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I. 18th Century, Enlightenment, Encyclopedism: the meaning of these synonymic terms - II. Diderot’s and d’Alembert’s project in the context of 18th-century encyclopedism - III. The Dieu entry in the Encyclopédie - IV. Voltaire: reason before God and the problem of evil - V. Concluding remarks.

Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers [(English: Encyclopaedia or a Systematic Dictionary of the Sciences, Arts and Crafts) (28 voll., Paris 1751-1772; suppl. in 5 voll., Amsterdam 1776-1777)] was the Titanic enterprise attempted by some of the most representative exponents of the French Enlightenment, combining some of the best 18th-century cultural products around the idea of a scientific and rational arrangement of the whole of knowledge. Moving from the conviction, expressed in the preface to that work, the Discours préliminaire (1751), that “Ideas which are acquired from reading and from association with others are the germ of almost all discoveries” [Preliminary Discourse, Part II], Denis Diderot (1713-1784) and Jean-Baptiste Le Rond d’Alembert (1717-1783) gathered a number of different  intellectuals into the socalled “Society of Men of Letters,” featuring a very diverse membership in terms of origin and cultural positions. Yet, the idea was so strong and attractive that the troubled work of the philosophes marked the entire century so much that, retrospectively, the 18th century is often  interpreted as the century of the Enlightenment or the century of Encyclopedism.

I. 18th Century, Enlightenment, Encyclopedism: the meaning of these synonymic terms

Far from being a regional phenomenon, the Enlightenment (Ger.: Aufklärung, Fr.: Philosophie des lumières, It.:  Illuminismo, Sp.: Illustración) is a complex European philosophical and spiritual movement combining a single shared atmosphere with many different and often contrasting outcomes. Despite its varied solutions, the Enlightenment mainly aimed at piercing the darkness of ignorance, superstition and prejudices with the light of reason, by affirming as a definitive acquisition of Western thought the ability of reason to order the world with its own strength, and at the same time the non-pessimistic awareness of man’s intrinsic limitations. Despite the different directions it took in its own development — which may include theism, atheism, rationalism, materialism, skepticism, and both the constitutionalist-liberal approach and the one leading to the 1789 Revolution — the Enlightenment was to become one of the fundamental categories of the modern view of the world wanting to reinstate nature’s own value and to celebrate reason as unconditioned source of all values. This dual need was met by a single act of courage through which reason was due to free itself from the metaphysical, dogmatic-religious, moral and traditional restrictions, eventually replacing the traditional-metaphysical system with a universal system of nature capable of proceeding exclusively from the data of experience as accessible to internal and external senses.

Kant’s own definition in his work What is the Enlightenment? (1784) has rightly become the classic one: “Enlightenment is man's release from his self-incurred tutelage. Tutelage is man's inability to make use of his understanding without direction from another. Self-incurred is this tutelage when its cause lies not in lack of reason but in lack of resolution and courage to use it without direction from another. Sapere aude! "Have courage to use your own reason!"- that is the motto of enlightenment. For this enlightenment, however, nothing is required but freedom, and indeed the most harmless among all the things to which this term can properly be applied. It is the freedom to make public use of one's reason at every point” (E. Kant, The foundations of the metaphysics of morals, and What is enlightenment?, transl. by Lewis White Beck, Upper Saddle River , NJ: Prentice-Hall, 1997, pp. 83-84).

For the Enlightenment, as was already the case with the intellect for John Locke (1632-1704), reason is a natural power (NB: not a “substance,” as it was according to the rationalist tradition following Descartes) common to all men and women, one and the same in its fundamental determinations, spontaneously usable whenever it is free, that is once it has been purified from the errors of ignorance and superstition. At the same time, though, as a power, it is limited, i.e. incapable of rising above the senses. Such a limitation does, on the one hand, define the field of application of rationality where reason is the absolute sovereign, but, on the other hand, excludes from its scope all that may not possibly be known through the senses. This does not mean that the Enlightenment is explicitly atheistic, but it does mean it is practically anti-metaphysical and certainly anticlerical: what it the object of faith, that is of  revelation, is not considered as a subject by the Enlightenment philosophes (hence not explicitly denied either) but only excluded from the realm of what may be known by man. Forced by its own definition to move within the confines of phenomenical knowledge, the Enlightenment can infer the existence of God from the nature of the universe itself, but this does not lead it to consider true (Kant’s Fürwahrhalten) what is excluded from those confines.

As the heirs of the Italian Humanism, following the exchanges with the English  tradition the philosophes added to the former the call to sensorial experience, the theistic traits, the teachings of natural law and the social contract and more generally the scientific ideas stemming from Newton’s revolution. Being critical as well as rationalist, historicist as well as anti-historicist, atheistic as well as theistic, the Enlightenment did not hide its motley and contradictory facets; its ambiguity  is in fact a consistent consequence of the application, in the most diverse fields, of the single shared will of knocking down every form of  tradition and superstition. Such a will, in 18th-century France, took on  markedly revolutionary traits, which were absent in the English Enlightenment. For the French Enlightenment, the criticism of tradition became radical anti-historicism, empiricism became sensism, utilitarianism degenerated into egotistical hedonism, theism practically became agnosticism and materialism and though it did not deny the divine, its “position, if it was consistently developed, would lead to atheism” (Bosco, 1977, p. 20).

The spiritual renewal the Enlightenment tended to and drew its energy from,  was embodied in the need for a systematic presentation of the entirety of knowledge. However, rooted as it was in the 17th century, when philosophical research was aimed at reducing reality to simple elements (think of the second rule of Descartes’ method) determined and controlled by reason, that need was mainly  expressed in mechanicism,  i.e. an optimistic application of human reason’s interpreting mechanisms to reality in order to glimpse its most intimate structures. This approach continued into the 18th century but began to crack, due to the widening gap between scientific research and ontological inquiry. Enlightenment philosophers reproached their 17th century predecessors for interpreting reason through an exclusively ontological-metaphysical lens: for René Descartes (1596-1650) as well as Baruch Spinoza (1632-1677), Gottfried Wilhelm von Leibniz (1646-1716) and Nicolas de Malebranche (1638-1715), prior to being a knowing power, reason was essentially both human and divine “substance”; it was in fact the divine seal on human reality. Thus, the approach to knowledge of 18th-century rationalism brought to a reversal of the rational understanding of reality from an  ontological point of view, which by its own definition opened up to the theological or theologizing interpretation of reality itself: the study of the essence was replaced by the search for a scientific law. Along these lines Descartes himself appeared to be over-dogmatic, whereas Isaac Newton (1642-1727) became the champion of the new course of philosophical research. Being heirs of Descartes’ revolution, but objecting Descartes’ own scholasticism, the young Enlightenment philosophes found in the experimental method of the new physics such a formidable element of scientific productivity that they raised it to the status of rational and universal investigation criterion to be applied to any  field of knowledge.

