The Philosophes and the Argument from Design: Voltaire and d’Holbach

The Enlightenment is usually viewed as a period of rising secularism, atheism and rejection of established religion. That the major thinkers of the 18th century were secular in their outlook is a firmly entrenched part of the academic canon, perhaps best exemplified by Peter Gay's The Enlightenment: An Interpretation, in which the Enlightenment is characterised as a grand conflict between reason and religion, between critical thought and established authority.1 Since the 1970’s, however, this formula has been largely superseded by a view that pits reason against Church rather than religion per se, as historians have come to recognise that many of the ‘enlightened’, including the supposedly anti-religious philosophes, retained a belief in God irrespective of their hostility to the Church.

Possibly the positivist view of the Enlightenment as an age of religion on the retreat, as a time where “religious explanations were slowly being displaced,”2 owes something to the writings of the reactionaries who opposed the changing zeitgeist. If one were to judge by the ‘grub street’ literature of mid-18th century Catholic writers in France, one might be tempted to conclude that theirs was a time of flagrant impiety and virulent atheism. The French religious reactionaries –- what Darrin McMahon has called ‘the Counter-Enlightenment from below’3 -– had no doubt that the lumiéres were godless villains aiming at the dissolution of civilized Christian society. In the reactionary propaganda of the time, the philosophes and their associates were denounced again and again as “ever impious, ever frantic” propagandists seeking to destroy God and religion with their critical philosophy and apotheosis of reason, “whether Atheist, Deist or Sceptic.”4 The atheists and deists, together with a wide assortment of Jansenists, Protestants, Jews and Freemasons, threatened the true Christian faith. The reactionary literature may be summed up as a collective cry of “O tempora, o mores!" – albeit one of targeted outrage rather than general lament. But to what extent can we take the reactionary claims at face value?

As statements about the reading public, or even the intelligentsia, these claims are patently false. There is not much to indicate that atheism was widespread among the reading public, and the violent public outcry in response to supposedly atheist publications, both in England and France, is testament to the marginalisation of atheism.5 The picture is more complicated in the case of deism, since it is not altogether easy to characterise what exactly should included under the deist label. Deism is typically defined as a belief in a non-interventionist creator-God without the trappings of revealed Christianity and institutional religious authority, sometimes accompanied by a belief in the immortality of the soul and life post mortem.6 The rational new politics of natural law and natural philosophy, it is said, called on a new, ‘rational’ religion stripped of superstition. On the whole, however, there is little to suggest that there existed a coherent deist movement, discernible as a social force in its own right. Only a small number of the people participating in ‘enlightened’ discourse were identifiably deists,7 notwithstanding claims that the number of deists was “immense”.8 While Freemasonry, the only recognizable 'movement' associated with deism, was on the rise throughout the 18th century, the masons soon veered towards Christian mysticism and even came to contain within their ranks fanatical Catholics such as Joseph de Maistre.9

Concerning polite 'enlightened' society at large, then, the reactionaries' claim that their century was one of rising atheism and deism, echoed though it is by many historians and philosophers of the 20th century, is not well grounded. But interpreted vis-a-vis the philosophes, that small circle of thinkers upon which much of the Enlightenment studies canon has focused, the statements of the reactionaries become more understandable. The charge of atheism leveled against the philosophes, for example, is certainly not without justification. Forthright, unabashed atheism did indeed make its public debut in the 18th century in the published works of La Mettrie and Helvétius and, most prominently, in Baron d'Holbach's System of Nature (1770). However, while these writers expounded uncompromisingly materialistic world-views in which there was no room for a deity, it would be wrong to assume that they were representative of the philosophes as a whole. The bulk of enlightened opinion opted for an ameliorated Christianity, and many of the philosophes were deists. Only a few of them went so far as to embrace outright atheism. Even the famously skeptical David Hume found the self-confident atheism of Frenchmen like Baron d'Holbach almost as distasteful as religious enthusiasm, since both went beyond what he regarded as the boundaries of reason.10

In retrospect, viewed through the lens of 20th century positivism, the deism of the philosophes appears strange. They had made the eradication of superstition their primary objective and proclaimed that everything should be subjected to critical inquiry. Nothing was to be admitted unless it withstood the test of reason. Why, then, did a belief in a higher being remain, albeit in the stripped down form of deism? Why did so many of the philosophes retain a belief in God despite their aggressive attacks on revealed and institutionalised religion? Why, in other words, was God not part of Voltaire's infame?

