This introduction broaches the question of how naturalism rose to dominance in the modern West. Naturalism in this context is understood as a rejection of belief in the supernatural. This distinctive feature of Western modernity is at odds, not only with its own religious past, but also with what has been true for virtually all other cultures. Whereas it was once impossible not to assume the existence of the supernatural, this has now become one option among others, and one that is typically thought to be lacking in rational support. The book seeks to account for this unique historical development in two related ways. First, it explores the histories of the two key terms in this understanding—‘belief’ and ‘supernatural’—showing how they came to take on their present meanings in the modern period. Second, it shows how advocates of naturalism necessarily subscribe to a progressive view of history that can vindicate the adoption of these two categories in their modern sense.

This chapter gives an account of the origins of our present understanding of the natural/supernatural divide, showing how the terminology of the ‘supernatural’ first emerged in the Middle Ages and gradually assumed its modern form between the seventeenth and nineteenth centuries. The attendant ‘isms’—naturalism and supernaturalism—arrive at the end of this period, during the 1800s. The original context for the naturalism/supernaturalism distinction was neither science nor philosophy, but the sphere of biblical criticism. From there it was imported into a scientific context. The nineteenth century also witnessed attempts to reconstruct the history of science with a view to arguing for a long-standing alliance between naturalism and science. A more accurate portrayal of the relevant history shows, to the contrary, that ‘science’ had been consistently aligned with theistic assumptions about the regularities of nature. These regularities were formalised as laws of nature in the seventeenth century, at which time they were understood as divinely authored imperatives to which nature necessarily conformed. In the nineteenth century, what had originally been understood as expressions of the divine will were simply redescribed in purely naturalistic terms by advocates of naturalism. Ironically, they were now claimed to represent evidence against theistic readings of nature.

This chapter traces the fortunes of our modern understanding of ‘belief’ which is deeply informed by its original uses in a religious context. It begins with an account of faith/belief (Greek: pistis) in early Christianity, showing how the primary meanings of the term related to trust rather than intellectual assent. In the medieval period, this social component of faith/belief was formalised in the conception of ‘implicit faith’, which enabled lay believers to affirm abstruse theological doctrines without the requirement of a full intellectual comprehension of what was being affirmed. While it is possible to speak of the propositional content of belief during this period, the identity of the faithful was established more by liturgical practice than assent to doctrinal propositions.

This chapter considers how the exceptionalism of Western naturalism was given legitimacy through an appeal to narratives of progress. These narratives were indebted to a Protestant model that divided history into two periods—one in which miracles were genuine, followed by another in which they were not. The latter was associated with fraudulent Catholic miracles. Protestants also understood the Reformation as having ushered in an age of light after a period of medieval darkness. Eighteenth-century philosophes generalised and extended this argument, contending that the miracle reports from all historical periods were fraudulent. History could now be divided into an earlier period characterised by a naïve credulity in relation to miracle reports, followed by a more mature phase of history during which there was increasing recognition of the falsity of miracle reports. These same eighteenth-century thinkers also arrogated to themselves the mantle of enlightenment. The progressivist histories characteristic of the early social sciences and endorsed by advocates of scientific naturalism were doubly indebted to religious models since they also drew upon providential or eschatological notions of historical directionality. This raises the question of whether their progressivist philosophy of history is problematically dependent upon covert theistic assumptions.

This chapter describes how, during the sixteenth century, implicit faith became one of the chief targets of the Protestant reformers, who insisted that individuals take full responsibility for what they believed. True belief was thought to entail explicit knowledge of what was being assented to, along with some capacity to justify that belief in a way that did not simply defer to authority. Critiques of implicit faith represent the first articulation of what is now referred to as the ‘ethics of belief’—the principle that we have an ethical duty to have evidence for the beliefs we hold. As a consequence, belief came to be thought of more in terms of intellectual assent than affective trust. These early modern changes to the sociology and philosophy of religious belief contributed to the subsequent epistemological preoccupations of modern philosophy.

This chapter explores the implications of the new status of belief by reconsidering traditional arguments for the existence of God. If disbelief in the supernatural was not a live option before the appearance of modern secularity, what was the point of articulating proofs of God’s existence? This chapter shows that the so-called classical proofs performed a very different function to the one that they were later to assume, being more akin to spiritual exercises than logical arguments constructed from neutral premises. Crucially, one of the central ‘proofs’—that based on universal consensus—involved an appeal to the ubiquity and universality of religious belief. The demise of this ‘argument’ in the early modern period signalled a major change in how belief in the supernatural came to be understood, indicating that the burden of proof was shifting from unbelievers to believers. This was accompanied by a new conception of natural theology, understood as an enterprise that could provide support for religious belief on rational grounds alone. The changing status of natural theology and proofs for God’s existence correlated directly with the appearance of a new notion of belief and the requirements for its justification.

This concluding chapter briefly considers the puzzle of why belief in the supernatural is endemic in certain times and places but not, for the most part, in modern Western Europe. It explores a range of theoretical possibilities: salience; the theory dependence of observation; the effects of language, concepts, cultural conditioning; and what might be called cultural and scientific myths and liturgies. It then moves to a brief consideration of how the general thesis of the book relates to other ‘modernity stories’, including those of Charles Taylor, Brad Gregory, John Milbank, and Alasdair MacIntyre.

David Hume’s famous argument against believing miracle reports exemplifies several key issues relating to the emergence of modern naturalism. Hume uncritically assumes the universal and unproblematic nature of core conceptions such as ‘supernatural’ and ‘laws of nature’. Hume’s argument also presents him with a dilemma. He relies upon the weight of testimony to establish his case against believing miracle reports, but must also contend with the weight of testimony, across different times and cultures, to the existence of the supernatural. Hume resolves this by an appeal to historical progress accompanied by a dubious racial theory. These enable him to discount testimonies emanating from the past and from other cultures. ‘Hume’s dilemma’ has not gone away and, if anything, is even more acute since the traditions and beliefs of non-Western cultures are now more difficult to dismiss on the basis of dubious historical accounts of Western exceptionalism. This dilemma amounts to a tension between the ethics of belief and the demands of epistemic justice.