1In his renowned Histories, the Greek historian Polybius argues that the optimal political organization is a Mixed Constitution, as it combines the strengths of three governing forms: the one (Monarchy), the few (Aristocracy), and the many (Democracy). Polybius considers the Roman Republic—with its Consuls, Senate, and Assemblies—to have embodied this ideal, where each form of power complements and checks the others, promoting stability and prosperity.

2At first glance, Citizen Knowledge might seem distant from Polybius’s challenge. For Lisa Herzog, the essential element of democracy lies in the quality of citizens’ epistemic lives. The book presents a broad view of the issues surrounding the role of knowledge in politics: How is knowledge acquired and shared? What kinds of individual traits and contexts are needed for a “good” epistemic life? How can politics function in a world where truth is constantly questioned? How do groups aggregate dispersed information and diverse judgments? How does technology influence our political beliefs and actions? Should we obey scientists and experts? Above all, citizens’ epistemic lives do not exist in a vacuum; rather, people are immediately embedded within epistemic institutions that can be either beneficial or threatening. Lisa Herzog identifies three main epistemic institutions: political deliberation, markets, and science practices. By analogy, Citizen Knowledge closely aligns with the Polybian challenge: these three institutions organize three distinct epistemic powers, each constantly threatened by corruption and corrosion, and each having complex interrelations with the others. How might we establish a Mixed Epistemic Constitution to ensure that we gain the benefits of all three while preventing any one of them from becoming exclusive and dominant?

3As such, the book makes a very important contribution to political epistemology, “an emerging field in philosophy at the intersection of epistemology and political philosophy that analyzes the interrelations between knowledge and political practices and institutions” (12; see also Hannon and de Ridder, 2021). The book’s aim is less to offer a fundamentalist defense of democracy than to provide practical and institutional arguments about democracy’s epistemic properties and to clarify the conditions under which liberal and democratic institutions can produce good epistemic outcomes. From this point of view, Lisa Herzog explains: “My argument, in contrast, holds on to the normative premise of democracy, but asks how the relationship between markets, experts, and democratic practices needs to be recalibrated in order to achieve better epistemic outcomes.” (9) On the one side, some scholars advocate for generalizing the Condorcet jury principle, arguing that collective decision-making in democracies has strong epistemic advantages. They believe that new forms of public debate and citizen participation—such as citizens’ assemblies—enhance citizens’ knowledge and renew democratic engagement. Hélène Landemore’s research exemplifies this perspective (Landemore, 2012). On the other side, some scholars question these epistemic advantages. They argue that democratic institutions like voting and deliberation are compromised by various side-effects that prevent them from delivering sound, rational, or impartial solutions. For example, they contend that citizens are often biased or apathetic toward politics, and that deliberation can lead to excessive polarization. They conclude that reducing democratic participation—restricting voting, for instance, to those deemed more capable—would yield better-informed outcomes. Jason Brennan’s work is representative of this viewpoint (Brennan, 2016).

4While Herzog considers this “For or Against Democracy” debate significant, she resists framing the issue as a binary choice focused narrowly on the legal and procedural aspects of collective judgment, such as voting rules and deliberation processes. Instead, she adopts an institutionally oriented view of democracy, one that “can be instantiated in different forms for different types of decisions, through various forms of public participation, diverse ways of incorporating expert knowledge, and multiple methods of selecting representatives.” (9) To understand the democratic individuals—their judgments, knowledge, and actions—Lisa Herzog argues that we must consider the epistemic division of labor within society. Markets send signals about the relative scarcity of resources and play a crucial cognitive role in society; scientists and experts communicate knowledge gained from scientific inquiry; and collective discussions refine individual and collective judgments. Each of these institutions relies on epistemic infrastructures that serve as institutional safeguards for the quality of social knowledge produced. Herein lies the book’s great contribution: it thoroughly examines the epistemic infrastructures each institution requires and explores the relationships among them.

