There is no period of history that has been more analysed, debated, celebrated and disparaged than the Enlightenment. Unlike, say, the Renaissance or the Reformation, the Enlightenment is not simply a historical moment but one through which debates about the contemporary world are played out. From the role of science to the war on terror, from free speech to racism, there are few contemporary debates that do not engage with the Enlightenment, or, at least, with what we imagine the Enlightenment to have been. Inevitably, then, what we imagine the Enlightenment to be has become a historical battleground. The historiography of the Enlightenment has come to be as contested as the Enlightenment itself.Jonathan Israel by Kenan Malik
Photo of Jonathan Israel by Kenan Malik

The story of the Enlightenment, of what it was and how it developed, began to be written by the philosophes themselves. To the question “What is Enlightenment?”, Kant responded that it was “Man’s release from his self-incurred tutelage”. For Kant and Voltaire, for Hume and Diderot, the importance of the Enlightenment was that it cleansed the European mind of medieval superstition and allowed the light of reason to shine upon human problems.

Subsequent historians developed this theme. Ernst Cassirer’s classic 1932 study, The Philosophy of the Enlightenment, was highly influential in setting the tone. Cassirer’s Enlightenment, like Kant’s, is primarily an intellectual project, the means by which the human spirit achieved “clarity and depth in its understanding of its own nature and destiny, and of its own fundamental character and mission”. Three decades later, Peter Gay’s magnificent two-volume study, Enlightenment: An Interpretation, reworked Cassirer’s themes for a new generation.

The vision expressed in such studies of a single coherent Enlightenment understood in terms of an intellectual transformation of the European mind has come to be challenged in the past half-century from a number of quarters. Some historians started developing national, rather than pan-European, accounts of the Enlightenment. The French Enlightenment, the German Enlightenment, the Scottish Enlightenment: each came to be analysed in its own terms, and often as a display of national pride.

Other historians began to stress not the intellectual but the social and cultural aspects of the Enlightenment. “Perhaps the Enlightenment was a more down-to-earth affair than the rarefied climate of opinion described by textbook writers,” suggested Robert Darnton, the most significant of these new cultural historians, “and we should question the overly highbrow, overly metaphysical view of intellectual life in the eighteenth century.”

A third group of scholars challenged the very idea that the Enlightenment was a good. Twelve years after Cassirer published his The Philosophy of the Enlightenment, Theodor Adorno and Max Horkheimer, founders of the Frankfurt School of Marxism, now exiled in America, published their seminal work Dialectic of Enlightenment. Like many radicals of the time, Adorno and Horkheimer asked themselves why it was that Germany, a nation with deep philosophical roots in the Enlightenment, should succumb so quickly and so completely to Nazism.

The answer seemed to lie in the nature of Enlightenment rationalism itself. Adorno and Horkheimer did not reject the Enlightenment in its entirety, but they saw it as not only lighting the way to emancipation but also enabling the darkness of the Holocaust. In recent decades these ideas have come to be developed within postmodern and postcolonial theory. Enlightenment rationalism and universalism, long seen as the foundation stones of progressive thought, are now often dismissed as Eurocentric, even racist.

Now, into this fractured and fractious Enlightenment landscape comes Jonathan Israel, with the intellectual version of a JCB, ripping up the terrain around him. Professor of Modern European History at the Institute for Advanced Study located in Princeton*, New Jersey, Israel built his reputation as a historian of the Spanish and Dutch empires. Over the past decade, however, he has published an extraordinary trilogy, Radical Enlightenment, Enlightenment Contested and Democratic Enlightenment, that has begun to reset the debate about the character of the period and its meaning for the modern world.

The size of Israel’s labours is eye-catching. Each work in the trilogy runs to almost a thousand pages; in total there must be close to two million words here. Equally eye-catching is the detail. Israel possesses an astonishing command of sources in English, French, German, Dutch, Spanish, Italian and Swedish. It sometimes seems as if there is no pamphlet he has not read, no debate he has not revisited, no intellectual alleyway into which he has not poked his head. What really sets the trilogy apart, however, is the way that Israel has wielded all that detail to cement a new structure for understanding the Enlightenment.

