3.1 Making Europe Christian

When Père Biard despaired of converting the Mi’kmaq to Christianity on account of their apparent lack of a basic conception of belief, there was a sense in which he was confronting not one foreign culture, but two. In addition to the alien thought-world of the indigenous Americans he had also to deal with the residues of medieval notions of implicit faith that had informed the proselytising endeavours of his predecessors in Port Royal. The very first missionaries to Acadia had negotiated the problem of creedal belief by the simple expedient of baptising the willing, rather than inculcating the doctrinal truths of Catholic Christianity. This approach drew upon the idea of implicit faith and reflected the conviction that membership of the Church was bestowed through the rite of baptism. Augustine had maintained that through the sacrament of baptism the infant becomes ‘a believer’ even though, needless to say, they are unable to assent to any doctrines.Footnote ² A subsequent and explicit affirmation of the truth represented by the sacrament would normally be expected when the ‘believer’ reached the age of reason, but baptism provided the first step. In keeping with this sentiment, throughout the Middle Ages the verb ‘christen’, in both its Latin equivalent and in the older European languages, meant ‘to Christianise’ or ‘make someone a Christian’.Footnote ³ Biard, however, refused to emulate what he regarded as the lax approach of his predecessors and, to the consternation of many of his charges, withheld baptism from those unable to articulate core Christian doctrines unless they were on death’s doorstep.Footnote ⁴ This stance reflected a significant change of attitude within the Catholic Church, as part of the Counter-Reformation response to the challenges issued by Protestants, on the fundamental question of who is counted as a true Christian. At the heart of this change were questions about what had to be explicitly believed, what was entailed by ‘believing’, and how central believing was to the Christian life.

While there is a widespread popular assumption that the medieval period was pre-eminently an age of Christian faith, historians vary in their assessments of just how Christian medieval Europe was.Footnote ⁵ These assessments are complicated by different criteria for what counts as being a Christian. There is little doubt that in the late Middle Ages the lives of most Europeans were governed by the cultic practices of Catholic Christianity, the divisions of time set out in the liturgical calendar, and notions of sacred and consecrated space. There is also clear evidence of widespread religious devotion and personal piety.Footnote ⁶ It is less obvious that there was a universal and explicit knowledge of core Christian doctrines, and this was true even for many of the clergy. Christianisation in early medieval Europe was not understood in terms of the adoption of a distinctive set of Christian beliefs. Instead, as one historian has recently observed, ‘it was primarily, though not exclusively, a ritual performance: the integration of individuals into Church communities through mandatory rituals’.Footnote ⁷ This was entirely consistent with Augustine’s suggestion that one becomes a ‘believer’ through baptism. We encounter a related idea in the principle articulated by Augustine’s disciple Prosper of Aquitaine (c.390–c.455 ad) who in the formula lex orandi, lex credenda (the law of prayer is the law of belief) suggested that liturgy and worship are, in a sense, constitutive of ‘belief’.Footnote ⁸ It is against this background that we are to understand the new consensus, across the spectrum of sixteenth-century religious reformers, that Europe needed to be re-Christianised. Integral to this programme of Christianisation was a mission to inculcate the populace with explicit doctrinal knowledge.Footnote ⁹ But for all the talk of re-Christianising, this programme amounted to the implementation of a new idea of what it was to be Christian.

Martin Luther complained in 1520 that ‘the Christian life’ is ‘unknown throughout the world. It is neither preached about nor sought after; we are altogether ignorant of our own name and do not know why we are Christian or bear the name of Christians.’Footnote ¹⁰ Much of this ignorance was credited to the scourge of implicit faith. Luther insisted that ‘every man is responsible for his own faith’, pointing out that just as no one can go to heaven or hell for me, neither can anyone believe or disbelieve for me.Footnote ¹¹ In a similar vein, John Calvin lamented that his Roman Catholic adversaries ‘deem it of little moment what each man believes concerning God and Christ, or disbelieves, provided he submits to the judgment of the Church with what they call implicit faith’. Implicit faith, he maintained, deludes the general populace: it ‘not only buries true faith, but entirely destroys it’.Footnote ¹² These observations bear more than a passing resemblance to Biard’s characterisation of the first Christian converts that he had encountered in America: their baptism notwithstanding, they knew no prayers or articles of faith, attended services only out of curiosity, and had barely a passing familiarity with the word ‘Christian’.Footnote ¹³

As Biard’s observations also make apparent, with the passage of time the insistence of Luther and Calvin that Christians have an explicit knowledge of what they believed came to be shared, at least to some degree, by Catholic reformers. The Catholic response to the Protestant Reformation, in the form of the protracted Council of Trent (1545–63), sought to bring greater attention to doctrinal and disciplinary matters. Historian Brad Gregory writes that the decrees and anathemas of the council represent an ‘unprecedented emphasis on interior assent to the propositional content of doctrinal truth claims’.Footnote ¹⁴ This shift towards doctrinal knowledge was reinforced by a new determination to promote religious literacy, especially among the clergy, and the recognition that sacramental practices should be accompanied by knowledge of Christian doctrines. Europe itself thus became a mission field, with Catholic and Protestant clergy alike seeking to school the laity, particularly rural populations, in the basic teachings of Christianity.Footnote ¹⁵

In all of this, faith became a much more individual matter, especially for Protestants. While Luther (like Calvin) strongly maintained that faith amounted to personal trust in God, that trust was less dependent upon communal practices or rituals. Faith was not attained through spiritual exercises – ‘Masses, ceremonies, vows, fasts, hair shirts, and the like’.Footnote ¹⁶ What was required was individual resolve, albeit aided by God’s grace. Faith was uprooted from a broader ecclesial and social context, making it more a matter of the individual’s direct relationship to God. Indeed, it has been argued, with some justification, that Luther introduced modern individualism into the West.Footnote ¹⁷ This resistance to the ecclesiastical governance of all aspects of the religious life would have other, far-reaching consequences.Footnote ¹⁸ It signalled the beginning of a new relationship between the faithful and the institution that had presided over the ritual performances in which belief was enacted. That same institution had also been the custodian of religious knowledge and guarantor of its truth. The radical rupture of that institution wrought by the Protestant Reformation necessitated new understandings of religious authority and the faith once vested in it. At the same time, and quite independently of the reformers’ intentions, it became possible to think of practice and belief as separate aspects of the religious life, even to the point where the relation could be seen as one of opposition – mindless ritual as an inferior substitute for genuine religious knowledge. Again, this move was consistent with the appearance of new notions of religion and of plural religions. ‘Religion’, once understood as a virtue, a form of piety, was reified, enabling the category of plural ‘religions’ which were understood in terms of their distinctive beliefs and practices.Footnote ¹⁹ This development is also distantly reflected in the modern sociological distinction between ‘believing’ and ‘belonging’.Footnote ²⁰

Accompanying this dismantling of a central ecclesiastical authority was a sustained attack on the Catholic clergy. The priesthood had been one of the prime targets of Luther’s reforming zeal. He denied that priests and monks were different in kind to anyone else. Individuals might be allocated different offices, but all share the same spiritual estate.Footnote ²¹ Calvin agreed that all Christians belong to a royal priesthood, a status conferred not by the Church, but by God.Footnote ²² While church organisation was important for Calvin, neither the Church nor its ministers mediated between God and the elect. New forms of Church polity necessarily impacted on practices of believing that had previously been distributed across the institution of the one holy and apostolic Church. These changes were accompanied by a loss of trust in the priestly order, the extreme manifestation of which was the emergence of the early modern idea of ‘priestcraft’. For those who subscribed to this notion, priests were regarded as members of a universal ‘type’ whose signal characteristic was the opposite of trustworthiness. Priestcraft entailed systematic deception and imposition on overly credulous populations.Footnote ²³

As a consequence of these linked developments – attacks on implicit faith, denial of the Roman Church’s authority in matters of doctrine, the separation of practice and belief, the undermining of the office of the priesthood – the burden for knowing and defending doctrinal details fell increasingly upon the individual rather than being distributed, on the basis of trust relations, across the community of the faithful. Jesuit Cardinal Robert Bellarmine, who in the late sixteenth century compiled the first systematic catalogue of key differences between Catholics and Protestants, pointed to the novelty of the reformers’ stance on this issue. Our present-day heretics (i.e., the Protestants), he charged, permit ‘private persons to be judges in matters of faith’.Footnote ²⁴ Insistence on the right to make private judgements, as we have seen, was the vice that lay at the heart of heresy. Essayist and philosopher Michel de Montaigne, writing around the same time as Bellarmine, offered a similar appraisal of the aftermath of Protestant attacks on Catholic religion:

In a post-Enlightenment age we typically celebrate this development. For Bellarmine and Montaigne, it was deeply regrettable.Footnote ²⁶

3.2 Implicit Faith and the Ethics of Belief

In his Lectures on the Philosophy of History (1822–30) the philosopher G. W. F. Hegel (1770–1831) observes that the ‘essential content’ of the Protestant Reformation is this: ‘man sets himself to be free’.Footnote ²⁷ Hegel’s historical pronouncements, it must be conceded, need to be treated with a degree of caution. But in this case he has a point. Arguably, one of the most iconic historical instances of the assertion of individual autonomy was Martin Luther’s appearance before the Imperial Diet at Worms in April 1521. In June of the previous year, Pope Leo had issued the bull Exsurge domine, threatening Luther with excommunication and demanding that he recant his teachings within sixty days. He had also ordered, for good measure, that Luther’s offending writings be sought out and burned in public.Footnote ²⁸ On the sixtieth day, 10 December 1521, Luther responded in kind, burning the papal bull along with a number of books of canon law. He was duly excommunicated. Under pressure from the German princes to end the standoff, Emperor Charles V called an assembly of the Holy Roman Empire in the Imperial Free city of Worms and invited Luther to attend under promise of safe passage. The emperor and the Church were looking for Luther to recant his teaching and writings; a number of the German princes secretly hoped that he would not, seeing in this occasion the opportunity to establish their independence from Rome. When confronted with his allegedly heretical views Luther was invited to recant. Unconvinced by the arguments against him and, crucially, the criteria that were in play, Luther offered the celebrated response: ‘Unless I am convinced by the testimony of the Scriptures or by clear reason (for I do not trust either in the pope or in councils alone …. I cannot and I will not recant anything, since it is neither safe nor right to go against conscience.’ Tradition has it that he went on to say: ‘Here I stand, I can do no other.’Footnote ²⁹

