Justin E.H. Smith
Justin E.H. Smith; illustration by Joanna Neborsky

How enlightened was the Enlightenment? Not a few critics have seen it as profoundly benighted. For some, it was a seedbed for modern racism and imperialism; the light in the Enlightenment, one recent scholar has suggested, essentially meant “white.” Voltaire emphatically believed in the inherent inferiority of les Nègres, who belonged to a separate species, or at least breed, from Europeans—as different from Europeans, he said, as spaniels from greyhounds. Kant remarked, of something a Negro carpenter opined, that “the fact that he was black from head to toe was proof that what he said was stupid.” And David Hume wrote, in a notorious footnote, that he was “apt to suspect” that nonwhites were “naturally inferior to the whites,” devoid of arts and science and “ingenious manufactures.”

The more general critiques take up larger intellectual currents in the eighteenth century. The era’s systematic forays into physical anthropology and human classification laid the foundation for the noxious race science that emerged in the nineteenth century. So did the rise of materialism: it became harder to argue that our varying physical carapaces housed equivalent souls implanted by God. A heedless sense of universalism, in turn, might encourage the thought that the more advanced civilizations were merely lifting up those more backward when they conquered and colonized them.

For critics like John Gray, the Enlightenment’s self-satisfied rationalism and belief in progress were bound to fuel notions of racial and civilizational hierarchy, and can be linked to twentieth-century totalitarianism. And its toll continues: liberal rationalism is, in Gray’s view, an impoverished creed that has asphyxiated richer forms of life. That’s why, he says, Western societies that rely on liberal Enlightenment values “are plagued with anomie and nihilism.”

Yet these objections don’t settle the matter. The expressions of prejudice from Kant and Hume are worth noting not because they’re peculiar to the so-called Enlightenment project but precisely because they aren’t: so commonplace were such views that even these rarefied intellects weren’t immune to them. What distinguished Voltaire from other Europeans was not his assumptions about the superiority of their stock but his eloquent opposition to slavery and colonialism. The grand projet of the era, the Encyclopédie, was rude about Africans but also filled with abolitionist fervor. Hume was no fan of slavery, mercantilism, or the apparatus of imperialism; Adam Smith, his compatriot, was more outspoken about these evils still.

As for Kant—well, his views seem to have evolved. In her study Kant and Cosmopolitanism (2012), the Dutch scholar Pauline Kleingeld persuasively argued that, in the 1790s, he moved away from hierarchical notions of human difference, perhaps partly under the influence of interlocutors like Georg Forster and Johann Gottfried Herder. He now offered a clear rebuke to slavery, imperial conquest, and great-power dominion. Given that slavery and imperialism are age-old practices, it may be more significant that so many Enlightenment figures opposed them than that some of them, in some respects, accommodated them.

What about the broader arguments? It’s perfectly true that the sort of empirical physical anthropology that Johann Friedrich Blumenbach pioneered would turn toxic; but Blumenbach himself was a skeptic of discrete types and of hierarchies among them. Viewing human beings as creatures continuous with the rest of nature, as the philosopher Justin E.H. Smith argued in his valuable 2015 book, Nature, Human Nature, and Human Difference, eased the way for the race science of the nineteenth century. But human beings are, in important ways, continuous with the rest of nature. The answer to bad science is good science, not no science.

So far, I’ve been using the term “Enlightenment” in its most conventional sense—referring to an eighteenth-century transnational movement that celebrated reason and was centered on philosophes and physiocrats in France (les Lumières) but that had important branch offices in Prussia (as die Aufklärung), Italy (l’Illuminismo), Scotland, and here in the Americas. Some scholars prefer a Long Enlightenment, which goes back to Descartes and Spinoza. Others talk of a fleet of distinct movements, partitioning an already cloudy phenomenon into smaller clouds. In this, as in all things, there are lumpers and splitters. But scholars who draw the lines differently have shared a larger worry about “rationalism” itself. In particular, what if the effort to shore up rationality invites its opposite? What if light is destined to generate shadows, Enlightenment a Counter-Enlightenment?