In this common spirit, form and contents of philosophical research are unified. Both convey the same message for which giving up looking for the essence, the primary causes, while generally discarding the deductive method, as well as favouring the anti-system drive of the epoch are clear trends present not only in the contents of this period’s works, but also in the authors’ favourite genres.

Aphorisms, dialogues,  letters, dreams and paradoxes replace the unproductive and above all static and impersonal Classical treatise. An example of this are the works of François M. Arouet (Voltaire, 1694-1778), who was also quite an unsystematic contributor to the Encyclopédie and to whom we owe the Lettres philosophiques of 1734, Candide of 1759, the Dictionnaire philosophique of 1764, as well as the Défense du Newtonianisme and Historie de Jenni, where one finds the following:  “a catechist proclaims God and Newton proves him to the wise” (the Attraction entry of the Encyclopédie, drawn up by d’Alembert, goes back to Newtonism on a similar note). Generally, a further example is provided by all the fundamental texts of the lumières coming out between 1750 and 1770,  that is in the years of the troubled publication of the Encyclopédie: Emile and Contrat social (both of 1762) by Jean Jacques Rousseau (1712-1778), Pensée sur l’interprétation de la nature (1754) by Denis Diderot, Histoire naturelle by Georges-Louis Leclerc Buffon (1707-1788),  De l’esprit (1758) by Claude-Adrien Helvétius (1715-1771), Système de la nature (1770) by Paul Heinrich Dietrich d’Holbach (1723-1789), Traité des systèmes (1749) by Étienne Bonnot de Condillac (1715-1800). Precisely reading Condillac is particularly relevant to shedding more light on the tension between innovating to the point of a revolution and carrying on with 17th century rationalism, which generally pervaded the Enlightenment and particularly its official  expression, the  Encyclopédie.

In his criticism of the system, de Condillac (explicitly taken up by d’Alembert in his 1751 Discours préliminaire) recognised how distinctive it is for human nature to tend to a totalizing knowledge of reality but, at the same time, he stated that such a systematizing need is opposed to the equally human need to stick to reality itself. The 17th-century system is thus interpreted as the fruit of an abstract rationalism which  ultimately ends up being mere arbitrariness, by building closed arrangements of knowledge just like in Mediaeval times. This is because in their effort to understand reality rationalists lost the way to nature and, with it,  the value of experience (cf.  the Système entry of the Encyclopédie, drawn up by Diderot). In this light it became inevitable to go back to the tree of knowledge of De digitate et augmentis scientiarum (1623) by Francis Bacon (1561-1626), which was read by encyclopedists in a dynamic-genetic light: the system was thereby seen as an open and communal compilation using the experimental method of sciences in the process of arranging and connecting notions from the point of view of their birth and generation within the subject.

To the rationalists’ systems the philosophes oppose an encyclopaedic vision of knowledge, centred on the unavoidable originality of nature. The system of nature is radically opposed to the anti-natural approach of rationalist constructions. What Diderot wrote in his Interprétation de la nature is emblematic: “I will let my thoughts develop under my pen in the same order in which objects have freely offered themselves to my reflection. This is because they will better represent my soul’s movements and progress.” In a prose style that closely resembles that of Descartes’ Meditationes (1641), the stress put on the naturalistic aspect prevails on the rational search for rational evidence.

By giving a voice to nature’s system — a typical starting-point of the Enlightenment going back to John Locke being that the state of nature is essentially good and that to live in truth man simply has to adjust to it — the 18th-centruy philosopher sees reality as an organic whole. If one could possibly get the internal connections of all objects, a single encyclopaedic body of knowledge could be assembled out of the single sciences as its particular components. Quite appropriately, then, the year when the Prospectus  presenting the Encyclopédie was published, 1750, was taken as a milestone to retrospectively embrace and arrange within that horizon all that preceded it in the field of culture. Ultimately, the whole European 18th century appears to be drenched with encyclopedism, so much so for some scholars the 18th century and Encyclopedism have become synonymous (cfr. Abbattista, 2000).

In order to adequately express the organic structure of the whole of reality,  the philosophes thus conceived the whole of knowledge not so much as a tree of knowledge, but as a map, a globe, symbolizing the actual coherence between the real and the conceptual systems, aimed at guiding the reader into the organic system of sciences in their mutual connections. The authors of the Encyclopédie, then, were well aware that an abstract and generic type of knowledge would degenerate into empty dogmatism, if it was reduced to a static arrangement of knowledge. This is why they undertook drawing up a work a parte subjecti, that is from the point of view of the powers of knowledge rather than that of objects. To express that different approach d’Alembert used the phrase esprit systématique opposed to esprit de système. In any case, the inevitable basic ambiguities of such an enterprise — that is the  extreme difficulty inevitably arising from wanting to turn the model of nature into the model of knowledge — were apparent to Diderot himself. As he looked back at the whole enterprise he did not fail to criticise his own work which, in his view, resulted from the chaotic convergence of “endless misinterpreted, mis-assimilated, good, bad, detestable, true, false, uncertain and ever inconsistent and disparate things.”

II. Diderot’s and d’Alembert’s project in the context of 18th-century encyclopedism

Apart from the work’s scientific value, the Encyclopédie represents the great enterprise of the Enlightenment spirit in an attempt (opposing traditional knowledge and above all religious tradition) to unify knowledge and sciences on an exclusively rational basis, forcing the sceptical and lay spirit of libertine culture, the ethical and political aspirations of the emerging bourgeois and the methodological needs of new sciences into a single unified synthetic framework. It ultimately amounts to an intelligent knowledge dissemination work drawn up at a time when faith in religion and in authorities was being questioned by reason and a new faith in the abilities of reason itself and in the achievements of science was arising.

