Why do only half of us vote in national elections? Answering this question has been so difficult, and the debate over it so controversial, that this cardinal act of participatory democracy has become the master problem of political science. If we had a better understanding of why people do vote - as opposed to why they don't - we might be better at persuading more to follow suit.
Let's consider some of the possibilities. Political scientists have traditionally assumed that citizens vote to help bring about the desired electoral outcome. Specialists call this an instrumental rationale: each person's vote is the instrument for electing the favored candidate. But in large national elections an individual vote has no detectable impact. One's risk of getting killed en route to the voting booth is greater than one's chances of swinging the election. Votes matter only in the aggregate, only when they add up to a majority.
Perhaps, then, voting is an expressive rather than an instrumental act. We might speculate, for example, that people see voting as an effective way to give voice to their political attitudes, or as a way of nurturing their reputations as responsible citizens among their peers. But this explanation does not suffice either. After all, there are better ways to reach these goals. Attitudes can be expressed in conversation, and reputations are best staked on actions yielding tangible outcomes, such as good deeds in the community. This leaves the possibility that people vote because they value the right to do so or because they act on a sense of duty. Such high-minded theories do little, however, to answer questions about why more people vote in some elections than in others.
Indeed, neither expressive nor dutiful voting can explain several well-known collective patterns. The percentage of voters who turn out, for example, increases with the size of the electorate and with the expected closeness of the race. Supporters of a candidate who is trailing the front-runner only slightly are the easiest to mobilize, and some supporters of dark-horse candidates choose not to vote for their favored choice but to transfer their votes to the least objectionable candidate who has a more realistic chance of winning.
We are thus forced to return to the idea of an instrumental rationale for voting. If we assume that voters act as if there were a direct utility to their behavior, the decision to vote (or to tactically change one's vote) makes sense. Most people do not fully understand the brute fact that their own contribution to the election is undetectably small; surely, if most voters were asked point-blank whether they thought their own vote might make a difference, most voters would say no. Yet research on social-perceptual processes has revealed two ways in which people can implicitly hold the belief that their own individual vote will make a difference. Voting requires a leap of faith that we might call the voter's illusion. One line of reasoning goes like this: My own decision to vote or to abstain is linked to the decisions of many like-minded others. A certain percentage of the supporters of my favorite candidate will ultimately vote. But because I do not know for sure whether most will vote, I can only assume that if I vote, most other supporters of my candidate will do likewise. Because I don't know what the opponent's supporters will do, I conclude that my vote may very well be a key factor in my candidate's success.
Note how similar this reasoning is to the Calvinist's efforts to forecast his or her own salvation. Calvinists believe that their salvation - or damnation - is predestined, as is their ability to be righteous and successful in this world. Finding success in this world can then signal - but not cause - salvation. The subtle distinction between signaling and causing events is easily lost, and so it might be argued that a voter acts like a Calvinist: both pursue socially desirable acts, such as doing good or doing well, with an eye on uncontrollable future consequences.
The other line of reasoning does not involve expectations of what others might do. Instead, potential voters may try to anticipate their emotional reactions to a favorable or an unfavorable electoral outcome by assuming either that they vote or that they abstain. The anticipated feelings tend to be egocentric. A vote cast feels more like a waste in the case of victory than in the case of defeat. Conversely, a vote withheld seems more of a missed opportunity after defeat than after victory. Consequently, people report that they are likely to vote in the future inasmuch as they do not perceive their own vote to be superfluous. They deny the brute fact of individual irrelevance.
Increasing voter turnout is an imperative of politics. For democracy to work, there must be a respectable voter turnout, but more than that, for elections to reflect the will of the populace, candidates must convince voters that they need each citizen's vote. Voters for their part must believe that the preservation of democracy and the results of elections are both dependent upon their influence. Paradoxically, people's less-than-rational intuitions lead them to contribute - however imperceptibly - to the common good. What remains is an ethical dilemma for those who seek to bring out the vote - as, for example, the Federal Election Commission does - by telling citizens that "every vote counts." They do count en masse, but this is little consolation to the individual who might want to spend a Tuesday evening pursuing more pleasurable activities.