Berlin’s Savoyard Vicar: Religious Skepticism and Toleration in Mendelssohn and Rousseau

Abstract

While both Mendelssohn and Rousseau were deeply spiritual thinkers whose writings continually reflect a profound belief in a benevolent God, they both still used religious skepticism in order to undermine the logic of religious intolerance. In doing so, these religious thinkers reflect a critical assumption they share with the far less religiously inclined David Hume, namely, that skepticism is a critical tool for the promotion of tolerance. This paper analyses the skeptical and tolerant similarities in Mendelssohn’s and Rousseau’s religious thought. It explores Mendelssohn’s reception of Rousseau, before focusing on Rousseau’s arguments for religious tolerance and showing both how they reflect a skeptical undercurrent and how Mendelssohn uses many similar skeptical arguments for the same purpose. Finally, this analysis will lead to concluding thoughts on the dialectic between skepticism, faith and tolerance in the Enlightenment, and more generally, for skeptical believers ever since.

1. Introduction

When we think of religious skepticism in the 18th century, it is probably David Hume’s name that most readily comes to mind. “Saint David”, as the renowned Scottish philosopher was rather ironically known (see Mossner 1980, p. 566), arguably wrote about religion more than any other subject (with the notable exception of the history of England),1 and most of the arguments he suggested about religion were deeply skeptical. So, for example, in his Dialogues Concerning Natural Religion, Hume systematically and comprehensively undermined the argument from design that was often perceived as foundational to the natural religion many of his more spiritually inclined peers in the Enlightenment argued was common to all human beings. Two hundred years before Darwin’s theory made the argument far less popular than it was to Hume’s contemporaries, Saint David attacked it with ruthless efficiency.

Hume first points out that the argument of design is based on the analogy of the universe and an artefact, such as a house. However, as the universe is so very different from a house or any other artefact, the analogy is very weak and any inference of a similarly intentional cause would be purely conjectural and highly uncertain (Hume 1990, pp. 54–55. See also, O’Connor 2001, p. 59).

Indeed, given that the universe is absolutely different from any particular object within it, given that it is, as Hume puts it, “without parallel” (Hume 1990, pp. 54–55), analogies are particularly ill suited in our attempt to understand it, if, that is, they are possible at all.

Furthermore, as arguments by analogy are a posteriori, experiential, and therefore too inductive, i.e., deduce a general principle from several particular instances, they depend on having experience of several instances of the relevant type. However, as Hume points out, the universe is a phenomenon we have only experienced a single instance of. Indeed, we would need to have experiential evidence relating to the origin of several worlds to make an inductive argument of any force whatsoever, but, as his Philo pointedly asks Cleanthes in the Dialogues, “have worlds ever been formed under your eye?” (Hume 1990, p. 62).

Moreover, Hume argues later in the Dialogues, if we are engaging in such highly conjectural and most likely unwarranted analogies, we could just as well look at instances of unintentional processes of generation, such as in biology. Why not think of the universe as an organized body rather than an artefact? If so, could the universe not have come into being as plants and animals do, namely, without conscious design? (Hume 1990, pp. 86–91).

The Dialogues are filled to the brim with such skeptical dismantling of the precious argument of design, as Hume gadflies away in a “vehement manner, somewhat between jest and earnest” (Hume 1990, p. 60),2 with a whole range of troublesome questions; would the assumption of similarity not necessarily involve an idolatrous anthropomorphism? Indeed, why would it be reasonable to deduce from the universe a single creator God rather than many, given that anything complex and designed in the human world usually has several creators? Moreover, why would it be a good, omnipotent and omniscient God creating the best of all worlds, rather than a childish one making a first sketch in a series that improved with time? Additionally, why stop the inquiry with the divine creator, and not further ask what created it? How, Hume further asks, repeating that most tremendous religious skeptical challenge known as the problem of evil, could we possibly derive our beloved omniscient, omnipotent and good God from this world so full of suffering and evil? (See Hume 1990, pp. 72–73, 77–79 and 108–109, respectively).

Hume ends his Dialogues and its relentless skeptical argumentation by concluding that while it is impossible to derive God from nature, we still can and should have faith in his existence because of revelation (Hume 1990, pp. 138–39). Of course, Saint David does not reveal in these passages that he undermined miraculous revelations in as ruthlessly efficient and comprehensive a manner in the two parts of his section on miracles in his Enquiry Concerning Human Understanding. The first part suggests that for us to believe in a testimony about a miracle, the possibility that the testimony is mistaken ought to be more miraculous than the event it describes (Hume 2007, p. 83). In the second part, Hume lists various reasons why it would in all likelihood always be more probable for the testimony to be ill guided than for the miracle to have taken place: there simply has not been a reliable testimony yet; people are wont to describe exciting supernatural events just as they are wont to spread exciting gossip; men of the church might be eager to spread their creed with tales of miracles; miracles from different traditions contradict each other; and most often, such stories date from more ancient and therefore too less evolved stages in the history of the cultures which remembers them (Hume 2007, pp. 84–94).

Hume, therefore, skeptically undermined both the possibility of deriving religious beliefs empirically from nature, as is reflected in his attacks on the argument of design, as well as the prospect of adopting such beliefs on the basis of miraculous, supernatural revelation. This comprehensive religious skepticism relates well to his distinctly non-spiritual tendency. Famously, when Adam Smith visited him on his death bed, Saint David was less concerned with eternal life than with closing the churches and discharging the clergy (see Mossner 1980, pp. 600–1). Though it is unlikely Hume could be categorized as what we would today refer to as an “atheist”, many of his arguments, or updated versions of them, are indeed those used by the proud atheists of today.3 Still, not believing in any God whatsoever could arguably cohere with his worldview, and even if Hume did apparently believe in something, one would be hard pressed to find in his writings anything beyond agnosticism or a willingness to entertain the possibility of some sort of a cosmic intelligence.4

We find with Hume, in other words, a religious position that seems to reflect a comprehensive and fully coherent skepticism; an agnosticism that relies on skeptical arguments to undermine those used by believers. Indeed, even Hume’s non-religious skepticism, whether about induction, causality or the continuous self, is, to some degree at least, also about religion. Craig convincingly argues that Hume’s project, as a whole, was aimed at comprehensively distinguishing the mind of God from that of man (Craig 1997, pp. 1–17). While Hume’s skepticism could seem impractical, and indeed unhealthy for one’s mental state,5 it did as a comprehensive project have a practical, political implication: Hume thought that people who believe they can be certain about how God thinks, and indeed, about what he wants, tend be intolerant and dangerous. After all, if I know exactly, with absolute divine certainty, what God loves, I could also rather quickly know what and who he absolutely hates, a realization seething with potential violent if not murderous consequences. Systematically undermining both the very possibility of any human attaining such divine certainty and the pretension of those who claim to have done so, therefore, very much does promote Hume’s enlightened agenda.

Unlike Hume, both Mendelssohn and Rousseau were deeply spiritual thinkers whose writings continually reflect a profound belief in a benevolent God, as well as a genuine appreciation for the religious faiths into which they were born. Mendelssohn was, of course, an observant Jew and a fervent believer in an omniscient, omnipotent and wholly good God who ensures the immortality and ultimate felicity of all men. That God, furthermore, also ensured every single human could easily become aware of his existence and providence (Mendelssohn 1983, p. 94; 1971, JubA, 8:161). For Mendelssohn, the kind of skepticism Hume advocated was a “disease of the soul” he had very little patience for or appreciation of (Mendelssohn 1983, p. 67; JubA, 8:134).

Similarly, while Rousseau had a characteristically complicated personal relationship with Hume (see Goodman 1991, pp. 171–201),6 he seems to have had a rather more straightforward relationship with the enlightened deity of natural religion. Moreover, while arguably not a traditional Christian in the sense in which Mendelssohn was a traditional Jew, he had, at the very least, a profound admiration for the figure of Jesus and his teachings, an admiration beyond the one he accorded to Socrates: “if the life and death of Socrates are those of a wise man, the life and death of Jesus are those of a god” (Rousseau 1979, p. 308). It is, therefore, perhaps not surprising that Hume himself is reported to have told Lord Charlemont that Rousseau “has a hankering after the Bible, and is indeed little better than a Christian in his way” (Cited in Mossner 1980, p. 523).

Nevertheless, as with Hume, and in spite of their religious existential and philosophical commitments, both Mendelssohn and Rousseau used religious skepticism in order to undermine the logic of religious intolerance. In other words, both philosophers argued for religious belief on the one hand, while using skeptical arguments not unlike those of Hume on the other, doing so in order to ensure that all, or most, religious traditions would be tolerated. We therefore find here, as opposed to Hume’ s more straightforward skeptical stance, a complex and seemingly hybrid position wherein skepticism and faith are interwoven.

Furthermore, the fact that all three used skepticism in their intellectual battle against intolerance, in spite of their differences in terms of religious belief, suggests that skepticism could potentially be more closely related to tolerance than to disbelief per se. Indeed, it also raises interesting questions about how religious skepticism can be used for a particular purpose, without necessarily following it through to its seemingly necessarily agnostic end.

