Virtual Union, the Seeds of Hatred, and the Fraternal Joining of Hands: Leibniz and Toleration

1. Introduction

In this paper,¹ I am interested in the conception of toleration that can be gleaned from the political and theological work of Gottfried Wilhelm Leibniz (1646–1716). Contrary to many previous commentators, I argue that Leibniz did not defend a notion of toleration comparable to a modern conception. Certainly, the term ‘toleration’ figures in his writings.² It even figures quite frequently in certain contexts, and most often as something positive. But his explicit conception of toleration was not forward-looking but rather shaped by a long past of post-Reformation religious wars and European theological-political turmoil.³ When speaking of toleration, Leibniz mostly looked backward in time, to figures like Georg Calixtus, his favorite theologian, and to texts like De tolerantia reformatorum where Calixtus had shown, in Leibniz’s words, that ‘even though there is divisive opinion, that should never prevent jungi dextras fraternitatis.’⁴ Leibniz’s aim with promoting such ‘fraternal joining of hands’ was principally securing peace and providing better prospects for future religious conciliation, not defending the kind of liberal embrace of religious pluralism and freedom of expression associated with toleration today.

And yet Leibniz is often presented as a champion of modern toleration on a par with Locke or Bayle.⁵ For a striking example, one can read the following in an introduction by John Christian Laursen to a volume on seventeenth-century theories of toleration: ‘The strongest legacy to toleration theory of the Thirty Years’ War may well have been in the writings of Gottfried Wilhelm Leibniz, who wrote at the end of the seventeenth and beginning of the eighteenth centuries, and pushed toleration theory well beyond anything Locke or Bayle could manage’ (Laursen 1998: 171). Others have made similar claims. Franklin Perkins writes that ‘Leibniz worked tirelessly to promote tolerance, peace, and the exchange of ideas, perhaps most in his attempts to bridge religious factions in Europe, but also in his receptiveness to the past and his attitude toward other cultures’ (Perkins 2002: 447). Maria Rosa Antognazza has dedicated several articles to the topic, currently the most sophisticated and extensive contributions to the discussion, where she argues that ‘a robust, many-layered, and unusually inclusive doctrine of toleration can be gleaned from Leibniz’s writings.’⁶

There is an obvious, literal sense in which such statements are problematic.⁷ They do not correspond to Leibniz’s explicit and most consistent use of the term ‘toleration’ which, as we shall see below, almost invariably occurs in the context of discussions about ecclesiastical toleration and church reunion, as part of an approach to religious diversity that remains subordinated to his irenical quest for reunion. There is however another sense in which one might say that Leibniz promoted toleration, namely if, within the framework of working toward Christian reconciliation (including the rational outreach to other religions that his conception of natural religion allowed, as can be seen in his writings on China for instance), he provided a conceptual framework that potentially, when rising above the consideration of the particular circumstances and explicit purpose of that framework, is comparable to a modern theory of toleration. Among commentators who have championed Leibniz as a thinker of toleration, this is the approach they most frequently adopt, less concerned with terminology, occurrences and specific contexts of use, than with the general theory lurking behind individual statements and the basic ethical commitments channeled by this theory. This is for example the perspective that Maria Rosa Antognazza adopts in her insightful contributions.

While I am wary of letting entirely go of the more literal and lexical issues, I think this is a fruitful approach. I will however argue below that, even when doing that, we will still not be able to dispel the clouds of doubt hanging over Leibniz’s credentials as a thinker of ‘modern’ toleration. For even on this less literal approach to the question, associating Leibniz with the doctrinal constellation which, in the late seventeenth and early eighteenth centuries, arguably provided the first outline of what is today considered toleration in the modern sense, remains problematic because it fails to take into account, not only the kind of theory that Leibniz did in fact promote, but also tends to gloss over the specificity of the modern notion of toleration that commentators are saddling him with. Thus, as I will argue below, Leibniz’s conception of toleration differed from the modern conception in the following three ways:

1. Literally, Leibniz understood ‘toleration’ in a narrow sense, as a political tool to be employed in order to facilitate the reunion of the Christian churches. It was not understood as a broad embrace of diversity in religious matters. In its two basic forms, civic and ecclesiastical toleration, it was a means to lay down the fundamental conditions—peace and security on the one hand; acknowledgment of people with differing religious views as legitimate discussion partners, on the other—for any possible negotiation toward future church reunion. In short, the two forms of toleration were designed specifically to end violence and to multilaterally suspend mutual accusations of heresy.

2. While Leibniz did promote toleration in some sense, and also did adopt some of the fundamental ethical tenets habitually associated with a modern conception of toleration, he did not consider toleration a constitutive value, a value in and by itself, but rather saw it as a means to an end, namely, as already said, the conciliation of the churches and the end of schism. On the more abstract level, one might say that Leibniz did not promote modern toleration because modern toleration is about affirming diversity as a value in and by itself, not about using such an affirmation to eventually cancel difference and work toward union.

