Jeffrey Collins's In the shadow of Leviathan is one of the best works of early modern British intellectual history to have appeared in the last quarter-century. In it Collins offers a new and persuasive account of how Thomas Hobbes's thought about religious conscience influenced John Locke's thought about religious conscience. Scholars have rarely tried to discern what, if any, influence Hobbes had on Locke. The so-called Cambridge school of intellectual history has tended to keep the two seventeenth-century English political philosophers separated, not least because of methodological commitments. Those associated with that school have rejected ‘canon-formation’, have denied that A-list thinkers ‘developed their ideas in dialogue’ and, indeed, have been wary of attributing influence altogether. Leo Strauss's work also encouraged the Cambridge school to quarantine Hobbes from Locke. For one thing, Strauss and Straussians have focused exclusively on canonical thinkers. For another, in the Straussian narrative, Hobbes and Locke play crucial roles as founding fathers of liberal modernity; insofar as they differ, Locke is supposedly the kinder, gentler purveyor of Hobbes's stark truths. Those working in the Cambridge school tradition have rejected both the Straussian approach and the Straussian narrative. Collins does too but, pace the Cambridge school, argues that we should ask what it meant for Locke to write in the wake of Hobbes. In showing what it entailed, Collins makes important historical, methodological and theoretical interventions.

Collins's historical argument is straightforward. From early on, there was a ‘fairly durable connection between the two thinkers, followed by a gradual emancipation of Locke from Hobbesian patterns of thought’. Collins carefully traces the process by which ‘Locke escaped the strictures of a politique, Hobbesian account of religious conscience, and developed an account oriented around natural rights, individual religious duty and resistance theory.’ The book opens with two chapters on pre-Restoration Hobbism and on Hobbes's Restoration-era attempts to repackage his earlier arguments in a more congenial idiom. Five chapters follow which chart changes in Locke's thinking about the conscience. Collins reckons that Locke was initially drawn to Hobbes's ‘science of sovereignty that might have tolerationist or anti-tolerationist implications’. By the late 1680s, though, Locke had jettisoned Hobbes's ‘logic of civil religion’ and had, instead, defended the individual free conscience and churches as ‘voluntary, sacred and autonomous societies’. So, while some late seventeenth- and early eighteenth-century contemporaries tried to lash together Locke with Hobbes, Collins argues that their conjoining reflected polemical exigencies, not actual fact.

In making this argument, Collins offers a model of how intellectual history should be done. His book appears in the Ideas in Context series, a series founded by Quentin Skinner, one of the progenitors of the Cambridge school, whose methodological hallmark is linguistic contextualism. In general, works in the Cambridge school vein have tried to identify the various discourses, each with its own particular grammar and rhetoric, and the various assumptions which framed the ways in which ideas got formed and articulated. In this book Collins does that and much more. In his analyses of Hobbesian and Lockean texts, he is interested not just in what authors read and wrote but in the precise political and social moments when they read and wrote. This allows him to illustrate how Locke's engagement with the work of Hobbes and of Hobbesians might have meant one thing in, say, the early 1660s, when Locke was writing the Two tracts on government, and something wholly different by the late 1660s, when he wrote An essay concerning toleration and helped to draft The fundamental constitutions of Carolina. The Hobbes who emerges from Collins's book is one whose fundamental positions deepened and intensified, while his Locke is an author whose logic altered and whose positions changed. Collins's sophisticated interpretative method enables him to convey this clearly and convincingly.

Unlike many works of intellectual history, In the shadow of Leviathan also makes significant interventions in political theory. Neo-republicans and Rawlsians are particularly in Collins's sights. His scepticism about the neo-republican project is longstanding, and he has previously taken Quentin Skinner to task for his historical account of non-domination liberty. In this book's fourth chapter Collins turns his critical eye to one of Skinner's fellow neo-republicans, the Princeton political theorist, Philip Pettit. Neo-republicans position their account as a via media between those who advocate for negative liberty and those who champion positive liberty. Neo-republicans argue instead for non-domination, a third sort of liberty that Skinner characterises as not being ‘constrained by living under an unaccountable power’ whose very existence robs one of ‘the freedom to abstain from saying or doing certain things’. Crucially, for neo-republicans, religious organisations are always agents of domination which therefore must always be constrained. Collins, though, shows that that during the Restoration debates over religious toleration, ‘[n]on-domination liberty was primarily nurtured by defenders of conscience rights’. Noting that Pettit ‘shares Hobbes's visceral hostility to the moral authority of non-state associations’, Collins unsparingly details the flaws in the historical account atop which Pettit's theory rests. ‘It would be historically inconvenient for the neo-republicans to concede that dissenters and tolerationists were the primary defenders of a non-domination account of liberty in the seventeenth century’, Collins jibes. ‘It would be still more awkward if that defence of religious freedom was understood as a reworked, individualized version of the libertas ecclesiae espoused by the corporate church of Christian tradition.’ The neo-republicans’ faulty history of liberty actually has ‘normative implications’, Collins furthermore argues, since the seventeenth-century historical actors who actually developed the notion of non-domination liberty also rejected the statist normative conclusions which neo-republicans have drawn from that faulty history (Collins calls it ‘current neo-republican mythology’).

What Collins does to neo-republicanism in chapter iv, he does to Rawlsian liberalism in chapter v. There he skewers John Rawls's ‘inadequate characterization of the Christian past [which] ignores the medieval origins of core Rawlsian concepts, such as individual equality, the rule of law, and secularism itself’. Moreover, he points out that one bit of the tolerationist Locke's prescriptions which Rawls particularly valued was the intolerant, anti-Catholic bit. As Collins puts it, ‘[i]n Locke's mind, there was no possibility of reconciling allegiance to a corporate, hierarchical church with the liberty of the individual conscience’. Perhaps it was understandable in the late seventeenth-century English context for Locke to counsel against giving full religious liberty to Roman Catholics; but, Collins concludes, his denial ‘played no small role in grafting this bias into a liberal tradition that has habitually commended his teachings on this point’. Neither Rawlsian liberals nor neo-republicans nor Straussians will probably like Collins's book, but such is the force of his argument that they will all now have to reckon with it.

Jeffrey Collins has written a hulk of a book, one carrying not an ounce of fat. Erudite and forensic, it is a challenging read. But it is also a book that shows what intellectual history at its very best can do, for it both offers a persuasive account of the past and helps the reader to understand how our present emerged from that past. One finishes the book realising that when it comes to the prevailing Western ways of thinking about religious conscience, we too live in the shadow of Leviathan.