The idea of a universal and reasoned encyclopaedia had permeated the whole of  18th-century Europe in various ways. The period teemed with dictionaries and lexicons which attempted to expound a reasoned inventory of the whole of human knowledge in an encyclopaedic format. In particular Pierre Bayle (1647-1706), with his Dictionnaire historique et critique (1695-1697), had conducted a hard fight for  the development of a critical sense of history, struggling against any forms of dogmatism for the liberation of consciences from any authority principle. The fundamental shortcoming of these, according to the encyclopaedists themselves, consisted in their having ignored sciences and consequently made the enterprise “tasteless” (cf. the Encyclopédie entry, drawn up by Diderot himself). Even though Bayley’s work  reveals quite a negative notion of reason, which is unable to sort out the disputes and to avoid mistakes, this and other works had already introduced a breakdown of universal knowledge which did not stem from a  theological, but from a purely rational view of knowledge itself. The dominant position of God seen as a  guarantor of the unity of knowledge was gradually superseded by rational principles, of a natural, sense-based and materialistic kind. In fact any other form of knowledge (be it technical, sensorial or metaphysical) could qualify to be included into a single knowledge system, given that, in any case, it was human knowledge.

This is the atmosphere the authors of the Encyclopédie experienced in their analysis of universal knowledge in three great phases: history, as a fruit of the powers of memory, passively collecting direct knowledge;  theoretical sciences, as a fruit of the powers of reason; liberal and mechanical arts, as a fruit of the powers of imagination, that is of the ability to imitate (please remember that in Bacon’s tree of knowledge reason followed imagination as the end-point and the summit of knowledge;  on the other hand, reason here has an intermediate position, playing a joining role, as a ring in the chain of  knowledge as a whole).

The Encyclopédie, then, was more than a scientific enterprise which was grafted on the earlier encyclopaedic tradition immediately turning into a philosophical, exclusively human enterprise, hence explicitly opposed to any forms of metaphysical or religious knowledge. In this respect, the excursus on the philosophical tradition of d’Alembert’s own Discours préliminaire is very revealing: it explicitly refers to Bacon, it extols Newton’s and Locke’s teachings (the latter was the one who had reduced metaphysics “to what it actually had to be: the experimental physics of the soul,”) wishing to demolish the whole of Medieval thought. As a sort of chronologically arranged (dynamic-genetic) inventory of human knowledge in different fields, in its final implementation the project was eventually due to enhance its revolutionary impact not only in the religious, but also in the political field. In his brief captatio benevolentiae (in the very same context of the Discours préliminaire)  regarding revealed religion, d’Alembert wanted to somewhat balance the more marked theistic, albeit not atheistic, overtones of some of the work’s entries.

In the Encyclopédie political propaganda against any form of  cultural, religious, political conservatism is combined with theoretical-philosophical action aimed at radically redefining the whole of knowledge, breaking with, but also following on the philosophical tradition of previous centuries. The theoretical, systematic and critical approach then makes it possible to set Diderot’s and d’Alembert work apart from similar ones, such as: the Encyclopedia (1630) by J. H. Alstedius; the Grand dictionnaire historique (1674) by Moreri; the already-mentioned Dictionnaire historique et critique (1695-1697) by Pierre Bayle; the Dictionnaire des arts et des sciences (1694) by the Académie française, drawn up by Thomas Corneille (1625-1709), re-published by Fontanelle in 1732; the Dictionnaire universel français et latin by Furetière, the so-called Dictionnaire de Trévoux (1704); Lexicum technicum or an universal english dictionary of arts and sciences (1704-1710) by John Harris; the Dictionnaire économique (1709) by N. Chomel; the Dictionnaire universel de commerce (1722-1730) by Jacques Savary-Desbruslons; the Spectacle de la nature (1732-1750) by abbé Pluche; the New General English Dictionary (1737) by T. Dycke and W. Pardon, and other further works. Among these historians have even numbered the 1737 project of a Universal Dictionary of All Liberal Arts and All Useful Sciences, Except Theology and Politics drawn up by the cosmopolitan adventurer André-Michel Ramasay, one of the promoters of “inter-masonry,” which was meant to involve the members of all European Masonic lodges (cf. Lettres de M. de Voltaire, avec plusieurs pièces de différents auteurs, La Haye 1738, p. 135). Although we have no records of the connections between this Masonic enterprise and Diderot’s Encyclopédie — with its introductory and dissemination Prospectus dated 1750 and its first volume of 1751 — this remark may be useful to locate it within a specific cultural ambiance in all its nuances.

The same terminological equivalence between the 18th century and  Encyclopedism may be found in the Italian context. The Vocabolario della Crusca (in six volumes, the last one dated 1738) was published in 1729, whereas, in the late 18th century the short-lived journal Il Caffè, was the greatest example of an original combination of  encyclopedism and journalism. The latter part of the century also witnessed the publication of the Dizionari Universali [“Universal Dictionaries”] (1744, 1746, 1757) by Gianfrancesco Pivani (1689-1764), the Notizie dei letterati [Men of Letters News] (1772-1773) by Isidoro Bianchi (1731-1808) and the unaccomplished idea launched by the Venetian Alessandro Zorzi (1747-1779) of a Nuova Enciclopedia Italiana which involved many Italian personalities of the Enlightenment, but only produced the Prospetto [“Outline”] of 1776. The Encyclopédie itself, in its later development, was influenced by Italian encyclopedism, which resulted in Fortunato Bartolomeo De Felice taking part in Yverdon’s 58-volume edition of the Encyclopédie between 1770 and 1780.

However, the one who started on the implementation of the encyclopaedic enterprise was Ephraïm Chambers, who in 1727 published (with the publishing date of 1728) his own Cyclopaedia or Universal Dictionary of Arts and Sciences. This work immediately enjoyed great success and was translated into various languages (including Italian by publishers in Naples, Venice and Genoa). The novelty of Chambers’ work, unlike its above-mentioned direct antecedents Lexicum technicum or the New General English Dictionary, lay in the systematic connection between various sciences inspired by Bacon’s tree of knowledge.

