This chapter returns to the start of Bayle’s publishing career, and the famous argument for the possibility of virtuous atheism in the Pensées diverses. Bayle’s sources and modes of argumentation are identified. Ultimately, the work was a relatively trivial piece of haute vulgarisation; to the extent that the book had an underlying message, it was to outline an anti-Pelagian anthropology. The book proved entirely uncontroversial until it was incorporated into the anti-Bayle campaign waged by Jurieu in the early 1690s. Only at this point did Bayle come up with the elaborate historicisation already discussed in II.1, which also served to expand greatly the canon of (moral) ancient and Asian atheists. But this argument also served another purpose: to further elaborate Bayle’s case for toleration, based on the rights of the errant conscience. This involved Bayle in the theological controversy over ‘philosophic sin’ that had been stirred up by Antoine Arnauld. It led him to develop his mature position. Philosophy had historically been valuable in morality, but disastrous when it came to conceptualising the divine. Christianity had resolved the situation by providing solutions to otherwise insoluble theological problems via its doctrine of creation ex nihilo by a transcendent creator deity (rather than a metaphysical first principle), and by supplying the common people with a set of moral doctrines clearer than those of any philosopher.

This chapter outlines Bayle’s mature vision of the best worldview that could be produced by a perfectly rational human mind, as advanced especially in some of the most famous articles in the Dictionnaire and in the Continuation des Pensées Diverses. It is shown that Bayle owed a huge debt to the Gassendi and his successors on this score, taking the most rational philosophy available to a pagan to be an atheistic monism in which the first principle was immanent in the world. Bayle’s sources were exactly those identified in I.3 as following Gassendi on this matter (Thomasius, Bernier, Parker), as well as the anti-Jesuit accounts of Chinese and Japanese religion. But for Bayle the philolosophico-theological payoff of this genealogical vision was not recourse to Gassendi’s own philosophy, but rather to Malebranche’s occasionalism, which for Bayle was the only possible ‘Christian philosophy’. This elaborate historicisation therefore allowed Bayle to make a natural-theological argument, which was deployed against Spinoza among others. But at the same time, Bayle also acknowledged the explanatory limits of Cartesian occasionalism, above all when it came to issues stemming from the incomprehensibility of mind-body interaction: the ‘place’ of immaterial substances and animal rationality. This position was neither scepticism nor fideism, but an argument about the practical limits of philosophy.

No less important a structural development than the emancipation of natural philosophy from metaphysics was the self-conscious emancipation of theology from philosophy, largely achieved by making philology and historical scholarship – rather than philosophy – the primary handmaidens to the discipline. This did not happen at the hands of a small band of liberal outsiders (‘Erasmians’, ‘latitudinarians’, etc.), but within the theological mainstream. In the Catholic world, all major locales (starting with the Spanish Netherlands, and culminating in France) witnessed a self-conscious shift from ‘scholastic’ to ‘positive’ theological method. By the second half of the seventeenth century, a similar development had occurred in all the major areas of the Reformed world. Crucially, this shift should not be taken for a form of ‘fideism’, even if its conceptual resources sometimes seem to imply it. At the basic epistemological level, conceptions of theological truth remained broadly the same as they had been since c.1300: divine mysteries could be above reason, but could not contradict it; the truths of natural theology could be proved rationally. But within this broadly continuous framework a huge methodological shift took place, one that significantly curtailed the cultural authority of apriorist philosophy. Calls for the separation of philosophy and theology usually worked to the detriment of the former.

This is the preliminary section to the structural history presented in Part I. It briefly describes the pan-European aversion to speculative and systematic philosophising c.1700, and contrasts it with the situation two centuries earlier. It asks how this remarkable transformation came about.