5From a methodological perspective, Lisa Herzog adopts an interdisciplinary approach centered on epistemic issues. Many social sciences fields have experienced an “epistemic turn”: epistemology increasingly focuses on social epistemology (Goldman, 1999); economics is strongly influenced by the “informational turn” (Hayek, 1945; Stiglitz, 2004); and psychology and sociology have embraced cognitive paradigms (e.g., Kahneman, 2011). Given the complexity of citizens’ epistemic lives, traditional disciplinary boundaries have become less relevant. Readers of Citizen Knowledge will be struck by Lisa Herzog’s skill in weaving together diverse findings from a wide range of sources into a coherent whole. As such, the book, particularly clear and well-written, may be viewed as a manifesto advocating for an interdisciplinary approach that integrates philosophy, politics, and economics (17).

7Our review will focus on how this interdisciplinary approach is fruitful to better understand the organization of these three epistemic mechanisms and how to consider their equilibrium in order to get a well-ordered democracy. In the first part, we insist on the fact that Lisa Herzog tries to combine findings from the two main political western traditions, liberalism and republicanism. This combination is required because of the project of Citizen Knowledge: characterizing the phenomena of power and corruption of epistemic institutions. Then, we discuss how her epistemic views renew the delineation, the legitimacy and the regulation of each institution. To this effect, I will mainly focus on markets. Third, our review questions the analysis of regulation provided in the book. Implicitly, the book makes substantial assumptions on the legal system. While the book is convincing regarding the legitimacy of regulation of epistemic infrastructures of markets, deliberation and expertise, the mechanisms by which the law could actually play this role are less clear and leave a number of questions about the epistemic political organization unanswered. The main ambiguity, here, lies in the nature of the epistemic infrastructures of the legal system itself.

1. Democracy Analysis between Liberalism and Republicanism

8The first key to understanding Citizen Knowledge is that the democratic institutionalism Lisa Herzog advocates seeks to combine elements of liberalism and republicanism, two major traditions that lie at the roots of modern politics. Liberalism emphasizes individual rights, normative principles, and formal equality among citizens but may overlook the economic and social forces that threaten true freedom. In contrast, republicanism focuses on the risks of corruption in Republics, the side effects of representative government, and defines freedom not only as the respect of private interests but also as the guarantee of non-domination. Many influential democratic thinkers—such as Montesquieu, Tocqueville, Hamilton, Sunstein, or John Stuart Mill—draw from both traditions, and Lisa Herzog follows these footsteps.

9Chapter 6 outlines the central aspects of democratic institutionalism, where republicanism is especially useful for Lisa Herzog because it addresses the political consequences of epistemic corruption: “Corruption through power, including epistemic corruption, has long been a theme that republican, or republican-minded, thinkers have noticed.” (257) The republican tradition is important because the threats to a good epistemic life are not always reducible to infringements of rights; the dynamics of power may be more complex than mere violations of legal norms as the following examples illustrate. Suppose a scientist publicly argues that smoking has no health consequences, without disclosing that he is funded by tobacco lobbies. This behavior would exemplify epistemic corruption, and a classical liberal perspective would critique it based on transparency, honesty and violation of legal obligations. Now, suppose that a Nobel Prize-winning physicist, with no conflicts of interest, takes strong public positions on issues outside his field of expertise—such as a vaccination campaign. From a liberal perspective, this behavior is neither illegal nor inherently condemnable. However, a republican view would be more critical. It would be an example of epistemic trespassing: the physicist leverages his authority in science to gain undue influence in politics and medicine.

10In several of the book’s conclusions, epistemic infrastructures are analyzed from both liberal and republican perspectives, given the potential side effects of power on their functioning. This dual lens raises important questions about the responsibilities of individuals participating in epistemic life and calls for new forms of regulations. It underscores the need to characterize how epistemic issues reshape our understanding of power dynamics in society.

2. Deliberations, Markets and Sciences from an Epistemic View

11Following several scholars, Lisa Herzog emphasizes that centering epistemic life within citizenship revitalizes many classical social science concepts, such as epistemic justice, testimonial and hermeneutical (in)justice, epistemic trespassing, and epistemic responsibilities. These new concepts complement traditional views on inequality and justice by recognizing that a well-organized society must consider the potential for each citizen to be treated equitably from an epistemic standpoint. From a critical perspective, these concepts are valuable for illuminating the mechanisms by which certain individuals experience new forms of inequality. However, several aspects remain open to debate.