In this symbolic moment we witness what appears to be a clear rejection of a corporate and institutional understanding of belief. Luther substituted individual conviction for trust in the Church and its councils, and elevated the alternative authorities of individual conscience, scripture, and reason (although he envisaged a carefully circumscribed role for the latter). Subsequently addressing the topic of ‘the freedom of the Christian’, he would expand membership of this tribunal to include a third authority – experience or, literally, ‘experiment’.Footnote ³⁰ This episode marks the inauguration of what has become a distinctive characteristic of the modern West – the principle that individuals ought to take responsibility for what they believe. This means not only being able to articulate the precise content of what is believed but, equally importantly, being able to offer a justification for what is held to be true. One of the major drivers of this new attitude to belief, as noted above, was the concerted Protestant campaign against implicit belief.Footnote ³¹ Indeed, the nub of the Protestant/Catholic divide, as one Protestant controversialist expressed it, could be understood in these terms: ‘whether they shall follow their own reason and judgment, or give up themselves to follow a Guide with a blind and implicite faith’.Footnote ³² In The Religion of Protestants (1637/1687), a popular seventeenth-century work and favourite of the philosopher John Locke, William Chillingworth had similarly concluded that the Protestant creed called for the rational judgement of the individual rather than a simple acceptance of things on trust:

There were several facets to the early modern critique of implicit faith. A common charge was that the medieval Church had substituted religious practice for the holding of correct beliefs, and that genuine Christianity was impossible without the latter. Preaching in 1684 on the theme of ‘rational service’ to a congregation of old Etonians, Joseph Layton asked his auditors to ‘turn your Eye to the Men of implicit Faith: … you shall see them creeping before Images, adoring of Wafers, paying Pensions for Purgatory, and Traffiquing for the price of Sins. In the midst of all this Pageantry, and this Nonsense, Their comfort is, they believe as the Church believes.’Footnote ³⁴ Religious devotion, at least the kind that was evidenced in ‘papist’ rituals, was said to go hand in hand with religious ignorance. It was a commonplace among Protestant controversialists that their Catholic opponents actively promoted the principle that ‘ignorance is the mother of devotion’.Footnote ³⁵ This maxim implied an inverse relationship between devotional fervour and religious knowledge, along with the necessity of a proper balance between practice and belief. The theory of Roman rites was a related target, and in particular, teachings about transubstantiation. According to Protestant critics, this irrational doctrine could subsist only because it was accepted without question.Footnote ³⁶ Huguenot controversialist Moïse Amyraut argued against ‘blind, brutal acquiescence’, insisting upon the ‘necessity of examination’ of all doctrines. To accept a dogma without understanding how it was grounded in scripture or rationally implied by some other well-founded doctrine was to fail to believe in it at all. Christians who uncritically receive what is taught, he concluded, are merely Christians by an accident of birth, in the same way that Turks are Mahommedans.Footnote ³⁷

The category of implicit faith was also alleged to have been a device invented by scholastic philosophers to justify their regrettable tolerance for nescience among the general population. Part of the problem with this scholastic version of the doctrine was its reliance upon an Aristotelian distinction between formal and material – specifically the ‘formal’ and ‘material’ objects of faith.Footnote ³⁸ For those who no longer subscribed to an Aristotelian metaphysics it became more challenging to provide a philosophically plausible account of how implicit faith operated.Footnote ³⁹ A more general critique was that it was a fancy label for ignorance: mere ‘ignorance garnish’d and set off with a plausible word, that has no meaning’; a pretext for ‘simple grosse ignorance’; synonymous with ‘virtual Unbelief’.Footnote ⁴⁰ Protestants were to deploy their own derisory designation for this kind of uncritical belief: the ‘faith of the collier’ (or charcoal burner). This was the vacuous commitment of the rustic simpleton who knew nothing except the need to reside trust in the teachings of the Church.Footnote ⁴¹ Huguenot writers also spoke dismissively of the ‘foi du charbonnier’, an expression that in various European idioms was in continual use until at least the mid-nineteenth century.Footnote ⁴² All of this signals a shift of attention, in conceptions of faith, to the content of belief and its justification, and away from an attitude of trust and the devotional practices that sustained it.

Unquestioning obedience and atrophy of the capacity for rational deliberation were also claimed to be the side-effects of implicit faith. There was a significant political dimension here, since the relevant trust relations and the accompanying demands on obedience ultimately led back to Rome. As one writer put it, implicit faith promotes ‘indisputable obedience, & absolute dependence on the Church and Court of Rome’.Footnote ⁴³ It was a device ‘to keep men under their obedience’, explained another.Footnote ⁴⁴ Critiques of implicit faith were thus related to both religious and political freedoms. Susceptibility to religious imposture was another undesirable consequence of acquiescent belief. Samuel Estwick contended that implicit faith ‘discards all Reasons and Motives of Credibility, closes and seals up the eyes and lips of the Votary, and thereby exposes him to all the fancies and extravagancies that Seducers can suggest to him’.Footnote ⁴⁵ In so far as implicit faith entailed the surrender of rational autonomy – often regarded as the distinguishing feature of human beings – it was said to reduce its adherents to a bestial servility. In his Antidote against the poyson of popery (1679), Christopher Ness declared that implicit faith ‘is a mere bruitish unreasonable thing; … like the motion of a Beast that is ordered by his Driver, but knows neither whither nor wherefore’.Footnote ⁴⁶

Common to virtually all critiques of implicit faith was the conviction that individuals had a religious duty to be able to give a reasoned account of what they believed and why. It was argued to be a sin against God-given reason to subcontract to an institution the responsibility for believing.Footnote ⁴⁷ ‘God calls upon us to employ our Talent’, contended Joseph Layton, ‘to Exercise our selves in these things, to Build up our selves in our most holy Faith, and to Stand fast in the Liberty wherewith Christ has made us Free’.Footnote ⁴⁸ God requires of us ‘a distinct knowledge of the points of our faith’, agreed John White, so that we are able ‘to expound, & manifest them’. ‘Having given us reason’, maintained Isaac Barrow, God requires it ‘as a matter of duty’ to exercise it in matters of faith.Footnote ⁴⁹ It was thus held to be a religious obligation to have ready reasons for holding particular beliefs and this imperative was supported by appeals to a range of biblical passages.Footnote ⁵⁰ In sum, being a true Christian was now thought to involve not only the explicit profession of certain beliefs, but also being cognizant of their content and capable of providing a justification for holding them.Footnote ⁵¹

Since the late nineteenth century this basic principle, stripped of its historical context and original theological justifications, has been known in philosophical circles as ‘the ethics of belief’ – the idea that we have a moral duty to be able to provide good evidence for holding the beliefs we do. In the 1877 paper that introduced that phrase into the philosophical lexicon the Cambridge philosopher William Kingdon Clifford summed up the basic idea in these words: ‘it is wrong always, everywhere, and for any one, to believe anything upon insufficient evidence’.Footnote ⁵² It should now be clear that something closely akin to this principle had been fundamental to critiques of implicit faith from the sixteenth century onwards. To the extent that the archaeology of this epistemic imperative has been excavated, John Locke has been proposed as its modern philosophical progenitor.Footnote ⁵³ It is certainly true that Locke does articulate something like this principle and seems to have been the first to expound it systematically in a philosophical context. Yet, in effect, he was formalising an impulse that had characterised Protestant critiques of implicit faith for well over a century. For this reason, implicit faith is Locke’s stock example of how not to arrive at reliable knowledge: ‘whilst some (and those the most) taking things upon trust, misemploy their power of assent, by lazily enslaving their minds to the dictates and dominion of others in doctrines, which it is their duty carefully to examine, and not blindly, with an implicit faith, to swallow’.Footnote ⁵⁴ A key problem to which Locke’s epistemology had been addressed was the resolution of competing knowledge claims, the most acute form of which, during the period, lay in religious differences.Footnote ⁵⁵ While an ‘ethics of belief’, as articulated by Clifford, was intended as a critique of religious convictions in general, the idea itself was hardly an innovation of the nineteenth century. It had its origins in confessional disputes of the early modern period when it was first wielded by Protestant controversialists.

Locke’s positive prescriptions for combating the evils of implicit belief are similarly to be understood against the background of contemporary theological discussions. Examination of the grounds of one’s beliefs was for Locke a divinely mandated duty: ‘He that believes, without having any Reason for believing … neither seeks Truth as he ought, nor pays the Obedience due to his Maker, who would have him use those discerning Faculties he has given him.’ The Christian has a ‘Duty as a rational creature’ to use the faculties with which God has endowed them.Footnote ⁵⁶ Reason, then, was to provide the means by which the holding of particular beliefs could be justified. Our duty is to believe or disbelieve ‘as reason directs’. Reason ‘must be our last judge and guide in everything’. As for faith, it was now understood by Locke to be nothing other than assent ‘based on the highest reason’.Footnote ⁵⁷ All of this assumed that reason itself was a divinely sanctioned organ of critical judgement.

It is one thing to propose that the free exercise of the faculty of reason offers the best prospect for resolving dispute-engendering religious differences. It is quite another to establish what ‘reason’ is, and how it is to be applied. In something of an understatement, the literary historian Douglas Bush has observed that ‘the meanings of “reason” in the seventeenth century admit a wide solution’.Footnote ⁵⁸ It would ambitious, in the span of a few pages, to attempt to offer a satisfactory account of the full variety of ways in which ‘reason’ was conceptualised in the early modern period, far less in the centuries that followed. For now, it suffices to identify two ends of a broad spectrum, along with a gradual shift in one direction. One version of reason retains a strong continuity with preceding traditions that emphasise its divine origins, a scope that encompasses both moral and epistemological concerns, and a substantive content along the lines of ‘innate ideas’. At this end of the spectrum, genuine religion was understood as more or less continuous with the cultivation of reason; hence the involvement of reason with matters of faith was imagined to be entirely natural and was justified on theological grounds. At the other end we encounter a narrower and more instrumental conception of reason, one that equates it with a calculative faculty of ratiocination that is capable of analysis but has no substantive content of its own. This established the conditions for a rather different relationship between faith and reason in which reason comes to act as a kind of independent arbiter of religious truth. In this role it could be supportive or critical. Over the course of the seventeenth and eighteenth centuries this latter conception becomes increasingly prominent.Footnote ⁵⁹ Paradoxically, though, this secularisation and instrumentalisation of reason was also initially informed by theological considerations, and hence the gradual shift in emphasis from one conception of reason to the other is the result of competing theological assessments of the proper scope of reason and its post-lapsarian capacities.

In sum, the Protestant critique of implicit faith represents the first articulation of a tightly connected set of principles that are now almost universally endorsed in the West: that individuals should be left to make up their own minds in the spheres of religion, morals, and politics; that claims about important matters of fact should not be taken on the basis of authority alone; that we have an obligation not to hold beliefs without being able to offer some kind of justification for them. This led to new attention being focused on the operations of reason and its role in providing the requisite support for beliefs.

3.3 God and the Light of Nature

In their popular, eleven-volume Story of Civilization, Will and Ariel Durant designate the period from 1550–1650 the ‘Age of Reason’, the period during which Europe set out on ‘the bumpy road toward the Enlightenment’.Footnote ⁶⁰ While the Durants did not present it in these terms, this age of reason is sometimes contrasted with a preceding ‘age of faith’, with the triumph of human reason representing a victory over the forces of darkness and superstition.Footnote ⁶¹ It is often thought, then, that the rise of philosophical rationalism in the seventeenth century is to be understood primarily as a challenge to traditional authorities. However, the championing of reason did not necessarily amount to a more naturalistic, secular alternative to ecclesiastical authority. For many thinkers, and particularly those influenced by traditions of Christian Platonism, the justification for ceding authority to reason ultimately derived from assumptions about its divine origin. Clearly, this complicates any simple story about an opposition between reason and religious faith.