This chapter charts the way in which the study of nature was made increasingly less philosophical between 1500 and 1700. At the start of the period, natural philosophy was largely conducted as a form of ‘metaphysical physics’. The erosion of this approach was driven by three factors: 1) the impact of humanist critique; 2) The colonisation of natural philosophy by physicians; 3) The colonisation of natural philosophy by mixed mathematicians. Despite a spirited fightback from the metaphysicians, by the middle of the seventeenth century the anti-metaphysical physicians and mixed-mathematicians – often operating in tandem – had won. A major concomitant of this is that the idea that most of seventeenth-century natural philosophy was grounded in ontological mechanism is wrong. To the extent that natural philosophers were mechanists, they were operational mechanists, who modelled nature on machines but refused to commit to an ontological reductionism, and often directly opposed it. In this and other respect, Descartes and his followers, far from being representative of seventeenth-century natural philosophy, were outliers.

This chapter introduces Part II, on Pierre Bayle. It provides an intellectual-biographical account of Bayle’s career, emphasising both his deep immersion in circles of Reformed scholars and theologians, and the reactive dimension of his writing, which were almost always shaped by his most recent reading. It urges caution about trying to find a coherent system in all of Bayle’s writings, and instead presents a framework for a developmental account of his thought. It also introduces the historiographical debate about Bayle, and the so-called ‘Bayle enigma’. It suggests that that enigma can be dissolved even if we carefully place Bayle in his own context, and avoid misleading categories such as ‘scepticism’ and ‘fideism’.

This chapter summarises the argument of the book. It also discusses the consequences of the dwindling status of speculative philosophy for the European system of knowledge in the eighteenth century and beyond.

The most famous subject on which Bayle has been claimed to be either a fideist or an atheist is his discussion of the problem of evil in the ‘Manichean’ articles of the Dictionnaire and in subsequent writings. This chapter contextualises those writings so as to outline Bayle’s sources, and to show that he was engaging in a tripartite polemic about the theological doctrine of predestination. From Gassendi, Bernier, and others Bayle had learnt to argue that the problem of evil had no full solution: a purely rational (pagan) philosophy led to a deterministic fatalism. Gassendi, Bernier and others had used this point to insist on the necessity of adopting a Molinist doctrine of free will. Bayle argued the opposite: while it was indeed impossible to reconcile predestination and free will, history had shown that this did not lead to moral laxness. At the same time, the predestinarian position was more rational than the Molinist one, since it best accorded with the idea of unitary, omnipotent deity (which all sides agreed was rational). It is shown that Bayle adopted this argument from several Reformed theologians with whose writings he was well familiar: his teachers Louis Tronchin and Francis Turretin, and above all Jacques Abbadie and his then-friend Pierre Jurieu. But for Bayle this conclusion also had a political pay-off that put him at odds with Jurieu: that the difficulties of theological doctrine should lead to mutual toleration of differing opinions, rather than to a destabilising odium theologicum.

This short chapter introduces the book as a study in the history of knowledge, and specifically of changing conceptions of what kind of knowledge was and wasn’t worth pursuing in the period 1500–1700, with speculative forms of philosophising coming out as the loser. It summarises the contents and argument of the book, and warns against reading early modern intellectual history from the perspective of the eighteenth and nineteenth centuries, with philosophical ‘rationalism’ as a driving force. It also sets out the book’s double approach: first, a longue durée structural account of the changing nature of the early modern system of knowledge; second, in-depth contextualisations of Bayle and Newton showing how they were individual products of that system. Both of them ended up developing elaborate genealogical visions of a ‘Kingdom of Darkness’ no less interesting and sophisticated than that of Thomas Hobbes. As for him, the inheritance of speculative philosophy ended up explaining almost all the evils (both intellectual and social) in the world.

