In 1848, revolutions and uprisings broke out all across Europe, from France to Sicily, Denmark to the Habsburg Empire. Historians have argued ever since about what explains the simultaneous outcropping of political unrest in so many disparate places. Today, a similar political wave, similarly mystifying in its synchronism, is sweeping across an even wider range of polities. What do Hungary, Turkey, Poland, India, Venezuela, the Philippines, Britain, and the United States have in common? Are they all afflicted by the same virus, or does the question itself entail a fallacy of composition?

For their part, political scientists are watching the populist ascendancy with an odd combination of horror and fascination. Horror, because we have a better idea than most about the fragility of democratic norms in the face of populist machinations. Fascination, because the contemporary wave of populism offers a rare opportunity to investigate these questions in real time. Will today’s populist regimes eventually succumb to electoral defeat, or will they swerve into full-blown authoritarianism? Or will they muddle along until the body politic, revitalized by the encounter, mounts an effective democratic response?

In most mental maps, populism is flanked on one side by democracy and on the other by fascism, but the boundaries are fuzzy and contested. In this astonishingly cogent book, Muller masterfully disambiguates these concepts, paying particular attention to distinguishing between populism and democracy. Absent such a distinction, populist movements may be mistaken as part of a healthy civic flora rather than an encroaching morbidity. In Muller’s telling, populism is a democratic affliction that flares up episodically, or, to use his metaphor, “a permanent shadow of modern representative democracy, and a constant peril” (p. 11).

What in the contemporary physiognomy of democracy predisposes it to populist capture? Much of the voluminous empirical scholarship on this question reprises the classic distinction between demands for redistribution and recognition. On one side are those who argue that populist politics triumphs on the back of socioeconomic grievance. Accordingly, today’s wave of populist revolts should be understood as a backlash against growing income and wealth inequality, the ever-shrinking scope of social assistance, first-world vulnerabilities created by globalization, the effects of de-industrialization and technological transformations on the labor force, not least in the form of unemployment and stagnating wages. However, these changes have been underway for some time. Why didn’t the great populist wave crest during the Great Recession, which deprived so many people of their homes, jobs, and savings, rather than in the wake of a successful recovery? Moreover, as Ronald Inglehart and Pippa Norris have argued, the socioeconomic thesis has difficulty accounting for populist movements that have thrived in affluent nations such as Austria and the Netherlands, egalitarian ones like Sweden and Denmark, and during periods of unprecedented prosperity, as in Turkey, where Erdogan’s populist message was never more enthusiastically received than during the country’s decade-long growth spurt (“Trump, Brexit, and the Rise of Populism: Economic Have-Nots and Cultural Backlash,” Harvard Kennedy School Faculty Research Working Paper [August 2016]). At the very least, these considerations complicate easy socioeconomic explanations.

For his part, Muller contends that populism is not primarily a form of class politics. Instead, he views it as a form of reactionary identity politics fueled by fears of rapid social change and cultural marginalization. Although he emphasizes that populists prosper “when identity politics predominates” (p. 92), Muller clearly believes that populists exploit existing identitarian anxieties rather than creating them out of whole cloth. The book leaves aside explanatory questions concerning the “supply-side” of the populist resurgence and attends to the message that contemporary populist politicians convey. As prescient and topical as Muller’s account is on this front, it is equally rewarding to read this book as a response to more enduring questions of democratic theory. Populism, Muller argues, exposes some of the tensions, vulnerabilities, and snags woven into the fabric of modern democratic politics.

To my mind, the book’s most pressing diagnosis is that populism short-circuits the key epistemic mechanism on which democracy relies. Drawing on Jurgen Habermas’s procedural conception of democracy, Muller argues that “a well-functioning democracy should be designed to multiply, but also in the end empirically to test, claims of representation” (p. 70). If an aspiring officeholder argues that it is in the people’s interest for their government to do X, wins power through elections, and does X, voters must be able to express through the electoral process whether they deem X to have advanced their interests. However, populism disrupts this circuit by framing its appeal in symbolic and moralizing terms that “cannot be disproven” (p. 39). In other words, what distinguishes populist claims of representation is that they are framed in non-falsifiable terms.

Like a good magic trick, this involves a series of seamless moves: First, “populists put forward the claim to stand for the whole, without remainder” (p. 37). Put differently, populism “necessarily involves a claim to exclusive moral representation” (p. 38, emphasis added). A populist is not a politician who advocates for the interests of common people; rather, she is a politician who claims epistemic and moral monopoly over the people’s interests. Clearly, such an appeal bears no necessary relation to the people’s “true” interests (assuming, arguendo, that these exist or could be known) or to the preferences expressed by a majority of public opinion. Quite the reverse: the people’s interests are what the populist says they are (p. 29). Whereas democracy “enables majorities to authorize representatives whose actions may or may not turn out to conform to what a majority of citizens expected or would have wished for; [populism] pretends that no action of a populist government can be questioned, because ‘the people’ have willed it so” (p. 77). This is also why the policy prescriptions of populist movements are so diverse as to frustrate the search for any substantive ideological core or a standard cluster of demands such as nativism, wealth redistribution, protectionism, or militarism. For the same reason, Muller rejects the twin propositions that populism could be a vehicle of popular empowerment, and that all demands for popular empowerment are populist in nature (pp. 68–72).