Like many before him, Israel lauds the Enlightenment as that transformative period when Europe shifted from being a culture “based on a largely shared core of faith, tradition and authority” to one in which “everything, no matter how fundamental or deeply rooted, was questioned in the light of philosophical reason” and in which “theology’s age-old hegemony” was overthrown. And, yet, despite language and imagery that hark back to Kant, Israel is also deeply critical of much of the Enlightenment, and hostile to the ideas of many of the figures that populate the works of Cassirer and Gay. At the heart of his argument is the insistence that there were two Enlightenments. The mainstream Enlightenment of Kant, Locke, Voltaire and Hume is the one of which we know, which provides the public face of the Enlightenment, and of which most historians have written. But it was the Radical Enlightenment, shaped by lesser-known figures such as d’Holbach, Diderot, Condorcet and, in particular, the Dutch philosopher Baruch Spinoza, that provided the Enlightenment’s heart and soul.

The two Enlightenments, Israel suggests, divided on the question of whether reason reigned supreme in human affairs, as the radicals insisted, or whether reason had to be limited by faith and tradition – the view of the mainstream. The mainstream’s intellectual timidity constrained its critique of old social forms and beliefs. By contrast, the Radical Enlightenment “rejected all compromise with the past and sought to sweep away existing structures entirely.”

In Israel’s view, what he calls the “package of basic values” that defines modernity – toleration, personal freedom, democracy, racial equality, sexual emancipation and the universal right to knowledge – derives principally from the claims of the Radical Enlightenment.

It is, as might be expected, a controversial and contested thesis. The resurrection of the old-fashioned history of ideas, the unashamed celebration of the Enlightenment, the trenchant critique of religion, the dismissal of previously venerated figures such as Locke, Hume and Kant, the seeming obsession with Spinoza, the supposed lack of nuance in both philosophical understanding and historical account – all have drawn criticism from many historians and philosophers. Others, however, myself included, while accepting that many of these criticisms are valid, have found Israel’s account a revelation, and have discovered in his framework an illuminating way of rethinking the Enlightenment and its legacy. So, when Israel came to speak at an academic conference on the Radical Enlightenment at the Free University in Brussels, I took the opportunity to take in the debate and to talk to Israel about his ideas.

* * * * *

“I’m tired of talking of Spinoza.” That was not exactly the response I had expected. I had met Israel at Brussels’ Bibliothèque Royale where he had been researching 17th-century Spinozistic pamphlets – there are clearly some he still has not read.

And in talking about his work and ideas, I started at the only place I could start: with Spinoza. “The trouble is,” Israel responded, “I’ve become so closely associated with the idea that Spinoza has been underestimated that it’s crowded out most of the rest. There’s a tendency of people to say that ‘Here’s an interpretation of the Enlightenment that wants to explain everything in terms of Spinoza’, and that’s a bit of a distortion.”

Israel’s work is indeed far richer and more nuanced than many of his critics suggest. But critical to the significance of his work has been the way it has challenged perceptions of Spinoza, and in so doing perceptions of the Enlightenment, too. Why, I wondered, had Spinoza been so ignored till recently? “He has in the English-speaking world,” says Israel, “less so in France or Italy or Germany where Spinoza was much more central to the development of intellectual life.” In part, he suggests, the refusal of the Anglophone world to take Spinoza seriously lies in the often fraught division between Analytical and so-called Continental philosophy. There are also “certain cultural tendencies, one of which is the belief that all the important intellectual developments come out of the Anglo-Saxon cultural tradition itself. Continental philosophy almost by definition had to be ignored. So, with a few exceptions, Spinoza has always been seen as an isolated figure, who doesn’t fit in anywhere.”

“Not fitting in anywhere” was also a theme of Spinoza’s own life. Born in Amsterdam in 1632 into a traditional Jewish family, Spinoza came to be sceptical of all theology. In 1656, he was excommunicated from his synagogue for his “evil opinions”. Cut off from the community that had nurtured him, he lived largely in isolation, training himself to make lenses. Spinoza, who never occupied an academic post, became the first major philosopher since antiquity to have earned his living working with his hands.