This paper analyses the skeptical and tolerant similarities in Mendelssohn’s and Rousseau’s religious thought. I will start by exploring Mendelssohn’s reception of Rousseau, before focusing in on Rousseau’s arguments for religious tolerance and showing both how they reflect a skeptical undercurrent and how Mendelssohn uses many similar skeptical arguments for the same purpose. Finally, this analysis will lead to concluding thoughts on the dialectic between skepticism, faith and tolerance in the Enlightenment, and more generally, for skeptical believers ever since.

2. Translated by Moses Mendelsohn

As with most intellectuals active in the second half of the 18th century, or indeed most of the European reading public of the time, Mendelssohn had a strong admiration for Rousseau’s literary talents, as well as for the daring, if at times eccentric, nature of his ideas. Part of Mendelssohn’s initiation into the enlightened world was his translation of Rousseau’s Discourse on the Origin of Inequality. It was his friend Lessing who suggested Mendelssohn undertake the project. Mendelsohn readily accepted, partly because he was eager to improve his German (see Altmann 1973, pp. 39, 48–49). Yet, other motives must have been at play, in particular from Lessing’s part.

Indeed, at the time of Mendelssohn’s translation, Lessing did much to encourage and champion his Jewish friend’s first steps in Berlin’s thriving cultural scene. So, for example, he eagerly spurred Mendelssohn on to write his Philosophical Dialogues, and then surprised him by arranging for their publication of in 1755. The same remarkable care for Mendelssohn’s burgeoning philosophical development and presence is echoed in his suggested translation project. Lessing’s suggestion reflects his awareness of quite how important a figure Rousseau was and how important he felt it was for Mendelssohn, for whom he acted as a cultural mentor of sorts at the time, to become acquainted with Rousseau’s thought and the philosophes more generally. Lessing’s suggestion, moreover, echoes his own earlier career; he had early on in his life as an intellectual initiated Rousseau’s reception in Germany with a review of his Discours sur les Siences et les Arts a few months after it had been published in France, referring to it as a “masterpiece” (see Nisbet 2008, p. 96). Lessing, furthermore, also translated a collection of essays by Voltaire, dramas and theoretical texts by Diderot (Nisbet 2008, p. 270). His suggestion that Mendelssohn translate Rousseau accordingly also reflects his own understanding of quite how critical familiarity with French culture was to successfully integrating Berlin’s intellectual scene (Nisbet 2008, p. 87).

Indeed, Frederick the Great, whose support for culture made him the most important political figure in the intellectual Enlightenment throughout Europe, had done much to make Berlin’s intellectual life rather French. This, of course, reflected Frederick’s own admiration for French writers and thinkers. In spite of his reservations with regard to Rousseau’s subversive political ideas, he had offered him refuge (see Blanning 2016, pp. 353–54). Frederick was furthermore an almost lifelong fervent admirer of Voltaire, a man whom, he wrote to Baron Grimm, Ancient Greece would have made “a god and raised a temple in his honor” (Blanning 2016, p. 361). While Voltaire’s extended stay at sans-souci ended somewhat poorly, the King and the philosophe kept corresponding until Voltaire’s passing (see Blanning 2016, pp. 360–61).7 This Francophile streak extended to Frederick’s royal academy, whose proceedings he ordered published in French, and whose presidency he entrusted in 1746 to the French mathematician and Philosopher Pierre Louis Maupartuis, who Voltaire had recommended he invite to Berlin (Calinger 1968, p. 240). Upon Maupartuis’ passing in 1759, he sought (and failed) to recruit D’Alembert, who together with Diderot had co-edited the Encyclopédie (Calinger 1968, p. 240). Indeed, Frederick had even offered protection and membership of his academy to the notorious La Mettrie, whose atheism and amoralism was perceived as extreme even among the most free thinking members of the Enlightenment (Nisbet 2008, p. 88).

More generally, the fascination of the Aufklärung and its cultural milieu for the intellectual heroes of the lumières was wide ranging. Kant, to go for the jugular, thought of Rousseau, in Cassirer’s apt phrasing, as “the Newton of the moral world” (Cassirer 1981, p. 8);8 Rousseau had revealed the underlying principles of human nature as Newton had done in the realm physics (Kant 1942, pp. 58–59. See also Cassirer 1981, p. 89 and Shell and Velkley 2017, p. 195). Kant’s admiration was such that his house held no pictures except for a portrait of Rousseau hanging over his writing desk (Kuehn 2001, p. 272), and he is famously said to have only missed his ever regular walks during the several days he was engrossedly reading Rousseau’ Emile (Cassirer 1981, p. 86; Stuckenberg 1882, p. 147).

Yet, at the same time, the German intellectual scene also reflects a widespread suspicion the philosophes. As Bourel notes, Aufklärung figures such as the philosopher Fülleborn, the theologian Eberhard or the poet and writer Wieland all affirmed “the abyss that separates French thought from German thought” (Bourel 1978, p. 310). Mendelssohn, for one, seemed to have carried a lasting distrust for what the French were up to intellectually. He disliked the frivolity, which, he felt, replaces serious thinking for a bon mot (Bourel 1978, p. 312), and was aghast at the more radical writers who advanced materialist, cynical and theologically pessimistic positions so radically different from the profoundly optimistic Leibnizian spirituality he himself tirelessly advocated (Altmann 1973, p. 30). So, for example, he rather angrily branded the notion expounded in Voltaire’s Candide that a more perfect world would very much be possible as “obvious nonsense […] utterly ridiculous” (Mendelssohn 1997c, p. 115; JubA, 1:360).

Indeed, Mendelsohn, usually a cautious thinker who sought to avoid unnecessary controversy (Altmann 1973, p. 215), even dared criticize his Francophile King in what was, given the circumstances, a rather scathing review of Frederick’s Poesies Diverses in Nicola’s weekly Literaturbriefe (Mendelssohn JubA 5.1, pp. 187–99. See also Shavin 2007, p. 19). In his French poetry, the King described the cruelty of this “unhappy universe” (Frederic 1760, p. 65), wherein nature “seems to enjoy their [human beings’] misfortune/Merit, Dignity, Birth/Nothing exempts from suffering/In our destinies, Evil prevails”.9 The pessimistic tone Frederick’s verses reflect is far nearer to Voltaire’s Candide than to Leibniz’ optimism. Tellingly, Frederick mentions Voltaire as having earned the one kind of immortality he did apparently believe possible, namely, enduring literary fame (Frederic 1760, p. 78).

Mendelssohn, who revealingly notes early on in his review that it is a pity the work is written in French rather than German (Mendelssohn JubA, 5.1:188–189), is clearly dismayed by Frederick’s high regard of Voltaire’s strain of thought and by its presence in his poetry. While adopting a respectful tone towards his ruler, Mendelssohn is particularly perturbed by the Frederick’s seeming denial of immortality. He carefully suggests it would be impossible to ascribe such a position to “the sage to whom we owe these poems”, before warning the audience that “this is by no means the true way of thinking of the crowned philosopher”, and that “the fallacies of an Epicurus are much too shallow for the soul of a Marcus Aurelius” (Mendelssohn JubA, 5.1:192).

All in all, it is not surprising, therefore, that for the Socrates of Berlin, “philosophy is at home in Germany” (Mendelssohn JubA, 5.1:321. See also Bourel 1978, p. 326). Still, Rousseau was no Voltaire and while Mendelssohn did have serious reservations about his thought, he also had a lasting interest in it. As he tells Lessing in the public letter accompanying his translation of the discourse, he very much appreciated working on it and was clearly fascinated by Rousseau’s ideas. Nevertheless, he was also very far from agreeing with his views, in particular regarding the superiority of the state of nature to social life (see Beiser 2009, p. 225). For Mendelssohn, that aspect of Rousseau’s thought had a childish ring to it. While interesting and written with “divine eloquence” (Mendelssohn JubA, 2:83), it was, to put it plainly, not of any genuine practical interest, and therefore not quite serious. Rousseau, Mendelssohn suggests, must have gone to such unconvincing length out of a “childish love of strangeness” (Mendelssohn JubA, 2:83).10

For Mendelssohn, a philosopher more concerned with actual lived reality rather than with the merely speculative, Rousseau could simply not really have wanted to do away with society, even if he was able to make a philosophical case, it would be better to do so. Indeed, Mendelssohn argues that Rousseau himself showed his appreciation of social life and culture in the foreword wherein he dedicates the book to Geneva (Mendelssohn JubA, 2:84). If social life would be so degrading, why would Rousseau have dedicated his work so enthusiastically to a beloved republic where he “had the good fortune to be born” (Rousseau 1997a, p. 114)?

Mendelsohn was again to explicitly critique Rousseau in his review of Julie, ou la nouvelle Héloïse. Mendelssohn deplores the novel, finds it boring, overly philosophical and therefore dramatically clumsy (Beiser 2009, p. 236). Still, Mendelssohn’s interest in the fascinating oddball that was Rousseau is clear nonetheless. Furthermore, while he does not mention in any of his writings the work this paper’s comparative investigation is most deeply engaged with, namely Emile or on Education, it is rather likely Mendelssohn read it, or at the very least knew some of its main tenets (Sorkin 2017, p. 106). Not that this is critical to the present analysis; however direct the line of influence between the vicar’s religious skepticism and Mendelssohn’s, the similarities here explored remain of great philosophical interest.

