The rationality of voting

There are a couple of posts at the Becker-Posner blog about voting, and about the reasons that people vote:

• Gary Becker: Why People Vote and What That Implies-Becker
• Richard Posner: The Paradox of Voting–Posner

Becker expresses the question with

This raises the very old question of why people vote in large elections when their chances of being a pivotal voter are virtually zero, and when voting takes time and is often inconvenient. The electorate is surely conscious of the cost to them of voting since, for example, turnout is usually much smaller when the weather is very bad. The common answer nowadays about this so-called paradox of voting is not that voters are irrational, but rather that they vote for reasons other than to influence outcomes. They may vote to indicate their moral support for particular candidates, or because they believe they express a precious right when they vote, or for other non-instrumental reasons.

In turn, Posner expresses his curiosity with:

The paradox of voting in national elections is that, since a single vote is almost certain to have no effect on the outcome (in a Presidential election, it will merely add one digit to an eight-figure number), there seems to be no benefit from voting. The cost is small enough (if it’s high for a person, he is unlikely to vote), but it’s positive, so that if the benefit of voting is zero the voter is being irrational. Yet, as Becker points out, more than 100 million people bothered to vote in the recent Presidential election.