It was a time of social and intellectual turmoil in Europe. The continent was ripped apart by religious conflict. Medieval Christian theology unravelled, and with it the concepts of human nature and moral and social order that it embodied. Spinoza’s importance, Israel suggests, is not just that he helped unpick medieval scholasticism, but that through his work he “imparted order, cohesion and formal logic to what was in effect a fundamentally new view of Man, God and the universe.” No other figure “became, in the century after 1650, remotely as notorious as Spinoza for challenging revealed religion, traditional morality and political authority.”

What makes Israel’s trilogy striking is the story it tells not just of Spinoza but also of the semi-clandestine Spinozist network of writers and scholars through which his influence spread across the Continent and through the Enlightenment. “Nobody knew about this network,” Israel observes, “unless they could read articles and research in Dutch – and there wasn’t much of that till the 1980s. A lot of this research was completely unknown to French, British and other scholars. I learnt about this because I had been asked to write a general history of the Dutch Republic. I started reading this literature. And that’s how I came eventually to write a history of the Enlightenment.”

The importance of Spinoza for Israel is two-fold. The first lies in his understanding freedom and tolerance. To be Spinozistic, he suggests, is to “take philosophical reason as the only guide in human life”, to “separate philosophy, science and morality from theology”, to “base theories of society on the principle of equality”, to insist on “full freedom of thought”, and to see “democracy as the best form of government”.

Israel draws an important and persuasive contrast between Spinoza’s ideas of tolerance and free thought and those of his contemporary, the English philosopher John Locke, who is generally viewed as setting the philosophical foundations of liberalism. Locke’s starting point for his discussion of tolerance was his desire to extend freedom of worship and theological discussion to nonconformist congregations. It was, Israel observes, a narrow view of freedom, “placing little emphasis on freedom of thought beyond what relates to freedom of conscience.” Locke was emphatic in refusing to extend toleration to many groups. Neither Catholics nor atheists were, in Locke’s view, deserving of tolerance, the former because they gave their allegiance to a “foreign prince”, the latter because their opinions were “contrary to human society”.

For Spinoza, on the other hand, what was important was not, as it was for Locke, the salvation of one’s soul, but the quest for individual liberty and freedom of expression. “Spinoza’s primary goal,” Israel argues, “is freedom of thought and speech. Saving souls plays no part either in his advocacy of toleration or in setting limits to it.”

The second reason for which Spinoza is crucial to Israel is his concept of “one-substance monism”. Christian theology was rooted, as were all monotheistic theologies, in the separation of body and soul into ontologically distinct substances. Descartes, the greatest of early modern philosophers, and the one whose mechanical philosophy helped undergird the scientific revolution, also cleaved to a dualist view of the world. Mind and matter, for Descartes, inhabited radically different realms and comprised distinct stuff. Matter was knowable to humans using science and reason. Mind, however, was foreclosed to human inquiry, at least through scientific means. Spinoza rejected such ideas, holding that the whole of the cosmos, whether matter or mind, whether body or soul, is made of one substance which he called Deus sive Natura (God or Nature), two aspects of the same reality that Spinoza took to be synonymous.

For Israel, these two issues – the metaphysical concept of monism and a political concept of freedom – are inextricably linked. Spinoza, Israel insists, “is only centrally important to the Enlightenment if you accept the premise that there is a connection between one-substance philosophy, the kind of philosophy which verges on materialism, and radical ideas about freedom and equality. My premise is that one-substance philosophy is the only way you could eliminate religious authority from politics. It is not so much the attack on religions in the early clandestine philosophical literature which seems so crucial as the attack on religious authority as a political and philosophical procedure. Our moral order is not something that is divinely revealed to us, it’s something that is relative to society only. Central to Spinoza is the concept that there is something such as a secular, material, common good or common will of society and that you will have a much better, happier society if you adopt laws that correspond to the common good.”

I agree with Israel on the importance of Spinoza’s political ideas of freedom and equality. I agree, too, that Spinozistic concepts of monism and determinism played a role in the development of modern ideas about materialism. Where I disagree is that the two are inextricably linked, and that there is a causal relationship between metaphysical ideas of monism and political ideas of freedom.

One reason for my scepticism is that many materialist philosophers were inimical to freedom. Thomas Hobbes is the classic example. Seen as the key figure both in challenging medieval scholasticism and in formulating an alternative, and hence in laying the groundwork for the Enlightenment, Hobbes’ reputation has long overshadowed Spinoza’s.