Here are the facts in brief: in 1745 Gottfried Sellesius, a scholar of German origins, proposed the French publisher André-François Le Breton to translate  Chambers’ work. By spring 1745 the first Prospectus explaining the work came out, drawn up by Sellesius himself and by the rich Englishman John Mill. Despite the failure of the Sellesius-Mill agreement, the favour it was met with in the French cultural circles and the sponsorship of the project by a number of people, such as Antoine Briasson, Michel-Antoine David and Laurent Durand, in June 1746 persuaded Le Breton to entrust the editorship of the work to abbot Gua de Malves – who, however, would withdraw in 1747 – assisted by Diderot and d’Alembert. The new Prospectus in which the translation of the English work is superseded by an original encyclopaedic work. The expectation was so great that as early as 1751 the Italian Giambattista Pasquali asked for the exclusive right to translate it (an enterprise which he was unable to complete due to the simultaneous effort by publishers from Lucca, successfully ended in  1758). Within a few months more than four thousand people had subscribed to the encyclopaedia and such a high demand enabled the authors to overcome the difficulties posed by the truly exceptionally converging criticism by Jesuits and Jansenists, as well as by the party faithful to the Court. By July 1749, Diderot had already been arrested due to the manifestly subversive vein of his Lettre sur les aveugles à l’usage de ceux qui voient, and only the intercession by the vice-chancellor, the Count of Argenson and by the Police Lieutenant General Berryer secured his release in November of that same year.

As far as he himself was concerned, Diderot skilfully moved  in the political arena involving, among others, the Minister Chancellor d’Aguesseau in the appointment of his staff, and commissioning articles dealing with more delicate subject matters (such as those on religious and on theology) to more moderate party members or to clerics (Mallet, Yvon, de Prades, Pestré, Morellet, Formey, La Chappelle, Sauvages, Lenglet, Polire de Bottens, etc.). Moreover, he only published the most innovative and revolutionary statements in scientific articles, or at any rate in those not explicitly devoted to those very subjects (precisely to escape the attention of government censors, who did, in fact, at first approve all the articles). Father Berthier, a Jesuit of the “Journal de Trévoux,”   was the first to call attention to the subversive content of some articles and of d’Alembert’s own Discours préliminaire itself. Some ecclesiastics were also involved in the affair and one of them, Fr De Prades, who was working on the Encyclopédie project, got his doctorate from the Sorbonne with a dissertation taking up some of the arguments of the Discours préliminaire, which caused deep resentment in Church circles. Subsequent to the suppression decree of 7 January 1752, publishing of the Encyclopédie restarted thanks to the personal intercession by the editor in chief, Monsieur Maleserbes. Yet, on 6 February 1759 a new sentence ensued, based more on political reasons than anything else. Nevertheless, this did not stop the editors’ work either. It officially restarted in 1766 with the excuse of publishing only the illustrating tables, which certainly could not contain harmful statements.

The publishing enterprise, more publicized than hindered by multiple censorships, granted its publishers an over five-hundred percent profit and Diderot’s own fee was only a tiny part of it. In any case he was paid a great deal more than any other members of the editorial team (d’Alembert himself had withdrawn from the enterprise in 1758 precisely on economic grounds). Subsequent publications, run by different publishers over a few years, prove how much the 18th-century spirit was deeply marked by the Encyclopédie “event.”

III. The Dieu entry in the Encyclopédie

While referring the reader to the specific entry for a more in-depth analysis of  (Ú) theism and all its features, in order to understand the nature of the relationship between science and faith in the lumières, it seems useful to study the Dieu entry in the Encyclopédie and to compare it with the same entry in Voltaire’s Dictionnaire philosophique.

The issue of God, and mainly the issue of His existence, is one of the most frequent discussion topics within the Enlightenment scholars’ own cultural debate. Theistic thinkers, atheist philosophers and sceptical scientists unceasingly dealt with what, after Descartes, seemed to be the main problem with gaining adequate understanding of scientific knowledge and of any kind of knowledge in general. It was precisely the strong scientific slant of 18th-century thought that made it possible for the issue to be interpreted more within the range of physical-naturalist arguments (to be subsequently approached by Kant in his own physical-theological argument), rather than with typically metaphysical arguments (like those by Malebranche or Spinoza). The treatment of the problem of God that started thereafter was no longer conducted in a theological-metaphysical context, but within the scope of a new “philosophy of nature” which,  as such, did not show any specific speculative novelties, but framed the problem of God in an originally new perspective.

The Dieu entry in the Encyclopédie, drawn up by Jean Henri Samuel Formey (1711-1797), a Reformed preacher, professor of philosophy, journalist and university administrator, in a surprisingly moderate style, is the faithful outline of the above-mentioned debate since, from the content point of view, Encyclopedists did not mean to produce anything new but only to offer a summarising picture of the achievements of  knowledge, embracing both science and technology, so as to disseminate their knowledge among common people at large.

The entry (cited from the fourth volume of the 1772 third edition) is divided into three basic parts. The first is a brief introduction concerning the difficulty of dealing with the issue of the divine, but affording a glimpse of the internal development of the whole entry, the constant leading theme, as it were, ultimately present throughout l’Encyclopédie: the naturalistic sceptic theism before metaphysical concerns. The second is a strong criticism of P. Bayle’s views, whose scepticism paves the way to atheistic deviations – Voltaire himself defined Bayle as “the first of the dialecticians and the sceptical philosophers”).  Finally, there is a long sketch of classical metaphysical arguments – both historical and physical ones in favour of the existence of God, as they were reworked by the most important Enlightenment thinkers: the metaphysical argument set out by Samuel Clarke (1675-1729), the historical argument by Jacquelot Isaac (1647-1708) and the physical one by Bernard Le Bovier de Fontenelle (1657-1757).

Thus Formey started off reporting the views of Classical authors concerning the difficulties met when trying to adequately define the notion of God. Beyond the rhetorical technique of starting in medias res, drawing a parallel with Voltaire’s Philosophical Dictionary (see below, section IV), it is easy to understand how these few starting words, cited  almost out of a reporting duty, did not simply play a marginal role, but echo a fundamental aspect of the  Encyclopédie’s philosophical message regarding the key issue of God. The remaining part only amounted to a pedantic and scholastic critical compilation, that is an aside aimed at presenting what can be said about God (or “the being-existing-for-him-self,” l’être existant par lui-même, as it is more often called), starting from purely rational and natural grounds. Pagan or Classical authors unmistakably back up the basic idea of the whole entry.  With a double reference — as a means to doubly distance himself — the author of the entry refers to Tertullian (a Christian apologetic) the words of Tales (the father of Greek philosophy) who, having been asked by Cresus about the godhead, was allegedly unable to give anything but vague replies. In the same way a doubled distance separated the reader from Cicero (an unquestioned Classical authority), who reported about Simonides (very fine and eclectic poet): the latter too, after various hesitations, had not allegedly been able to answer the question regarding the nature of God. “From the two philosophers’ embarrassment — Formey argues — it may be concluded that there is no subject worthy of more caution in passing judgment  than that of the godhead: it is inaccessible to our view […]” (Dieu entry). Besides, Formey called on St Augustine’s religious authority to back up the Classical ones (represented by a philosopher and a poet): “In fact, as Augustine says, God is being which is talked about without being able to say anything  and which is above all definitions” (ibidem).