It is tempting to attribute the proclaimed deism of the philosophes to considerations of social utility. Although Voltaire sought to crush l'infame of institutionalised Christianity, he and most of the other philosophes were more or less united in their belief that religion was the most powerful force of moral constraint in society. They themselves were 'natural friends of peace' and behaved morally without the required fear of the afterlife, but the same would not be the case with the teeming masses. Without something to keep them in check, the common people would sink into depravity and iniquity.11 Voltaire asserted that a society of atheists was impossible, a paradox, "because it seems impossible that men without constraint would ever live together ... a God of vengeance is necessary who will punish sinners who escape human justice, in this world as well as the next."12 He even went so far as to oppose the open publication of d'Holbach's atheistic philosophy, fearing that it might exert a pernicious social influence. Montesquieu too approved of religion as a method for social control, arguing in his Spirit of Laws that "even a false religion is the best security we can have of the probity of men."13 But aside from the public utility of religious faith, the deism of the philosophes was based on intellectual arguments – most notably the so-called ‘argument from design’.

Voltaire, the most polemical and effective publicist of the philosophes, is a case in point. He was an empirically minded man, inspired by Locke's radical empiricist epistemology, and well read in the sciences of his time. With his Letters on the English, he did much to introduce the French intelligentsia to the works of Newton. During his exile in England, he had been greatly impressed by those “sublimest of discoveries”14 contained in the Principia Mathematica (1687), where Newton had coupled the mathematical exposition of his physical laws with a mechanical, clock-like view of the universe. In the “General Scholium” at the end of the third book in the 1713 edition of the Principia, Newton argued that the harmonious arrangement of the heavenly bodies could be explained only as the creation of an intelligent agent. It was quite inconceivable to him that such harmony could be the result of mere mechanical causes. Voltaire concurred.15 To him, atheism was only "the vice of a few intelligent persons"16 – so strongly did the mechanical world suggest a divine engineer. Voltaire's esteem for the argument from design was further increased by his reading of Francis Bacon, whom he deeply admired as the "father of experimental philosophy".17 In his popular writings, he enthusiastically advocated the inductive ‘Baconian method’ and lauded Bacon's attacks on the dry, desiccated Aristotelian rationalism of the scholastics. The new Baconian emphasis on induction clearly lent further weight to the argument from design. If the purely logical arguments for the existence of God were, to quote Bacon's much-used metaphor, "cobwebs of learning, admirable for the fineness of thread and work, but of no substance or profit,"18 the same could not be said for the argument from design. It was no grand metaphysical construction based on questionable axioms and dubious logic, but an inference based on sound empirical premises. The complexity and orderliness of the world was clear experiential evidence of a creator.

It is, it seems to me, to stop one's eyes and understanding to maintain that there is no design in nature; and if there is design, there is an intelligent cause, there exists a God. 19

The presence of complex order in nature, on which the entire argument rested, was in Voltaire's view self-evident to anyone who cared to look. In accordance with the principles of his idols Newton and Bacon, he believed that rigorous empirical reasoning could only lead one to infer from this the existence of a Creator. Voltaire concluded that "one must be blind not to be dazzled by this spectacle [of nature] ... one must be stupid not to recognize the author of it."20 Despite this enthusiasm, he seems to have realised the limitations of the argument from design, as is evident in the following passage from the unpublished Traité de metaphysique (1736) where he discussed the watchmaker analogy:

From [the argument from design], I cannot conclude anything more, except that it is probable that an intelligent and superior being has prepared and shaped matter with dexterity; I cannot conclude from this argument alone that this being has made the matter out of nothing or that he is infinite in any sense. However deeply I search my mind for the connection between the following ideas — it is probable that I am the work of a being more powerful than myself, therefore this being has existed from all eternity, therefore he has created everything, therefore he is infinite, and so on — I cannot see the chain which leads directly to that conclusion. I can see only that there is something more powerful than myself and nothing more.21

He thus acknowledged that order in nature indicated only the existence of a powerful, intelligent designer and gave no clues as to the properties of this designer, who might or might not be the eternal Platonic God conceived by the deists. In other words, a belief in a definite conception of God went beyond what could be strictly inferred from empirical observation.

In sharp contrast to Voltaire were the views of Paul-Henri Thiry, Baron d'Holbach, the most outspoken atheist among the French philosophes, whose System of Nature contained an uncompromisingly godless and materialistic philosophy of nature. D'Holbach was not at all persuaded by the argument from design, which to him did nothing to settle the question of why the world was orderly and contained complex constructions such as those witnessed in nature. Not only was the very notion of order problematic and misconceived – the very postulation of a designer-God to explain it only raised further questions.

