Is voting reasonable?
I think that the correct answer is: it depends.
If the reason you’re voting is to affect the outcome of the current election, then it seems pretty unreasonable to me. As the number of voters grows, the probability of your individual vote swaying the election approaches zero. As the article I refer to later says:
Since the chance of one’s own vote proving decisive is less by several orders of magnitude than the likelihood of being maimed in an auto accident while on the way to the polls, it would seem that a truly rational person will instead devote the half hour in question to reading a good book, drinking whiskey sours, or pursuing some other end that yields a perceptible positive return.
But is there another, rational, reason to vote?
In it, Lomasky argues that rational people vote for expressive reasons rather than the instrumental reason of deciding the outcome of the election. He gives the analogies of cheering at a football game or giving a “Get Well Quick!” card to a sick friend. We don’t do these things because we expect to change the outcome (or, more precisely, that the probability of changing the outcome multiplied by the value to us of that change exceeds the cost of the action). We do them because we want to express our support. We want other people to know what we support, and to just feel good about doing something that expresses that support. If you value the returns from this expression more than the expected costs to you, then it makes sense for you to do it.
So, suppose that you favor libertarian policies, but would prefer that a Republican candidate win vs. the Democrat candidate. This election has a Libertarian candidate as well. What should you do? It seems to me that the reasonable thing to do depends on what you’re trying to accomplish.
If you’re trying to sway the election, you should forget about it and go read a good book or something.
But, if you’re voting for expressive reasons, then I think you should vote for the candidate who best represents your preferences. And that candidate is the Libertarian. I think you should do this even if you don’t really want this particular candidate to win (let’s say his approach to how to transition to libertarianism is different from yours). You should want people who analyze the results of the election to get the right message from your vote. You should want them to know that there was one more voter who favors libertarian policies, and hopefully they’ll modify their behavior to try to accomodate libertarians a bit more. But if you vote for the Republican, you’ll be sending the wrong message (or at least an ambiguous one).
So, if you want to send a libertarian message you should vote Libertarian. If you want to send a Republican message, you should vote Republican.
If you want to send a Democrat or Green message, you shouldn’t bother voting. Your vote won’t affect the outcome.