A couple rational guys try to figure out why people do something apparently irrational: Vote in an election that there is little or no chance they will be able to sway. One person's vote out of 100 million will not change results, but ...
Posner sees a similarity to clapping:
Some people vote because the political campaigns make it costly for them not to vote—one technique in “get out the vote” drives is pestering people to vote so that they will feel uncomfortable not voting. Some vote because they think that it will encourage others to do so. Some vote because they consider it a civic duty. Some voting is purely expressive—a way of expressing strong feelings pro or con a candidate (or pro one and con his opponent); certainly anger played a role in votes against Romney by members of groups that he or his party seemed to disrespect, and anger at Obama played a role in the large number of votes that Romney received. In this respect voting is like booing or cheering at an athletic event or other entertainment. One person’s applause at a concert is inaudible to the performers, yet people applaud, and not mainly I think because others in the audience would look askance at them if they did not. And finally people interested in politics like to vote to convince themselves and others that their interest is serious—they are willing to put their money (not money exactly, but the cost in time and bother of voting) where their mouth is.
No one thinks that applauding is irrational, even though like voting it has no instrumental value, and has some, though very slight, cost.
Becker is concerned that the fact that we know our vote does not matter makes it unlikely we will learn about the candidates we are voting for:
Since the great majority of voters presumably do not expect to influence election outcomes, who they support is influenced disproportionately by campaign rhetoric, debates among candidates that have little intellectual content, and by other methods of persuasion that are not very informative about the candidates. I like to say that consumers put more time and effort into deciding which cereal to buy and into other small consumer choices than in gathering information on economic and other issues about presidential candidates.
But I am not claiming that voters are less “rational” than consumers of everyday products. Individuals pay more attention to what they buy than whom they vote for because what they buy has a direct and tangible effect on their wellbeing. Since the incentives to become well informed are radically different, “rational” voting implies very different kinds of behavior than does rational choice of cereals or peanut butter.