An open access publication of the American Academy of Arts & Sciences
Fall 2012

On the Importance of Public Opinion

Lee Epstein
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LEE EPSTEIN, a Fellow of the American Academy since 2006, is the Provost Professor of Law & Political Science and the Rader Family Trustee Chair in Law at the University of Southern California. She is the author, coauthor, or editor of fifteen books, including Constitutional Law for a Changing America, 7th ed. (with Thomas G. Walker, 2011) and Advice and Consent: The Politics of Judicial Appointments (with Jeffrey A. Segal, 2005). Her current book project, The Behavior of Federal Judges: A Theoretical and Empirical Study of Rational Choice (with William M. Landes and Richard A. Posner), will be published in late 2012.

“The president’s job approval rating is up”; “50 percent of Americans believe that their taxes will increase in the next year”; “The incumbent senator is the projected winner by a 2-1 margin.” This is how most of us follow and understand public opinion: through survey and election results that seem to be everywhere. But there is much more to public opinion than a percentage or an outcome reported in a headline, posted on a website, or tweeted, emailed, or texted. The authors in this issue speak to the “much more.”

How do we learn about public opinion, and what does it tell us? These are the questions considered in our first four essays. D. James Greiner and Kevin Quinn begin the volume with a fascinating glimpse into the world of polling, especially exit polls. Greiner, an expert on voting rights, and Quinn, a political scientist with expertise in statistical methodology, are uniquely poised commentators. The two have conducted exit polls of their own–but that may be damning with faint praise. After the debacle in Florida with the 2000 presidential election, many of us are skeptical of exit polls. Greiner and Quinn share our skepticism, suggesting that exit polls “are most prone to fail when we most want them to work”–that is, in close elections. But this is not their only concern. In a day and age when conventional (telephone) and more au courant (Internet) polling techniques can provide vast amounts of information far more cheaply, Greiner and Quinn question whether exit polls will and should survive.

Their answer is yes, though not as a device for calling elections or even for mapping voters’ preferences. Rather, Greiner and Quinn suggest that the exit poll is an apt mechanism for learning about the administration of elections. As the authors remind us, U.S. history is full of attempts at vote manipulation–whether through poll taxes, literacy tests, or, more recently, discretionary application of voter ID laws.1  Because exit polls are nearly contemporaneous with the act of voting, they can be a powerful method for detecting bias.2

As a policy recommendation, Greiner and Quinn’s is meticulously developed. As a descriptive matter, we know that news organizations will continue to rely on exit polls, along with many other types of surveys, to predict electoral outcomes and, more generally, to provide a snapshot of public preferences. So how should we interpret all the numbers that so bombard us weekly, if not daily? Do they provide candidates and policy-makers with meaningful information about “We the People”?

To address these and other questions emerging from the plethora of polls, we turn to essays by two deans of the study of mass behavior, James Stimson and Robert Erikson. Together (with Michael MacKuen) they wrote The Macro Polity, a landmark study on the impact of public opinion on elections and public policy.3 Individually, their contributions to the field have been no less impressive, as their essays here well exemplify.

Stimson takes us on a tour of public policy mood, a concept and measure he invented more than two decades ago.4 Despite its age, Stimson’s concept remains central to social science inquiries into public opinion. One reason is that his idea of mood is simple to understand: it is a single number summarizing the mood of the public along a liberal/conservative dimension (see Figure 1 in Stimson’s essay). Higher numbers indicate a more liberal public mood, lower numbers a more conservative mood. (In his essay, Stimson explains how he uses public opinion surveys to construct the mood measure.)

Another reason why Stimson’s invention took public-opinion research by storm: it helps forecast election outcomes. Well before anyone predicted a Democratic win in the 1992 presidential election, Stimson identified the then-unnoticed drift “toward a liberalism of substantial proportions.”5 A year later, Bill Clinton won 370 (68.8 percent) electoral votes.

Erikson’s essay demonstrates that mood (separately and in relation to a candidate’s ideology) and the public’s partisan leanings (“macropartisanship”) provide a highly satisfactory explanation of election results–even better than the state of the economy. But it is not only elections that respond to mood. Erikson shows that when the “electorate asks for an ideological change in policy . . . eventually–perhaps after many years, given the roadblocks in the way of congressional policy-making– the demand is satisfied.”

Erikson and Stimson focus on the aggregation of individual opinions: for example, the fraction of the public that supports gun control (“macro” public opinion). James Druckman, a scholar well known for his work on how Americans make decisions, and Thomas Leeper, a doctoral student and collaborator with Druckman, turn to the individual opinion itself: for example, an individual’s preference for gun control (“micro” public opinion). Among the puzzles they investigate is whether public opinion is stable. The importance of this question is obvious. If preferences are stable, then all of us, Americans and our representatives alike, could place some stock in the poll numbers. On the other hand, if preferences are unstable, the meaning of those numbers at any point in time could be called into question. Druckman and Leeper’s work reveals that the answer depends on whether we look at macro or micro trends in the data. While Americans’ policy preferences are stable at the macro level, this is decidedly not the case at the micro level. Druckman and Leeper consider the explanations for this disconnect, as well as its consequences.