We are incessantly told to acknowledge and revere the hand of God, of an infinitely wise, intelligent and powerful maker, in so wonderful a work as the human machine. I readily confess, that the human machine appears to me surprising. But as man exists in nature, I am not authorized to say that his formation, is above the power of nature. But I can much less conceive of this formation, when to explain it, I am told, that a pure spirit, who has neither eyes, feet, hands, head, lungs, mouth nor breath, made man by taking a little clay, and breathing upon it. 22

D'Holbach seems to have been quite content to regard the order observed in nature as the product of chance, as a spontaneously ordered maelstrom of matter in motion which just happened to fall into the patterns observed. Even if order in nature did not arise by chance – even if we were ignorant of how it arose – this did not justify postulating a deity. It was only ignorance of natural causes that gave birth to a God, since the postulation of a deity only pushed the question a step back. D'Holbach even claimed that the very notion of order was simply the product of man's unavoidably teleological perception of the world. "This order, which we admire as a supernatural effect" was only a series of motions mistakenly believed to be directed to some end.23

It represented

nothing more than a mode of considering, a facility of perceiving ... the different relations of a whole; in which is discovered, by its manner of existing and acting, a certain affinity or conformity with [man's] own.24

Thus, order could in his view be explained – or rather, explained away – as a matter of epistemology. Man's perception of the world imposed order on it, and the appearance of design required no further explanation.

Voltaire and d'Holbach are fairly good representatives of the two opposing views, deism and atheism, within the philosophe camp. It is interesting to note that Voltaire, for all his polemics, never saw it fit to reply to Baron d'Holbach's criticisms of the design argument, recognising perhaps that their differing evaluations of it were essentially irreconcilable. This irreconcilability is arguably due to the nature of the inference pattern on which the argument relies. A brief analysis of the argument may therefore shed some light on the differing positions of these two thinkers: The argument from design makes use of so-called ‘abductive’ reasoning – a type of inference to the best explanation. In short, abduction consists in choosing the hypothesis that best explains the accepted facts. Given an agreed-upon explanandum, we search for an explanans. In the case of several competing explanans, all accounting in some way for the explanandum, abductive reasoning requires us to pick the one that accounts for it in the most succinct, parsimonious and plausible way. The strength of the argument from design therefore rests crucially on the perceived quality of rival explanations of the order in nature. The 18th century thinkers did not come up with many developed alternatives to the existence of a creator-God. To those who found explanations like d'Holbach's ‘spontaneous order’ highly implausible, the deist explanation therefore carried a lot of weight.

In evaluating the strength of the design argument in the mid-18th century, it is important to consider the historical context. It would still take a century or so before Darwin published his Origin of the Species (1859). The ‘irreducible complexity’ of flora and fauna was very much an unsolved puzzle and seemed to call on a divine designer or creator. The argument from design, historically just one of Thomas Aquinas' five proofs for the existence of God, became stronger as the natural world turned out to be much more sophisticated than previously supposed. In the early 17th century, Galileo had turned his telescope to the heavens and found the universe to be an enormous physical space exhibiting terrestrial properties, and in the second half of the century, Antony Leeuwenhoek, Robert Hooke and the other natural philosophers of the Royal Society had observed nature through the newly-invented microscope to find the natural world a great deal more detailed and elaborate up close than anyone had previously imagined. The mechanistic philosophies inspired by Descartes, seeking to account for the natural world in terms of interacting particles and through the machine metaphor, were reinforced by these new discoveries, and the new world-views emerging during the Scientific Revolution thus did much to lend a new weight to the old Thomistic argument from design. Given the state of natural philosophy in the mid-18th century, a strong case could be made that the best explanation of the complexity and the orderliness of the world at the time was the existence of a creator or architect of the world. Atheism was perhaps not, in retrospect, as tenable an intellectual position as it may seem today.

In conclusion, the division within the philosophe camp on the question of the existence of a God is not evidence that they shied away from a full application of their self-proclaimed critical philosophy, nor does it indicate irrationalism on their behalf. Due to the underdetermination of the argument from design, it is understandable that many were deists – for it is to a large extent their acceptance or rejection of this argument which split them on the question of the existence of a God. Voltaire, Montesquieu and Rousseau all accepted the argument from design as a legitimate inference to the best explanation, while others, notably Baron d'Holbach and d'Alembert, rejected it. The position of men such as Hume and Diderot is more difficult to determine. Hume observed that “the whole frame of nature bespeaks an intelligent author,”25 but attacked the design argument in his posthumously published Dialogues Concerning Natural Religion (1779). His ambivalence suggests that he recognised the problematic, subjective nature of the abductive reasoning on which the argument from design relied.