That’s the thesis of Justin E.H. Smith’s new book, Irrationality: A History of the Dark Side of Reason. The difficulty posed by reason, he suggests, is

evidently of a dialectical nature, where the thing desired contains its opposite, where every earnest stab at rationally building up society crosses over sooner or later, as if by some natural law, into an eruption of irrational violence. The harder we struggle for reason, it seems, the more we lapse into unreason.

Irrationality is not a tract, treatise, or systematic overview. This is a loosely plotted book, stippled with fascinating meditations and vignettes, although not necessarily where you might expect to find them. In addition to chapters on logic and on Enlightenment, there are chapters on dreams and what people have made of them over the centuries; on art (including a plangent account of Isaac Babel’s lethal falling out with Soviet authorities); on pseudoscience (including a discussion of a creation science museum and the nature of flat-earth theory); on the Internet (deplored as a “Shiva-like” destroyer); on animal cognition (including an assessment of the wily, wriggly octopus); on death (including a visit with Tolstoy’s Ivan Ilyich). Exemplars of irrationality range from Jacques Derrida to Donald Trump. Exemplars of hyperrationality—Gottfried Wilhelm Leibniz, the AI researcher Eliezer Yudkowsky—don’t always come off much better.


It’s best to read the book as an assortment of mini essays—at its best, Sebald without the sojourns. At one point, Smith ruminates on the memes of the far right and wonders whether the irrationalism in segments of the 1960s New Left has reappeared with an opposite ideological spin: “Pepe the Frog owes more to Abbie Hoffman than to William F. Buckley; by certain measures Trump himself has more in common with, say, Wavy Gravy, than with Richard Nixon or Ronald Reagan.” In a discussion of lies, he ponders the troublesome phrase “the whole truth”:

The whole truth would be an infinite concatenation of mostly irrelevant facts…. So we do not tell the whole truth; we tell carefully crafted stories, and we do this even when our moral purpose is to tell the truth.

Elsewhere, he compares his fear of flying with racism, which might seem like another irrational phobia. Why do we insist on intellectual justifications for the second while freely admitting the irrationality of the first? Perhaps it’s because the aviophobe suffers through in-flight turbulence with a deep sense of solitude, he conjectures, while the racist enjoys solidarity with people not in the despised race.

A particularly delightful story in the book concerns an 1850 proposal for a “pasilalinic sympathetic compass”—a set of relay circuits for the projection of thoughts over distances that would be powered by telepathic snails. Smith suggests that the fact that our technologies can be imagined even before they are technologically feasible shows the continuities that underlie seeming transformations. The Internet of mollusks then prompts reflections on Russian interference in the 2016 election, via social media, and the way the St. Petersburg trolls mobilized activists on the left and the right. The Internet, he says, “has destroyed or is in the process of destroying long-familiar objects: televisions, newspapers, musical instruments, clocks, books. It is also destroying institutions: stores, universities, banks, movie theaters, democracy.” Before long, he is arguing with Judith Butler’s theories of gender and lamenting the media’s preoccupation with identity, the rise of online “cancel culture” (Mao and Robespierre are invoked), and the vulnerability of moderates in an age of extremes.

Despite these nonlinear webs of association, the book has a fixed spindle: it’s what Smith describes as the “continuous movement between the two poles of rationality and irrationality—the aggressive turn that reason takes, transforming into its opposite.” The book is an homage, of sorts, to Max Horkheimer and Theodor Adorno’s Dialectic of Enlightenment, produced in 1944. That work, a wartime opus that the Frankfurt School Marxists produced while in California (“in strange sun-kissed exile,” Smith winningly says), used the term “Enlightenment” broadly and variously, reaching back certainly to Francis Bacon, and possibly to Homer. “Enlightenment, understood in the widest sense as the advance of thought, has always aimed at liberating human beings from fear and installing them as masters,” Horkheimer and Adorno wrote at the start of the book. “Yet the wholly enlightened earth is radiant with triumphant calamity.” Instrumental rationality had traced an arc down to twentieth-century fascism, and they anticipated that liberal political ideology was bound to follow a similarly malign path.

Smith’s book, though it shares these broad temporal horizons, finds an emblem for the dialectic; it regularly conjures a sort of double-pan balance in which Enlightenment and Counter-Enlightenment sit in equipoise. As he notes, it’s a model that was popularized almost half a century ago by Isaiah Berlin and was given a new polemical charge a decade and a half ago by the intellectual historian Zeev Sternhell. In Sternhell’s formula, which Smith enlarges upon, the same period “marks not only the birth of rationalist modernity, but also its antithesis.”