Incidentally, while it seems unlikely Rousseau read anything Mendelssohn wrote, we do have some reason to think he was interested in his work. In a fascinating testimony of his encounter with Rousseau, Christian Felix Weisse, the writer and pedagogue widely regarded as the father of modern German children’s literature, visited Rousseau at Montmercy. Weisse reports that he gave Rousseau Mendelssohn’s translation of his Discourse on the Origin of Inequality, as well as Mendelssohn’s Phädon. This seemed to have awakened Rousseau’s curiosity, as he made Weisse tell him everything he knew about Mendelssohn. Hearing about the Socrates of Berlin, Rousseau reportedly said that “he wanted to have Mendelssohn’s observations translated, so that he might read them, because they came from a Jew; for otherwise there was not a book in the world he would read” (Waterhouse 1922, p. 114).

In 1759, when Rousseau expressed to Weisse his interest in reading observations written by a Jew, he was, by his own account, already working on his Emile, a work which in his Confessions he claimed had cost him “twenty years of meditation and three years of labor” (Rousseau 1995, p. 324). The crux of the book’s position on religion, religious skepticism, and tolerance is embedded in the famous profession of faith of the Savoyard vicar. Indeed, according to Rousseau, this passage contains “more or less” the result of his arduous research into the moral and religious questions that had concerned him since childhood (Rousseau 1986, p. 55).

Mendelssohn’s own position on religious skepticism and toleration is, at least in some ways, parallel to the vicar’s. In order to explore the similarities between Mendelssohn and Rousseau’s vicar, we will now analyze the arguments Rousseau uses in this critical passage to promote toleration and the ways in which they relate to skepticism, and show how similar arguments for toleration, as well as their pronounced skeptical leanings, can be found in Mendelssohn’s writing as well.

3. Professions of Faith, Skepticism and Tolerance

While Rousseau’s vicar at times exhibits a skeptical attitude, and uses skeptical arguments to, among others, promote toleration, it is clear from his profession that he does not think of himself as a skeptic. Indeed, he explicitly states that a life of doubt is, to him, one of suffering: “I have never led a life so constantly disagreeable as during those times of perplexity and anxiety, when I ceaselessly wandered from doubt to doubt” (Rousseau 1979, p. 268). The suffering of doubts are such that Rousseau finds it hard to think there can be genuine skeptics: “How can one systematically and in good faith be a skeptic?” asks his vicar, before saying that “these skeptic philosophers either do not exist or are the unhappiest of men. Doubt about the things it is important for us to know is too violent a state for the human mind, which does not hold out in this state for long” (Rousseau 1979, p. 268).

Mendelssohn’s position is very similar. He too describes doubts as terribly painful. Discussing a time in his life when his “feet wandered from the blessed path of truth”, Mendelssohn writes that “like hellish furies, cruel doubts about providence tortured me” (Mendelssohn 1997b, p. 27; JubA, 1:64–65). Furthermore, Mendelssohn too believes skepticism is one among highly implausible positions only confused philosophers could come to hold, positions that cannot really be taken seriously by anyone who has not lost his common sense in dangerously befuddling speculations: “The idealist denies the actual existence of a material world. The solipsist, if anyone actually could be one, denies the existence of all substances other than himself, and the Spinozist says that he himself is not an independently existing being but rather a mere thought in God. And, finally, the skeptic finds everything a matter of uncertainty and subject to doubt. I cannot believe that anyone has ever maintained in earnest the truth of these far-fetched suppositions” (Mendelssohn 2012a, p. 71; JubA, 3.2:79).11

For Rousseau as well as for Mendelssohn, the skeptical confusion arises because of the overly abstract nature of speculative philosophy. In Mendelssohn’s case, the crux of the problem relates to the inherent unreliability of our language when it is brought to bear on highly abstract and abstruse metaphysical matters. So, in his prize essay, Mendelssohn explains that given the unreliability of abstract metaphysical language, “the slightest inattentiveness makes it possible for thought to lose sight of the subject matter, leaving behind merely empty signs,” making the most cogent philosopher “appear to be only playing with words” (Mendelssohn 1997a, pp. 272–73; JubA, 2:290–291. See also Fogel 2016, p. 57). In a similar vein, when discussing Spinoza’s metaphysics, Mendelssohn writes that “we are in a region where our thoughts allow themselves to be grasped only by virtue of the silhouettes of the words we use for them”, a region where accordingly it is “easy to fall into error”, which is why, Mendelssohn says, he is so “inclined to explain all the disputes of the philosophical schools as mere verbal disputes, or at least as originally springing from verbal disputes. Change the least little thing in the silhouette, and straightaway the whole picture takes on a different aspect” (Mendelssohn 2012a, p. 92; JubA, 3.2:104). Accordingly, in Jerusalem he writes that “too much talk about a matter does not render it any clearer, but rather obscures whatever faint light of truth there is” (Mendelssohn 1983, p. 89; JubA, 8:156).12

The vicar again speaks rather similarly: “the jargon of metaphysics has never led us to discover a single truth, and it has filled philosophy with absurdities of which one is ashamed as soon as one has stripped them of their big words” (Rousseau 1979, p. 274). This is not to say that Mendelssohn’s and Rousseau’s critiques of speculative philosophy are analogous. While the vicar does here complain, in a rather Mendelssohnian tone, about the misleading nature of metaphysical language, the focus of Rousseau’s critique is not the linguistic aspect of philosophical speculation per se. Rousseau’s case against speculative philosophy is part of a wider rebuke of philosophy as encapsulating the kind of vanity, dishonesty and decadence that characterizes modern human life and distances it from the simpler, more authentic and honest natural existence. Indeed, philosophers do not seek truth; rather, they rely on sophisticated argumentation to distinguish themselves and find glory. “If the philosophers were in a position to discover the truth, who among them would take an interest in it?” asks the vicar, before adding that “there is not a single one of them who, if he came to know the true and the false, would not prefer the lie he has found to the truth discovered by another. Where is the philosopher who would not gladly deceive mankind for his own glory?” (Rousseau 1979, pp. 268–69. See also Quadrio 2009, p. 190). Rousseau therefore presents himself not as a “scholar” or a “philosopher” but as a simple man, “a friend of the truth” (Rousseau 1979, p. 110). Similarly, the vicar states that “I am not a great philosopher and I care little to be one. But I sometimes have good sense, and I always love the truth” (Rousseau 1979, p. 266). It is the philosophers’ pride that takes us beyond the limit of our natural faculties and betrays a healthy, humble awareness of the insufficiency of the human mind, drawing us to dangerously confusing abstract speculation. Accordingly, the vicar realizes that far from delivering him from his “useless doubts”, philosophers would only “cause those which tormented me to multiply and would resolve none of them” (Rousseau 1979, p. 269).

So, on the one hand, both Mendelssohn and Rousseau deride skepticism, and tend to think of it as the result of an overly speculative, and thoroughly misguided, or even dishonest, philosophical position. On the other hand, however, precisely by virtue of their belief overly speculative thinkers are lead astray by their unreliable form of thought, both are skeptical of the possibility of attaining philosophical precision in metaphysical matters. In other words, they exhibit a kind of skepticism towards philosophy itself. Critically, however, this does not mean they believed they could not reach any metaphysical knowledge whatsoever. They are after all both believers in a metaphysical God. But beyond that proposition, which in and of itself is already of course a rather significant one, they are both reluctant to commit themselves to any detailed metaphysical position and remain wary of any pretense to absolute clarity about that shadowy realm of metaphysics.

In order to avoid the seemingly obvious contradiction between their belief in a metaphysical God and their metaphysical skepticism, they both present their path to their belief in a providential God as one which eschews complex speculation, and consists instead of simple, commonsensical inferences. Indeed, as mentioned above, the vicar does not have high opinions of philosophers more generally. Having leafed through their books, he finds them “all to be proud, assertive, dogmatic (even in their pretended skepticism), ignorant of nothing, proving nothing […] If you ponder their reasoning, they turn out to be good only at destructive criticism”. It is clear to the vicar, as indeed to Rousseau, that listening to them is “not the means of getting out of my uncertainty” (Rousseau 1979, p. 266). While the vicar does suggest some basic inferences for his belief in God,13 the general sense is that his fate rests less on philosophical argumentation, and more on an immediate, natural sense of his sublime presence. Accordingly, having realized philosophers would not deliver him from his “useless doubts” the vicar decides to “consult the inner light” (Rousseau 1979, p. 269) and eventually does reach spiritual clarity “I perceive God everywhere in His works. I sense Him in me; I see Him all around me”. This clarity, furthermore, remains as long as he does not veer into overly abstract speculation: “as soon as I want to contemplate Him in Himself, as soon as I want to find out where He is, what He is, what His substance is, He escapes me, and my clouded mind no longer perceives anything” (Rousseau 1979, p. 277).