Having ascertained and confirmed, thanks to Classical authority, the essential incomprehensibility of God for the investigating reason (be it philosophical, poetic or religious), the author quickly draws a distinction between incomprehensibility and  inexistence. The latter not only cannot be deduced from the former, but the opposite is in fact true and demonstrable. According to the classic theistic standard, the understanding of the existence of God is self-evident, grounded as it is on the sole observation of the natural world in terms of a philosophy of nature, without any need for a thorough metaphysical mediation, and certainly without any interest in any  connection with a possible divine revelation, which was more often than not explicitly denied. The entry reads: “But even though God is incomprehensible, one should not infer thereof that he is in everything: if this were the case, we would not be able to have any idea of him and we would have nothing to say.  To the contrary, we can and must claim that God exists, that he is endowed with intelligence, wisdom, power, strength, because He has granted such prerogatives to his works: yet He possesses these qualities at a level that overrides what we are able to conceive, possessing them (1) by His nature and by necessity of His own being, not by  communication or by imprint and (2) possessing them all together joint in one simple and indivisible being and not like they are in creatures, that is in parts and scattered; possessing them finally (3) like in their sources, whereas we have them as emanations of the infinite, eternal, ineffable being” (ibidem).

As such, then, God himself is incomprehensible, but, despite this, His existence has a high degree of natural accessibility which comes to him from being cause and ordering force of the universe and of nature. One can easily find in these the traces of Dante’s “divin fattore” the ‘divine creator’ and, in the same way, He can be assigned all the qualities that nature itself possesses —  the only quantitative difference being that He possesses them to the highest degree. “There is nothing easier than knowing that God exists— the author goes on to say — that He has eternally existed, that is it impossible for Him not to possess to the highest degree the intelligence and all the good qualities that are found in creatures” (ibidem). This is followed by the almost lyrical extolment of nature as the effect of a cause that is supremely superior to man and, at the same time, as the image that in every aspect speaks of his creator. The argument is then summarised very well in the closing quotation from Racine: “L’éternel est son nom, le monde est son ouvrage.”

With the analysis of Bayle’s arguments the brief theoretical introduction ends and the more typically descriptive one starts. Pierre Bayle, in his radically critical vein, not only had wanted to deny any metaphysical validity and natural accessibility of the notion of God, but had also undermined its relevance for common sense by proclaiming the unreliability of the “consensus of nations” on this subject, the irrelevance of the latter in the search for truth and, finally, the  impossibility of drawing an adequate distinction between what comes from man’s nature and what comes to him from education (the latter argument, in line with Hobbes’ statement of the basic negative character of human nature openly opposes Locke’s teaching, embraced by the vast majority of Enlightenment scholars, about the fundamental negativity of human nature). Formey responds to Bayle that “there is a  great difference between knowing that a God exists and knowing his own nature” and concedes that this second type of knowledge is inaccessible to our “deboli lumi” [‘weak eyes’]. However, it is in the nature of man to be forced by reason to admit the existence of something that he does not understand: he is well aware of the need for this eternal being, but does not understand this being that is necessarily bound to exist, or the nature of his eternity; he understands that she is, and not what she is” (ibidem).

The third and last part of the entry analyses the contributions of the theist Enlightenment to the issue of the existence of God in the metaphysical, historical and physical realms. Samuel Clarke, a disciple of Newton’s, in his work A demonstration of the being and attributes of God: more particularly in Answer to Mr. Hobbs (sic!), Spinoza and their followers (1705), makes such an effort to demonstrate the basic truths of religion on the basis of the scientific knowledge of the time, that he argues that atheism (being common to Hobbes and Spinoza) may be assigned either to stupid ignorance, or to moral corruption or, finally, to a false kind of philosophy. From a typically theistic perspective, he states that religion and science are fully in agreement and so fully, we may add, to come as far as seeming almost the same thing (which is echoed by the already mentioned statement by Voltaire, who held him in high esteem: “a catechist proclaims God and Newton proves Him to the wise”); it is quite exemplary in this context that the Encyclopedist should set out “the metaphysical argument”  expounded by a follower of Newton’s: the identity of the science of nature, or natural philosophy, and metaphysics is a firm belief of theists.

From this point of view it then behoves to highlight the semantic shift undergone by the term “metaphysics” itself. Since Newton, it has become the doctrine of the ontological autonomy or dependence of matter.  If matter is interpreted as autonomous and ontologically sufficient, capable of determining the whole of nature simply by its features and movement, then natural philosophy cannot but have an atheist outcome; if, on the other hand, it is not autonomous but, in its set-up and order, requires a creative and ordering Mind, then natural philosophy becomes theistic. Theism and atheism are then nothing but two facets of the very same post-Newtonian materialism, which calls itself metaphysics to compensate, at least nominally,  the “weakness” brought about by the loss or of any references to what exceeds the limits of possible experience.

We do not wish to take up more geometrico the argument Clarke himself derived  from Newton and which Formey faithfully reproduced in order to support the theist case against atheism. It only behoves to point out that with Clarke’s work, and with his final public dissemination by Encyclopedists, the final word is said on the issue of the content of metaphysics and room opens up for the subsequent “transcendental” twist of research: no longer, then, the content, as limited and canonically outlined by Encyclopedism, but the feasibility itself of the scientific  proof of the existence of God and of a metaphysical entity in general, would become the fundamental issue.