The individual most often depicted as the quintessential rationalist, René Descartes (1596–1650), offers an instructive example. The standard ‘birth of modern philosophy’ narrative has him eschewing all preceding philosophical traditions and starting anew solely on the basis of reason – as one wit has recently suggested, a kind of turning philosophy off and then back on again.Footnote ⁶² Until relatively recently it was not uncommon for university courses in the history of philosophy to leap from the ancient Greeks to Descartes as if nothing of philosophical import had been transacted in the intervening eighteen centuries. This state of affairs was based on the identification of philosophy with modern epistemology, along with a mistaken assumption that the ancients shared something like a modern set of philosophical preoccupations. That said, it is significant that Descartes himself presented his programme as revolutionary. His quiet resolution to start afresh, detailed in the Meditations (1641), is akin in some respects to Luther’s earlier and more public attempt to reconfigure the whole basis of religious authority and in the received version of the history of philosophy was no less momentous.Footnote ⁶³ Yet Descartes’s reliance on his scholastic forebears remained strong, and when we examine exactly what he understood by ‘reason’, for example, we find him reasserting what in many respects is a quite conventional religious understanding of this human capacity. He describes reason as ‘a sort of spark of the divine, in which the first seeds of useful ways of thinking are sown’, employing Augustine’s image of ‘the mark of the craftsman stamped on his work’.Footnote ⁶⁴ He also consistently refers to reason as a ‘natural light’, by which he means not so much a capacity that is natural in a sense that opposes it to ‘supernatural’, but a light that is proper to our natures as human beings because God has bestowed it upon us.

Descartes’s self-proclaimed originality notwithstanding, the overlap of human and divine in the processes of understanding, along with the use of the light metaphor for knowledge, had been a philosophical commonplace. The rational faculty or capacity to reason, on these understandings, was the divine component of the human being, and the recipient of the ‘light’ of eternal truths. These ideas had a pedigree that extended back to Presocratic thinkers. Around 500 bce, Heraclitus had described reason as that ‘which is in common and divine, and by participation in which we become rational’.Footnote ⁶⁵ His successors put forward variations on this theme. Plato taught that ‘God gave the sovereign part of the human soul to be the divinity of each one.’ Accordingly, the pursuit of knowledge and wisdom leads to ‘thoughts immortal and divine’. Aristotle declared (in an admittedly ambiguous passage) that the active intellect is ‘immortal and eternal’. ‘The starting point of reason’, he tells us in the Eudemian Ethics, is God. In the conclusion to Nicomachean Ethics he describes the intellect as ‘divine’ and commends the cultivation of the divine within as the ultimate goal of life.Footnote ⁶⁶ The Stoic philosopher Seneca taught that reason ‘is nothing else than a portion of the divine spirit set in a human body’, and ‘a common attribute of both gods and men’.Footnote ⁶⁷ In the same vein, Epictetus taught that while humans have a body in common with the beasts, they also have reason and intelligence ‘in common with the gods’.Footnote ⁶⁸ For Plotinus, the third-century founder of Neoplatonism, the ‘higher soul’, in which the particular excellence of human beings resides, contains ‘some effluence from the Divine Reason’.Footnote ⁶⁹ In the periods of late antiquity, and into the Middle Ages and Renaissance, Platonic and Aristotelian thinkers, Greek, Latin, and Islamic, built upon these ideas.Footnote ⁷⁰

A persistent theme in the Platonic tradition was that the goal of life was to cultivate or restore that portion of divinity within, with the goal of becoming god-like. The cultivation of reason would then be identical to leading a religious life. Classicist David Sedley has suggested that were we to enquire of any educated Roman what Plato held as the goal of philosophy they would unhesitatingly cite the Theaetetus: ‘becoming like a god so far as is possible’.Footnote ⁷¹ Platonist thinkers of the early Christian era certainly made this the central feature of their philosophy. Plotinus explains that we have fallen away from ‘our resemblance to the divine’. This is to be restored through the exercise of ‘the reasoning part of [our] nature’ which will secure the likeness to God of which Plato spoke.Footnote ⁷² The fourth-century Platonist Hierocles of Alexandria accordingly defined philosophy as ‘a purification and perfection of human life: a purification from our irrational, material nature and the mortal form of the body, a perfection by the recovery of our proper happiness, leading to a likeness with the divine’.Footnote ⁷³ Full realisation of the potential of reason was thus both the goal of philosophy and a religious quest. The Aristotelian tradition was consonant with this to a large degree, with Aristotle regarding rational contemplation as the activity most proper to human beings and an emulation of, or participation in, the contemplative activity of the gods.Footnote ⁷⁴

The notion of deification subsequently became a central aspect of the Greek patristic tradition, and indeed for Greek Orthodoxy thereafter. An oft-repeated description of the purpose of the Incarnation among the Greek Church Fathers was that God became human so that humans might become gods.Footnote ⁷⁵ An important parallel to the philosophical idea of reason as the divine within was provided by the biblical human beings as created in the image and likeness of God (Gen. 1:26).Footnote ⁷⁶ The goal of the Christian life could thus be understood as the full realisation (or restoration) of this indwelling likeness to the divine. Maximus the Confessor (580–662) wrote: ‘If we are made, as we are, in the image of God (Gen. 1 :27), let us become the image both of ourselves and of God … so that we may consort with God and become gods, receiving from God our existence as gods.’Footnote ⁷⁷ For thinkers of the Latin West, admittedly, this programme was complicated by the fact that while human beings may have originally been created in God’s image and likeness, important questions remained about just how much of that image persisted in our present fallen condition. Varying answers to these questions provide a point of difference between Christian and Platonic traditions, and a source of disagreement among Christian thinkers. Yet as it relates to discussions of reason in the early modern period, there are noteworthy convergences of Platonist and Christian understandings of reason as likeness to God, along with the goal of restoring that likeness. These informed discussions about the nature of reason and of its relation to faith. Broadly speaking, reason, in this rich and expansive sense, could never be opposed to true religion, but was in fact integral to its realisation.

Descartes’s reference to the ‘light of nature’ is also consistent with a tradition of deploying light metaphors in relation to the operations of reason.Footnote ⁷⁸ Again, the key source is Plato who, in the Republic, set out the analogy of the sun: ‘just as we see objects when they are illuminated by the light of the sun, so the mind sees truths when they are illuminated by the Good’.Footnote ⁷⁹ The most celebrated elaboration of this insight was Augustine’s theory of divine illumination. Puzzling in the Confessions over how human minds have the capacity to grasp shared truths, Augustine tells the reader how he came to the realisation that his mind ‘needed enlightenment from some other light source in order to participate in the truth’. That light was God.Footnote ⁸⁰ While there are Platonic resonances here, Augustine also drew upon various biblical sources, prominent among them the incipit of Psalm 27, ‘The Lord is my light’, which will be familiar to some as the motto of the University of Oxford – Dominus illuminatio mea.Footnote ⁸¹

There have been differing views about the precise nature of Augustine’s theory of illumination and about its subsequent fortunes. What is not in doubt is that the language of divine illumination was commonplace up until the thirteenth century and, as we will see, persisted into the seventeenth century.Footnote ⁸² Usually regarded as the chief spokesman for the doctrine in the high Middle Ages, Franciscan friar Bonaventure (1221–74) taught that ‘nothing can be understood at all unless God immediately illumines the subject of knowledge by means of the eternal divine truth’.Footnote ⁸³ Henry of Ghent (c.1217–93), the leading theologian at the University of Paris in the period following Aquinas’s tenure, maintained similarly that ‘Pure truth … or perhaps any truth at all, cannot be known without God himself doing the teaching.’Footnote ⁸⁴ Even Thomas Aquinas, who is often regarded as having dispensed with the Augustinian model, retains key elements of the basic idea: ‘the intellectual light itself which is in us, is nothing else than a participated likeness of the uncreated light’.Footnote ⁸⁵ These sentiments would continue to inform the epistemology of Renaissance Platonists such as Marcilio Ficino (1433–99), who stresses that the reliability of our knowledge is related to its divine origins: ‘our minds bear the same relationship to God as our sight to the light of the Sun, and … therefore they can never understand anything without the light of God’.Footnote ⁸⁶

Modern readers may find this widespread assumption that human knowledge relied upon God’s presence, that it was in some sense ‘miraculous’, rather odd. But part of this puzzlement arises from our present assumption of an exclusive disjunction between ‘natural’ and ‘supernatural’. For Augustine, and indeed many of the ancients, it was perfectly natural (in his sense) for the porous human soul to be a site of divine activity. God, Augustine insists, is ‘the first principle of our nature’.Footnote ⁸⁷ Our natural desire for truth (and happiness) is simply an indication of this. Augustine pointed out that the Platonists had also held this view: that God is ‘the principle of reason, and the rule of life’, ‘the light by which things become known, and the good for which things are done’.Footnote ⁸⁸ Accordingly, Augustine did not imagine himself to be authoring an idiosyncratic and theologically extravagant theory of knowledge, but adding a Christian refinement to a long-standing philosophical tradition which held that when the mind makes a true judgement it is in contact with something that is eternal and unchanging.Footnote ⁸⁹ The ubiquity of this cluster of ideas – in Plato, Aristotle, Neoplatonism, medieval Christianity and Islam – suggests that it was perfectly ‘natural’ to assume that human knowledge and right living required, at a theoretical level, some transcendental grounding and, at a practical level, a process of mental training (or askesis) that would facilitate access to the transcendent. The prominence of this idea of divine illumination in the Western tradition might prompt us to reflect upon how difficult it is to provide an adequate naturalistic (in our modern sense of the term) account of how our minds might come to share common convictions that certain things are true, and that these things are, in fact, true. That problem has never really gone away and neither the neurosciences nor cognitive psychology have made this less puzzling. From the perspective of our predecessors, it would be an astonishing coincidence, verging on the miraculous, that creatures who evolved through blind natural processes might end up being able to access truths that had nothing to do with their mere physical survival.

All of this is by way of pointing to the fact that an early modern appeal to ‘reason’ does not initially rest on a hard and fast distinction between (natural) reason and (supernatural) revelation, since reason is already deeply theologically inflected. This relates to a more general thesis about the late historical emergence of a natural/supernatural divide. The initial turn towards reason already assumed its divine origin and natural receptivity to revelation. However, there would also be theological challenges to traditional understandings of reason, not least on account of a renewed emphasis on the fallen condition of human minds. In the end, a modern version of ‘reason’ would be severed from its theological roots and forced into the role of independent arbiter of religious claims. This would be an instrumental reason that passed judgement upon the theological assumptions upon which, paradoxically, its own reliability had originally been grounded.