The Counter-Enlightenment, in this sense, refers not to the worldly adversaries of the philosophes—to their numerous ecclesiastical or royalist opponents—but to a small number of intellectuals who are said to have developed a contrary body of thought, opposing universalism with particularism, rationalism with vitalism. In Berlin’s account, the Enlightenment thinkers erred in their triumphalist belief that all real values could be harmonized. “They fought the good fight against superstition and ignorance,” Berlin remarked once. “So I am on their side.” Yet their hubris had to be checked: Berlin was inclined to see Soviet communism as a curdled version of the Enlightenment project. There was much to learn, he thought, from its Counter-Enlightenment foes. In Giambattista Vico, Johann Georg Hamann, and Herder, Berlin saw danger, but also genuine insight into the plural nature of values. According to Berlin, these thinkers recognized something crucial: that you couldn’t neatly reconcile the great goods—you couldn’t establish a Thomas Cook–style exchange rate between, say, freedom and equality. A choice might have to be made between them.


Sternhell’s fiercely Manichaean book The Anti-Enlightenment Tradition starts with roughly the same stage set, but paints over Berlin’s hues of gray in black and white. The great minds of what Sternhell calls the Franco-Kantian Enlightenment—a berth that comfortably accommodates both Voltaire and Rousseau—created the basis for modern democracy, we’re told, while the Counter-Enlightenment, exemplified by Edmund Burke and Herder, paved the way to fascism. Just a handful of begats, he suggests, separated Herder from Hitler. Because Berlin found some fault with the Enlightenment and some value in the likes of Herder, Sternhell denounced him as a conservative apologist for irrationalism and nationalism.

Between Berlin and Sternhell, Smith doesn’t take sides; or, rather, he is on the side of sides—the model of Enlightenment and Counter-Enlightenment, as opposing endeavors that are dialectically linked. That model is, after all, the clearest illustration of his book’s thesis. Smith follows Berlin in talking about the “hypocrisy and limitations” of the Enlightenment (its philosophical spirit, Smith thinks, has a “real genealogical link” to the Bolsheviks and the Khmer Rouge); he follows Sternhell in seeing the Counter-Enlightenment as proto-fascist. (“Herder’s nationalism was soft while Hitler’s was ‘hard,’” Smith allows.) But how convincing is the basic distinction?

Here are two eighteenth-century European writers. One holds that Jews are not Europeans but “Asiatics,” “all of them born with raging fanaticism in their hearts, just as the Bretons and the Germans are born with blond hair. I would not be in the least bit surprised if these people would not someday become deadly to the human race.” Blacks “are not men, except in their stature, with the faculty of speech and thought at a degree far distant to ours.” He despises democracy and consorts with despots.

Voltaire; drawing by David Levine

The second writer favors the full enfranchisement of Jews, whom he thinks are owed an apology for centuries of abuse. He argues for human equality across nations, writes movingly about the ill-used humanity of Africans, and favors republican democracy. He believes in the love of humankind over the love of fatherland and cherishes individual autonomy: “No individual has the right to believe that he exists for the sake of another individual, or for the sake of posterity.”

The first is Voltaire, of course. The second is Herder—the paragon, for Berlin and Sternhell alike, of Counter-Enlightenment thought. How did they turn this open-hearted humanist into an arch-enemy of Enlightenment? By offering a version of him that was tendentious to the point of caricature. Berlin saw Herder as “the father of cultural (and ultimately every kind of) nationalism in Europe,” in ways driven by Herder’s “hatred of cosmopolitanism, universalism.” In Sternhell’s opinion, “Herder had a hold on European thought whose importance for the modern world can scarcely be exaggerated,” and very much for the worse. Herder was not only “antirationalist,” he was “antiuniversalist, anticosmopolitan, particularist, and by that very fact, nationalistic.” What’s more, he was committed to “the insignificance of the individual.”1 (Cue the camps, the gulags.)

