This is a weighty volume in many ways. In the most important sense, it takes big steps toward answering a central question of political science: How democratic is the American version of democracy? To the authors of The Unheavenly Chorus, democracy requires more than the free expression of political voice, or the opportunity to make one's views heard. They argue that equal political voice is vital. Decision makers need to hear the reactions of a chorus of voices that fairly represents the citizenry as a whole, and they need to be motivated to respond to a representative chorus. It is not easy to envision how we would determine the exact makeup of that truly representative chorus. But Kay Lehman Schlozman, Sidney Verba, and Henry E. Brady make a compelling case that American politics diverges substantially from it. The louder voices belong to those who are able to go beyond the use of the vote—a powerful but inarticulate form of communication—to make more explicit statements to public officials about their preferences. The louder individual voices, the authors show, systematically overrepresent wealthier and better-educated Americans. The louder voices among organized groups are those of business.

The distortion of representation in favor of voices with upper socioeconomic status is not a new finding, of course. E. E. Schattschneider's contention that the “flaw in the pluralist heaven is that the heavenly chorus sings with a strong upper-class accent” (The Semi-Sovereign People, 1960, p. 35) must be one of the most widely repeated statements in political science. Several other first-rate works have also recently examined inequality in the American political system, most notably Larry Bartels's Unequal Democracy (2008) and Martin Gilens's Affluence and Influence (2012).

Even so, The Unheavenly Chorus is a significant advance in our understanding. It is the most recent in the pathbreaking investigations that began with Gabriel Almond and Verba's The Civic Culture (1963), which addressed empirically as well as conceptually the debate among pluralists, elite theorists, and others as to whether American politics offers voice to all citizens. During the succeeding 40 years, these authors and their collaborators and students have produced a remarkable series of books and articles that created and analyzed new data sets, refined their questions, and provided more nuanced discussion of this fundamental issue.

It is admirable that Schlozman, Verba, and Brady use a variety of methods and types of data to reach their conclusions: close historical analysis, content analysis of state constitutions, one-shot and panel surveys, and demographic data. Their analysis of state constitutions, for instance, is a valuable way to demonstrate the long history of American ambivalence about equality. It shows that since the beginning of the republic, the complex notion of equality has had more to do with equal opportunity in politics and the economy than with any practical application of economic egalitarianism.

The authors also raise the fascinating question as to how to conceptualize and measure political equality in participation by organized interests. In addition to data problems, it is a challenge to understand how an organization might represent its members or constituents in a relatively equal manner, both internally and externally. This is especially problematic because the great majority of the organizations in the interest-group universe are not membership associations. The authors make good use of Dara Strolovich's finding that even in the case of membership groups claiming to speak for the least privileged, it is the voices of the most privileged of these least privileged that tend to be amplified. (“Do Interest Groups Represent the Disadvantaged? Advocacy at the Intersections of Race, Class, and Gender,” Journal of Politics 68 [2006]: 893–908).

The book proposes a number of very insightful ways to rethink our approach to studying representation. The authors note the benefits of modifying measures of the median voter to account for the more substantial influence of the median campaign donor, the donor of the median campaign dollar, and the median campaign volunteer. That, in turn, suggests a need to examine more closely the ways in which different types of political activism affect candidates, legislators, appointed officials, and public opinion. By what means, for instance, do campaign contributions or extensive social-network dissemination of particular ideas affect officials' perceptions of public opinion, not just their roll-call votes or committee behavior? The authors also recommend reweighting the impact of political participants according to the number of votes that their contributions or time may have been responsible for generating.

Another especially interesting finding, which my own research confirms, is that although political activists have more conservative attitudes on economic policy, compared with voters and all citizens, activists also tend to have less conservative attitudes than the average citizen on such “values issues” as abortion and school prayer. This lack of moderation among activists encourages polarization. But it also indicates that the position of defenders of so-called traditional values in recent political debates may be less secure than it often seems.

The authors also do us a great service by suggesting what could be the most sensible position in the long debate between Morris Fiorina and Alan Abramowitz on the extent to which partisan and ideological polarization penetrates the American public or characterizes political activists only. They demonstrate (pp. 258–61) that less active partisans (especially Republicans) have become more ideologically polarized since the 1970s, though to a lesser extent than activists have—a finding that political scientists in both contending camps should be able to accept. The interesting question, then, is not whether ideological polarization has increased, as well as partisan sorting—it appears they have—but under what conditions this process has affected which types of citizens. The Unheavenly Chorus illuminates this question, as does research by Thomas Carsey, Geoffrey Layman, and others.

The main point of the current book is this: “Our analysis of the roots of political inequalities makes clear how deeply embedded they are in social, educational, and economic inequalities” (p. 539). Mitigating these inequalities, then, would require much more radical change than “mere institutional tinkering.” Such radical change is not only highly unlikely in current politics, the authors conclude, but might also be inordinately risky, given our long experience with the unintended consequences of well-meaning reform. The greatest inequality, they argue, involves campaign contributions—a problem that the Supreme Court and some other federal courts have worsened substantially with recent rulings deregulating campaign finance.

I agree with the authors that this deregulation threatens to blow holes in the fabric of representation. But I am a little more hopeful about the possibilities for change. Since the 1960s, antiregulatory presidents have not only dominated the White House but also demonstrated a more acute awareness, compared with their Democratic counterparts, of the advantages that come from nominating Supreme Court and other federal judges who are not only highly conservative but also relatively young. Their legacy has led us directly to Citizens United and SpeechNOW. Greater balance in judicial appointments would require more effort by Democratic presidents and senators to stand firm on their nominations. But even some of the antiregulatory appointees have shown awareness that rulings that step outside the (admittedly vague) boundaries of what seems “right” can threaten the institution's legitimacy, as the Supreme Court's ruling on the Affordable Care Act suggests. Previous campaign finance regulation has had some impact on funding disparities. It can again.