Someone once joked that economists are people who see something working in practice, and then wonder if it will also work in theory.   One practice that mainstream economists have long failed to explain theoretically is voting.    Following the (so-called) rational choice models of Arrow and Downs, they calculate the likely net monetary benefit of voting to an individual voter, and compare that to the likely net costs to the voter.  With long queues due to inadequately-resourced or incompetently-managed voting administrations (such as those in many US states), these costs can be considerable.  Since one vote is very unlikely to have any marginal consequences, economists are stumped as to why any person votes.
One explanation for voting, of course, is that voters are indeed feeble-minded or irrational, unable to calculate the costs and benefits themselves, or, if they can, unable to act in their own self-interest.   This is the standard explanation, and it strikes me as morally reprehensible:  a failure to explain or model some phenomenon theoretically is justified on the grounds that the phenomenon should not exist.
Another explanation for voting may be that the rational-choice models understate the benefits or overstate the costs to individuals of voting.   Some economists, as if in a parody of themselves, have now  – in 2008!  – discovered altruism.  Factor in the benefits to others,  this study claims, and the balance of benefits to costs may move more in favour of benefits.
A third explanation for voting may be that rational-choice models are simply inappropriate to the phenomena under study.  The rational choice model assumes that citizens in a democracy are passive consumers of political ideas and proposals, with their only action being the selection of representatives at election times.   Since at least the English Peasants’ Revolt of 1381, this quaint notion of a passive citizenry has been rebutted repeatedly by direct political action by citizens.  The most famous example, of course, was the uprising against colonial taxation known as the American War of Independence, which, one imagines, some economist or two may have heard speak of.   There’s also the various revolutions and uprisings of 1789, 1791, 1848, 1854, 1871, 1905, 1910, 1917, 1926, 1949, 1953, 1956, 1968 and 1989, just to list the most important since economics began to be studied systematically.
An historically-informed observer would surely conclude that a model of voting in which citizens produce as well as consume political ideas is likely to have more calibrative traction than one in which citizens do nothing except (if they so choose) vote.   Such a theory already exists in political science, where it goes under the name of deliberative democracy.   One wonders what terrors would strike the earth were an economist to read the relevant literature before modeling some domain.
People vote not only out of their own self-interest (if they ever do that), but also to influence the direction of their country, to act in solidarity with others, to elect to join a group, to demonstrate membership of a group, to respond to peer pressure, because the law requires they do, or to exercise a hard-won civil right.  Only a person with no sense of history – an economist, say – would fail to understand the importance – indeed, the extreme rationality – of this last factor, especially during a year when a major political party has nominated a black candidate for President of the USA, and the other party a woman for Veep.  At the founding of the USA, neither candidate would have been allowed to vote.
Not for the first time, mainstream economics has ignored social structures and processes when studying social phenomena, focusing only on those factors which can be assigned to an individual (indeed, some idealized, self-interested, desiccated calculating machine) and, within these, only on factors able to be quantified.   The big question here is not why people vote, which is obvious, but why economists seem unable to recognize social structures and processes which can be clearly seen by most everyone else.  What is it about mainstream economists that makes them autistic in this regard?   Do they simply have an under-supply of inter-personal intelligence, unable to empathize with or reason about others?
 
References and Acknowledgments:
Hat-tip to Normblog. 
Kenneth J. Arrow [1951]: Social Choice and Individual Values. New York City, NY, USA: Wiley.
J. Bessette [1980]: “Deliberative Democracy: The majority principle in republican government”,  pp. 102-116, in: R. A. Goldwin and W. A. Schambra (Editors): How Democratic is the Constitution? Washington, DC, USA: American Enterprise Institute.
James Bohman and William Rehg (Editors) [1997]: Deliberative Democracy:  Essays on Reason and Politics.  Cambridge, MA, USA: MIT Press.
Anthony Downs [1957]: An Economic Theory of Democracy. New York City, NY, USA: Harper and Row.