Paradox of voting

The paradox of voting, also called Downs paradox, is that for a rational, self-interested voter, the costs of voting will normally exceed the expected benefits. Because the chance of exercising the pivotal vote (i.e., in an otherwise tied election) is minuscule compared to any realistic estimate of the private individual benefits of the different possible outcomes, the expected benefits of voting are less than the costs.

This argument does not account for the most trivial possible case of an election, that with only 2 electors voting. Since neither elector can exercise a pivotal vote, assuming the other casts a vote, the argument implies that voting in such an election has zero value, which is absurd.

The issue was noted by Nicolas de Condorcet in 1793 when he stated, "In single-stage elections, where there are a great many voters, each voter's influence is very small. It is therefore possible that the citizens will not be sufficiently interested [to vote]" and "... we know that this interest [which voters have in an election] must decrease with each individual's [i.e. voter's] influence on the election and as the number of voters increases." In 1821, Hegel made a similar observation in his Elements of the Philosophy of Right, "As for popular suffrage, it may be further remarked that especially in large states it leads inevitably to electoral indifference, since the casting of a single vote is of no significance where there is a multitude of electors." This problem in modern public choice theory was analysed by Anthony Downs in 1957.

Alternative responses modify the postulate of egoistic rationality in various ways. For example, Brennan and Lomasky suggest that voters derive 'expressive' benefits from supporting particular candidates. However, this implies that voting choices are unlikely to reflect the self-interest of voters, as is normally assumed in public choice theory; that is, rational behavior is restricted to the instrumental as opposed to the intrinsic value of actions.

Some have hypothesized that voting is linked genetically with evolved behaviors such as cooperation. One study of identical and fraternal twins' voting patterns concluded that 60% of differences in turnout among twins can be accounted for by genetics, but another interpretation of this study put the figure at 40%.

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