In fact, Herder was a pupil of Kant’s in the early 1760s and found much of value in Kant’s work, which was an enduring influence on him. (He was an enthusiast of Hume, too, along with the earlier work of Lord Shaftesbury.) He was also, deeply, a cosmopolitan who railed against narrow nationalism and detested Prussian parochialism. Yes, he held to a pluralist notion of cultural diversity (each people, each nation, had its particular way of being in the world), but it was always chastened by a universalist notion of Humanität—a shared human nature, a shared human dignity. Far from advancing the “insignificance of the individual,” he cherished individuality and personal development, in ways that filtered down to John Stuart Mill. In “On the Cognition and Sensation,” Herder wrote, “If a human being could sketch the deepest, most individual basis of his enthusiasms and feelings, of his dreams and trains of thought, what a novel!”

Some have imagined a crevasse separating Kantian universalism from Herder’s pluralism. Yet Kant, especially in his later work, thought good cosmopolitans should be patriotic citizens of their nations, too. In his Lectures on Ethics, he said that both a “dutiful global and local patriotism…are proper to the cosmopolite, who in fealty to his country must have an inclination to promote the well-being of the entire world.” The words are Kant’s, but the sentiment could be Herder’s. To hive off one as representing a “Counter-Enlightenment” is to caricature the Enlightenment.

There are other reasons to doubt the Counter-Enlightenment schema. Where to position Rousseau? For Sternhell, he’s central to the Enlightenment; for several notable scholars of the era, he’s central to the Counter-Enlightenment. Rousseau could certainly be a defender of local customs, but Kant didn’t see him as a foe: he kept a picture of him in his study and credited his work with having awakened him to the truth of humanity’s common dignity. The instabilities persist. Vico, whom Berlin took as a figure of the Counter-Enlightenment, emerges, in the work of the Enlightenment’s most exhaustive modern chronicler, Jonathan Israel, as a major figure of the Radical Enlightenment, the movement at its best and boldest. Any demarcations of an intellectual territory will have vague borders, but these aren’t border disputes: they run through the heartland.

I have no problem with models that imperfectly reflect reality: idealizations work because they idealize. All we ask of such models is that they help light our path. Given the strong impression that the “Counter-Enlightenment” mainly spreads shadow, though, it’s hard to resist the thought that the very concept is due for retirement.

Even the equation of the Enlightenment with rationalism, with what Smith calls the “exaltation of reason,” obscures as much as it reveals. Smith tells us that the Counter-Enlightenment has been wary of setting up reason “as the supreme principle of social organization.” But elsewhere he tells us the very same thing about the Enlightenment:

The great majority of canonical Enlightenment philosophers placed great value on the role of the sentiments and passions in guiding the conduct of our lives, and warned of the many dangers of subordinating ourselves to the supreme authority of the faculty of reason.

It has been said, indeed, that the eighteenth century was less the Age of Reason than the Age of Feelings—because so many Enlightenment thinkers took pride in recognizing the importance of the sentiments, as their intellectual predecessors often had not. (In Hume’s famous line: “Reason is and ought only to be the slave of the Passions.”) The aim of building a rational society meant contending with the ways in which human beings are not creatures of sweet reason. And that meant, in turn, having some way of deciding what rationality demanded.

Rather boldly, Smith has written a book on irrationality without even sketching an account of what rationality might consist of. Much modern thinking about that subject flows from distinctions, drawn from Max Weber, between formal, instrumental, means-ends rationality (Zweckrationalität), which aims to secure some end without judging its worth, and substantive rationality (Wertrationalität), which relates reason to clusters of norms and values. When Horkheimer and Adorno warn about the dangers of rationality, they seem to have in mind a Weberian notion of instrumental rationality within a disenchanted world—a realm of amoral scientists and technocrats ordering things to their liking, reducing all values to one, perhaps that of the marketplace. So there have been efforts to flesh out a substantive concept of rationality that encompasses moral judgment.

For better or worse, though, the modern philosophical literature on rationality figures little in Smith’s capacious book. Unasked questions whisper beneath the floorboards. Is partiality toward kith and kin a departure from rationality (as the utilitarian William Godwin infamously proposed) or a constitutive part of it? How must theories of how we ought to be relate to how we actually are? How does the rationality of beliefs relate to their utility and to their truth? Is it a lapse of rationality when we employ rules of thumb or is it a rational recognition of the limits of our rational faculties?