In a similar vein, when summarizing in To the Friends of Lessing his view that Judaism consists of revealed law (rather than revealed doctrine), and therefore presupposes conviction based on reasonable evidence, Mendelssohn adds that he is “not talking about the metaphysical arguments we are accustomed to carry on in books, nor about scholastic demonstrations that have stood the test of the most subtle refinements of critical probing, but about the dicta and the judgments of a simple common sense that looks things straight in the eye and calmly takes their measure.” While Mendelssohn proclaims he is “a great admirer of metaphysics”, and believes the truths of natural religion can be proven as apodictically as those of geometry, his conviction in their truth does not depend on metaphysical arguments: “one can cause me to have doubts about my arguments” he writes “one can show me that in places my reasoning is in error, but yet my conviction remains unshaken” (Mendelssohn 2012b, p. 157; JubA, 3.2:197).

So far, then, we have in both Mendelssohn and Rousseau a line of thinking which rejects skepticism as a comprehensive position, yet skeptically denies having attained certainty on the basis of philosophical argumentation. Their tone might be different: Mendelssohn related his love and admiration for philosophy, Rousseau, in a characteristically contrarian move, thoroughly deprecates philosophers. Yet, both still explicitly refuse to depend on philosophical argumentation as anchor of their faith.14 Mendelssohn might suggest they are in principle possible, but still both he and Rousseau certainly remain skeptical of philosophical proofs for the critical beliefs about natural religion they both nevertheless still take to be true because of other forms of reasoning.

Theirs, therefore, is a “limited epoché”15 which is applied to philosophizing, but not to inferences portrayed as simple and commonsensical. Of course, the differentiation of positions classified as “simple” and those perceived as “speculative” is in and of itself controversial. It seems likely that plenty of opposition could be found, whether in terms of argumentation or perhaps more relevantly in terms of common sense or natural sentiment, to the doctrines of natural religion both Mendelssohn and Rousseau fervently believed in. These religious views might be commonsensical to them, but of course that does not make them ipso facto commonsensical tout court.

Yet, even if limited, their thinking does very much reflect a skeptical streak that suspends judgment about speculative metaphysics. Indeed, both furthermore at times engage in religious skepticism, making arguments not unlike those of Hume. Critically, they primarily make such skeptical arguments about religion not to undercut religious belief as much as to argue for religious toleration. Let us begin by explore Rousseau’s arguments for toleration, before looking for similar arguments in Mendelssohn.

As we saw above, Rousseau’s vicar proudly proclaims not to be a philosopher. His arguments for religious tolerance are therefore not developed in a systematic and clearly delineated manner. Looking at the passages wherein these claims are presented, however, it seems to me that we can find at least five related but different arguments against religious intolerance.

First, Rousseau presents arguments for the universality of natural religion and its God. “If one had listened only to what God says to the heart of man, there would never have been more than one religion on earth” the vicar says, before adding that “one must be possessed of a mad vanity indeed to imagine that God takes so great an interest in the form of the priest’s costume, in the order of the words he pronounces, in the gestures he makes at the altar, and in all his genuflexions” (Rousseau 1979, pp. 295–96).

Second, the vicar argues for the impossibility of an exclusivist hold on religious truths out of the impossibility of an evil God. A God that would create humans and leave them bereft of the possibility for salvation, because, for example, they have no access to the one path to blessedness, would be evil. Accordingly, the vicar states that: “If there were a religion on earth outside of whose worship there was only eternal suffering, and if in some place in the world a single mortal of good faith had not been struck by its obviousness, the God of that religion would be the most iniquitous and cruel of tyrants” (Rousseau 1979, p. 297).

Third, the problem of human testimony. Indeed, any revelation is always related to us by other human beings, and these testimonies, the vicar says, are “at bottom only that of my own reason and adds nothing to the natural means God gave me for knowing the truth” (Rousseau 1979, p. 297). He adds that enthusiastic apostles will of course say that God himself spoke, though of course, regrettably, he always speaks through other men: “it is men who are going to tell me what God has said. I should have preferred to have heard God Himself” (Rousseau 1979, p. 297).

Fourth, the argument of endless comparative religious research: were there to be only one salvific religion, we would all have to spend our lives comparing all options in order to find it. After a life of endless pilgrimages all over the world, with the instability and hardships that would inevitably follow, “he who has enjoyed the most robust health, best employed his time, best used his reason, and lived the most years will hardly know what to think in his old age; and it will be a great deal if he learns before his death in what worship he ought to have lived”(Rousseau 1979, p. 306).

Fifth, the argument from the problematic status of miracles. Exclusivistic religions are often based on miraculous revelations, but, somehow, these miracles “are worked at crossroads, in deserts, within the confines of a room; it is there that they have an easy time with a small number of spectators already disposed to believe everything” (Rousseau 1979, p. 299). Beyond the issue of the frailty of human testimony already mentioned above, Rousseau suggests a further problem with miracles as attesting the truthfulness of a revelation, namely, that those that proclaim God perform miracles also claim the Devil sometimes does, accordingly, “after the doctrine has been proved by the miracle, the miracle has to be proved by the doctrine, for fear of taking the Demon’s work for God’s work” (Rousseau 1979, p. 299).

It seems to me that out of these five arguments, two are positive and three are skeptical. The positive arguments are those about the universality of religion, and the impossibility of an evil God who would deny the possibility of salvation from any of his creatures. Both make positive claims; the former that there is a common religious core, and the latter that there is a good God, rather than a mischievous or a frankly evil one. The arguments about testimonies, miracles and comparative research are skeptical. Indeed, specifically those about the problematic nature of testimonies and miracles are rather similar to the arguments made by Hume in his own critique of miracles. The argument about comparative research is a reductio ad absurdum, a kind of argument that is of course often found in skeptical writings.

Mendelssohn agrees with Rousseau’s positive arguments. He clearly believes there is a common, universal religious core, one that can be grasped by the common light of human reason. A Greenlander observing a sunrise would have the same religious insight, he writes, as the writer of the psalms (Mendelssohn 2012b, p. 158; JubA, 3.2:198). Unlike Rousseau, however, he does not advocate or entertain the thought of one universal religion. He argues explicitly that the multifacetness of the variety of religions that all express that universal core reflects God’s will (Mendelssohn 1983, p. 138; JubA, 202). This, incidentally, enables him to go beyond tolerance and reach the higher threshold of pluralism; a position that not only tolerates differences, but finds some positive aspect to them (Mendelssohn 2011, p. 32; JubA, 19:178).16

Mendelssohn also agrees with Rousseau’s second positive argument, namely, that a God who would leave humans stranded, incapable of gaining access to an exlusivistic salvific creed, would be evil. So, in a letter to Rabbi Jacob Emdem, Mendelssohn asks “shall all the inhabitants of the earth from east to west, except for us, be cast into a pit of annihilation and be abhorrent to all flesh if they do not believe in the Torah, which was given as an inheritance to the congregation of Jacob alone?” (Mendelssohn 2011, p. 32; JubA, 19:178). A few lines later, Mendelssohn insinuates—similarly to Rousseau—that a God who treats his creatures so would be a tyrannical ruler (Mendelssohn 2011, p. 33; JubA, 19:178).17

Indeed, in his public response to Lavater, in which according to Sorkin he “appears to have acted on, or indeed acted out, Rousseau’s ‘Vicar of Savoyard’” (Sorkin 2017, p. 106), Mendelssohn rebukes the notion that Judaism posits itself as the sole valid pathway to achieving the loftiest human goals. Mendelssohn is eager to emphasize Judaism does not present itself as the exclusive path to salvation, writing that if a “Confucius or a Solon lived among my contemporaries, I could, in accordance with the principles of my religion, love and admire the great man, without hitting on the ridiculous idea of wanting to convert a Confucius or a Solon” (Mendelssohn 2011, p. 10; JubA, 7:12). This enables him to subtly contrast his faith to Lavater’s; while Christianity is burdened with “this ridiculous idea”, Mendelssohn notes that “the religion of my fathers does not wish to be disseminated. We are not supposed to send missions to either of the Indies or to Greenland” (Mendelssohn 2011, p. 10; JubA, 7:12).

The care for every person reflected in a position that seeks to avoid denying salvation to those from outside one’s religious community is according to Mendelssohn fully backed by Jewish tradition and perfectly sustainable within a Jewish context. As the following passage from Jerusalem eloquently states, for Mendelssohn, “according to the concepts of true Judaism, all the inhabitants of the earth are destined to felicity; and the means of attaining it are as widespread as mankind itself, as charitably dispensed as the means of warding off hunger and other natural needs” (Mendelssohn 1983, p. 94; JubA, 8:161).