12The first point of contention is that a social epistemology perspective suggests that people experience varied epistemic lives, some richer, some more truth-oriented than others. Epistemic inequalities, therefore, may stem from either individual or institutional factors, and Lisa Herzog appears somewhat ambivalent on this issue. At times, individual responsibilities seem crucial:

Such epistemic responsibilities, connected to moral or other responsibilities, are also part of our everyday life and private social relations, and we can be blameworthy for failing to acquire relevant information or knowledge if that leads to a failure to do what we have a responsibility to do. (38)

13Yet at other times, she suggests that epistemic inequalities primarily arise from social causes. A note on virtue epistemology highlights this point: in discussing the type of social epistemology she advocates, Lisa Herzog writes,

For reasons of consistency, I will not draw on virtue epistemological vocabulary and literature in my discussion, though many of my arguments could be reformulated in virtue epistemological terms. Given that I focus on social processes and institutions, however, the virtue ethical terminology—which, after all, remains tied to individuals as bearers of virtues—seemed not the best choice for my project. (30)

14This tension between individual and institutional responsibilities runs throughout the book. Take cognitive biases, such as confirmation bias, for example. Here, an epistemic agent may err by favoring information that confirms prior beliefs. Should we say that he is individually responsible for this error (due to a lack of sufficient caution in belief formation), or that he is not at fault, given that cognitive biases can be reinforced by the surrounding cognitive context or by others’ strategic efforts to exploit such biases? The answers to these questions are crucial in determining effective regulatory approaches for epistemic infrastructures. In a sense, they represent the “epistemic counterparts” to the liberalism/republicanism dichotomy discussed earlier.

15The second point to be discussed is the fact that the nature of epistemic life varies depending on whether individuals are involved in market activities, political deliberation, or scientific research. This is the core focus of the book. For Lisa Herzog, each sphere adheres to its own epistemic principles: markets provide information about the scarcity of goods and the efficiency of resource allocation; deliberation offers mechanisms for making political decisions; and the field of expertise encompasses truth-oriented practices. Lisa Herzog’s main argument is that each sphere is legitimate as long as it remains confined to its own domain. She criticizes those who believe that one sphere’s epistemic approach is valid for the others: scientists should not be bound by market mechanisms, and political deliberation should not be overly influenced by experts. This perspective is really convincing and leads Lisa Herzog to analyze two topics: the efficiency of each institution in its specific domain and the interactions between these spheres. Two types of epistemic corruption may arise: the first is a malfunction within institutions’ own epistemic infrastructures, and the second is due to epistemic trespassing.

16One of the book’s most interesting and productive development is the examination of the comparative epistemic efficiencies of markets, experts, and deliberation. To illustrate the point, I shall take the example of the markets. Lisa Herzog follows the Hayekian idea that the market is a powerful institution for providing information to producers and consumers—a cognitive view of markets that is widely shared among economists. However, markets sometimes fail in their epistemic function: speculative bubbles, informational asymmetries, monopolies, cartels, and externalities are examples of such informational inefficiencies. In these instances, markets require robust epistemic infrastructures. Tools like labels, Pigovian taxes, and regulations on banking and advertising help markets to efficiently send signals about the social and the private costs of goods and behaviors. Lisa Herzog goes further, arguing that epistemic infrastructures should also protect individuals against manipulations and interferences in the preference-formation process to ensure that autonomy and freedom be respected.

17However, the list of epistemic failures is so extensive that it raises an essential question: “Describing all these epistemic—and other—failures of markets leads to an obvious question: why should one think that they are worth endorsing at all?” (169) This question is not merely rhetorical, though the answer remains fairly conventional: “If one wants to defend markets on epistemic grounds (as a basis for claims about efficiency), one has to endorse the claim that it is possible to regulate them in ways that do in fact bring about these epistemic benefits.” (170) Yet, it is unclear whether such inefficiencies are so significant that it becomes nearly impossible to uphold a thesis on the “informational efficiency of markets”. This uncertainty explains some ambiguities in Lisa Herzog approach to the scope of regulatory schemes that should be implemented. This will be our final point.

