Tuesday 6 November 2018

Rational voting?

Andrew Gelman argues it could be rational to vote. Sure, you're only trivially likely to change the outcome. But if you do change the outcome, the outcome is changed for lots of people. Add up the benefits across that broad set, specify that people are at least somewhat altruistic, and all's good, right?

He could be right in the current election cycle. I expect there is substantial value in the GOP being punished hard in each and every place it can be, all the way down to the vote on city dog-catcher. That outfit has to understand that reputation matters, and that failing to constrain Trump has more cost than benefit. It should be made to understand that backing a demagogue brings electoral death. It needs to be more scared of supporting Trump than of not supporting Trump. The party needs to be turned off and on again.

But the argument does require that the voter places himself or herself in an epistemically privileged position. You only change the outcome if you make or break a tie. You only make or break a tie if half of the voters in your district think you're providing a public bad with your vote rather than a public good.

Why do you think that your half of the electorate's the right one and the other half's wrong? Shouldn't you be updating, at least a bit, based on that half the electorate disagrees with you? Maybe you're the one who's done all the sums and has gotten things right, and the other side is full of idiots who'd wreck the country. But maybe there's a marginal voter on the other side who's your mirror image and thinks the same of you.

There's probably somebody reading this now who thinks my second paragraph is complete rubbish and that there's a lot of value in stopping particular Democrats from being elected. And that person could be right!

So I don't think this makes for a generalised "Yes, it's rational to vote" argument. It could be combined with a Jason Brennan "If you're going to vote, you have a duty to vote well", so that it's rational to vote if you have really good reason to think you're better informed than other voters. Feel lucky?


1 comment:

  1. Aren't there other reasons why it might be rational to vote that require less altruistic motives.

    Firstly if you know that a group of people think in a very similar way to you then the way that you choose to vote will end up being strongly correlated with their choices so the chance of the group being a deciding factor in the election will be a lot higher.

    Secondly it seems like there are lots of decisions that politicians make based on how they believe that people's vote choices will change based on those decisions. Like which policies to promote or the way they treat their opponents. If you think of voting more like a reward or a punishment then the immediate rationality isn't really the point.It's the fact that politicians have beliefs about how their decisions will affect your voting decisions that matters, and if you don't vote based on the likely decisiveness of your single vote it's like not following through on a threat or a promise which means you will have less influence.