It is tempting to think that metaphysical talk of an interior ‘divine light’ would be swept away with the inception of modern philosophy. Older models of the history of philosophy, which jump directly from antiquity to Descartes, tend to assume this, with the options of ‘rationalism’ and ‘empiricism’ offering non-theological and relatively unproblematic secular foundations for knowledge. However, as is already evident, Descartes regularly invokes the idea of natural light, along with concomitant notions of innate ideas and the image of God. These, in turn, inform his ontological arguments for the existence of God, with God subsequently acting as a guarantor of the reliability of our knowledge.

The theme of illumination is especially conspicuous in the thought of Descartes’s most famous follower – the philosopher and priest Nicholas Malebranche (1638–1715) – who espoused what is an unmistakably Augustinian view of divine illumination, albeit in a Cartesian guise. While now relegated to the second division of philosophical thinkers, Malebranche was highly regarded in his own time. His contemporary Pierre Bayle, who was not easily impressed, lauded him as ‘the premier philosopher of our age’ and if Malebranche drew upon Augustine and Descartes, he also authored novel and influential solutions to philosophical problems.Footnote ⁹⁰ He is perhaps best known for his championing of occasionalism, the doctrine that God is the only true cause (although this idea has a much longer history going back to the medieval Ash’arite school of Islamic philosophy and was espoused by medieval Christian thinkers such as Nicholas of Autrecourt).Footnote ⁹¹ Equally prominent in his philosophy was the related idea that knowledge is possible only because human minds participate in God’s knowledge. Malebranche insisted that God must be responsible for our ideas since our immaterial minds could be susceptible only to the influence of some other immaterial substance. He also repeated Augustine’s argument that since all minds intuit the same set of necessary truths, they must all be illuminated by the same light.Footnote ⁹² While Malebranche is the best-known representative of this view, he was not the only one. In England, the philosopher John Norris also maintained that in so far as we know anything at all, we do so by participating in ideas in the divine mind.Footnote ⁹³ This stance would also inform the idealism of Bishop George Berkeley (1685–1753) who, as is well known, argued for the counterintuitive thesis that minds and ideas are the only things to exist.

Thinkers who may have been reluctant to go all the way with Malebranche’s version of divine illumination nonetheless endorsed the key principle that reason was reliable on account of its divine origins. Among the most prominent advocates of this idea were the ‘Cambridge Platonists’ (with whom John Norris was well acquainted).Footnote ⁹⁴ Benjamin Whichcote, regarded as the intellectual father of the group, had described reason as ‘God’s mansion’, the ‘impression of God’, ‘the image of the Creator, copied out in the creature’.Footnote ⁹⁵ This was the common view of his fellow Platonists who, following Whichcote, repeatedly made the claim that reason was ‘the candle of the Lord’.Footnote ⁹⁶

Reason, understood as the ‘light of nature’, was thus ‘natural’ in the way that ‘laws of nature’ were – at least as the latter were originally conceived. Both notions concern the powers with which God imbues nature, or which he stamps upon it. Reason is natural in the sense that it is proper to our natures, but it was a light given by God and authoritative in proportion to its retention of an original, created integrity.Footnote ⁹⁷ In an Aristotelian framework, which assumed a teleological order to things, reason worked because it was naturally oriented towards the discovery of truth. For Aristotle, that is just how things are. Whichcote defers to this general principle when he remarks that: ‘It is natural and proper, for mind and understanding in man, to tend towards God, as for heavy things to tend towards their centre …. All understandings seek after God, and have a sense and feeling of God; and the mind and spirit of man is a candle in man lighted by God and doth discover God.’Footnote ⁹⁸ Such teleological assumptions, still deeply embedded in much thinking about human nature, were reinforced by the biblical idea that persons were created in the image of God. It was the supposition of a natural affinity between revelation and an internal, God-given reason that made it possible for reason to be the judge of supposedly revealed truths. As Whichcote put it: ‘reason is the recipient of whatever God declares’, reprising Aquinas’s contention that because the soul is the image of God, it is naturally capable of grace.Footnote ⁹⁹ As the natural intersection of divine and human, then, the mind is the place where ‘spirituals and naturals join in and mingle’ making it impossible to distinguish between religion and reason.Footnote ¹⁰⁰ Reason was thus the site of human permeability to the divine.Footnote ¹⁰¹

In view of these considerations we can say that the familiar story about Descartes, the birth of modern philosophy, and the rise of a reason and a foundationalist view of knowledge (the idea that all of our knowledge rests upon some non-inferential knowledge or indubitable belief), has a significant element of truth: it is just that the ultimate foundation of rational knowledge, on this broad conception of reason, turns out to be God. To some degree, then, the transition from implicit beliefs grounded in authority to explicit beliefs grounded in reason amounts to a shift in emphasis from one kind of religious source of knowledge to another.

Acknowledgement of the theistic grounding of knowledge was commonplace in the early modern period. Descartes himself remarked that ‘man cannot achieve correct knowledge of natural things so long as he does not know God’.Footnote ¹⁰² ‘It is necessary to know God’, Malebranche agreed, ‘if we want to be fully convinced that the most certain sciences … are true sciences’.Footnote ¹⁰³ Leibniz, too, insisted that ‘the same God who is the source of all goods is also the principle of all knowledge’.Footnote ¹⁰⁴ For François Fénelon, ‘the superior reason that resides in Man, is God himself’.Footnote ¹⁰⁵ In England, the physician and natural philosopher Walter Charleton (1620–1707) declared that ‘no one thing in Nature can be known, unlesse the Author of Nature be first knowne’.Footnote ¹⁰⁶ Cambridge Platonist Ralph Cudworth spoke similarly of God as ‘the First Original Knowledge or Mind, from whence all other Knowledges and Minds are derived’.Footnote ¹⁰⁷ On this view, it was less a matter of reason providing grounds for believing in God, than it was God providing grounds for believing in reason.Footnote ¹⁰⁸

Others drew the obvious implication that without some faith in a providential Deity we would have no reason to reside confidence in the reliability of our mental faculties. Here the connection between knowledge and the divine was less direct, but equally crucial. According to Isaac Barrow (1630–77), the gifted mathematician, theologian, and classicist who preceded Isaac Newton in the Lucasian Chair at Cambridge, the dependability of the mind’s logical operations ‘does in some sort suppose the Existence of God’.Footnote ¹⁰⁹ Anglican divine, Fellow of the Royal Society, and subsequently Archbishop of Canterbury, John Tillotson agreed that our confidence in the reliability of our clear and distinct ideas is grounded in the conviction that God imbued us with trustworthy faculties. God guarantees the trustworthiness of ‘the frame of our understandings’.Footnote ¹¹⁰ Even without subscribing to a fully developed theory of divine illumination, then, many early modern thinkers could still hold that the reliability of reason called for a divine guarantor.

Understood as a portal to the transcendent, reason was also thought to encompass moral considerations and fundamental religious truths.Footnote ¹¹¹ The common early modern expression ‘right reason’ signals the moral orientation of human rationality. Again, this drew on a long tradition extending back to Plato’s insistence on the convergence of knowledge and virtue.Footnote ¹¹² The Stoics, in turn, had developed this understanding further, connecting reason to the idea of natural law and introducing the terminology of ‘right reason’. Cicero, for example, proposed that ‘virtue is nothing other than right reason (recta ratio)’.Footnote ¹¹³ Aquinas subsequently linked right reason with God’s eternal law. Human beings participated in the eternal law by virtue of the light of nature, which was itself an imprint of the divine light.Footnote ¹¹⁴

In the early modern period, Richard Hooker (1554–1600), one of the most articulate defenders of the use of reason in matters of religion, explained that everyone, excepting children, innocents, and madmen, has the capacity to discern right from wrong though the exercise of right reason.Footnote ¹¹⁵ As we will see, in the wake of the Reformation, there was considerable discussion about the reliability of right reason on account of the fallen human condition. But it was usually allowed that right reason continued to function to some degree, especially in a sanctified state and with the assistance of divine grace. Calvinist divine George Hakewill thus spoke of ‘the torch of right reason, yet left amongst the remainders of Gods image in man’.Footnote ¹¹⁶ John Donne used the expression ‘rectified reason’, suggesting that it was a natural partner for faith: ‘They are not continuall, but they are contiguous, they flow not from one another, but they touch one another, they are not both of a peece, but they enwrap one another, Faith and Reason.’ Ultimately, he would conclude that ‘rectified Reason is Religion’.Footnote ¹¹⁷

It follows that when many early modern thinkers sought to mobilise reason in the sphere of religion, they did not imagine themselves to be calling upon some ‘external’ or ‘neutral’ human capacity that was competent to pass judgement on the validity of various religious propositions. If anything, the appeal to reason was motivated by the assumption that it could provide a more direct channel to the divine than the fallible institutions and councils of the Church. It was not simply a natural (in our sense) cognitive instrument, moreover, but was the bearer of the divine image, a receptable of innate truths, and already attuned to revelation.Footnote ¹¹⁸ This amicable partnership between reason and revelation was destined for a troubled future, however, with the emergence of more narrow and instrumentalist understandings of reason. Reason was set to be pried loose from its metaphysical and theological foundations, emptied of substantive content, and forged into a device for rational calculation. This ‘secular’ understanding of rationality first arose from a competing theological account of human rationality.