“The historical argument” associated with the Protestant theologian Jacquelot, whose absolute irrelevance for a 21st-century reader suggests we just give a brief synopsis,  is aimed at undermining the worth of the arguments of a certain kind of materialist empiricism which, on the basis of historic facts, believes it can undermine the doctrine of the creation of the world and with it the metaphysical  derivation from a superior Intelligent Mind. Although the argument is based on a comparison between Biblical quotations and historical witnesses (wishing to prove that there are no certain historical references prior to that “date of creation” of the universe which was drawn from Moses account to be 2.140 or 3.943 years before), it is interesting to point out how the dispute was once again fully settled at the level of  possible experience: both the empiricist argument and its theist confutation do not  get out of the purely natural plain, thus confirming the radical anchoring of Enlightenment reason precisely to that natural boundary, which simultaneously defines its power and its limits.

At the same level is also the “physical argument,” taken up by Corneille’s grandson, the writer Fontenelle, for which the animals’ generation (peculiarity that no observation has ever denied), as far as its origin is concerned, requires an ordering Intelligent Mind. Accident-based theories can by no means be rationally accepted on the  basis of natural experience. An accidental clash of atoms should not have produced animals at the initial stage of their development (a stage at which these would by no means have been self-sufficient so as to be able to start  a new species) but at a mature or at least  an intermediate stage (at which they could survive and reproduce themselves): such a situation was clearly impossible as it clashed with the very laws of animal  development. The physical argument therefore ends up grounding the existence of God on the fact that living beings, in their own peculiar generation, are bearers of a seal (inscription) of infinity which refers to a God that is both the creator of the universe and its ordering mind.

IV. Voltaire: reason before God and the problem of evil

The Dieu entry of the Encyclopédie is as long and verbose as the Dieu entry of Voltaire’s Philosophical Dictionary is conversely short and succinct. First printed in 1764 and subsequently modified and enriched in a number of further editions, the Dictionnaire philosophique represents, along with Candide, the highest point of the author’s philosophical speculation, expounded in a clear, approachable style and with anti-systematic clearness. The stratagem of publishing it anonymously and – further stratagem within the stratagem — attributing the most controversial entries to other people whose views were merely reported, as well as the implicit agreement reached in France for a few years not to blame the author for any material that came under public fire,  made it possible for Voltaire to approach the hottest issues in matters of religion with irony and simplicity. This does not mean that the issue of God is not a fundamental issue in Voltaire’s thought; on the contrary, it is precisely the light tone of the discussion of  God that reveals the fundamental pitch (but also the existential tragedy) of the author’s own philosophical voice. His reflection, as is widely known, aims at religious tolerance, which often slips into indifference to any forms of positive religion (which Voltaire sums up in fanatic dogmatism), but in various places the basically political grounding of his polemic emerges.

The issue of God is approached, in the 1764 entry, in the form of a dialogue. Logomacus, a Byzantine theologian, holds a discussion with the Barbaric Shiite Dondinac. The punctilious Logomacus, simultaneously urged by disdain and by apostolic fervour, engages in a catechetical struggle with a member of the most natural of all religions. Indeed, the Shiite prays to God thanking him for the goods he enjoys and the evils he is tested by and is certain of the existence of  God because the whole of nature shows it. Well, this natural devotion (despite being able to become aware of God being the creator that will reward for good and will punish for evil) certainly   affords no grasp of the nature of God’s infiniteness, of the place where He is, of the way in which He can create from scratch… Such ignorance, though, does not shake the  “Barbaric infidel” who does not even realize the inessentiality of the “essential” theological issue raised by the Byzantine and who simply says: “I do not want to be a philosopher, I only want to be a man.” And concerning the knowledge of God’s nature: “will I be a fairer person, when I know it, or a better husband, a better lord, a better citizen?” The theologian is unable to find responses to such objections and while he gets ready for endless (one imagines) “preliminary instructions,” the peasant insistently concludes: “I had just built a closet at the end of my garden; I heard a mole arguing with a cockchafer. "That's a fine building," said the mole. It must have been a very powerful mole who did that piece of work." " You're joking," said the cockchafer. " It was a cock-chafer bubbling over with genius who is the architect of this building." From that time I resolved never to argue.” (God entry in The Philosophical Dictionary, Selected and Translated by H.I. Woolf, [New York: Knopf, 1924], scanned by the Hanover College Department of History in 1995). God is not a problem for Voltaire. His existence is undisputable, just as it is that every effect has a cause. In fact, the existence of God itself is one of the philosophical truths which are accessible to reason and therefore provable. But how God actually acts and what his features are is not for us to know. All the disputes of Classical and Medieval thinkers regarding God’s features are inessential, because they are absolutely inaccessible, basically indifferent to human beings from the practical point of view. Likewise there are no answers for the fundamental questions about man: “Who are you? Where do you come from? What do you do? What will you become?», says Voltaire in his The Ignorant Philosopher (1766), “It is questions that all creatures of the universe have to be asked and yet none of them answers.” God is therefore the creator and organiser of nature and of man, nothing more is accessible to man: the rest is superstition. However, the struggle against superstition (that is against any forms of knowledge meaning to go beyond the mere worship of a supreme Being and the submission to his eternal commandments; cf. Voltaire, Superstition in Philosophical Dictionary), is precisely the self-evident core of the Encyclopedists’ own philosophical message for which it is tantamount to slavery, that is an ill-omened submission to an authority’s tyranny. Besides, Voltaire, even more than Diderot and d’Alembert, does not hide that the counterpart of his polemical debate is constantly the Church. His ironic tone emerges as he writes in the “Religion” entry: “After own own holy religion, which is undoubtedly the only good one, which would be the least bad? Would it not perhaps be the simplest? Would it not be the one who taught a lot of morals and very few dogmas? Which tended to make people more ethical without forcing them to unfeasible, contradictory, offensive things for the godhead and harmful to the humankind, and did not dare threaten eternal punishment to anyone preferring to hold on to common sense? Would it not perhaps be a religion which did not support with its influence bloody tyrants, and did not flood the earth with blood due to incomprehensible sophisms?” (Voltaire,  Religion entry in his Philosophical Dictionary).

Within Voltaire’s endless output, his Dictionary lies in the second period of his philosophical activity. The first, starting with the Treatise on metaphysics (1734), is marked by a radical optimism and by the criticism against any forms of atheism, materialism and dogmatism. The second, following the upsetting experiences of the death of his friend du Châtelet (1749) and of the “metaphysical scandal” of the earthquake in Lisbon (25 November 1755), is not characterized by the abandonment of theism or by the atheistic shift to a renunciation of God, but it is marked by a dramatic awareness of a misalignment between the rational certainty of God and the rational certainty of the world. These two, despite lying both directly open to investigating reason, lead to opposite outcomes: the former to optimism, the latter to scepticism, or otherwise to pessimism.