Because its hallmark is a peculiar distortion of democratic discourse, populism has sometimes been described as a variety of political rhetoric rather than a form of regime (e.g., Michael Kazin, The Populist Persuasion, 1995). Such features of populist politics as the exclusive claim to speak for the people, the portrayal of all dissent as conspiratorial or treasonous, and the reification of “elites” as corrupt and self-serving (Cas Mudde, “The Populist Zeitgeist,” Government and Opposition 39 [Autumn 2004]: 541–63; Daniele Albertazzi and Duncan McDonnell, Twenty-First Century Populism, 2008) are not the features of a political regime so much as rhetorical devices that monopolize the domain of legitimate political speech. They do not necessitate a particular set of institutions, though they can be aided by a pliant judiciary, a servile bureaucracy, and strict limits on civil liberties.

Second, populist movements deflect the people’s frustrations towards a more vulnerable culprit, real or imaginary. This is why populists, even when they are manifestly corrupt and incompetent, are so difficult to boot out of office. A tanking economy, depleted public finances, and deteriorations in national security are treated as occasions to consolidate power rather than relinquish it. In the face of mounting challenges, populists demand greater constitutional powers (e.g., by expanding the scope of executive authority), wider institutional latitude (e.g., by dismantling parliamentary or judicial authority), or a bigger mandate (e.g., electoral reforms that award the ruling party a larger share of legislative seats) to root out threats and conspiracies. And once domestic institutions are so consolidated that few domestic points of resistance remain, populists must turn their attention to external enemies, such as global financial elites, international institutions, competitor states, refugees, terrorists, and other adversaries, real or imagined. Populist politics is a spiral that devours ever greater powers.

Third, populist movements circumvent and manipulate the truth in order to credibly maintain their claim to be the exclusive and authoritative knowers of the public good. It is no coincidence that 2016, a bumper year for populist movements, also saw the word “post-truth” added to the Oxford English Dictionary. When they are in opposition, populists sow doubts about official data on everything from immigration to the economy to elections. When in power, they can be expected to manipulate this data to their advantage, if not fabricate it outright. Populism’s most irreversible legacy may yet be this callous squandering of public trust in reliable and independent sources of information on the basis of which political debate can be conducted.

On the basis of these features, one might conclude that far from being democracy’s “permanent shadow,” populism is the acceptable face of authoritarianism today, marshaling the legitimacy lent by elections to push a fundamentally anti-democratic and illiberal agenda. As a conceptual matter, however, Muller insists that populism is not a form of authoritarian rule. While countries such as Hungary and Poland have ceased to be healthy democracies, they are also not authoritarian regimes like Russia or Belarus. To Muller’s mind, populist movements typically stop just shy of doing away with the bedrock institutions of democracy, including elections, opposition parties, relatively free speech, and civil society. Although populism relentlessly wears away at these institutions, it does not liquidate them as, say, fascist regimes do. While the question of whether a populist movement is just fascism in the juvenile stage is best answered in historical retrospect, Muller argues that populist regimes, properly so called, do not undertake wholesale regime change. Instead, populism can be likened to a metabolic disorder of democracy, one that hampers the healthy functioning of democratic systems by amplifying and distorting features that are intrinsic to them.

In particular, Muller argues that populism hijacks democracy’s aspiration to be a form of popular self-rule by exaggerating the identity of the collective “self” and the coherence of its interests. By positing a unified people with a homogeneous set of values and aims, populists cast anyone who diverges from these as an enemy of the people. Whereas the democrat interprets dissent as a sign of the unavoidable political divisions and conflicts that characterize any political community, the populist views it as prima facie illegitimate and hostile (p. 3). The populist is an anti-pluralist democrat, which perhaps means that she is no democrat at all.

Perhaps Muller’s point should be pushed a step further. What enables populists to distort the ideal of collective self-rule is a powerful but flawed idea that is central to the democratic imaginary, namely that of the common good (Cas Mudde and Cristóbal Rovira Kaltwasser, “Exclusionary vs. Inclusionary Populism,” 48 Government and Opposition [Spring 2013]: 147–174). Appeals to the common good as a regulative ideal are ubiquitous in everyday political discourse. Usually uttered in the singular with a definite article, it denotes two implausible assumptions; first, that there is a determinate good that is common to all and second, that it is knowable (Ian Shapiro, The State of Democratic Theory, 2003). Populism reifies this illusory ideal and uses it to suppress the pluralism that defines democracy (Nadia Urbinati, “Democracy and Populism,” 5 Constellations [Winter 1998]: 110–124). In other words, populism exploits a critical vulnerability in democracy’s own physiognomy, attacking it like an autoimmune disease attacks the body.

Perhaps, then, the antidote to the populist pathology is to abandon the idea of the common good once and for all, to acknowledge that we are never all in the same boat, that any political decision will create winners and losers, and that the best we can hope for is a long-term accommodation of conflicting interests, classes, and identities. This is, indeed, the enduring insight of the tradition of the mixed republic, which rejects the ideal of a coherent public good in favor of institutionalizing the coexistence of competing constituencies. As it happens, the American Republic is the most illustrious contemporary heir of that tradition. It has rarely faced a more strenuous test.