3.4 Reason Secularised

Luther’s impassioned appeal at the Diet of Worms to scripture and clear reason may come as a surprise to some because Luther is commonly depicted as an implacable opponent of reason. For his harshest critics he was an embodiment of irrationality: a ‘crass ignoramus’ (Heinrich Denifle), a man ‘wholly and systematically ruled by his affective and appetitive faculties’ (Jacques Maritain), an unintelligent rabble-rouser (Goethe), a philistine (Thomas Arnold), the coarse and foul-mouthed leader of a revolution (Ralph Inge), etc.Footnote ¹¹⁹ In recent popular (albeit historically unreliable) writings Luther has been presented as the personification of an opposition between reason and religious faith.Footnote ¹²⁰ In his less temperate moments, of which there were more than a few, Luther certainly provides some justification for these assessments. Reason was ‘a mangy, leprous whore’ and ‘the devil’s bride’, ‘the greatest enemy that faith has’.Footnote ¹²¹ This sceptical outlook was motivated partly by an identification of reason with aspects of Aristotelian philosophy, partly by Luther’s emphasis on the fallen condition of humanity and his reckoning of the damage wreaked upon human reason by the Fall. Both Luther and Calvin maintained that the degree of rationality that we now possess is but a pale shadow of the original gift of reason granted to Adam. On the one hand, we retain some of the powers of the original gift of reason, in so far as the divine image was not completely effaced by the Fall. Its residual powers are sufficient for us to govern human affairs and make modest advances in the sciences. On the other hand, and comparatively speaking, these residual powers of reason were deemed to be ‘leprous and dull’ (Luther) or ‘seriously injured’ (Calvin).Footnote ¹²²

Luther and Calvin sought to distinguish their assessments of human reason from those of their scholastic predecessors who, in their view, had overestimated the integrity and scope of fallen reason – not least on account of the undue influence of the Pagan philosopher Aristotle.Footnote ¹²³ The key implication, for Luther in particular, was diametrically opposed to the quasi-Platonist positions set out above: unaided human reason cannot provide us with direct access to the divine.Footnote ¹²⁴ Its limitations extended even to our knowledge of the natural world. A truly scientific knowledge of nature, as Aristotle had imagined it, was for Luther a lost cause: the operations of nature have become a mystery to us after the Fall of Adam, on account of the ‘perversion’ of reason.Footnote ¹²⁵ This more sceptical assessment of the powers of reason thus also distinguished Luther, Calvin, and their followers from those early modern Platonists and rationalists who, as we have seen, discounted the impact of original sin and focused more on the traditional connection between human reason and its divine source.Footnote ¹²⁶

That said, Luther carved out a space for the operations of this attenuated reason. In keeping with virtually all early modern thinkers, Luther understood reason to have originally been a gift from God and he would describe it as ‘the most important and the highest in rank among all things … the best and something divine’. As his declaration at Worms illustrates, reason could also serve as a criterion for our judgement, too.Footnote ¹²⁷ Crucially, though, reason was gifted to us in order to assist in our secular callings. It was ‘the inventor and mentor of all the arts, medicine, laws, and of whatever wisdom, power, virtue, and glory men possess in this life’.Footnote ¹²⁸ Reason, in spite of its fallen state, would thus enable us to muddle through in a world that shared its fallen condition.

Calvin adopted a similar stance. While reason was ‘weak and immersed in darkness’, there remained ‘some residue of intelligence and judgement’ which made it possible for human beings to establish stable social orders and glean some knowledge of the operations of nature. In delimiting the scope of reason, Calvin made a crucial distinction: ‘we have one kind of intelligence of earthly things, and another of heaven things’. Mere reason was deemed largely incompetent in the higher spiritual realm and when applied to matters concerning the future life. When it came to knowledge of God and his favour towards us, even the most ingenious are ‘blinder than moles’.Footnote ¹²⁹ But reason could operate tolerably well in the present life – when applied to the spheres of ‘policy and economy, all mechanical arts and liberal studies’.Footnote ¹³⁰ The secular world was the legitimate sphere of operations for what, in essence, was a natural or secular reason – literally a reason fit for use in the saeculum, the imperfect in-between age that occupied the unstable temporal space between the Incarnation and the end of the world. While the original intention of Luther and Calvin had been to limit the scope of reason to mere ‘earthly things’, their efforts would eventually have the opposite effect. Once the domain of the here-and-now took precedence over the more remote region of ‘heavenly things’, there would be a corresponding expansion in the scope and status of natural reason. If the secular realm is all that there is, then reason tends to become omnipotent.

Attempting to delimit the scope of reason was by no means the sole preserve of Protestant thinkers. Catholic thinkers with strong Augustinian commitments were also inclined to reflect on the consequences of the impact of sin on the operations of reason. The basic strategy of Nicholas Malebranche’s Search after Truth (1674–5) was thus to reflect upon ‘the order found in the faculties and passions of our first father in his original state, as well as the changes and disorder that befell him after his sin’.Footnote ¹³¹ The Jansenist philosopher and mathematician Blaise Pascal wrote that ‘if man had never been corrupted, he would, in his innocence, confidently enjoy both truth and felicity’. In our present state, however, we are unhappily suspended between ‘absolute ignorance and certain knowledge; so obvious is it that we once enjoyed a degree of perfection from which we have unhappily fallen’.Footnote ¹³² Pascal rated the efforts of the ancient philosophers similarly: ‘they knew the excellence of man, they were ignorant of his corruption; so that they easily avoided sloth, but fell into pride’.Footnote ¹³³ The sanguine assumptions of Plato and Aristotle about the capacities of human reason were thus judged to have been misplaced on account of their ignorance of the fallen state of humanity. The ancient sceptics had gone to the other extreme, lacking any sense of human beings created in the divine image. Pascal would reach the conclusion that: ‘Reason’s last step is the recognition that there are an infinite number of things which are beyond it … and if natural things are beyond it, what are we to say about supernatural things?’Footnote ¹³⁴ Again we see an emphasis on the limits of reason and a key distinction between earthly and heavenly spheres of competence.Footnote ¹³⁵

Theological anthropology and the narrative of the Fall were not the only sources for early modern efforts to delimit the operations and scope of reason. Metaphysical considerations were also important – especially the far-reaching influence of the nominalism of the late Middle Ages. In essence, nominalism was a denial of the existence of universals – those shared properties of individual things such as ‘redness’ or ‘beauty’. Plato’s theory of the forms is the most influential exemplification of the conviction that universals are real. Against this approach, William of Ockham (1285–1347) maintained that universals played a role only in the realm of logic, and should be understood only as abstractions from individual things.Footnote ¹³⁶ Ockham also held the view, later adopted by Locke, that the mind, at birth, was a blank slate or tabula rasa.Footnote ¹³⁷ We do not come into the world with eternal truths or intuitions of the forms written into our souls. Cutting a very long story short, on this view of things, the proper business of reason lies in the performance of logical operations, and not participation in eternal truths. Reason did not, indeed could not, be involved in unearthing and giving expression to innate ideas, since these did not exist. There was no necessary connection between this stance on universals and negative views of reason arising out of a particular interpretation of the Fall, although clearly they could be mutually reinforcing.Footnote ¹³⁸

The story of the impact of these considerations on the trajectory of the modern West has been told many times, albeit in different versions, none of which need be rehearsed in detail here.Footnote ¹³⁹ In essence, from the thirteenth century onwards, a strong emphasis on divine omnipotence led to questions about whether God was limited by putatively universal principles of reason and morality. Nominalists responded to this question in the negative. God was radically free to will any state of affairs that he chose, and to legislate what was right and wrong. This provides a link between nominalism and voluntarism, with the latter emphasising the priority of the divine will. It followed that what had once been thought of as eternal and immutable features of the world were to be understood either as arbitrary divine commands, or as human creations that help us navigate the world. Universals have no transcendental status and serve merely as signs. Controversially, the same was often held true for moral universals, too. Expressing the implications of this position simply, if there are no eternal and unchangeable notions of the good and the true, a model of knowledge that has human reason participating in these universals is no longer viable. Nominalism, in combination with voluntarism, was thus destined to leave an indelible mark on subsequent theology, politics, and the natural sciences. It also promoted a revised understanding of human reason.

Thomas Hobbes offers a good indication of how such commitments would play out in early modern philosophy. Perceptively characterised by the polymath philosopher G. W. Leibniz, as ‘a super-nominalist’, Hobbes proposed in the Leviathan (1651) that reason ‘is nothing but Reckoning (that is, Adding and Subtracting) of the Consequences of general names agreed upon, for the marking and signifying of our thoughts’.Footnote ¹⁴⁰ Given Hobbes’s commitment to mechanistic understandings of the world, this amounted to a view of reason as a straightforward calculating device. The appeal to common consent also received short shrift: ‘no mans Reason, nor the Reason of any one number of men, makes the certaintie; no more than an account is there well cast up, because a great many men have unanimously approved it’.Footnote ¹⁴¹ Hobbes expressed a similarly deflationary approach to ‘right reason’. Right reason was simply ‘the act of reasoning, that is, the peculiar and true ratiocination of every man concerning those actions of his, which may either redound to the damage or benefit of his neighbours’.Footnote ¹⁴² This was a clear anticipation of the hedonistic calculus of later utilitarians who understand moral judgement as a computing of the balance of benefits and harms caused by particular acts, but without any overriding conception of the good (which right reason had traditionally been thought to provide). With substantive matters now lying outside the scope of a merely calculative reason, Hobbes referred issues of morals and religion to the determination of a human judge.Footnote ¹⁴³ This is clearly a step towards the secularisation of reason. For Hobbes, as Peter Dear observes, ‘the supernatural has been quietly replaced with civil authority, which provides the absolute criterion for reason’.Footnote ¹⁴⁴ But all of this was originally motivated by a particular understanding of divine omnipotence.

John Locke represents a further example of the way in which reason came to be reconceptualised. While he retained the traditional descriptions of reason as a ‘spark of the divine nature’, ‘the candle of the Lord’, and ‘the voice of God’, he also took pains to stress ‘the weakness of our faculties in this state of mediocrity’.Footnote ¹⁴⁵ Crucially, for Locke, reason had no substantive content. Against the ‘established opinion’ that there were innate principles attested to by universal consent, Locke contended that the mind was a blank slate that could be written upon only by experience. This is one of the central messages of the Essay concerning Human Understanding (1689), a foundational source for modern epistemology. It is significant that a primary target of the book was Herbert of Cherbury’s ‘common notions’ and the tradition that they represented.Footnote ¹⁴⁶ (This tradition will be discussed in more detail in Chapter 4.) For Locke, reason is a content-free engine of inference and calculation – the capacity to make deductions and judgements of probability based on ideas that ultimately derived from sensations.Footnote ¹⁴⁷ Reason in this sense had the potential to act as a kind of arbiter in matters of faith, which was increasingly understood as the act of assenting to propositions. What God reveals is undoubtedly true, Locke allows, but whether it is a true revelation ‘Reason must judge.’Footnote ¹⁴⁸ With Locke, reason moves from being intimately connected to divine revelation to being an independent judge of what actually counts as revelation in the first place.Footnote ¹⁴⁹

Again, Locke’s intention was to place constraints upon reason. With its modest reach, it was sufficient for our activities in the present world, God having equipped us for ‘the conveniences of life and the business we have to do here’.Footnote ¹⁵⁰ And even our knowledge of the natural world is significantly circumscribed: ‘what a darkness we are involved in, how little it is of being, and the things that are, that we are capable to know’. We know nothing of the true nature of the universe and remain ignorant about physical bodies and the causes of events. Our faculties, Locke wrote, ‘are not fitted to penetrate into the internal fabric and real essences of bodies’ and the knowledge that our senses provide yields ‘but judgment and opinion, not knowledge and certainty’. They might allow us to ‘draw advantages of ease and health, and increase our stock of conveniences for this life’, but fall well short of providing us with genuine science.Footnote ¹⁵¹ Again, reason serves well enough for secular purposes in the here and now.