In the seventeenth century, European thought about the capacities of a perfectly rational mind (i.e. that of the best pagan philosopher) underwent a major transformation. This transformation had three sources: (i) philological scholarship concerning the history of religion that rejected patristic narratives of pagan/Judaeo-Christian similarity; (ii) reconsiderations of Asian theology as reported by missionaries and travellers; (iii) new approaches to pagan philosophy, which was more and more conceived of as fundamentally incapable of achieving the ‘true’ metaphysical and cosmological worldview held by Christians, above all because of its universal adherence to the rational principle of ex nihilo nihil fit. As a result, by 1700 a consensus emerged that the rational pagan mind bereft of revelation would tend to some kind of animism, pantheism, vitalism, or even monism. The debate was whether this pagan worldview concealed a latent monotheism (a view held by John Selden, G.J. Vossius, Tobias Pfanner, Ralph Cudworth, and others) or to a monistic atheism (a position first articulated by Pierre Gassendi, and then further developed by Jakob Thomasius, Samuel Parker, François Bernier, and many others). By the end of the century, the second view had largely triumphed.

In the years after the publication of the second edition of the Principia, Newton further elaborated his vision of the genealogy of knowledge, and his subsequent conception of the limits of ‘legitimate’ knowledge. Metaphysics now emerged for him as the unifying force that explained all the evils of intellectual life, above all pagan idolatry; the hubristic rationalism in theology that gave birth to odium theologicum and persecution; and the unwarranted search for speculative, causal explanations in natural philosophy. In a set of elaborate writings, ranging from the ecclesiastical-historical ‘Of the Church’ (in which we see the influence of Bayle’s close friend Jacques Basnage) to further polemical writings against various followers of Leibniz and Malebranche, he developed his mature vision of a Kingdom of Darkness at the centre of which lay speculative, metaphysical philosophy. The manuscript ‘Tempus et Locus’ should be dated to this period, rather than to the 1690s. Finally, it is shown that Newton’s earliest followers understood perfectly the broad methodological message which he was trying to advance, and continued to disseminate it aggressively in their writings. The earliest decades of the eighteenth century were devastating for the practice of ‘philosophy’ as it had been conducted for much of Western history.

This chapter explores the development of Newton’s methodological thought up to c.1700, as well as that of his first followers. Newton’s caution in not antagonising Huygens in particular is highlighted. It was only in this decade that Newton started to emphasise the natural-theological significance of his natural philosophy, especially in manuscripts related to the Classical Scholia. But there was no metaphysical component; rather, Newton insisted on the analogical predication of the divine. Even more important was his reconsideration of the Hypotheses of the first edition, which eventually became the Rules of Philosophising of the second. It is shown that these were not abstract methodological principles, but rather a set of dialectical arguments designed to negate the possibility of weightless matter. Nonetheless, they shaped Newton methodological agenda and language for the rest of his life. His position was understood perfectly by his earliest follows: David Gregory and John Keill, both of whom were teaching in Oxford.

This chapter expands the conclusions of II.2 to explore how Bayle thought it was still rational to be a Protestant, even if the mysteries of faith were beyond the grasp of reason. Bayle had been deeply influenced by certain Catholic theologians, above all Pierre Nicole and Antoine Arnauld, who had argued for the incomprehensibility of dogma, and the need to adopt a positive rather than a philosophical method in theology. But while for them this led to an emphasis on the authority of the Catholic Church, Bayle deployed the argument to defend (Reformed) Protestantism. For him, even if one acknowledged the incomprehensibility of the mysteries, there were still rational grounds to choose to believe some mysteries (e.g. predestination) over others (e.g. the Real Presence in the Eucharist). These reasons were grounded in historical testimony, approached probabilistically. In turn, we can completely revise of our understanding of Bayle’s debate with the so-called ‘rationaux’ (above all Jean Le Clerc and Isaac Jacquelot). Bayle was no more or less fideist than his opponents, who were no more ‘rationalist’ than him; indeed, Bayle’s position was directly influenced by Le Clerc. The debate between them was in reality a confessional one, with both sides accusing the other of rationalism. Le Clerc was arguing that Bayle was a rationalist beholden to philosophical determinism, and that a non-philosophical biblicism revealed the truths of Christianity – which happened to be Arminian. Bayle was arguing that Le Clerc was a philosophical rationalist beholden to the idol free will, and that a non-philosophical biblicism revealed the truths of Christianity – which happened to be Reformed.