Hobbes was an atheist and a materialist – probably more so than Spinoza. He was also a political authoritarian. In his most famous work, Leviathan, Hobbes presented a picture of humans as innately egotistical beings, driven solely by self-interest. In the state of nature, before the creation of society, humans were constantly at war. To find peace and protection, individuals established a “social contract”, handing over their liberty to a central power that had absolute authority to maintain social order. The only liberty a subject possessed was the liberty to do anything not regulated by the sovereign.

“The trouble with Hobbes,” Israel suggests, “is that he is not vesting sovereignty in the people. He is transferring sovereignty to a king or a republican oligarch. The basis of legislation is not the common good.” Spinoza, he adds, “had a much wider conception of why individuals want freedom. We don’t form a society just because don’t want to live in fear. That may be one element in it. But there are lots of other things people want. There’s much more you can do when you collaborate with other people. For Spinoza, sovereignty still resides in the people.”

This is true. It reveals the importance of Spinoza and of the Radical Enlightenment to modern concepts of freedom, an importance that was sorely underestimated until Israel’s work. It does not show, however, that monism is necessarily key to freedom. Doesn’t Hobbes’ philosophy suggest, I asked Israel, that it is possible to hold a materialist, one-substance monist view without necessarily accepting Spinozistic political and ethical arguments? He agreed, pointing to other examples, too, such as La Mettrie, the French physician, philosopher and materialist, celebrated for his 1748 book L’Homme Machine. La Mettrie, Israel observes, “held something like a Spinozistic one-substance doctrine but was not interested in establishing a new moral order.”

If monism was not a sufficient condition for holding radical beliefs about freedom and equality, was it a necessary condition? Were there dualists who held such radical ideas? This is a more complex issue, since the relationship between monism, religious belief and political radicalism is not easy to disentangle. “The Radical Enlightenment,” Israel accepts, “cannot in any way be simply equated with ‘atheism’. Religious people played an important part in the radical Enlightenment, as they did in the French Revolution. But they were always Unitarians or Socinians of some kind. [The Socinians were a 16th-century dissenting Protestant sect, mainly in Italy and Poland.] They were people like Joseph Priestley or Richard Price or John Jebb or Tom Paine. These are believers but believers who can’t accept the idea of a religious authority which is linked to the state. It’s not just that they’re democrats, they’re also aiming for a complete elimination of religious authority. They were relentless in proclaiming reason as the sole guide, rejecting tradition and Revelation and authority. Religion for them is something the individual believes in but there is no need for any kind of institutional organisation which directs people to think about religion. You just discussed, you tried to persuade others that your belief is better than theirs. That was the only basis of religion.”

If this sounds like a very protestant vision of faith, it may be because the roots of many of these groups lie in the radical end of the Reformation. The Reformation, like the Enlightenment, had its radical and moderate wings. The Reformation of which we know, the Reformation of Luther and Calvin, was in fact an intensely conservative religious reaction against the spirit of reason that Thomas Aquinas had introduced into Christianity in the twelfth century by marrying theology to Aristotelian philosophy. The reformers insisted on the absolute sovereignty of God over His creation and saw the human race as a “teeming horde of infamies”, as Calvin put it, whose innate sinfulness degraded any autonomy except for the autonomy to be wicked.

Luther’s rebellion against the Catholic Church appealed to many monarchs and princes, especially in northern Europe, chafing at the constraints imposed by Papal power. The so-called “magisterial Protestantism” wrenched power away from the Pope, but did not abandon the idea that the rule of the monarchs was authorised by God. Many, such as Charles I of England, insisted on the “divine right of kings”.

There were, however, more radical strands to the Reformation. From the Anabaptists in the Low Countries and in German-speaking lands in the mid-16th century to the Levellers and Diggers in England a century later, such movements sought to challenge the power not just of Popes but of monarchs too. They took Luther’s idea of the “priesthood of all believers” as an expression of the moral equality of all humans, and as a challenge to all religious authority. The Levellers, for instance, were a political movement during the English Civil Wars that held to a notion of “natural rights” and emphasised popular sovereignty, extended suffrage, equality before the law and religious tolerance.