This restrained vision of reason fitted well with an experimental programme of science that had as its primary aim the relief of the human condition in the present world. Francis Bacon had earlier outlined how, once human knowledge-making confronted the limitations imposed by the Fall, it might be oriented towards the charitable goal of human welfare: ‘knowledge being now discharged of that venom which the serpent infused into it, and which makes the mind of man to swell, we may not be wise above measure and sobriety, but cultivate truth in charity’.Footnote ¹⁵² This approach informed the mission of the early Royal Society and its programme of experimental natural philosophy. Robert Hooke, the Society’s first curator of experiments, thus noted that on account of an innate corruption, human beings were prone to error and misfortune. Experimental science was addressed to a partial rectification of those errors and to ameliorating ‘the mischiefs, and imperfection, mankind has drawn upon it self’.Footnote ¹⁵³ On this understanding, which is some distance from later assessments, science (or, more strictly, natural philosophy) was a kind of consolation prize, and the human faculties that enabled it were accorded a status that was correspondingly modest.Footnote ¹⁵⁴

In sum, over the course of the sixteenth and seventeenth centuries, much of the discussion of the powers of reason and its status in comparison to other authorities (experience, tradition, scripture), was linked to specific theological commitments. In relation to human nature, these can be correlated with differing interpretations of the biblical Fall and along varying assessments of the damage to reason that it had wrought. In relation to the divine nature, the question was whether divine omnipotence could be trammelled by human conceptions or was ultimately inscrutable. More generous appraisals of reason, characteristic of the Cambridge Platonists and, before them, many scholastic thinkers, were linked to relatively sanguine readings of the Fall along with the assumption that predicates such as ‘goodness’ could be reliably applied to the Godhead. But for those who argued that more severe and comprehensive losses had attended Adam’s lapse, and who also stressed the inscrutability of the divine will, reason and its operations were thought to be seriously compromised and limited in their reach. It was the latter stance that advanced the secularisation of reason, now understood to be a diminished natural power and not a luminous divine presence in the human mind.

3.5 The Eclipse of Trust

The Lockean proposal that instrumental reason, in spite of its limitations, could provide a more reliable guide to religious truths than trust in fallible authorities led to a new understanding of what counted as ‘reasonable religion’. As Thomas Sprat declared in 1667: ‘The universal disposition of this Age is bent upon a rational religion.’Footnote ¹⁵⁵ The vogue for rational religion was of a piece with criticisms of unreflective, implicit faith. But given the range of understandings of reason, what counted as ‘rational religion’ varied widely. At one end of the scale, those who shared the Cambridge Platonists’ generous and broad assessment of human rationality, essentially regarded the perfecting of reason, understood as the image of the divine within, as one of the chief aims of the religious life. Henry Hallywell summed up this approach with his observation that ‘Christianity is not only agreeable to, but perfective of our Rational Powers.’Footnote ¹⁵⁶ Many of his contemporaries endorsed this view.Footnote ¹⁵⁷ Importantly, the specification of Christian religion meant that believing revealed truths and the mysteries of Christianity was included in the package.

At the other end of the scale, however, for those who regarded reason as an instrument of calculation – reason as ratiocination – rational religion might be understood as a minimalist religion consisting only in those truths that were rationally comprehensible and supported by argument. This was the position associated with an (admittedly diverse) group of ‘deists’.Footnote ¹⁵⁸ One of the prominent deists, the Irish freethinker John Toland, notoriously insisted that no true religious doctrine could be ‘above reason’ or ‘against reason’. This, he contended, was an implication of the principle, urged by both Locke and the Cambridge Platonists, that reason was ‘the candle of the Lord’. For Toland, this reason was the measure of the intrinsic reasonableness of any purported doctrine.Footnote ¹⁵⁹ As he expressed it: ‘For as ’tis by Reason we arrive at the Certainty of God’s own Existence, so we cannot otherwise discern his Revelations but by their Conformity with our own natural Notices of Him.’Footnote ¹⁶⁰

Again, critique of implicit faith and the ethics of belief were central concerns. Toland insisted that if we are to be morally responsible for what we hold to be true, we must fully comprehend its content: ‘as long as he conceives not what he believes, he cannot sincerely acquiesce in it’.Footnote ¹⁶¹ Arguing that Christianity cannot enjoin belief in things that are above or against reason, Toland pointed to what was at stake: if salvation depends upon belief, then ‘the Subject of Faith must be intelligible to all’. But this logic assumed a quite new understanding of faith. Medieval thinkers endorsed the premise, but drew the different conclusion that for many, if not most, faith must be implicit and involve an attitude of trust. Such faith was the precondition for knowledge. Toland demurred: ‘I stand by it that Faith is knowledg.’Footnote ¹⁶² A new kind of moral commitment would necessarily attend this reconstrued ‘faith’: not trust in others, but a capacity on the part of each individual to fully comprehend and provide reasons for holding those propositions that now constituted religious faith.

It may seem that the principle of deploying reason to determine the veracity of revelation seems simply a repetition of Locke’s view with echoes of the Cambridge Platonists. But Locke had still been committed to the principle that many things exceeded the scope of reason, and that such things might be revealed. It was given to reason to judge the reliability of the source of revealed truths rather than judge their intrinsic intelligibility.Footnote ¹⁶³ The tendency of the deists was to omit this key step, which had still allowed for the possibility that reason might judge it necessary to accept things that went beyond its scope. This takes us to the broader question of ‘evidences’ for Christianity and rational judgements of the trustworthiness of sources of revelation (which will be considered in the next chapter).

For now, it should be clear that the dismantling of implicit faith required a new understanding of faith in which the role of trust was reassessed and diminished, while reason, however conceived, was elevated. The question of the role of trust in relation to belief had been tackled head-on by Thomas Hobbes. In his no-nonsense analysis of ‘believing in’ and how, if at all, it differs from ‘believing that’, Hobbes insisted that ‘by Beleeving in, as in the Creed, is meant, not trust in the Person; but Confession and acknowledgement of the Doctrine’.Footnote ¹⁶⁴ In direct opposition to first-century understandings, Hobbes contended that to believe in God is not to put one’s trust in God, but rather to give intellectual assent to the proposition ‘God exists’. Hobbes’s collapse of the distinction between belief-in and belief-that, and his exclusion of the trust relations, became increasingly common in the late seventeenth century, even among those less theologically suspect than Hobbes.

The classicist Meric Casaubon observed that some who had written on belief and unbelief ‘have chiefly, under that title, insisted upon trust, or trusting’. Casaubon was having none of it, making it clear that for him belief was about histories of things done and credited as true.Footnote ¹⁶⁵ We find comparable assessments among many orthodox religious thinkers. Isaac Barrow maintained that faith and belief are the same thing, referencing Aristotle’s Topics. To reinforce the point, he offers this definition: ‘To believe πιστεύειν [pisteuein] is the effect … of a persuasive argument, and the result of ratiocination.’ The object of faith, he goes on to say, is not a person or institution but ‘a proposition, deduced from others by discourse’. It follows that ‘to believe on a person, or thing’ is just a ‘figurative manner of speaking’ that can be reduced to ‘the being persuaded of the truth of some proposition relating in one way, or other, to that person’.Footnote ¹⁶⁶ We find a similar view of faith and belief being advocated by the Anglican divine and popular preacher Edward Stillingfleet. In his aptly entitled Rational Account of the Grounds of the Protestant Religion (1664) Stillingfleet tells us that faith is ‘a rational and discursive act of the mind … an assent upon evidence, or reason inducing the mind to assent’. Whenever God requires us to believe anything as true, Stillingfleet maintained, ‘he gives us evidence that it is so’.Footnote ¹⁶⁷ Matters of faith are not simply a matter of taking someone’s word for it. Faith was essentially a form of knowledge in which justificatory reasons played a stronger role than interpersonal trust.Footnote ¹⁶⁸ John Tillotson was in agreement. Faith, he declared, ‘is an assent of the mind to something as revealed by God’. All such assent, he continues, ‘must be grounded on evidence; that is, no man can believe anything, unless he have, or think he hath, some reason to do so’.Footnote ¹⁶⁹ The shift is from trust to an appeal to the evidence. On these new understandings, to believe in God or Christ was not so much to reside trust in them as persons, but to believe their edicts and utterances on the basis of some independent evidence. To the extent that faith might seem to require a degree of trust, determining the trustworthiness of a source was the business of reason.

John Locke set out a similar position on belief and its objects. To ‘believe’, Locke suggests in the Reasonableness of Christianity (1695), is to ‘assent to the Truth of Propositions’.Footnote ¹⁷⁰ This assertion effectively repeats a stance already taken in the Essay, according to which ‘Faith, as we use the word, has to do with … Propositions … which are supposed to be divinely revealed.’Footnote ¹⁷¹ Specifically, to become a Christian one need only assent to the proposition that ‘Jesus is the Messiah’.Footnote ¹⁷² Locke, admittedly, holds that other things must be believed after one has become a Christian, and in other contexts would admit that faith was also in some sense a gift that required obedience.Footnote ¹⁷³ But he could easily be construed as proposing that what faith consisted in was an objective belief in a single article.Footnote ¹⁷⁴ Locke thus shared with Herbert of Cherbury a concern to identify the fundamental propositional beliefs necessary for salvation, but rather than turning to innate ideas he looked instead to the doctrinal content of the gospels.

The demise of implicit faith and the accompanying emphasis on rational determination of the content of belief on the part of the individual will be parsed differently depending on the extent to which reason is itself evacuated of theological significance. But the direction of travel is clear, as narrower, more secular conceptions of reason gained currency. The theological origins of these new conceptions of reason notwithstanding, increasingly they will no longer mesh neatly with revelation but will rather stand over against it. If we move to the middle decades of the eighteenth century we get a good sense of where these developments are headed by considering the definitions of reason set out in the Encyclopédie (1765) of Diderot and d’Alembert.Footnote ¹⁷⁵ The relevant entry in this monument of Enlightenment scholarship offers us four meanings of ‘reason’ which fortuitously divide neatly along the lines of the two conceptions of reason under consideration. The first two refer to the more expansive understandings: (1) ‘natural faculty with which God endowed us to know the truth’, followed by (2) ‘notions which we have from birth, and common to all men of the world’. The next two, however, suggest a more restrictive, calculative reason: (3) reason as a faculty or reasoning process; and (4) sequences of truths that can be known ‘without being assisted by the light of faith’. Reason, in these latter senses, is divorced from faith and invested with the authority to render judgement on putative truths of faith, now understood in propositional terms. Over the course of the eighteenth and nineteenth centuries we witness the ascendancy of the last two, secular, instrumental conceptions of reason. Today, the first two senses of reason are now almost virtually unrecognisable except as historical relics. Reason in the two new senses might either challenge religious beliefs or lend support to them. But either way, reason is separated out from religious convictions that are now understood as consisting in knowledge claims of the kind that stand in need of the external confirmation that reason might provide.

