I would like to join David Bernstein in commending Bryan Caplan's new book, The Myth of the Rational Voter. It is the most important work on political ignorance in at least a decade, and possibly longer.
Previous scholars, including myself (e.g. here and here), have explored the deleterious consequences of the average citizen's massive ignorance about politics and public policy. Since the 1950s, economists and political scientists have known that it is actually rational for voters to be ignorant, because the chance that any one voter will have a significant impact on the outcome of an election is infinitesmally small. There is little incentive to spend time and effort acquiring knowledge about politics that won't make any difference to political outcomes anyway.
Bryan, however, goes beyond the standard rational ignorance analysis. He emphasizes that it is rational for voters to not only learn very little about politics, but to do a poor job of evaluating the information they do have. Good analysis of political information - like learning the information in the first place - requires considerable time and effort that rationally ignorant voters have little incentive to undertake. Instead, voters are likely to fall prey to systematic errors in considering political information. As Bryan shows in detail, this helps explain why the majority of voters routinely fall prey to gross fallacies in their analysis of public policy - such as the belief that protectionism helps the overall economy; that the rise of modern technology is a major cause of longterm unemployment; and that foreigners are beggaring the American economy (all of these are actual examples from the book).
Because there is so little incentive to acquire and analyze political information to become a "better" voter, most of those citizens who do invest in political knowledge are likely to do so for other reasons. These include reinforcing their preexisting biases and prejudices, using politics as "entertainment" (much in the same way that sports fans acquire knowledge about their favorite teams for similar reasons), and signaling membership in a social group. As Bryan's work suggests (and I discuss in some detail in this article), such motives for acquiring information are extremely conducive to biased and irrational evaluation of the knowledge gained. Bryan calls this kind of systematically biased thinking "rational irrationality." The title of the book is actually slightly misleading. Bryan is not arguing that voters are stupid or irrational. Rather, he contends that it is actually rational for the individual voter to engage in biased and severely flawed evaluation of public policy. Unfortunately, behavior that is rational for individuals can lead to very harmful collective outcomes.
I do have a few disagreements with Bryan's analysis. In particular, I am skeptical of his argument that transferring more political power to knowledgeable experts is a good solution to the ignorance of the average voter. Ironically, the libertarian Caplan here makes the same kind of argument for increasing the power of experts as liberal Supreme Court Justice Stephen Breyer in his 1993 book Breaking the Vicious Circle. Anticipating Caplan, Breyer argued that the ignorance and bias of voters justifies transferring power over regulatory policy to "nonpolitical" expert bureaucrats. I have serious doubts about both Bryan's and Breyer's paeans to expertise.
Be that as it may, Bryan's book is a must-read for anyone even remotely interested in democratic theory and political participation.
CONFLICT OF INTEREST WATCH: Bryan and I are collaborating on a related project.
UPDATE: To avoid misunderstanding, I should note that Bryan also argues that voter ignorance and irrationality justify limiting the size and scope of government in order to leave more decisions in the hands of the free market and civil society (where incentives for rational information acquisition and evaluation are generally better). I have made the same argument in my own works linked in the post. However, this argument is in some tension with Bryan's simultaneous claim that the deficiencies of voters should be addressed by transferring more power to experts.