Metaphysical certainty and historical certainty — that is those which Pascal called the “Pre-Christian” ways of approaching God, — originally in agreement in theist optimism, ultimately split under the weight of the existential tragedies for which God, for the philosopher, ultimately loses his historical self-evidence. Though he did not lose the hope that derived him from the metaphysical certainty of God’s existence (a certainty that is still clear in his homily On atheism of 1765), Voltaire was so deeply disturbed by the experience of evil that no logical argument could disprove. As the most faithful witness of the Enlightenment culture, he then produced a crack in the optimism of reason, which, as a result,  had to give way to the hope that stems from the belief in the immortality of the soul, from which only it is possible to infer the existence of God, the possibility of  moral order and justice for the world: indeed, if man was to be deprived of immortality and the resulting recovered optimism (which, though, is called “hope”), this would pave the way to an endless series of crimes and to the wreck of the whole of human society.

Published almost at the same time as the London homilies, the Dictionary, therefore, reveals Voltaire’s constant ever-confessed faith in theism. The discussion of the Dieu entry proves how, despite the profound crisis of optimism caused by the “metaphysical scandal,” his philosophy (being in this respect a paradigmatic example of the whole Enlightenment) always lies within the “pre-Christian” element referred to by Pascal (that is to say in between the way of  the pagans, who see in God the guarantor of the order of nature, and the way of the Jews, for whom God is the guarantor of the providential order of history). The biased impossibility of resorting to any forms of transcendental revelation (the Christian element), then, defines the possibilities of a philosophy which, extolling the human element anchored within the boundaries of  possible experience, of sensism and materialism, ends up stalling between the optimistic rational construction, on the one hand, and  lucid existential pain, on the other.

V. Concluding remarks

To reconstruct the development of the connections between faith and reason and between religion and scientific thought, then, 18th-century Encyclopedism, with the undeniable and essential role it played in the incubation, discussion and dissemination of the European Enlightenment, no doubt represents one of the key moments in the intellectual history of the whole of the Modern Age. In particular, the Encyclopédie is an informative work, drawn up in order to define once and for all — as pointed put by  M. Horkheimer and T. Adorno in their Dialectics of the Enlightenment (1947) — the sphere of reason’s uncontested dominion, in order to free man of the fear of the unknown and the world from magic, as well as to reverse imagination into science, by cleaving the immeasurable. The authors of this monumental work intended to show how in this context faith no longer finds any room. God does still have room, but he has to pay the toll of a theist metamorphosis. An unexpected event, though, upset the plans of the philosophes. As they were harshly criticising positive religion and any dogmatism in the name of the light of reason, precisely an event (like the death of our dear ones, a devastating earthquake, or the French Revolution itself) cast a shadow on what seemed the uncontested dominion of reason, the world of nature, its mechanical, scientific and rational explanation. The impossibility of explaining evil cracked what then turned out to have been more like faith than science: the faith in the Enlightenment reason, the goddess  Reason.

It is not accidental that Karl Jaspers (1883-1969), a German existentialist long overshadowed by Heidegger’s glow, as he took up many of the Kantian Encyclopedist overtones, resorted to the phrase “philosophical faith” (philosphische Glaube) to refer to the genuine exercise of philosophy in the open and suspended sphere of chance, a sphere that would otherwise be swallowed up by the scientific will of universal determination. Once any form of Transcendence has been denied, philosophy, faced with the awareness of the limitations of scientific investigation (not abstract awareness but one deriving from the personal experience of finitude, as transparently witnessed by Horkheimer and by Adorno), discovers that its own knowledge is basically a belief founded on the suspension of knowledge itself, that is the certainty of something that does not reveal and cannot reveal its grounding truth. Faced with the prospect of the shipwreck of knowledge, humans find themselves to be believers at root. Whether such human faith applies to the unaccomplished scientific truths or to their assumptions, whether it applies to the frail truth of a life that by searching practises philosophy, or again to Revelation’s message of salvation, opening up to transcendence and seeing its own finitude not as a limitation but as a chance still remains an inalienable inner need of human nature (cf. K. Jaspers, Philosophical Faith and Revelation, [London: Collins, 1967]). Whenever this does not happen, as is the case of the spirit of Encyclopedism, it is existence itself,  history, life, that breaks into the system, crashing the weak  certainties  of a thought that was meant to be strong.

Arising from the exaltation of the light of reason, due to its strongly sensistic and materialistic overtones (also with clear sceptical derivations), the Enlightenment ends up depriving reason of dignity and autonomy, and revealing the internal  contradiction of a movement which, faced with a natural need for wholeness, had focussed all its force on revolution and denial. The will to see the limit (Ger.: Grenze) as a barrier (Schranke) – words that were exalted on the altars of philosophical speculation by Kant and Hegel, – which was typically embodied by Voltaire’s theistic rational and inescapable suffering,  was to find in Romanticism, through the mediation of transcendental criticism, its sharpest confutation. Rousseau’s work, though, already marked, in this respect, a clear reversal of Encyclopedism into its opposite, laying the foundations for a philosophy which liked conscience more than science, feeling more than reason. So the exaltation of the light of reason entailed the realisation of its weakness. Existence crashed optimism, whether it be in the metaphysical rationalism of Descartes’ followers or in the scientific empiricism of Newton’s ones. It is not an accident that the Enlightenment ideology was both consecrated and overcome by the 1789 Revolution.