Let us now move on to the vicar’s three skeptical arguments, i.e., the impossibility of endless comparative research, the unreliability of human testimony and the problematic status of miracles. While some of these claims are partially reflected in Mendelssohn’s writing, they are not as fully endorsed, or at least not stated in as bluntly a skeptical tone. First, I find no parallel to the argument of the impossibility of continual comparative research. Second, with regard to miracles, Mendelssohn partly agrees with Rousseau that miracles are a weak basis for faith. The reasoning for that specific conclusion is similar to claims made by Rousseau’s (and by Spinoza for that matter),18 about how even if miracles did occur, they remain controversial as sole basis for establishing the truthfulness of a specific revelation. In a letter to Bonnet, Mendelssohn writes that even in ancient times “miraculous deeds were not regarded as infallible proof of a prophet’s divine mission” (Mendelssohn 2011, p. 255; JubA 7:324). Noting that both Moses and Jesus taught that false prophets can work miracles, Mendelssohn writes that “I do not comprehend how their followers and defenders can pretend, despite what scripture clearly says, that miraculous deeds are an infallible source of tradition” (Mendelssohn 2011, p. 255; JubA 7:324). Yet, while Mendelssohn does not think that miracles are an infallible source of tradition, unlike Rousseau, who expresses doubt about testimonies of miracles, he still very much seeks to argue that they can and did occur.

In the above quoted letter, Mendelssohn seems to seek to defend the most important Jewish supernatural event of all, namely the giving of the law on Sinai, by referring to it as a “great divine manifestation” rather than a “miraculous deed”.19 That manifestation, he claims, is a far more secure foundation for faith than a mere miracle, primarily because it was witnessed by the entire Israelite nation who saw with their own eyes “and heard with their own ears how God had appointed Moses His emissary and interpreter. Therefore, the Israelites as a whole were ocular and aural witnesses to this prophet’s divine calling and required no additional testimony or proof” (Mendelssohn 2011, p. 255; JubA 7:324).

In other words, Mendelssohn frankly disagrees with the vicar’s doubts about human testimony of supernatural events, at least with regard to the revelation in Sinai. The most important Jewish testimony of this kind, is very much accepted by him as reliable and as a steadfast proof of the veracity of the Jewish bond with God and the ensuing validity of the ceremonial law. While Mendelssohn suggests the often repeated argument that this particular testimony is convincing because it was witnessed by a whole people rather than just one person or a few individuals,20 the point remains he is willing to accept human testimony of a supernatural divinely guided event.

However, while less critical of human testimonies with regard to miraculous or divine manifestations, Mendelssohn still does recruit thoughts about the unreliability of human intermediacy in order to promote tolerance. So, for example, Mendelssohn claims in his Jerusalem that it does not make sense to ask for religious oaths because the degree of vagueness that necessarily accompanies any theologically sophisticated language is such as to make it practically impossible to know with any degree of precision what the oath actually demands we sign on to (Mendelssohn 1983, p. 66; JubA, 8:134). Accordingly, as long as some basic natural religious positions are shared, there is no point arguing about the remaining subtle and inessential differences. Mendelssohn, therefore, does, here as well as elsewhere, rely on linguistic skepticism to promote toleration.21 In other words, in so far as he doubts the ability of language to exhaustively carry supreme truths, Mendelssohn does cast some doubt on human intermediacy, even if the basic testimony of Sinai remains, in so far as he is concerned, secure and trustworthy.

4. Limited Skepticisms

I began by comparing Hume, the paradigm of 18th-century skepticism, with Mendelssohn and Rousseau, whose use of skepticism is far more moderate. We can now further make the point that while both Rousseau and Mendelssohn rely on skepticism to further aspects of their philosophical efforts, Rousseau’s arguments are more frankly skeptical than Mendelssohn’s. He is, for example, more bluntly skeptical with regard to miracles or human testimony of them than Mendelssohn is. In fact, Rousseau presents these arguments in ways that are rather similar to Hume’s argumentation in his attack on miracles and miraculous revelations.

This already suggests that rather than being a binary question, skepticism is a matter of degrees.22 Hume is more skeptical than Rousseau, who in turn is slightly more skeptical than Mendelssohn. Importantly, the notion that skepticism is a matter of degrees, and the categorization of Rousseau and Mendelssohn as moderately skeptical, suggests that skepticism can be limited. This, in and of itself, is not obvious. Descartes’, for example, was clearly alarmed that once activated, skepticism ends up undermining all beliefs, including the most dearly held religious ones. That is precisely why, as Popkin argued, he thought that only by carrying skepticism to its extreme, could anyone ever hope to overcome it (Popkin 1979, p. 179). Confronting anything less than the extreme skepticism his panicked mediations reflect would not genuinely resolve the crise pyrrhonienne he felt no one else had managed to contain (Popkin 1979, pp. 172–73). It is, in other words, because Descartes thought that skepticism, once unleashed, is all-crushing, that he thought the only solution would be to find out what, if anything, could withhold its most unbridled form. Indeed, responding to Pierre Bourdin’s criticism of his method of doubt as excessive, Descartes notes it would be irresponsible not to examine the foundations of all knowledge; otherwise, he asks, how would it be possible to “answer the sceptics who go beyond all the boundaries of doubt? How will he refute them?” (Descartes 1984, p. 374).

This leads us to the question of how Mendelssohn and Rousseau thought it possible to successfully avoid the all absorbing tendency skepticism seems to have. It is interesting, in this context, to look at how both describe moments in which they refuse to follow the path leading to all enveloping skepticism. In a passage of his Jerusalem wherein he vehemently rejects the “imputative inferences” or “consequenzerey” that makes his adversaries think his line of argument necessary leads to the “odious intention of overthrowing the religion [he] professes”, Mendelssohn explains that “not everyone who holds a certain opinion is prepared to accept, at the same time, all the consequences flowing from it, even if they are ever so correctly deduced” (Mendelssohn 1983, p. 86; JubA, 8:153). In other words, Mendelssohn is willing to stop the philosophical train, if he senses it is derailing, and, as mentioned above, it is not philosophy, but common sense that to him is sets the appropriate criteria for when that happens.

Similarly, Rousseau too leaves the skeptical train once it travels beyond the beliefs he thinks naturally impose themselves. So, for example, reflecting on the materialistic hypothesis about the nature of the human mind, the vicar states that “No material being is active by itself, and I am”, and tellingly adds “One may very well argue with me about this; but I sense it, and this sentiment that speaks to me is stronger than the reason combating it” (Rousseau 1979, p. 280).

Both Mendelssohn and Rousseau are less anxious than Descartes presents himself to be, because they do not seek philosophical justification for that which appears commonsensical to them. While Descartes is struggling with whether his hands really exist or with whether he even is awake for as long as he finds no demonstrable philosophical argument to reassure himself with, Mendelssohn and Rousseau refuse even to seriously address such esoteric concerns. Rousseau’s vicar tells us that he is resolved “to accept as evident all knowledge to which in the sincerity of my heart I cannot refuse my consent” as well as all that appears necessarily connected to it and “to leave all the rest in uncertainty without rejecting it or accepting it and without tormenting myself to clarify it if it leads to nothing useful for practice” (Rousseau 1979, p. 270).

Striking a rather similar tone, Mendelssohn writes in a letter to Jacobi that “whenever I have been clambering along the way of speculation for any length of time, through thorns and shrubs, I seek to orient myself by means of bon sense, and look round at least for the way by which I can get back to it”,23 adding that his credo is: “What I cannot think to be true, does not trouble me with doubt” (Mendelssohn, JubA 3.2: 201–203; translated in Jacobi 1994, pp. 352–53. See also Gottlieb 2011, p. 91.). In Morning Hours, he suggests that there is “no good reason” to ask what a thing is in and of itself, adding that “Philosophers for ages have often been tortured with questions that are in principle unanswerable because they consist of empty words that carry no meaning” (Mendelssohn 2012a, p. 52; JubA 3.2:60).

Mendelssohn and Rousseau’s limitation of skepticism, is a limitation of the existential seriousness they are willing to attribute to philosophy. It reflects a moment wherein they are willing to suspend speculation in order to maintain common sense. When philosophy leads to threatening skeptical doubts, when, as Descartes puts it, one feels as if one is drowning,24 they suggest jumping the boat of philosophical speculation altogether. As Mendelssohn puts it in his last letter to Sophie Becker, “I stay with [philosophy] as long as she is a good companion; when she pulls supercilious, frosty, or even sour faces and gets into a bad mood, I leave her along and play with my children” (Mendelssohn JubA, 13:333, translated in Altmann 1973, pp. 718–19). The distraught tone of Descartes’ second meditation, on the other hand, describes a man living within his philosophy, unable to let her go even when she does get into a rather terrifying mood. Under these circumstances, the threat of skepticism becoming a tangible, physical danger. But of course, humans do not necessarily live within their speculative adventures. Descartes could simply have ceased speculating about his own existence if these thoughts were actually drowning him in panic, or at least, he could have tried. Mendelssohn and Rousseau do not allow philosophy to pursue itself to a full-blown panic attack. When the going gets not only rough but uncommonsensically so, they simply revert to what they take to be a natural, universal bon sens.

