between multiple people is an everyday activity.  For example, there have been countless times where I've been with a group and we can't decide which restaurant to go to.  To negotiate, we each express preferences, and try to convey the strength of those preferences.  We weigh the decisions by the strength of people's preferences.  For example, if we have a vegetarian in the party, we might avoid steakhouses, even if that's what everyone else weakly prefers.

This is basically range voting, with some wrinkles.  In normal range voting, you give each choice a score between 0 and 1.  In deciding a restaurant, it's tough to say where the boundaries of your votes are.  If people's preferences are extremely strong, I suppose the vote breaks down and the group splits up.  It's also difficult to compare the strengths of different people's preferences, since some people just have more insistent personalities than others.

Although the funny thing about range voting is that the optimal strategy is to be dishonest about your preferences.  In the limit of large numbers of voters, it's best to rank each choice either 0 or 1, with nothing in-between.  This is not necessarily true in small elections where you're uncertain about other people's votes, but it seems like it still may be useful to exaggerate preferences.

But exaggerating preferences may hurt the group as a whole.  If everyone only voted 0 or 1 without being honest, then we may miss it when somebody truly does have a strong preference (like the vegetarian example).  It's a bit of a prisoner's dilemma.  Luckily, there are social costs incurred by exaggerating one's preferences.  People may figure it out (or they may simply believe you have an "insistent" personality), and start devaluing your expressed preferences.

I'm not really going anywhere with this, but voting theory is interesting.  A lot of practical ethics is about negotiating the preferences of multiple people, and these are the complications we immediately run into.


Dale said...

A link!

So surely you've seen that, even with strategic range voting, the electorate comes out ahead when compared to even honest plurality voting? (And in some cases, better than even honest instant runoff voting?)

miller said...

I'm a fan of approval voting as an alternative to plurality voting! Range voting is about as good. Though to be honest I don't understand a lot of voting theory.