Smith touches on an important point when he writes, in a passage linking Newton’s rejection of Aristotelian authority to the anti-vaxxers of our own age:

It is not rejection of authority that is the problem, but only rejection of authority at the wrong times and for the wrong reasons. But how can we be sure of our ability to make such distinctions? It is not enough to say that the science itself is clear and dictates to us in its own clear voice, rather than in the voice of its human representatives, what is true and what is false. For most of us do not have a handle on the science at all. We have not read even a fraction of the relevant scientific literature, nor could we read it if we tried; far less have we carried out the relevant experiments ourselves.

This is so. The conclusion to be reached is that rationality, in a critical sense, isn’t an individual attribute. Here I’ve sometimes found it convenient to distinguish between rationality and the individual trait of reasonableness. The distinction I have in mind is between cognitive and practical procedures that are likely to be successful, given the way the world is (which I’ve called “rational”); and procedures that a normal human being in a society has no reason to doubt will be effective, whether or not, in fact, they are (which I’ve called “reasonable”). My father, as was the norm among Asante of his generation, thought that there were many invisible spirits in the world, who could advance his causes if he conformed to rules they had laid down, and he was taught that “avoid eating bush meat,” a stipulation of his particular Asante clan, was one of those rules. He was being reasonable, therefore, in his avoidance of eating bush meat. From an outside perspective, though, we can see that it was not rational, because there are no such spirits. (Sorry, Dad.)

It’s a critical fact that the cognitive division of labor in advanced societies provides each of us with epistemological resources far greater than any that would fit between our ears. We can talk casually about entangled electrons, the Bantu migration, gram-negative diplococci, and Petrarchan sonnets because there are communities of researchers who know about these things. “‘Meanings’ just ain’t in the head!” the philosopher Hilary Putnam once observed: that is, the meaning of our sentences involves both a particular relation to reality and a particular relation to other, expert users of the language. Rationality, a fortiori, isn’t in the head, either. It’s something we do with one another and the world. To learn about an illness, my Asante ancestors might have consulted a fetish priest; today we might send a blood sample off to a lab. On an individual level, my Asante ancestors, acting on the basis of trusted authority, weren’t less reasonable than we are. But the analysis of rationality must expand beyond the individual level. Where traditional belief practices and natural science differ is as institutions: the social organization of inquiry makes all the difference.2

“The structural irrationality that allowed Trump to end up where he never should have ended up, is one that in part channels the irrationality of individual members of society,” Smith writes.

But he ended up there in part, also, as a result of a poorly designed system, by disorder in the way things are set up: gerrymandered voting districts that have no plausible justification in the language of democracy; an electoral college that trumps popular will; and mass media that make it effectively impossible for the low-information voter to apprehend what the relevant political issues in the campaign are.

Here, where a sense of crisis is near at hand, Smith allows himself the technocratic language of Weberian rationalization. Contributing to the spread of conspiracy theories like Pizzagate and the florid offerings of QAnon, he says, is a “structural irrationality, the failure of the algorithms to ensure serious political debate.”

The observation is eminently plausible, but notice that it’s about compounding irrationalities. What guidance is provided by Smith’s central dialectic, in which reason turns into its opposite? Should we conclude that rational solutions—improved algorithms, better voting systems—are bound to worsen the underlying irrationality? Smith says that irrationality is “humanly ineradicable, and that efforts to eradicate it are themselves supremely irrational”; but the efforts he largely has in mind, it seems, are efforts to manage human irrationality, not to eradicate it, and such efforts can be given old-fashioned, rationalist names: good governance, prudent policy.

Smith suggests, at one point, that we “consider the legacy of the Enlightenment in a far more cautious way than the usual presentation of the binary options, to accept or reject, would dictate.” It would be tempting, instead, simply to echo Gandhi’s (apocryphal) response to the question of what he thought about Western civilization: “It would be a good idea.” For Enlightenment is a project that has not been and cannot be completed. By the same token, rationality itself is an ideal, both in the sense that it’s worth aiming for and in the sense that it can’t be realized. Yet no principle of cultural physics stipulates that every action must produce an equal-and-opposite reaction, that rationality is inherently a self-poisoning phenomenon. We can’t solve all human problems with reason alone; but we can’t solve any of them without it.