This limitation of skepticism, as well as the notion of degrees of skepticism discussed above, emphasizes the degree to which skepticism can be used as a strategy by philosophers who refuse to be skeptics. Both Rousseau and Mendelssohn vehemently deny being skeptics, but clearly use skepticism in their writings. Of course, it is not at all clear that all thinkers who Rousseau and Mendelssohn think of as skeptics, are actual skeptics rather than philosophers using blunter or more comprehensive versions of skepticism strategically. Is Hume a skeptic? Or does he just use skeptical arguments more forcefully than Rousseau or Mendelssohn? After all, Hume does not seem overly skeptical about, for example, the need to undermine religious authority with skepticism. Indeed, as mentioned above, Hume’s philosophy could be construed as the strategic use of skepticism to deflate religious fanaticism and its ensuing religious intolerance. Hume himself declared that while “a Stoic or Epicurean displays principles, which may not only be durable, but which have an effect on conduct and behavior”, a Pyrrhonian “cannot expect that his philosophy will have any constant influence on the mind, or if it had, that its influence would be beneficial to society. On the contrary, he must acknowledge, if he will acknowledge any thing, that all human life must perish, were his principles universally and steadily to prevail” (Hume 2007, p. 118).

These reflections suggest that one could use skepticism without being a skeptic. But what then does ultimately differentiate a skeptic from a writer using skeptical strategies? Two suggestions seem to rise from our analysis. First, strategic skeptics, such as Rousseau and Mendelssohn, limit their skepticism; they are not interested in uprooting any and all beliefs. They are, for example, thoroughly theistic rather than agnostic. The skeptic would presumably not limit her skepticism and be rather committed to uprooting all belief, or at the very least generating a non-dogmatic attitude towards whatever beliefs she does have.25 Second, as strategies have aims, so too the strategic skeptic uses skepticism for a particular aim. So Descartes uses the method of doubt to find an epistemological anchor, and Rousseau and Mendelssohn use doubt to encourage toleration. In contrast, a skeptic would presumably engage with skepticims for its own sake.

This, however, seems to raise Rousseau and Mendelssohn’s suspicion, or indeed Hume’s, that true skepticism would be impossible.26 After all, could anyone practice skepticism aimlessly or for its own sake? Could Phyrro himself not be said to have used an all-encompassing form of skepticim in order to reach ataraxia? And even if ataraxia arose serendipitously from Phyrro’s epoché, would anyone following his example not pursue skepticism with the explicit aim of attaining ataraxia? Perhaps, therefore, if a skeptic should have to practice skepticism for its own sake or aimlessly for him to be a skeptic rather than merely using skepticism, could Phyrro himself, or at least anyone following his example, genuinely be said to be a skeptic? Demanding skepticism for its own sake, therefore, might make being a skeptic nearly impossible. But while such thoughts might seem to prove Rousseau’s and Mendelssohn’s suspicion, they perhaps mainly suggest that such a purist criterion is irrelevant. Whether in Rousseau and Mendelssohn or in Phyrro, skepticism always aims at some good; whether toleration for the former or ataraxia for the latter.

One could, of course, very well be skeptical that skepticism does in fact lead to ataraxia. Phyrro might have believed skepticism led to inner peace, but Hume, Rousseau and Mendelssohn all describe skepticism as a torturous phenomenon. While they are accordingly to some degree, to use Rousseau’ apt phrase, entangled in an “involuntary scepticism” (Rousseau 1979, p. 308), they still, however, willingly use skepticism to advance religious toleration. Indeed, the fact that Mendelssohn and Rousseau use skeptical arguments in spite of their association with a philosophical mindset and identity they both denigrate, indicate they felt they had to. In other words, they implicitly believe that skepticism is necessary for toleration. This, then, takes us to a critical question; if they do not believe that skepticism leads to inner peace, which presumably would ipso facto make someone more tolerant, why do they still believe skepticism to be so important for toleration?

5. Religious Skepticism and Social Ataraxia

The relation of religious skepticism and toleration does not at first sight seem obvious or necessary. One could prima facie imagine a dogmatist, absolutely certain that he is right about his religious beliefs, yet adamant too that he will nonetheless refrain from censuring or oppressing anybody else’s faith. Yet, even if that theoretical possibility exists, both Rousseau and Mendelssohn, as well of course as many others enlighteners, seem to have reached the same conclusion; promoting at least some degree of religious skepticism is the most efficient intellectual path to social ataraxia. A live and let live society, at least with regard to religion and religious toleration, is one wherein members need to have some degree of doubt about their own religious dogmas. Why, however, would that be the case? It seems to me that Mendelssohn’s and Rousseau’s argumentation suggests that skepticism encourages religious toleration because it undermines what they identify as its underlying cause, namely fanaticism, and that it does so because of at least three related reasons; skepticism challenges the dogmatic certainty of religious condemnation, exposes dangerous false beliefs and, finally, promotes humility. In what follows, we will first establish that both Rousseau and Mendelssohn thought skepticism undermines fanaticism, before looking at why they thought it does so.

The notion that skepticism can be used as an antidote to religious fanaticism was widespread in the Enlightenment. We saw above that while Hume’s skepticism could be at times perceived as impractical, the overarching direction of his skeptical investigation, namely, differentiating the mind of God, with the presumed availability of indubitable truths, from human thinking that can always be shown to be prone to doubt, does have a very practical political purpose. It undermines the fanatic’s claim of having obtained absolute certainty about religion, which in turn justifies intolerance towards views which are then construed as undoubtedly mistaken.

While Rousseau and Mendelssohn, whose works reflect a skepticism of lesser degree than Hume’s, seem very eager to show they have surmounted skeptical doubts about the basic truths of natural religion by relying on meta-philosophical grounds for their faith, they do clearly share Saint David’s view that some doubt, some uncertainty, does indeed undermine a fanatical spirit. The notion that a complete lack of doubt and questioning is a sure symptom of fanaticism was, therefore, widely agreed upon, even among enlighteners of different religious sensitivities.

Indeed, those who the Enlightened philosophers themselves would have thought of as fanatics very much agreed as well. So, for example, in his Les Erreurs de Voltaire, the Jesuit priest Claude Francois Nonotte writes: “For, what is it, this intolerance of the Catholic Church? It is the fidelity and the firmness to conserve, in all its purity, the sacred deposit of the divine truths. Accordingly, intolerance is as essential to it as its very sanctity”. Nonotte’s certainty is very much, therefore, what drives his intolerance. His church, he writes, is “essentially and necessarily intolerant” because it must “always teach, uphold, defend truth, proscribe anything that is opposed to truth” (Nonnotte 1770, pp. 271–72). Intolerance, l’abbé Nonotte declares a few lines later, “follows necessarily from sanctity and certitude” (Nonnotte 1770, p. 274). Voltaire probably thought about such arguments when he wrote about fanaticism that “there is no other remedy to this epidemic disease than the philosophical spirit” (Voltaire 1764, p. 191).

As we saw above, Voltaire’s nemesis among the philosophes, Rousseau, as ever the contrarian, repeatedly proclaims his lack of respect and patience for philosophers. It is therefore perhaps not altogether surprising that in a footnote to his Emile, he offers some praise for fanaticism. Indeed, while he fully agrees with Bayle that “fanaticism is more pernicious than atheism”, he also argues that “fanaticism, although sanguinary and cruel. is nevertheless a grand and strong passion which elevates the heart of man, makes him despise death, and gives him a prodigious energy that need only be better directed to produce the most sublime virtues” (Rousseau 1979, p. 312). Furthermore, Jean Jacques cares to add that “irreligion - and the reasoning and philosophic spirit in general - causes attachment to life, makes souls effeminate and degraded, concentrates all the passions in the baseness of private interest, in the abjectness of the human I, and thus quietly saps the true foundations of every society” (Rousseau 1979, p. 312).

Rousseau finds an admirable fearless vitality to fanaticism, and, he—the writer who despised books, the philosopher who despised philosophy—describes the philosophic spirit, so healing with Voltaire, as sordid and nefarious. However, while he praises fanaticism, he does so as a form of energy that should be “better directed”, which could, to quote Trousson, “elevate man beyond himself and render him capable of higher sacrifices” (Trousson 2009, p. 51). Moreover, however contrarian or provocative Rousseau might have at times wished to be, he still agrees with Bayle that fanaticism, directed at stamping out varying beliefs, is terribly dangerous. Indeed, that kind of fanaticism, which, in spite of their many differences, he combatted with his enlightened peers, was one which Rousseau thought drives people mad and makes them believe absurdities (Trousson 2009, p. 53). Accordingly, while the vicar does tell Emile that “proud philosophy leads to freethinking”, he also adds that “blind devoutness leads to fanaticism” and urges the boy to “avoid these extremes” (Rousseau 1979, p. 313).

