Your Vote "Matters" as a Signal of Your Policy Preferences

Every so often I will talk about the economics of voting in econ 101. With a Presidential election taking place this semester, we will certainly discuss it. We establish that one individual vote is virtually certain not to determine who becomes president (or Senator, or county treasurer, or dog collector). So what is a good reason to vote? Voting can be a very cheap way to signal your preferences or to endorse a particular set of ideas. By voting for Candidate X, you can send a relatively cheap signal that says "I agree with this platform more than the other available choices." Many people will vote for either Barack Obama or John McCain not because they endorse either platform but because they are voting "against" the candidate they like the least. Given, however, that an individual vote is unlikely to matter, people shouldn't lose any sleep over voting for someone who isn't McCain or Obama. Some would argue that the irrelevance of voting means that people shouldn't vote at all. I disagree, but I understand and respect the position.