3. Regulation: Back to Polybius?

18I hope the discussion above has convinced the reader of the profound thesis held by Lisa Herzog and the great quality of her argumentation. My third point is related to regulation, and I will be a little more critical. In many cases, Citizen Knowledge leads to justifying public regulation of epistemic infrastructures. As we have seen, epistemic infrastructures need to be protected against internal or external corruption. For Lisa Herzog, public regulation is required and possible. But the book is not specific on the feasibility and the very nature of regulation. And regulation appears both to be a keyword of many of the conclusions of the book and a blind spot of the demonstration. I think three topics have to be distinguished.

19The first concerns the libertarian challenge to those advocating for public intervention. Libertarians acknowledge the existence of market failures but argue that the (public) remedy may be worse than the disease. This argument is primarily comparative, and while Lisa Herzog acknowledges it (“Of course, all evaluations of concrete institutions—not abstract ideal types, but actually existing institutions at a certain time, in a certain place—ultimately need to be comparative”, 170), she does not fully address its implications. Specifically, market advocates argue that many solutions to information failures in markets arise from decentralized behaviors. For example, private firms create labels to address information asymmetry, private rating agencies inform on qualities of assets, internet sites provide ratings of services, ... In these cases, market failures do not necessarily lead to strong public intervention.

20This argument implies that one cannot directly jump from recognizing market failures to advocating for public regulation. As we have seen, Citizen Knowledge proceeds in two steps: first, justifying the principle of regulation, and second, defining specific types of regulation. However, the libertarian challenge questions this two-step reasoning, arguing that if public regulation is ineffective, then the very principle of regulation becomes irrelevant and illusory. Even though the strongest version of this argument may not be entirely convincing, a weaker version is more widely accepted: regulators often create tools that combine decentralized and centralized elements. Examples include the European Emission Trading System, public auctions, and public matching algorithms—all regulatory tools enacted by law. It remains unclear how Lisa Herzog would categorize these types of epistemic infrastructures which are mixed schemes between markets and planification.

21The second topic concerns the role of law within the Citizen Knowledge framework. Should we view law as an epistemic sphere in its own, or as a shared normative foundation underpinning the other three epistemic infrastructures? This issue is a common challenge for social scientists who attempt to define autonomous social and normative domains—from Michael Walzer’s Spheres of Justice to Jon Elster’s Local Justice. In Citizen Knowledge, the legal system seems to play a pivotal role in providing regulatory support to the epistemic infrastructures without itself being classified as a distinct epistemic infrastructure. Lisa Herzog tends to overlook the mechanisms through which laws and judges fulfill this regulatory function. Much of the law’s effectiveness in regulating the three other epistemic institutions depends on its own epistemic processes.

23The third regulation-related topic deals with epistemic infrastructures as social powers. One could interpret Citizen Knowledge as a depiction of three epistemic powers in competition. Each one attempts to dominate the others: market participants seek to be the sole organizers of collective choice, politicians aim to govern science and the economy, and scientists aspire to become philosopher-kings à la Plato. Lisa Herzog’s approach largely suggests the existence of a legitimate fourth power—primarily embodied by the law—capable of regulating these three powers, although one might question the existence and benevolence of such a power. Yet this model presupposes an external regulator, only displacing the problem. An alternative approach, more aligned with republicanism, would emphasize an equilibrium of powers. Indeed, the book’s primary thesis, which aims to keep epistemic infrastructures free from corruption, is a foundational step toward considering their balance within society. Thus, by analogy with debates on the division of powers and the checks and balances, one of the questions raised by Citizen Knowledge would be how to conceptualize an organization of these three powers that could genuinely safeguard freedom and individual epistemic autonomy, a Mixed Epistemic Constitution. Even though it does not fully answer this question, the book is a remarkable tool for serious reflection on the subject.