The ensuing discussion in the Encyclopédie makes the implications of these developments plain. Reason is now ‘the true competent judge’ of all things of which we have clear and distinct ideas. It must exercise ‘jurisdiction over religion’.Footnote ¹⁷⁶ Even for those who cherished religious commitments, plural religions could be regarded as one of the most common manifestations of irrationality, excepting only one’s own religion, which was typically imagined to uniquely enjoy the support of rational judgement. For critics of religion in general, however, the accusation of irrationality could be extended to all manifestations of religion without exception. Such critique became a common feature of one strand of the Enlightenment and emerges as an implication of the first position. But across the board, reason was understood less as a participatory act or sharing in the ideas in the divine mind. Neither did it consist in a set of common notions that attracted universal assent. Reason was now a natural faculty that enabled individual judgement – albeit judgement that supposedly drew upon universally held principles.Footnote ¹⁷⁷ The putative universality of the judgement of reason was the one thing that carried over into these understandings, even as the original theological justifications for that universality silently fell away. This now made possible an opposition between faith and reason that would have been largely incomprehensible before.

Immanuel Kant would later nuance the sharp divide between reason and faith with his distinction between speculative and practical reason, stressing the limitations of the former when it came to moral and religious matters. To some degree, this is a continuation of the long-standing Protestant restriction of reason to the secular sphere. But in the meantime, considerable effort was also expended in exercises that sought show why instrumental reason was not necessarily hostile to traditional Christianity. One of the more conspicuous consequences of the ascendancy of instrumental reason and an ethics of belief was the development of new forms of natural theology. This consisted in rational proofs for God’s existence, developed in response to demands that core theistic commitments be embraced on the basis of evidence and not authority. These transitions will be the subject of the next chapter. Before turning to these proofs and their new role in providing foundations for religious belief, it is important to consider, albeit briefly, the place of early modern science in relation to these new understandings of rationality and evidence-based knowledge.

3.6 Slogans of Modernity

There is a sense in which religion was the main game in town for sixteenth- and seventeenth-century Europe. But it was not the only one. Another emerging cultural phenomenon also raised acute questions about the foundations of knowledge. This was the new science or, as the historical actors referred to it, ‘experimental natural philosophy’. Just as the Reformation had thrown open the question of the nature of religious commitment and its foundations, so the scientific revolution necessitated a re-examination of how scientific knowledge is acquired and justified, paralleling the challenges to implicit faith and trust in traditions that had taken place in the religious sphere. This is not the occasion for a full account of the rise of modern science or even of the religious factors involved in its emergence and consolidation.Footnote ¹⁷⁸ But there are intriguing parallels between the treatments of implicit faith and appeals to reason and experience in the two spheres and these cast a long shadow over subsequent developments.

One parallel lies in the appeal to first-hand experience or experimental knowledge. ‘Experiment’ is a term that we naturally associate with the methods of the sciences. However, when we examine the use of the expressions ‘experiment’ and ‘experimental’ in seventeenth-century English sources, it is striking that by a significant margin the most frequent references occur not in connection with scientific matters but in various genres of religious literature. Most common is the phrase ‘experimental knowledge of God’, but we also regularly encounter ‘experimental apprehension of God’, ‘inward experimental feeling’, ‘experimental prayer’, ‘experimental reading of scripture’, ‘experimental witnesses’, and ‘experimental divines’.Footnote ¹⁷⁹ This terminology has its origin in the Latin experimentum, which denoted ‘experience’, ‘trial’, or ‘test’. A simple translation of ‘experimental knowledge of God’ would thus be ‘experiential knowledge of God’, but the connotations of ‘trial’ and ‘test’ were also present, as was a contrast with ‘speculative’ knowledge.

In the context of the epistemic crisis precipitated by the Reformation, this emphasis on experimental religion emerged as an alternative to reliance upon authority, tradition, book learning, and speculative metaphysics.Footnote ¹⁸⁰ Martin Luther maintained that only those with ‘experimental proof’ of Christian faith were qualified to know what it is and speak authoritatively about it.Footnote ¹⁸¹ Seventeenth-century Puritan writers also emphasised the priority of experiment in the religious life. John Downame would propose that ‘experimental divinity needeth not so much reading and studying … as conference, observation and experience’.Footnote ¹⁸² First-hand ‘experimental’ knowledge of God, according to another Puritan divine, Francis Roberts, contrasts with ‘speculative’ knowledge which is ‘remote, general, confused, consisting in certain empty, comfortlesse, swimming notions, arising from natural or artificial abilities’. Roberts went on to explain, in what were standard tropes in this literature, that the distinction is akin to what physicians learn from books as opposed to direct experience with their patients, or what scholars know of distant lands from maps as opposed to what travellers encounter when they get there.Footnote ¹⁸³ Anthony Burgess linked the distinction to his critique of implicit faith, contrasting ‘dogmatical assent’ to speculative knowledge with ‘a practical, and experimental receiving of holy Truths’.Footnote ¹⁸⁴

The religious literature has abundant examples of these usages and the significance of parallel usages in the scientific context did not go unnoticed. Johnathan Edwards observed that ‘as that is called experimental philosophy, which brings opinions and notions to the test of fact; so is that properly called experimental religion, which brings religious affections and intentions to the like test’.Footnote ¹⁸⁵ More generally, it seems clear that the speculative/experimental distinction, borrowed from the religious context, was the way in which seventeenth-century thinkers conceptualised what we now think of as the rationalist/empiricist divide, a distinction that was retrospectively applied to the early modern period by later Kantian historians of philosophy.Footnote ¹⁸⁶

The sentiment that one should discover things for oneself and seek assurances for what one held to be true thus became part of the self-understanding and rhetoric of the new experimental philosophy. In keeping with this sentiment, the motto adopted by the Royal Society, founded in 1660, was nullius in verba – ‘take no one’s word for it’ or, expanding on its original context, ‘I pledge allegiance to the authority of no master’.Footnote ¹⁸⁷ Leaving aside the irony that the advice to take no one’s word for it is borrowed from an ancient authority (the Roman poet Horace), this is a clear articulation of a principle that runs directly parallel to Protestant critiques of implicit faith and reliance on authority. In this case, like advocacies of experimental knowledge, the injunction is to ignore the voice of authority and satisfy oneself about knowledge claims on the basis of first-hand evidence. The parallel becomes even more conspicuous when we consider the fact that the epigram from Horace had already been deployed in a religious context to support the rejection of implicit faith.Footnote ¹⁸⁸ This again suggests the temporal priority of religious discussions of knowledge and its justification.

An even deeper irony than the borrowing of the epigram from Horace and previous religious sources is that the new scientific enterprise was just as dependent on a version of implicit faith as medieval Christianity.

The corporate and cumulative character of the new natural and experimental philosophy meant that reliance upon the testimony of others and acceptance of ‘historical’ records of observations and experiments was foundational to the whole enterprise. Even today, and notwithstanding popular misconceptions about ‘the scientific method’, virtually everything we know about the natural world comes to us second-hand. Given an increasing specialisation of knowledge and division of labour this is true even, and perhaps especially, for natural scientists themselves. Wittgenstein has remarked in this context that justification is a social practice.Footnote ¹⁸⁹ Speaking more specifically about the public acceptance of the science of climate change, Bruno Latour has similarly insisted that scientific facts remain robust only when they are supported by ‘a common culture’ and ‘by institutions that can be trusted’.Footnote ¹⁹⁰

In the seventeenth century, with knowledge acquisition becoming a corporate and collaborative affair, natural historians and natural philosophers had to determine whose observations and experimental reports they would regard as reliable. Then as now, scientific knowledge, as Steven Shapin has demonstrated, had an ineradicable social dimension, resting upon protocols about which individuals and groups could be regarded as trustworthy. Shapin rightly points out that ‘no practice has accomplished the rejection of testimony and authority and that no cultural practice recognizable as such could do so’.Footnote ¹⁹¹ Augustine had said as much in the fifth century, and de Tocqueville repeated it in the nineteenth: ‘There is in this world no philosopher so great that he does not believe a million things on the faith of others, and who does not assume more truths than he establishes.’Footnote ¹⁹² There is a largely unacknowledged disparity, then, between the ostensibly unmediated rational and empirical foundations of natural science that is part of its public image, and the on-the-ground reality of needing to trust in others, especially when what is reported is counterintuitive and contrary to mundane experience.

On occasion, and despite a motto that suggested otherwise, this was acknowledged by the relevant parties, especially those concerned to show affinities between scientific and religious forms of knowing. Robert Boyle pointed out that when Galileo described the craters on the moon it was received by others in the astronomical community ‘upon an implicit faith, upon his authority’.Footnote ¹⁹³ Because this was a scientifically heterodox claim, based on the unsubstantiated observations of a single individual, Galileo’s status as a reliable observer was a key factor in determining the credibility of his reports. Boyle also pointed out that an ordinary seaman travelling with Columbus could have furnished the learned of Europe with knowledge of the new world capable of rectifying ‘divers Erroneous Presumptions and Mistakes, which till then they thought very agreeable to … Sciences, and so to Reason’.Footnote ¹⁹⁴ In a third example, Boyle compared experimental reports to the information conveyed by a deep sea diver who has unique access to objects that ‘lye conceal’d from other men’s Sight and Reach’. Boyle admitted that he had revised his own views about ‘submarine parts’ on the basis of such reports. He went on to suggest that the depths of God are similar to the depths of the ocean in that our opinions on divine matters need to be informed and rectified by ‘preachers of the Gospel’.Footnote ¹⁹⁵

Boyle also conceded that he relied heavily upon his assistant Denis Papin to conduct and record the outcomes of experiments because ‘I had cause enough to trust his skill and diligence’.Footnote ¹⁹⁶ Papin’s contributions were rarely acknowledged in the official accounts of experiments (which themselves were typically written by amanuenses who were equally invisible). These parallels between complex scientific networks of authority and trust, and a medieval epistemic ecosystem that relied upon implicit faith, are to some extent obscured by the rhetoric of modern science and official versions of its history.Footnote ¹⁹⁷ The nineteenth-century emergence of the idea of ‘the scientific method’ has tended to make scientific practitioners invisible – with the exception of the rare celebrity scientist – with an apparently impersonal set of procedures providing science with the requisite epistemic legitimacy.Footnote ¹⁹⁸

Yet another parallel between religious and scientific modes of knowing concerns the comprehensibility of what is being assented to. Again, it was Boyle who pointed to the fact that even naturalists must ‘admit several things, wherof they cannot clearly explicate’.Footnote ¹⁹⁹ A case in point was the hidden mechanical operations postulated as explanations of natural effects. These remained hypothetical because similar effects could be produced by different underlying mechanisms, as the contemporary example of mechanical clocks with their diverse modes of operation demonstrated.Footnote ²⁰⁰ (This situation falls under what philosophers of science refer to as the problem of underdetermination: incompatible explanations of phenomena are often empirically equivalent.Footnote ²⁰¹) Boyle also thought that the precise nature of certain laws – such as those determining mind–body interactions – were unknown and perhaps ultimately unknowable.Footnote ²⁰² Gravity offered another example of a phenomenon whose effects could be described with considerable mathematical precision, but whose ultimate nature remained a mystery. Newton offered (largely private) speculations about what gravity was, but this was never settled definitively.Footnote ²⁰³ His successors eventually came to be comfortable with ignorance about the nature of gravity and how it worked, and this again exemplifies the little commented upon contraction of explanatory ambitions that characterised the new natural philosophy. The insistence that we must fully understand the things to which we lend intellectual assent, which seems quite reasonable at first sight, has never been a realistic aspiration for those within the experimental sciences, far less those outside the scientific community. Boyle was fully aware of this as, too, was the astute Jonathan Swift, who observed that while God might command us to believe things that we do not understand: ‘this is no more than what we do every day in the works of nature, upon the credit of men of learning’.Footnote ²⁰⁴ Swift’s judgement notwithstanding, reliance on the much-derided implicit faith became one of modern science’s best-kept secrets.

