This is an important and well-timed book. Its title, though unassuming, is most apposite: offering a variety of perspectives, this collection of essays enables a reappraisal of the Radical Enlightenment. Its twofold aim is to offer a synthesis of the state of the art and to advance research on the Radical Enlightenment (Ducheyne, ‘Introduction’, 2). The origins and development of the term and its opposite number Moderate Enlightenment are elaborated in an illuminating chapter by Frederik Stjernfelt. Google Ngrams reveal that current usage originates in mid-nineteenth century German philosophy and theology. The concept then was imported to the USA by Leo Strauss in the 1920s, and has risen to prominence from the 1980s onwards, owing to the work of Margaret C. Jacob and Jonathan I. Israel (95-97). Both scholars have contributed a chapter to this collection, and their theories inform all the other chapters, several of which evince a preference for the views of Jacob (Chisick, Davis) or Israel (Leask, Devellennes, Schröder). Though Jacob was the first to offer an extended and full-fledged account of the Radical Enlightenment, it is unmistakeably Israel’s enormously influential thesis of the Radical Enlightenment as the intertwinement of philosophical monism (implying a principled rejection of all supernatural explanations) and political radicalism that constitutes the core concept on which this book focuses. Even in Jacob’s own chapter, the subtext is a veiled critique of the premises of Israel’s thesis: she dissociates herself from a restrictive account of the Radical Enlightenment, from monocausal explanations (48) and from an obsession with Spinoza (51). Instead, she advocates a broad, inclusive approach: ‘All should be welcome in any credible account of the origins of modernity’ (57). The part played by religion in this process cannot be denied, especially when it comes to the position of women (54) – an observation fully borne out by the analysis given by Davis in chapter 15.

The first chapter of the volume is a vigorous defence by Israel of his thesis, albeit with several modifications. To begin with, Israel now describes the interconnection of one-substance monism in philosophy and democratizing republicanism in politics as a ‘marked propensity’ (22) of these two phenomena to occur in tandem, rather than as a necessary combination. In the rest of this volume, this combination (whether unavoidable or only predisposed) remains a heavily debated issue. Furthermore, in his earlier work Israel had inferred egalitarianism, deemed an essential feature of the political agenda of the Radical Enlightenment, directly from Spinoza’s view of the state of nature, in which (on Israel’s interpretation) all human beings are morally equal: ‘All the radical writers […] followed Spinoza down this path, this being one of the defining traits of the radical tendency.’1 We now read, however, that Spinoza (like d’Holbach) ‘totally rejects “equality” in every natural or simplistic sense’ (32). Moral equality does not emerge until a full century later: ‘radical enlighteners embraced universal and equal rights […] only […] from the 1770s onwards’ (29). One element in the emergence of equal rights was ‘a fully secularized “general will” doctrine [which] commenced as far back as the men involved in the cercle spinoziste in the 1660s’ (31). This, then, appears to be a third modification of Israel’s Radical Enlightenment thesis: most readers of his earlier work excusably understood Israel to situate the origins of the Radical Enlightenment and of modernity as a whole in Spinoza’s thought.2 This is now denied; Israel even describes the thesis imputed to him that the roots of the Enlightenment are to be found in the works of Spinoza as absurd. The Enlightenment’s origins are to be sought in larger developments like the general crisis of the seventeenth century, confessionalization, the wars of religion, the rise of science; ‘not in any individual or individuals’ (38). Even so, Israel states that ‘a group launched the Radical Enlightenment in its main essentials in the 1660s’, consisting of Franciscus van den Enden, Pieter and Johan de la Court, Johannes Bouwmeester, Lodewijk Meyer, Adriaan Koerbagh, and – in particular – Spinoza (39). The enumeration is puzzling: Bouwmeester and Meyer left no writings on politics3, and the De la Court brothers, Van den Enden, Koerbagh and Spinoza cannot be considered a homogeneous group with a coherent programme. Moreover, even if they did launch the Radical Enlightenment, it remains to be explained how exactly it caught on and developed. Since Israel attempts to trace the growth of the Radical Enlightenment as the spreading of radical ideas, and not, as Jacob does, in institutional terms (cf. Chisick’s observation in chapter 3, 62), the claim that it was launched by this group, then and there, remains open to question. Israel’s chapter is structured as a set of replies to his critics, divided into ‘negative’ and ‘positive critique’. An incidental remark on page 15 seems to place the negative critique in the long tradition of the Radical Enlightenment’s adversaries: ‘Vehemently opposed from the outset, Radical Enlightenment remains fiercely contested today.’