The healthy middle way here for the vicar is one of moderate, limited skepticism. If the incredulity and irreligion of philosophical skepticism is one extreme, the blindness Rousseau warns of is one lacking any skepticism whatsoever. A degree of skepticism, therefore, is what differentiates blind from perceptive devoutness. Mendelssohn very much agrees that the healthy path lies between blind devoutness and skepticism. A clear example can be found in the eighth lecture of his Morning Hours, in which he discusses Basedow’s principle of the “duty to believe”, according to which we are obliged to accept as true any proposition without which our happiness is not possible (Mendelssohn 2012a, p. 62; JubA, 3.2:69). Of course, for Basedow, just as for Mendelssohn, happiness is impossible without believing in God, providence and immortality, providing immediate grounds to adopt these beliefs come what may. Mendelssohn, however, refuses the notion that there is any duty with regard to knowledge except for inquiry. Critically, Mendelssohn does not only decline religious wishful thinking, but also praises those who “expend all their energies in order to awaken doubts that may cost them their peace”. Without this “sacrifice to the truth” he writes “all knowledge would soon degenerate into prejudice and blind faith” (Mendelssohn 2012a, p. 64; JubA, 3.2:72). Indeed, these doubts are critical in order to maintain the vitality and critical spirit without which, faith becomes blind, leading to superstition and fanaticism.

So while Mendelssohn believes both skepticism and fanaticism are “diseases of the soul that threaten with it moral death”, he also suggests that “not infrequently Providence prescribes one disease to counter the other in order to restore the body to health” (Mendelssohn 2012a, p. 64; JubA, 3.2:72). Accordingly, not only is Mendelssohn, like Rousseau, deeply suspicious and wary of skepticism (even if he has, rather characteristically, far more understanding and empathetic when describing those who practice it), he also, again like Jean-Jacques, realizes that blind faith is its dangerous opposite. The middle path, therefore, is one which both believes and doubts. For both Rousseau and Mendelssohn, some skepticism does heal fanaticism, even if it is a cure the dosage of which we should be careful with.

As mentioned, skepticism challenges fanaticism for at least three related reasons; it undermines the certainty required for religious condemnation, exposes dangerous religious mistakes and encourages religious humility. First, with regard to religious condemnation, both Mendelssohn and Rousseau provide mechanisms by which its certainty is skeptically challenged. So, for example, in above mentioned passage of his Jerusalem wherein Mendelssohn discourages the administration of religious oaths and the ensuing religious discrimination, Mendelssohn argues the necessary metaphysical and theological precision necessary to ensure the words one is made to swear upon carry to same meaning for both parties is unachievable: “My neighbor and I cannot possibly connect the very same words with the very same internal sensations, for we cannot compare them, liken them to one another and correct them without again resorting to words” (Mendelssohn 1983, p. 66; JubA, 8:134). Mendelssohn, in other words, relies on his linguistic skepticism, to suggest differing expressions of internal religious perceptions cannot possibly satisfy the threshold of certainty needed to engage in religious condemnation. This skepticism with regard to the precision we are able to muster with regard to either our inner perceptions or the words we use to express them, in and of itself makes violence with regard to interreligious dispute repellant. Who would risk wrongly injuring an innocent out of religious reasons, if one has reasonable doubt he might not be as idolatrously mistaken as my understanding of his words suggest he is? Indeed, a healthy dose of doubt makes fanaticism absurd even towards my own religious devotion; “Many things for which I would suffer martyrdom today, may perhaps appear problematic to me tomorrow” (Mendelssohn 1983, p. 66; JubA, 8:134).

A similar theme arises when Rousseau’s vicar makes the above mentioned argument about the absurdity of endless comparative research. If we are to exclude all religions and find the single right one, the vicar argues, “they must all be examined, and in any matter whatsoever one must not condemn without hearing” (Rousseau 1979, p. 302). However, attaining the certainty necessary for condemnation, if possible at all, would require of every single person to engage for years and years in study, meditation, disputation and travel. After all “no one has a right to rely on the judgment of others” (Rousseau 1979, p. 306).

The utter impracticality of a having to study every single religion just to provide oneself with a fair shot at salvation reveals the absurdity of the notion of an exclusivistic faith, and further emphasizes how mistaken any sense of having achieved the kind of religious certainty necessary to condemn all but one religion is. After all, you could only be sure all religions except your own are to be condemned, if you have encountered and studied them all. Clearly, most fanatics have not travelled across the globe to study all religions, access their schools and learn from their clergy. How then could fanatics be completely convinced they, and only they, are right?

Furthermore, fanatics themselves ensure that their evidence for condemnation is thoroughly invalid. Rousseau explains in this context that however dearly fanatics might seek to make the case of Christian superiority, as they themselves have ensured that Jews are not free to openly express their opinion, the matter has not been pursued or resolved convincingly. Were a book to appear in which Judaism would be openly favored, Rousseau writes, “we would punish the author, the publisher, the bookseller. This is a convenient and sure policy for always being right” (Rousseau 1979, p. 304). Indeed, as Sorkin points out, the vicar here describes Mendelsohn’s own situation quite precisely (Sorkin 2017, p. 106), and Mendelssohn himself raises the fragile political status of Jewish people when explaining to Lavater why he carefully avoids religious disputes (Mendelssohn 2011, pp. 12–13; JubA, 7:14–15).

Second, while both Rousseau and Mendelssohn thought genuine religious belief is critical for individual well-being as well as for social cohesion, they both too were deeply aware of how dangerous mistaken religious beliefs can be. And what if not critical questioning dismantles such dangerous mistakes? Indeed, for Rousseau, the danger these mistakes involve is such that he suggests not teaching anything whatsoever about the deity to children before they have reached the age of reason during which they might be able to conceive of God properly. Indeed, in their childish imagination, they will only conceive of a God within the confines of their limited experience: “if one speaks to them of God’s power” Rousseau writes, “they will estimate Him to be almost as strong as their father” (Rousseau 1979, p. 257). Accordingly, “every child who believes in God is, therefore, necessarily an idolater or at least an anthropomorphite. And once the imagination has seen God, it is very rare that the understanding conceives Him” (Rousseau 1979, p. 256). The problem is that once the religiously mistaken and deficient view of God has been acquired, it tends to be maintained throughout life: “the great evil of the deformed images of the divinity which are drawn in the minds of children is that they remain there all their lives; when the children become men, they no longer conceive of any other God” (Rousseau 1979, p. 259).

Forcing on children a conception of God they have absolutely no capacity to genuinely understand actually means teaching them how to lie early (Rousseau 1979, p. 257). One can only expect proper religious beliefs from agents able to develop them. Imposing a belief in God without even the necessary groundwork for its proper understanding, is the high road to a world of fanatic intolerance as it engrains the logic of imposing belief, blindly, without understanding and therefore too without actual significance beyond a superficial verbal assent: “You must believe in God to be saved. This dogma badly understood is the principle of sanguinary intolerance and the cause of all those vain instructions that strike a fatal blow to human reason in accustoming it to satisfy itself with words” (Rousseau 1979, p. 257).

Accordingly, for Rousseau, avoiding religious misunderstanding is more important than risking intolerance by trying to bring about understanding by force. He believed that “it would be better to have no idea of the divinity than to have ideas of it that are base, fantastic, insulting, or unworthy. It is a lesser evil to be unaware of the divinity than to offend it” (Rousseau 1979, p. 258).

Mendelssohn draws a similar point about the danger of mistaken religious belief and the ensuing potential for fanaticism and intolerance with great eloquence in his Jerusalem. Relying on a description of the origin of contracts, Mendelssohn explains why the state can achieve its end with external motives if necessary, while the church must rely only on interior ones. Human beings need each other’s services and are impelled to enter into social connections wherein contracts must ensure their rights are protected in case of conflict. The social contract is no exception. Human beings renounce their independence for social life, and the state, in return, has rights towards individuals within it, as well as being responsible for the contracts its citizens reciprocally engage in. It can, in other words, not only impose taxes, but also enforce a contract one side is illegitimately disrespecting. Therefore, as it is concerned with actions, “it may punish and reward. The duty toward my neighbor is externally satisfied if I render him his due, irrespective of whether my action be enforced or voluntary” (Mendelssohn 1983, p. 57; JubA, 8:126).

This, however, is not the case with the church. Indeed, the church has no right to punish, reward or enforce itself externally in any way, simply because there cannot be any clash between human rights and the rights of God. The reason why people have gotten this wrong, Mendelssohn suggests, is because of a form of anthropomorphism which imagines that God is similar to a human agent in that his rights could come into conflict with those of human beings. Similarly mistaken, Mendelssohn writes, is the belief duties towards myself may clash with those toward God as they might with those toward my neighbor (Mendelssohn 1983, p. 58; JubA, 8:126). While Mendelssohn believes these propositions are rather obviously absurd, he still thinks they are the source of much evil: “All the violence and persecution which they have perpetrated, all the discord and strife, mutiny and sedition which they have plotted, and all the evils which from time immemorial have been perpetrated under the cloak of religion by its fiercest enemies, hypocrisy and misanthropy, are purely and simply the fruits of this pitiful sophistry, of an illusory conflict between God and man, the rights of the Deity and the rights of men” (Mendelssohn 1983, p. 58; JubA, 8:126).