The story of the radical Reformation is important because of the centrality of equality to Israel’s account. The thinkers of the Radical Enlightenment, having broken with traditional concepts of a God-ordained order, were, Israel observes, driven to pursue their ideas of equality and democracy to their logical conclusions. There was for them no “meaningful alternative to grounding morality, political and social order on a systematic radical egalitarianism extending across all frontiers, class barriers and horizons.”

“If you are going to construct a moral order in the modern world what other basis do you have?” asks Israel. “If it is not the voluntaristic preferences of some divinity to be interpreted for us, then the only way we are going to come to an agreement is if we agree to consider our interests as equal. Why would we agree to cooperate unless we start by saying, ‘OK, we want different things but we will treat each other as moral equals.’”

I agree wholeheartedly with this. Israel’s treatment of equality, and of its importance to the construction of a new moral order, is one of the most important aspects of his work, and throws new light on moral debates both in the Enlightenment and today. “If God does not exist, everything is permitted.” The misquoting of Dostoevsky has become the almost reflexive response of believers when faced with an argument for a godless world. Without belief in God, runs the argument, we cannot anchor moral beliefs and will be lost in a miasma of nihilism. That is only true, Israel suggests, if we reject the idea of equality.

The paradox, though, is that the roots of this idea of equality lie not in the Radical Enlightenment but in religiously shaped movements that emerged from the radical wing of the Reformation. Israel accepts that such groups were often highly progressive, particularly in their attitudes to equality, women’s rights and slavery. But where they failed, he insists, was in developing “a fully comprehensive philosophy which would incorporate a whole package of elements which would create what you might call a revolutionary democratic vision or awareness.” What distinguishes the thinkers of the Radical Enlightenment is their ability to “fit together a whole package of ideals”. So, “while the Quakers in Pennsylvania might say, ‘We are against slavery’, they don’t have a complete vision, nor the idea of transforming the whole of society, nor a sense of a universalism which will one day will be shared by all peoples and all nations.”

Israel’s work divides readers for much the same reasons the Enlightenment does. Postmodernists are riled by his unashamed celebration of the Age of Reason. Traditional defenders of the Enlightenment bristle at the way he has set out, in the words of the eminent historian Margaret Jacob, “to obscure the basic principles of the western Enlightenment, and to turn its progenitors into members of warring factions”. Believers cavil at his insistence that traditional believers could not be political radicals.

There are, of course, important criticisms of Israel’s account. The intellectual and political divide between the radicals and the mainstream is not as clearcut as Israel assumes. The relationship between metaphysical monism and political liberty is more complex than he allows, as are the historical and political roots of such ideas. And yet, valid though some of this criticism is, much of the debate also misses the point of Israel’s reworking of the Enlightenment. A retelling as monumental as this is bound to raise a myriad issues. Its significance is in constructing a powerful and cogent framework through which to understand intellectual and social conflict both in the Enlightenment and in the post-Enlightenment world.

When Israel talks about the Radical Enlightenment “package” (another idea that has drawn much criticism from both traditionalists and postmodernists) what he means is that the radicals disseminated a startling new vision of society. It was, however, a vision contested from within the Enlightenment itself, a contestation that came to shape both the Enlightenment and the post-Enlightenment world. This is, it seems to me, a far more nuanced approach to the increasingly arid debate over whether the Enlightenment was “good” or “bad”.

Why did Hobbes and Hume and Voltaire row back on ideas of equality and democracy, freedom and liberty, while Spinoza and Diderot and Condorcet embraced more radical beliefs? It was not so much that the unwillingness of the moderates to break with tradition and theology made it impossible for them to accept a radical stance. It was more that their fear of revolutionary change led them to embrace tradition and theology. Because of Israel’s attachment to the old-fashioned history of ideas, this relationship between the intellectual and the social gets submerged in his narrative. But implicit in his argument is the acknowledgement that the division between the radicals and the moderates was not simply an intellectual distinction but an expression also of social conflict – and that it is this that also lies at the heart of contemporary debates about the meaning of the Enlightenment.

*This original version of this article wrongly stated that Jonathan Israel is a Professor of European History at Princeton University. In fact, he is a Professor at the Institute of Advanced Study, which, though located in Princeton, New Jersey, is not affiliated with Princeton University. Article corrected on 27.06.13.

This piece is from the July/August 2013 issue of New Humanist. Subscribe