This is an excerpt from an obituary published today in the New York Times.
Tony Downs, Economist Who Studied Why People Vote, Dies at 90
In his work on politics, Mr. Downs concluded that most voters, while not completely self-interested, decide whom to support on the basis of what he called “utility income.” He defined that as voters’ perception of which candidate would best preserve or increase the benefits they received from government.
But Mr. Downs also said that voters make up their minds on the basis of “rational ignorance.” By that he meant that people often vote without taking the time to study the issues or candidates because they doubt that their individual votes will count, and because they have no economic incentive to understand the role of politicians.
“The behavior of voters may be ignorant,” Stanley Kelley Jr., a political science professor at Princeton, wrote in his introduction to Mr. Downs’s “An Economic Theory of Democracy,” “but that is not equivalent to its being irrational.”
Simply put, R = P x B — C. In other words, the rationality of voting (R) equals the perceived probability that a ballot will make a difference (P), multiplied by the benefit of victory by the voter’s preferred candidate (B), minus the costs of voting (C).
On an optimistic note, it is easier to influence the thinking of an ignorant person than it is to influence the thinking of an irrational person. An ignorant person may be convinced to change their perceptions with sufficient and credible factual information.