Indeed, if I misunderstand God as needing my protection as a human might, I might engage in the most frightful forms of violence under the guise of devoutness. But, in doing so, I only emphasize the degree to which I have lowered the image of God to that of a frail, human all too human figure. God, Mendelssohn writes, does not need our assistance, our service (in the usual sense of the word) or the sacrifice of our rights. Indeed, “His rights can never come into conflict and confusion with ours. He wants only what is best for us, what is best for every single individual” (Mendelssohn 1983, p. 59; JubA, 8:127).

For Mendelssohn as well as Rousseau, therefore, while critical to human well-being, religion, if misunderstood, can be terribly dangerous. The fanaticism and intolerance both despised, thrives on such misunderstandings. Anthropomorphic and idolatrous conceptions of God are not merely mistaken, they are dangerous and fuel violence. A second reason, therefore, for why skepticism undermines fanaticism and intolerance is that it encourages the kind of critical thinking that dismantles the dangerously mistaken and absurd religious illusions that cause them.

A third reason both Mendelssohn and Rousseau take skeptical arguments to encourage tolerance, is that they develop a healthy humility in the believer, a humility which again reduces the inclination to violently impose one’s position. A common thread of their kind of skeptical religiosity is a very humble appraisal of the degree of certainty one can hope to achieve in theological matters. While both strongly believed in God, they were also perennially aware that the mysteries of the deity, of the universe and of human life are beyond our grasp. For Rousseau, the reason all philosophers are continually quarrelling is pride as well as “the insufficiency of the human mind”. Indeed, the vicar tells Emile that “impenetrable mysteries surround us on all sides; they are above the region accessible to the senses”, and adds that “we believe we possess intelligence for piercing these mysteries, but all we have is imagination […] Nevertheless we want to penetrate everything, to know everything. The only thing we do not know is how to be ignorant of what we cannot know”. We are, Jean Jacques tells us, “a small part of a great whole whose limits escape us” and only vanity could make us “want to decide what this whole is in itself and what we are in relation to it” (Rousseau 1979, p. 268). As he puts it later on in his profession of faith, “the more effort I make to contemplate His infinite essence, the less I can conceive it. But it is; that is enough for me. The less I can conceive it, the more I worship it. I humble myself” (Rousseau 1979, p. 268).

“Nothing” Mendelssohn resolutely states in To the Friends of Lessing, “can be more beyond question than that in the visible world that surrounds us, as well as [the invisible world] within ourselves, final causes are realized and purposes are carried out”, adding that he “cannot possibly believe any philosopher ever seriously doubted this” and that “one need only open one’ eyes and give heed, with even the slightest modicum of attentiveness, to any of nature’s works, and one will be completely persuaded of this truth” (Mendelssohn 2012b, p. 170; JubA, 3.2:212). But while wholly convinced of the existence of a providential God, Mendelssohn still refuses to claim much knowledge about God beyond that. Indeed, beyond the simple realization of God’s existence throughout the glory of creation “and all the beauty and the perfection that it contains”, in each “mote of dust” and “sunbeam”, Mendelssohn believes that the question “what is God himself” is beyond the limit not only “of human knowledge, but of all cognition in general” (Mendelssohn 2012a, pp. 51–52; JubA 3.2:60). Similarly, in his commentary of Exodus 33:23, “You will behold my Presence from behind; my Countenance, however, cannot be seen”, Mendelssohn states that that while it is possible for humans to apprehend God’s ways “from the aspect of His exalted deeds”, it is impossible for any created being to apprehend God “from the aspect of his Essence” (Mendelssohn 2018, pp. 442–41; JubA 16:248).

This, for Mendelssohn, was a long held position. While in his Phädon Socrates very much argues for the existence of a perfect, providential God who ensures our immortality (admittedly quite a lot in and of itself), God remains a mystery. The soul, Mendelssohn’s Socrates explains, cannot grasp the essence of the “Maximum Being” in its full extent, as it can never form an “idea of a thing of a superior nature than itself, or form an idea of a thing of higher ability than it possesses itself” (Mendelssohn 2007, p. 82; JubA 3.1:54). It is only after death, Mendelssohn adds, that we can hope to behold that “Maximum and Supreme Being”; as long as we are still among the living God himself remains beyond our reach as “it is not allowed that the unholy touch Holiness itself” (Mendelssohn 2007, p. 84; JubA 3.1:56). Similarly, while the Phädon’s main thrust is proving immortality, Mendelssohn’s Socrates does not delve into the nature of the afterlife he is convinced awaits us. So, for example, he refuses to commit to the “all comforting hope” we will be reunited with lost loved ones (Mendelssohn 2007, p. 77; JubA 3.1:49),27 and refrains from speculating on what on what forms of purification the wicked will have to undergo, or what kind of bliss the blessed will encounter (Mendelssohn 2007, p. 143; JubA 3.1:113).

It is therefore not surprising that when, in the above mentioned appraisal of Frederick’s poetry, Mendelssohn seeks to emphasize the skeptical passages of Frederick’s work wherein the king “casts doubt on all merely speculative truths” in order to oppose “the dogmatic tone” of Lucretius which he cannot accept Frederick genuinely adopts, Mendelssohn praises the “socratic humility of thought” of the “philosophical poet” (Mendelssohn JubA, 5.1:189–190).

The humility both Rousseau and Mendelssohn seek to promote28 conflicts with the arrogance of fanaticism and its essential assumption of an exclusivistic hold on religious truth. While the common ground of natural religion and common human morality is something they will adamantly argue for, both are religiously humble enough to refuse to impose the particularities of their specific tradition as absolute truths that must be accepted by all.

So, Mendelssohn claims to have for many years “occupied, as it were, a kind of middle position between dogmatist and sceptic”; while there are many religious and philosophical points about which he has straightforwardly adopted what he understands to be the Jewish position, he explains that he nonetheless still acts “just as sceptically whenever I am supposed to judge my fellow men” (Mendelssohn 2011, p. 24; JubA, 7:99). Indeed, in his letter to Lavater, Mendelssohn suggests to consider extremely carefully whether it is worthwhile criticizing religious opinions that have done much to promote the good. Though he might disagree with Christian tenets, for example, he sees no point in engaging in religious disputes so long as these opinions are not directly threatening natural religion and in particular if they seem in fact to promote the good. Not every position Mendelssohn himself thinks of as erroneous must be urgently corrected in his fellow citizen. Indeed, he explains that “such modesty is all the more obligatory if the nation that in my opinion cherishes such errors has also made itself worthy of admiration through virtue and wisdom and contains a number of great men who deserve to be called benefactors of the human race” (Mendelssohn 2011, p. 12; JubA, 14). “If you are just”, Mendelssohn writes elsewhere, “then the points that are still disputed between us can remain undecided forever. Neither virtue nor truth can lose thereby. Why, therefore, do we need to argue?” (Mendelssohn 2011, p. 30; JubA, 106).

Rousseau’s vicar strikes a similarly humble tone “I serve God in the simplicity of my heart” he tells Emile, adding that “I seek to know only what is important for my conduct. As for the dogmas which have an influence neither on actions nor on morality, and about which so many men torment themselves, I do not trouble myself about them at all.” While he performs “with all possible exactness” the tasks the service of his church, all particular religions are fine for the vicar, as long as they serve God suitably: “The essential worship is that of the heart. God does not reject its homage, if it is sincere” (Rousseau 1979, p. 308). Towards the end of his profession, he adds that “If I were more sure of myself, I would have taken a dogmatic and decisive tone with you. But I am a man; I am ignorant and subject to error” (Rousseau 1979, p. 310).

Religious skepticism, therefore, undermines the certainty needed for religious condemnation, disentangles dangerous religious mistakes and encourages humility. For both Rousseau and Mendelssohn, these are all critical in encouraging the kind of tolerant politics they both championed. Indeed, the overarching realization of the importance of skepticism for toleration seems to draw together many more great thinkers of their time, and while we also focused on Hume and mentioned Voltaire in this context, many more enlighteners carried similar ideas.29

It seems worthwhile to here keep in mind Spinoza’s emphasis of the notion of the theological-political. One among many of Spinoza’s insights constitutive to the Enlightenment is that a theological shift was needed for a significant political change to occur.30 Mendelssohn’s and Rousseau’s theological arguments are in this important sense, theological-political. Their quest for a non-dogmatic theology, which encourages skeptical thought even as it maintains its core beliefs, is critical to them because they realized it enables and promotes tolerance. A skeptical faith, in other words, was in their eyes the most suitable theological grounding for a politics of tolerance. The theology of the Enlightenment could perhaps be identified as uniquely skeptical in that sense. At any rate, an enlightened skeptical theology is, at the very least, the one Rousseau and Mendelssohn thought would be most suitable for the tolerant modern political culture they championed.

The notion of a skeptical theology, rather than an anti-theological skepticism, suggests, furthermore, that the dynamics between faith and doubt are potentially far more complex than mere opposition. Indeed, both Mendelssohn’s as well as Rousseau’s professions of faith and of skepticism reflect more complex dialectics between belief and disbelief than those merely seeking to contrast them. Religious skepticism is often taken to mean skepticism about religion. This, for example, is what it means when we think of Hume. Rousseau and Mendelssohn show that it can also be the skepticism of a genuinely religious spirit as well.