Sveinbjorn Thordarson
Edinburgh, 2007


1. Peter Gay,The Enlightenment: An Interpretation, Volume 1 – The Rise of Modern Paganism (New York, 1966).

2. Gay, p. 388.

3. Darrin M. McMahon, Enemies of the Enlightenment : the French Counter-Enlightenment and the making of modernity (Oxford, 2001).

4. Augustin Barruel, Memoirs Illustrating the History of Jacobinism, translated by the Hon. Robert Clifford, F.R.S.& A.S. (London, 1798).

5. S. J. Barnett, The Enlightenment and religion: the myths of modernity (Manchester, 2003).

6. Barnett, p. 17.

7. Barnett, p. 12.

8. W. R. Ward, Christianity under the Ancien Régime, 1648-1789 (Cambridge: Cambridge University Press, 1999), p. 162.

9. David S. Katz, The Occult Tradition from the Renaissance to the Present Day (London, 2005).

10. Ward, p. 166.

11. Ronald I. Boss, “The Development of Social Religion: A Contradiction of French Free Thought”, Journal of the History of Ideas, Vol. 34, No. 4. (Oct. - Dec., 1973), p. 577-589.

12. Voltaire, Philosophical Dictionary, translated by H. I. Woolf (New York: Knopf, 1924), “Atheism”.

13. Charles de Secondat, Baron de Montesquieu, The Spirit of Laws, translated by Thomas Nugent, revised by J. V. Prichard (London: G. Bell & Sons, Ltd., 1914).

14. Voltaire, Philosophical Letters, translated by Ernest Dilworth (New York: Bobbs-Merrill, 1961), Letter XVII “On Infinity and On Chronology”, p. 80.

15. P. Casini, "Newton's 'Principia' and the Philosophers of the Enlightenment", Notes and Records of the Royal Society of London, Vol. 42, No. 1, Newton's 'Principia' and Its Legacy. (Jan., 1988), pp. 35-52.

16. Voltaire, Philosophical Dictionary, “Atheism”.

17. Voltaire, Philosophical Letters, Letter XII “On Chancellor Bacon”, p. 46.

18. Francis Bacon, The Advancement of Learning (Oxford: Clarendon Press, 1900), Book I

19. Voltaire, Philosophical Dictionary, “Final Causes”

20. Voltaire, Philosophical Dictionary, “On Religion”

21. Voltaire, Traité de metaphysique, (Manchester : Manchester University Press, 1957), Chapter 2: “Mais de ce seul argument je ne peux conclure autre chose, sinon qu’il est probable qu’un être intelligent et supérieur a préparé et façonné la matière avec habileté; mais je ne peux conclure de cela seul que cet être ait fait la matière avec rien, et qu’il soit infini en tout sens. J’ai beau chercher dans mon esprit la connexion de ces idées: « Il est probable que je suis l’ouvrage d’un être plus puissant que moi, donc cet être existe de toute éternité, donc il a créé tout, donc il est infini, etc. » Je ne vois pas la chaîne qui mène droit à cette conclusion; je vois seulement qu’il y a quelque chose de plus puissant que moi, et rien de plus.”

22. Paul-Henri Thiry, Baron d’Holbach, Bon Sens, ou idées naturelles opposees aux idées surnaturelles (Londres, 1772), Chapter 42: “Reconnoissez, nous crie-t-on fans cesse, la main d'un Dieu, d'un ouvrier infiniment intelligent & puissant, dans un ouvrage aussi merveillux que la machine humaine. Je conviendrai fans peine que la machine humaine me paroit surprenante; mais puisque l'homme existe dans la nature, je ne me crois pas en droit de dire que sa formation est au-des-fus des forces de la nature; j'ajouterai que je concevrai biens moins la formation de la machine humaine quand, pour me l'expliquer, on me dira qu'un pur esprit, qui n'a ni des yeux, ni des pieds, ni des mains, ni une tete, ni des poumons, ni une bouche, ni une haleine, a fait l'homme en prenant un peu de boue & en souflant deffus.”

23. d’Holbach, Système de la nature ou des loix du monde physique et du monde moral, (Londres [i.e.] Amsterdam, 1770), Chapter 5: “…cet ordre, que nous admirons comme un effet surnaturel…”

24. d’Holbach, Système de la nature, Chapter 5: “une façon d'envisager et d'appercevoir avec facilité l'ensemble et les différens rapports d'un tout, dans lequel nous trouvons par sa façon d'être et d'agir une certaine convenance ou conformité avec la notre.”

25. Quoted in Ward, p. 165


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