Despite their different approaches, Stimson, Erikson, and Druckman and Leeper agree on the important role public opinion plays in shaping public policy. Perhaps this isn’t so surprising in a democracy; we expect elected representatives to pay some attention to those who elect them. That’s one reason why social scientists shower attention on public opinion. But what of the unelected federal courts? Should we expect a connection with the public in that domain?

What better commentator to address this question than Linda Greenhouse, who for thirty years covered the U.S. Supreme Court for The New York Times and now teaches at Yale Law School. For the uninitiated, Greenhouse provides an analytic review of the literature on “how the Supreme Court and the public observe and understand one another.” Ultimately, the answer seems to be better than we might expect. These observations frame her case study of Roe v. Wade (1973). Her focus is not on Roe’s constitutional aspects but rather on how the ruling became “Roe”: a polarizing decision over abortion–and the Court itself. The answer, Greenhouse tells us, lies less in this one decision than in how strategists from the emerging New Right used it to help create a “pro-family” movement consisting largely of Catholics and Evangelicals.

If strategists can use a single Supreme Court decision to bring about major political change, it would seem that the media–whether through political programs or campaign advertisements–too could influence the public’s opinion of candidates. Surely, most Americans think as much, and it is hard to blame them given the enormous amounts of money spent on campaigns, the ubiquitous ads on television and elsewhere, and the emergence of a profession devoted to electing candidates. But they are wrong. At least when it comes to the direct effect of the media on voters’ decisions, social scientists have called the impact “marginal at most,” as Diana Mutz writes in her essay.

Explaining the gap between public perceptions and reality, as well as assessing its implications, is no small task. Mutz, director of the Institute for the Study of Citizens and Politics at the University of Pennsylvania, is more than up to confronting the challenge. For decades now, Mutz has provided both scholars and the public with crucial insights into public opinion and political communication. Her essay here is no exception. Mutz begins by taking us through the history of the divide between the public and the experts on the media’s influence. This makes for a fascinating read, but Mutz’s goal is not solely descriptive. She argues powerfully that Americans are not “well served by [their] extreme beliefs in media power.”

We end with two essays that examine public opinion and perceptions in the Latino and black communities, respectively. The author of the first, Gary Segura of Stanford University, is unparalleled in his knowledge of Latino politics. Not only has he written extensively on the subject, he is also a principal in Latino Decisions, which provides independent polling data to decision-makers and news outlets.6 James Gibson, of Washington University in St. Louis, is an equally savvy observer of mass behavior. For his work on this and related topics, Gibson has received numerous honors, including the Decade of Behavior Research Award for 2000–2010.

Readers will quickly see that Segura’s essay both reinforces and challenges some conventional understandings of Latinos. Segura confirms that this community is growing rapidly, from 12 percent of the population in 2000 to more than 16 percent in 2010. No doubt about it: “What Latinos think about government and politics matters a great deal to the future direction of the country,” he asserts.

It is what Latinos think that may come as a surprise. Latinos may embrace the idea of self-reliance, Segura explains, but they also see a crucial role for government in solving societal problems. Taken with the other data Segura has amassed, the implication is that the Democratic Party is likely the winner in the partisan race for the Latino vote today and in the future. Segura writes: “The most rapidly growing segment in the American electorate is increasingly unified and demonstrably left of center.”

Gibson’s take on race is equally enlightening. His concern is less with the political preferences of black and white Americans than with their perceptions of political freedom–whether they feel free to speak their minds or whether they feel free, for example, to organize a public meeting to oppose the government. Using survey data he has collected over the years, Gibson demonstrates that both blacks and whites believe that there are fewer constraints on their freedom than there were two decades ago. But differences between the two groups persist. Only 32.3 percent of whites but fully 50.5 percent of blacks believe that the government would not allow them to organize meetings, to provide but one example. Gibson also shows that Barack Obama’s election in 2008 empowered black Americans, increasing their perception of political freedom, but the effect was short-lived. By 2011, perceptions had returned to 2005 levels.

These analyses, along with Gibson’s data on intrablack differences, deserve close attention. Indeed, all the essays in this volume merit careful study. Each illuminates a fascinating aspect of a subject that occupies an important place in the social science literature. Even more than that, taken together they make a compelling case for why public opinion should matter to all of us.


  • 1Rachael Cobb, D. James Greiner, and Kevin M. Quinn, “Can Voter ID Laws Be Administered in a Race-Neutral Manner? Evidence from the City of Boston in 2008,” Quarterly Journal of Political Science 7 (1) (2012): 1–33.
  • 2Ibid. The exit poll the authors conducted for their study captured clear evidence of racial bias by poll workers.
  • 3Robert S. Erikson, Michael B. MacKuen, and James A. Stimson, The Macro Polity (New York: Cambridge University Press, 2002).
  • 4James A. Stimson, Public Opinion in America: Moods, Cycles, and Swings (Boulder, Colo.: Westview Press, 1991). The second edition was published in 1999.
  • 5Ibid., 117.
  • 6See