As economic inequality has ballooned over the past several decades, it has become an increasing topic of discussion and concern among academics, public officials, journalists, and everyday citizens. As anyone familiar with the history of political thought will know, however, such concern is hardly new. On the contrary, philosophers have pondered the sources and effects of large differences in wealth—both among individuals and among nations—for thousands of years. It is somewhat surprising, then, that a book like The Greatest of All Plagues—one that examines how economic inequality has been viewed by canonical philosophers from Greek antiquity to the nineteenth century—has not already been written. This is a timely work on an important topic.

The book’s seven chapters each focus on a different thinker: Plato, Jesus (or the authors of the New Testament), Thomas Hobbes, Jean-Jacques Rousseau, Adam Smith, John Stuart Mill, and Karl Marx. Although these figures had radically divergent aims and ideals, David Lay Williams seeks to show that they all deemed glaring differences in wealth to be a major obstacle to achieving them. Civic harmony, divine love, a stable leviathan (or state), the general will, mutual sympathy, maximal utility, and freedom from domination and alienation—all are threatened, if not made downright impossible, when some individuals have much more than others. Thus, the focus throughout the book is on economic inequality rather than on poverty. That is, Williams examines how these thinkers addressed not only the ills of material deprivation, but also and especially those caused by “concentrated” or “excessive” wealth. What matters, on this view, is not just the size of the overall pie, or even the size of the smallest slice, but also the basic fact that some slices are so much bigger than others.

As Williams notes, whereas contemporary commentators, particularly on the political left, tend to take the viciousness of economic inequality for granted, the thinkers that he highlights were at pains to explain exactly why it is so harmful. The problems that they cited were generally less economic in nature—for instance, the ways in which extreme inequality might inhibit growth or socioeconomic mobility—than psychological, moral, social, and especially political. Williams writes that the thinkers whom he treats “argue with striking consensus that excessive inequality threatens to divide communities, pit citizens against one another, undermine democratic legitimacy, and, in the most extreme cases, even foment revolution” (5). Other problems that are discussed at length include the ways in which inequality emboldens society’s wealthiest individuals, freeing them from the constraints of the law and positioning them as rivals to the political authorities—and the ways in which it fosters feelings of envy and shame among the poor, even as it encourages selfishness and arrogance among the rich. A recurrent theme is the role that these thinkers accord to insatiable greed, or pleonexia, as both cause and consequence of economic inequality. Williams also describes the remedies that these thinkers proposed to combat the ills produced by economic inequality, ranging from various forms (and degrees) of redistribution to moral and civic education to outright revolution. He wisely treats these proposals less as a set of potential policy prescriptions for our own day than as a means of shedding further light on these thinkers’ political ideals, and perhaps stimulating our imaginations about the different ways of addressing the problems posed by inequality.

The book was a decade in the writing, and it shows: it is remarkable how much ground it covers and how rich the analysis is. Each chapter constitutes a serious, standalone piece of scholarship, one that pays careful attention to the relevant historical context and that engages the voluminous secondary literature dedicated to each thinker. In several of the chapters, Williams mines these figures’ longer and lesser-read works rather than restricting himself to the ones that garner the bulk of scholars’ and students’ attention. More space is devoted to Plato’s Laws than to The Republic, to Mill’s Principles of Political Economy than to On Liberty, and to Marx’s Capital than to the Communist Manifesto. Williams does not set out to develop particularly novel or controversial readings of these works or thinkers; instead, he zeros in on his theme and shows how it connects to the broader concerns in each thinker’s corpus. The interpretations are generally persuasive, although inevitably specialists will have their quibbles. This reviewer would raise a few queries about the reading of Smith, for instance, despite the generous citations to my work. Among other nits that I would pick, although Smith certainly worried that economic inequality would hinder mutual sympathy, he was not particularly worried that it would also undermine political stability, as Williams suggests (186-87). On the contrary, Smith believed that inequality would bolster political stability by helping to create and maintain the requisite “distinction of ranks.”

More importantly, however, it should be noted—although Williams scarcely alludes to this, beyond a brief aside on Bernard Mandeville (140-41)—that the story that the book traces constitutes one side of what was in reality an ongoing debate within the history of political thought. Obviously, all of the figures that Williams treats are hugely important, and some of them—particularly Plato, Hobbes, and Smith—will be surprising inclusions for some readers. Yet, it would be easy enough to draw up an equally long list of equally canonical thinkers who deemed economic inequality to be unproblematic, or even a positive good. For instance, the old idea of the mixed regime, which has had adherents as varied as Aristotle, Niccolò Machiavelli, and Edmund Burke, assumes—even requires—an economy that is split between rich and poor so that the two groups can be led to balance, check, and control one other (and sometimes also the monarch) within the political realm. John Locke, like Mandeville after him, regarded economic inequality as not only an inevitable result of a flourishing economy but also a means of prompting people to labor more and trade more, thereby enabling the economy to grow and society to progress. Alexis de Tocqueville and Friedrich Nietzsche regarded handwringing about economic inequality as part and parcel of the democratic rage for leveling in all aspects of life, which they believed was all too likely to undermine liberty and greatness. By mostly ignoring such arguments, Williams portrays the Western canon as more uniformly hostile to economic inequality than it really is. Indeed, one could imagine a book written as a sort of counterpart to this one bearing the subtitle “The Benefits of Economic Inequality from Aristotle to Hayek.”

That said, the concerns that Williams raises via his chosen figures are significant, pressing, and far too often overlooked within contemporary debates that fail to take advantage of the riches offered by the history of political thought. This book is a major contribution and deserves a wide readership.