It is not unreasonable to conclude, then, that while suspicion of implicit faith radically altered the religious landscape, it continued to play a covert role in the one context where we might least expect it. Knowledge did not cease to be embedded in networks of trust. It was just that the networks were different ones, established outside fractured ecclesiastical structures in the newly formed institutions of the experimental sciences.Footnote ²⁰⁵ Scientific societies strived to establish universal criteria for making knowledge claims while at the same time avoiding religious controversies that seemed to militate against consensus.Footnote ²⁰⁶ It was gentlemanly virtue, especially that of the Christian virtuoso, rather than ecclesiastical office, that conferred the necessary authority and grounded the new trust relations. Robert Boyle’s remarks on the topic of the ‘scientist as priest’ are revealing in this context. The activity of the natural philosopher, he proposed, ‘is a more acceptable act of religion, than the burning of sacrifices or perfumes upon his altars’.Footnote ²⁰⁷ Christian natural philosophers could be trusted as theological authorities; the priestly class, not so much. Yet all of this was disguised beneath a rhetoric that stressed reason, experience, and liberation from authority – a rhetoric necessitated by the tainted associations of implicit faith with the early modern travails of faith-based religion.

Historical amnesia about the borrowings of the new sciences from the sphere of religion is paralleled in the subsequent sloganising of Enlightenment thinkers. As we will see in more detail in Chapter 6, Enlightenment philosophes appropriated for themselves what was originally a Reformation image of an age of light after darkness. The same is true for the famous Enlightenment slogan that appears in Immanuel Kant’s celebrated essay ‘What is Enlightenment?’ (1784): Sapere aude (‘dare to know’ or ‘have the courage to use your own reason’). Again, this is taken from Horace, who seems to have been the first port of call for moderns in search of mottoes.Footnote ²⁰⁸ Kant’s usage turns out to have been doubly unoriginal. In 1518, on the eve of the Protestant Reformation, Philip Melanchthon alluded to the maxim in his inaugural address to the University of Wittenberg, implying that the principle ‘dare to know’ accurately characterised the mood of both Renaissance humanism and the impending religious reformation.Footnote ²⁰⁹ Subsequently in the seventeenth century, Catholic priest and early advocate of Epicureanism Pierre Gassendi adopted the phrase as his personal motto, imprinting it on his published works. Gassendi’s rejection of scholastic Aristotelianism and his championing of empiricism and atomism make him a seminal figure in the development of early modern science.Footnote ²¹⁰ It is likely that Kant first encountered the phrase in one of these writers. But the larger point concerns what these earlier usages signal, namely that the slogans adopted by Enlightenment thinkers had already been deployed in characterisations of the earlier movements of the Reformation and scientific revolution. Much Enlightenment rhetoric thus consists in ‘a transformed appropriation of Christian-reformatory insights’ as Edgar Thaidigsmann has put it.Footnote ²¹¹

Some nineteenth-century thinkers, in closer proximity than us to both the Reformation and the Enlightenment, also drew this conclusion. On numerous occasions Hegel identified the Protestant Reformation as a decisive moment in the evolution of human freedom. Gotthold Lessing also maintained that the true spirit of Lutheranism ‘requires that no man may be prevented from advancing in knowledge of the truth according to his own judgment’.Footnote ²¹² Theologian and philosopher of religion Ernst Troeltsch (1865–1923) would agree that Protestantism is ‘the religion of conscience and conviction, without dogmatic compulsion’.Footnote ²¹³ These were not merely expressions of the nationalistic pride of German authors. Scottish essayist and historian Thomas Carlyle announced that Luther’s declaration at the Diet of Worms was ‘the greatest scene in Modern European History … from which the whole subsequent history of civilization takes its rise’.Footnote ²¹⁴ In his influential and widely read History of Civilization in Europe, the brilliant French historian François Guizot described the Protestant Reformation as ‘a great movement of the liberty of the human mind, a new necessity for freely thinking and judging its own account, and with its own power’.Footnote ²¹⁵ While in more recent times ‘the Enlightenment’ would lay sole claim to this impulse, and (in its French manifestations in particular) set itself over and against religion, it is not unreasonable to argue that the first and decisive move towards the principle of thinking for oneself (for better or worse) came with the Protestant rejection of implicit faith.

If those in the early modern period thought in terms of ‘grand challenges’ and ‘wicked problems’, as many do today, at the top of their list would have been the problem of religious pluralism and confessional conflict. At a personal level, the eternal destiny of the individual soul came to be understood as vitally dependent upon the adoption of correct beliefs and practices. But which beliefs and practices? As Herbert of Cherbury had poignantly expressed it: ‘What … shall the layman, encompassed by the terrors of divers churches militant throughout the world, decide as to the best religion? For there is … none almost that does not deny possibility of salvation outside its own pale.’Footnote ²¹⁶ At the political level, moreover, religious uniformity had long underpinned social stability. Not only did post-Reformation religious diversity generate psychological uncertainty and distress, it was also accompanied by warfare, bloodshed, and suffering.Footnote ²¹⁷

Looking well ahead to the nineteenth century (and to Chapter 6), the fledgling social sciences would eventually seek to articulate rational, scientific principles that could compensate for the loss of the cohesive power of a single, unifying religion. In the interim, however, there emerged pragmatic, juridical procedures to manage the anomic political consequences of religious pluralism. These involved setting aside the truth claims of the competing traditions and seeking legislative solutions to secure a compromised but peaceful coexistence.Footnote ²¹⁸ On one account, these solutions amount to nothing less than the formation of the modern nation-state.Footnote ²¹⁹ Arguably, this de facto side-lining of religious truth claims promoted secularisation, allowing a pluralism of partly incompatible beliefs to quietly foster a scepticism about whether any of them might be true. At the same time, it had the practical consequence of quarantining religious differences by consigning them to the private sphere, again facilitating the emergence of a putatively neutral, public, secular space. This solution represented the importation into the political and legal sphere of a form of methodological naturalism. While initially a kind of legal heuristic that attracted the support of the religiously committed, it had longer-term practical implications for the status of the religious truth claims to which they all subscribed.Footnote ²²⁰

Whatever their political benefits, legal-procedural solutions were the wrong instrument for the alleviation of intense personal anxieties about what needed to be explicitly believed in order to secure salvation. In this new context, implicit faith offered little comfort, either. On the contrary, rather than providing a solution, it was often regarded as central to the problem. As a consequence, systematic approaches to propositional belief and its justification – what we now call epistemology – arose in tandem with a new understanding of Christianity in which a kind of evidence-based belief came to be elevated over a communal, trust-based, faith. Religious truths were now rendered into propositional form and defended or critiqued outside of the ecclesial and ritual contexts that had been their native environment. Early modern discussions about the ethics of belief thus first appear in the context of debates about implicit faith. An unintended consequence of thinking about religious faith in this way was the distillation of the modern idea of religion (and plural ‘religions’) understood as constituted by propositional beliefs, the holding of which required some form of rational justification. At the same time, this contributed to the birth of a modern version of philosophy in which questions to do with the foundations and justification of knowledge became a central preoccupation. This development is especially evident in the trajectory of Anglophone philosophy from Herbert to Locke. While on opposite sides of what we now call the rationalist-empiricist divide, both were responding to a new problem of religious pluralism precipitated by the perceived limitations of implicit faith.Footnote ²²¹

It must be said, in all of this, that while the overall trend is clear, the traffic was not one-way. Some Catholic thinkers continued to defend implicit faith, especially during the sixteenth and early seventeenth centuries. The doctrine even found qualified support among a few Protestant thinkers, not least because the difficulties to which implicit faith had originally been addressed had not gone away.Footnote ²²² The element of trust originally attached to faith was also strongly defended in certain quarters, not least by the reformers themselves.Footnote ²²³ In the eighteenth century, John Wesley was a conspicuous example, reacting against what he considered to be over-intellectualised versions of Christianity. Wesley invoked the authority of Luther to define faith as ‘a lively and a steadfast trust in the favour of God, wherewith we commit ourselves altogether unto God’. Genuine faith, he protested, ‘is not barely a speculative, rational thing, a cold, lifeless assent, a train of ideas in the head; but also a disposition of the heart’.Footnote ²²⁴ It is crucial, then, to observe a distinction between the teachings of the Protestant reformers on the one hand, and the epistemic crisis engendered by the Reformation on the other. The understanding of faith preached by the reformers, in combination with their rejection of implicit faith, turned out to be unable to bear the weight of the justificatory demands now placed upon it in the new context of religious pluralism. There was a mismatch, in other words, between the central thrust of some Reformation doctrines and the social and epistemic conditions to which the Reformation gave rise.

Overall, the Reformation and its aftermath represent a key stage in the evolution of a distinctively modern and Western notion of belief and, indeed, of religion. The older conception of faith/belief was to become isolated from its social and institutional context and the role played by trust diminished and derided. This placed a new moral burden on the individual believer – to be in a position to articulate evidential support, typically on the basis of reason and experience, for what was believed. At the same time, the increasingly differentiated enterprises of philosophy and science came to assume authority in these respective domains, making religious beliefs answerable to external authorities. These would come to be regarded as neutral epistemic spaces, paralleling the creation of a religiously neutral political sphere. Between the sixteenth and eighteenth centuries, this rarely constituted a problem for the legitimacy of religious belief as such, since the core propositions of Christianity were widely held to be consistent with the demands of reason and experience, and hence of philosophy and science. But all of this represented a momentous shift in the nature of belief and a key stage in the evolution of this distinctively Western, modern conception.

One way of tracking the significance of these transitions is to consider the changing nature and status of proofs for the existence of God upon which, for some accounts at least, the evidential basis of religious belief rests. Standard treatments of proofs tend to assume a set repertoire of arguments and that these arguments are to be understood against a uniform background of fixed evidentiary expectations. However, if the demise of implicit faith and accompanying rise of ethics of belief is an early modern phenomenon, and one that placed entirely new evidential demands on religious believers, ‘proofs’ must have served different functions in the pre-modern period. Along the same lines, if it were impossible not to believe in God in the medieval period, proving God’s existence would seem to be a rather pointless exercise. The next chapter explores traditional arguments for the existence of God with a view to showing how their significance radically changes in the post-Reformation period.