The issue of a split between a Radical and Moderate (or mainstream) Enlightenment – unavoidable categories for an account of the Enlightenment, according to Israel (as summarized by Ducheyne, 3) – is discussed in a number of contributions. Chapter 3, by Harvey Chisick, is an incisive investigation of the viability of the distinction. Analysing d’Holbach’s reservations about democracy and equality, and Condorcet’s caution with regard to abolishing slavery, Chisick shows that materialism in metaphysics does not automatically result in social and political radicalism. This outcome is not problematic for Jacob’s position in the debate, but it does detract from Israel’s thesis that the Radical Enlightenment requires a combination of the two. Chisick’s conclusion is that a sharp demarcation between Enlightenment radicals and moderates is difficult to maintain.

The Marquis de Sade is mentioned by Chisick (chapter 3, 74) as one of the hard nuts to crack if one postulates a strong connection between metaphysical materialism and Enlightened social and political theory. Winfried Schröder rises to the challenge in chapter 13: was the radical critique of philosophy and religion intrinsically tied to an emancipatory agenda (260)? The case of Sade seems to falsify this hypothesis. Schröder argues that an investigation of Sade’s sources does not confirm the popular picture of the Radical Enlightenment as a slippery slope that eventually led to Sade’s ethics of evil (267). Sade was indeed radical, and it has become apparent only fairly recently that he was well acquainted with Spinoza and Spinozism (261). Yet, according to Schröder, his anti-moral glorification of evil and violence owes more to the vivid descriptions of the horrifying consequences of atheism and materialism by anti-philosophes than to the Radical Enlightenment (265). The chapter ends with an ad hominem argument: those who blame the Radical Enlightenment for the ideas of Sade are ‘presumably motivated by an anti-modernist ideological stance’ (268).

The French priest Jean Meslier, self-styled atheist and materialist, is the subject of a perceptive contribution (chapter 8) by Charles Devellennes. It challenges the dichotomy between Radical Enlightenment and Moderate Enlightenment as opposing camps, a model Devellennes deems inapplicable to thinkers like Hume, Shaftesbury and Rousseau. He prefers to speak of a certain resonance of atheism and political radicalism instead. In the case of Meslier this resonance emerges as a genuine harmony (161). After blue-pencilling, his writings were published posthumously by Voltaire. Devellennes makes a compelling case for taking Meslier’s philosophical atheism seriously, but he appears to have a somewhat superficial view of the seventeenth-century concept of atheism as intrinsically immoral, attributing to Bayle a notion that was in fact a traditional prejudice famously debunked by Bayle (167).

In chapter 9, Wiep van Bunge unfolds a broad and very well-documented panorama of the waning of the Radical Enlightenment in its homeland, the Dutch Republic. It petered out in the eighteenth century, as the conditions that had helped its proliferation gradually disappeared. Van Bunge’s analysis is a model case study of the way Radical Enlightenment was hedged in and disposed of by its moderate opponents, who built on Newton’s natural philosophy and on physico-theology. The chapter takes into account the most recent scholarly work.

Chapter 10 is an extended, and initially somewhat meandering, contribution to the ongoing historiographical debate on the Enlightenment (singular) or Enlightenments (plural). Its author, Eric Palmer, connects his methodological observations with an appraisal of almost forgotten independent Christian thinkers in France, collectively designated as abbés. His argument is that they do not fit into the divide Radical–Moderate Enlightenment, a distinction that has been read retrospectively into a history written by victors (217). Rather than sticking to that dichotomy, or multiplying Enlightenments to include religious currents (209), Palmer proposes to concentrate on persons and alliances, or ‘wings’ as he prefers to call them. This results in an interesting analysis of the networks of the abbés. Palmer’s approach allows different kinds of inquiry into institutions, e.g. bibliometric research (214).

That the distinction between Radical and Moderate Enlightenment can become a straitjacket is again argued in chapter 11, by Falk Wunderlich, who discusses two Christian materialists at Göttingen university in the latter half of the eighteenth century: Christoph Meiners and Michael Hißmann. They cannot be classified as either radical or moderate, and their philosophical and religious commitments run against Israel’s assumption that Radical Enlightenment materialism is necessarily welded to one-substance monism (233). The Göttingen materialists are in fact much closer to Priestley and to Socinianism than to Spinoza, and Wunderlich presents a cogent plea for a broader perspective on the Radical Enlightenment, allowing more metaphysical diversity (233-234).

In chapter 12, Ultán Gillen sets out to portray the United Irish rebellion of 1798 as a conflict between the Moderate and Radical Enlightenments. An important proviso is that he does not take into account philosophical positions, focusing instead on political principles such as religious toleration, republicanism and democracy (241). Yet towards the end, Gillen wanders off in a nominal conundrum when he tries to decide whether the United Irishmen should be pigeonholed as radicals or moderates (253). The question remains undecided: radical in politics, non-committal in metaphysics. The chapter gives a fascinating account of the intellectual background to the rebellion, which owed a good deal to a specific reception of Locke, Montesquieu and the French Revolution.