General studies on the Enlightenment: M. BONFANTINI, Introduzione alla lettura di Diderot (Torino: Tirrenia-Stampatori, 1963), N. BOSCO, “Razionalismo illuministico,” in Dizionario Teologico Interdisciplinare (Torino: Marietti, 1977), 3 voll., vol. 3, pp. 17-21; H. DIEKMANN, Il realismo di Diderot (Roma-Bari: Laterza, 1977); P.  CASINI, Diderot «philosophe» (Bari, Laterza, 1962), Introduzione all’Illuminismo. Da Newton a Rousseau, 2 voll. (Roma-Bari: Laterza, 19802) and Scienza, utopia e progresso. Profilo dell’Illuminismo (Roma-Bari: Laterza, 1994); E. CASSIRER, La filosofia dell'illuminismo (1932) (Firenze: La Nuova Italia, 19894); P. CHAUNU, La civiltà dell’Europa dei Lumi (Bologna: Il Mulino, 1987); L.G. CROCKER, Un’età di crisi. Uomo e mondo nel pensiero francese del Settecento (Bologna: Il Mulino, 1975); F. DIAZ, Filosofia e politica nel Settecento francese (Torino: Einaudi, 1962); IDEM, Per una storia illuministica (Napoli: Guida, 1973) and Dal movimento dei lumi al movimento dei popoli, L’Europa tra illuminismo e rivoluzione (Bologna: Il Mulino, 1986); P. FAVILLE, D’Holbach e la filosofia scientifica del XVIII secolo (Milano: Feltrinelli, 1976);  C. GIUNTINI, Toland e i liberi pensatori del ‘700 (Firenze: Sansoni, 1974); L. GOLDMANN, L’Illuminismo e la società moderna (Torino: Einaudi, 19713); N. HAMPSON, Storia e cultura dell’Illuminismo (Roma-Bari: Laterza, 19763); M. HORKHEIMER, T. ADORNO, Dialettica dell’Illuminismo (1947) (Torino: Einaudi, 1974); C. MOZZO DENTICE D’ACCADIA, Preilluminismo e deismo in Inghilterra (Napoli: Libreria Scientifica, 1970); S. NICOLOSI, Modernità e ricerca di Dio  (Roma: Seam, 1997); D. OUTRAM, L’Illuminismo (Bologna: Il Mulino, 1997); A. POSTIGLIOLA, La città della Ragione. Per una storia filosofica del Settecento francese (Roma: Bulzoni, 1992); G. ROGGERONE, Controilluminismo. Saggio su La Metrie ed Helvétius (Lecce: Micella, 1976); P. ROSSI, Gli illuministi francesi, (Torino: Loescher, 1962); A. SANTUCCI (a cura di), Interpretazioni dell’Illuminismo (Bologna: Il Mulino, 1979); M. SINA, L’avvento della ragione. “Reason” e “above reason” dal razionalismo teologico inglese al deismo (Milano: Vita e Pensiero, 1976); A. VARTANIAN, Diderot e Descartes (Milano: Feltrinelli, 1958); C. VASALE, La secolarizzazione della teodicea (Roma: Abete, 1978); F. VENTURI, Giovinezza di Diderot (1713-1753) (Palermo: Sellerio, 1988); M. VOVELLE (a cura di), L’uomo dell’illuminismo (Roma-Bari: Bulzoni, 1992); A.M. WILSON, Diderot: l’appello ai posteri (Milano: Feltrinelli, 1977) and Diderot: gli anni decisivi (Milano: Feltrinelli, 1984).

Studies on the Encyclopédie: G. ABBATTISTA (a cura di), “L’enciclopedismo in Italia nel XVIII secolo,” in Studi Settecenteschi 16 (2000); S. AUROUX, La sémiotique des encyclopédistes (Paris: Payot, 1979); J.E. BARKER, Diderot’s Treatment of the Christian Religion in the Encyclopédie (New York: King’s Crown Press, 1941); È. CAILLET, La tradition littéraire des idéologues, in “Memoirs of the American Philosophical Society,” Philadelphia 1943; P. CASINI (a cura di), La filosofia dell’“Encyclopédie” (Bari: Laterza, 1966); S.R. DE GROOT, Voorvitzichten van het Encyclopaedisme (Amsterdam, 1949); L. DUCROS, Les encyclopédistes (Geneva: Slatkine Réprints, 1967); D.H. GORDON, N. TORREY, The Censoring of Diderot’s E. and the Re-Extabilished Text (New York: Columbia University Press, 1945); R. HUBERT, Les sciences sociales dans l’Encyclopédie (Paris: 1923); J. LOUGH, Essays on the Encyclopédie of Diderot and d’Alembert (London: Oxford University Press, 1968); J. LOUGH, The Encyclopédie (New York: D. McKay, 1971); B. MAGNINO, Alle origini della crisi contemporanea: illuminismo e rivoluzione, (Roma: Raggio, 1946); R. PASTA (a cura di), Cultura, intellettuali e circolazione delle idee nel Settecento (Milan: Franco Angeli, 1990); J. PROUST, Diderot et l’Encyclopédie (Paris: Colin, 1962); IDEM, “Questionnes sur l’ Encyclopédie,” Revue d'Histoire Littéraire de la France 72 (1972), pp. 36-52 and Encyclopédie. Storia, scienza e ideologia (Bologna: Cappelli, 1978); J. PROUST, W. TEGA, L’unità del sapere e l’ideale enciclopedico nel pensiero moderno (Bologna: Il Mulino, 1983); D. ROCHE, Cultura dei lumi. Letterati, libri, biblioteche nel XVIII secolo (Bologna: Il Mulino, 1992); A. SALSANO, Il sogno di Diderot, Sull’Enciclopedia (Ancona: Il Lavoro Editoriale 1986); F. SCHALK, Einleitung in die Encyclopädie der französischen Aufklärung (Münich: M. Hueber, 1936); R.N. SCHWAB, W. REX, J. LOUGH, Inventory of Diderot’s Encyclopédie (Geneva: Institut et Musee Voltaire, 1971); M. SPALLANZANI, Immagini di Descartes nell’Encyclopédie (Bologna: Il Mulino, 1990); W. TEGA, Arbor scientiarum. Enciclopedie e sistemi in Francia da Diderot a Comte (Bologna: Il Mulino, 1984);  F. VENTURI, Le origini dell’Enciclopedia (1946) (Torino: Einaudi, 19803);  P. VERNIÈRE, Spinoza et la pensée française avant la Révolution, 2 voll. (Paris: Presses Universitaires de France, 1954); E. WEIS, Geschichtsschreibung und Staatsauffassung in der französischen Encyclopädie (Wiesbaden: Steiner, 1956).

Some of Voltaire’s works in English: The Philosophical Dictionary, Selected and Translated by H.I. Woolf (New York: Knopf, 1924, Scanned by the Hanover College Department of History in 1995); The best known works of Voltaire: the complete romances, including Candide, The Philosophy of History, The Ignorant Philosopher, Dialogues and Philosophic (New York: Blue Ribbon books, 1927). 

Paolo Zanna