Several chapters in this book deal with the core issue of equality and egalitarianism. The brilliant contribution of Beth Lord (chapter 6) is a concise, meticulous exposition of Spinoza’s views on equality, and a sustained critique of Israel’s interpretation. She convincingly shows that for Spinoza moral equality cannot be the foundation of the democratic state, as the existence of such a state is a condition for it to emerge (136). Rather than prefiguring modern egalitarianism, Spinoza’s treatment of democracy looks back to classic exclusivism. Building on the work of Genevieve Lloyd, Moira Gatens and Susan James, Lord argues that while moral equality is a fiction, it acquires reality because people behave in accordance with laws that advance equal treatment (135-138).

The putative correspondence between Radical Enlightenment philosophy and equality is investigated in Devin J. Vartija’s excellent chapter 14, focusing on the rise of empathy. He pleads an approach that pays more attention to the role of emotions in the genesis of social and political reform. The Radical Enlightenment did not have a single, philosophical view of equality, as the ambiguous ideas of Condorcet and Diderot make clear (282). Vartija elaborates on themes developed by Lynn Hunt and Siep Stuurman, arguing that emphatic responses in the eighteenth century to unequal treatment and prejudice were the driving force behind the rise of modern equality (277). The sober historiographical observations with which the chapter concludes merit attention. The Radical Enlightenment ‘is a concept that present-day scholars use, not a seventeenth or eighteenth-century category into which thinkers consciously placed themselves’; it is one of the ‘labels that scholars invent to make sense of historical development’ (286). Like other labels it can be useful and appropriate, but it has ‘anachronistic potential’ (287). Elsewhere, Vartija points to the inability of the Radical Enlightenment thesis to accommodate thinkers who were radically egalitarian not in spite but precisely because of their religious convictions (279, on Quaker abolitionism; cf. also 287: Picart and Bernard’s commitment to toleration and equality).

The final chapter 15 by Jennifer J. Davis broadens the scope by including the transatlantic empires of Britain, France and Spain, and bringing out the impact of the Enlightenment on women’s lives (292). Davis does not divide thinkers into radicals and moderates, and rejects using the Radical Enlightenment as a checklist of beliefs – many important feminists would fail the test (293). Most philosophers blended radical, moderate and conservative ideas; not all radicals were feminists, nor were eighteenth-century feminists generally radicals (293). Women’s movements were diverse and developed unlikely alliances, in which the Radical Enlightenment did not always play a positive role (294), as the exclusion of women from public life in Peru shows (303).

In a scholarly and rich essay (chapter 7), Ian Leask presents John Toland as a ‘(neo-)Spinozist’, thereby exhibiting the wider influence of Spinozism on the Radical Enlightenment. Leask claims that in Origines Judaicae (1709) Toland intensified Spinoza’s views on miracles, Scripture and religion. On this interpretation, the Origines was the rejoinder to Pierre-Daniel Huet that Spinoza could not write, as Huet’s attack came out after Spinoza’s death. Leask clearly has a point, but the argument loses some of its force because Toland’s Spinozism (set forth on 146-149) turns out to be not just an intensification but also a simplification of the more sophisticated critique of religion developed by Spinoza.

The quality of the individual contributions to this volume is generally high, but for one exception. Nancy Levene (chapter 5) purports to deal with ‘Spinoza the radical’ from the perspective of ‘materialist readings’ of his philosophy (Althusser, Matheron, Negri, Balibar, Warren Montag, Hasana Sharp). It is by far the weakest chapter in the book, even to the extent that one wonders how it came to be included at all. It is devoid of any argumentative thread whatsoever, and written in a vacuous prose that appears to be deliberately hazy. An example: ‘By giving this movement a beginning (Theological-Political Treatise) when this beginning has always already happened (Political Treatise), Spinoza is simply saying that the difference of the human in nature – the difference of human nature – is the possibility of this movement, this translatio, at all’ (120). Moreover, Levene evinces an inadequate grasp of the basics of Spinoza’s philosophy when she confuses attributes and modes (115, on natura naturans and natura naturata).

The other fourteen chapters provide a fascinating, kaleidoscopic view of the Radical Enlightenment, and do indeed advance our understanding of it. If we can discern a tendency in this range of recent work on the Radical Enlightenment, it is that the heuristic force of the thesis that it is (predominantly or even necessarily) a combination of metaphysical monism and political radicalism seems to be on the wane. Fortunately, the volume also testifies that the research in this area continues to be lively, innovative and eminently relevant. One minor criticism: throughout the book, the noun ‘practice’ is virtually always misspelt as ‘practise’ (even when quoting from a source in which it was spelt correctly: 200; correct on 276, at note number 9).