3. Leibniz did not establish any intrinsic link between toleration and freedom of expression, and even argued that toleration, in the sense in which he promoted it, would require that licentious speech and writing be curbed and a regime of (moderate) censorship put into place.⁸

2. The Construction of Modern Toleration: Locke, Bayle, Spinoza

Before embarking upon any discussion of Leibniz and toleration it is crucial to establish a point of reference. What kind of doctrine is it, exactly, we attribute to Leibniz if we situate him among the first champions of modern toleration? One could for example consider toleration to mean principally a resistance to religious coercion, opposition to the use of force to thwart opinions and persecution in matters of conscience. If that is what toleration is, Leibniz was, as Maria Rosa Antognazza argues persuasively, a firm and unequivocal proponent. The textual evidence is overwhelming but a few examples will suffice. In 1692, the French cleric Paul Pellisson-Fontanier published his epistolary exchanges with Leibniz under the title De la tolérance des religions (Pellisson-Fontanier 1692). The exchange was presented by Pellisson as a discussion on ‘the unity of the church, and on the question whether it should tolerate sects’ (Pellisson-Fontanier 1692: 3). In it, Leibniz developed an argument against persecution of confessions and sects considered heretical by insisting on the involuntary character of belief.⁹ As also in his correspondence with the intransigent Bishop Bossuet, Leibniz insisted on a distinction between material and formal heresy, arguing that only formal heresy, i.e. intentional error or obstinacy, gave sufficient grounds for blame and excommunication. Citing the involuntariness of belief, Leibniz also denied the very possibility of genuinely renouncing upon truths one sincerely believes to possess, for example for a natural philosopher to genuinely disavow his own scientific knowledge on account of a perceived conflict with church doctrine:

To believe or not to believe is not a voluntary thing. If I believe I see a manifest error, all the authority of the world could not change my view if this [authority] is not accompanied by some reasons capable of satisfying my difficulties or of overcoming them. And if the whole Church were to condemn the doctrine of the movement of the Earth, the able astronomers of this opinion could certainly dissimulate, but it would not be in their power to give up [their view].¹⁰

Hence, on this definition of toleration, as a principled resistance to the coercion of beliefs, Leibniz was undoubtedly a champion of toleration. This, however, as we shall see below, was not Leibniz’s own definition of toleration. Moreover, and more importantly, it is not clear that, more broadly, it is a satisfactory and sufficient characterization of the modern conception of toleration either. Certainly, it is a part of such a conception. Good reasons exist, however, to think that there are further requirements to fulfill. It is for this reason that a clearer point of reference must be established.

In the following sections, I will try to situate Leibniz in relation to three contemporaries who were among the most prominent proponents of toleration, namely Locke, Bayle and Spinoza. Let me be clear from the outset that the following outlines are not intended as full-fledged accounts of the doctrines of toleration of those three authors, an ambition obviously far beyond the scope of this paper. What I am interested in is how the reference to those three authors’ basic conceptions of toleration are constantly taken up by historians of philosophy when accounting for the contributions of late seventeenth-century philosophers to what they often describe as a modern or contemporary notion of toleration. I neither embrace nor reject those accounts. I am only interested in how they have contributed to a common notion of modern toleration and its seventeenth-century background in present-day commentary which explains what is generally meant when historians of philosophy ascribe a doctrine of ‘modern toleration’ to this or that thinker. Certainly, the conceptions of toleration that can be gleaned from Locke, Bayle, or Spinoza are not the only conceptions available for conceiving of such a notion of toleration. And I do not deny that Leibniz may be situated differently in the intellectual landscape if we evaluate his position according to other, competing conceptions, both earlier and later, like those of, say, Sebastian Castellio,¹¹ Gotthold Ephraim Lessing,¹² or John Stuart Mill.¹³ Nonetheless, I have chosen Locke, Bayle and Spinoza as providing a useful and non-anachronistic point of reference, because those three figures are frequently, and in very influential historical commentaries like those of Perez Zagorin, Jonathan Israel, Philip Milton, or Rainer Forst, taken to be paradigmatic early modern thinkers of toleration.¹⁴

At the same time, these three philosophers cannot be said to promote the same aspects of toleration or even be seen as consciously contributing to a common conception. In fact, in the late seventeenth century, toleration was by no means a well-defined intellectual rallying-point, but rather a shared component in a family of related doctrines, some of which explicitly promoted toleration under that name, while others might not necessarily have used the term but still advanced arguments that contributed to the constitution of the meaning of it. Some ‘doctrines of toleration’ were even only described as such pejoratively, as implying an accusation of religious laxity and a license to heresy.¹⁵ It is however not unreasonable to maintain that Locke, Bayle and Spinoza were, in different ways, among the most prominent members of that sprawling family and that, consequently, as Rainer Forst puts it, ‘the modern discourse concerning toleration … reached its political-philosophical culmination in the works of Spinoza, Locke and Bayle’ (Forst 2013: 170).

One way, then, of getting a better grip on how Leibniz stands precisely with regard to the question of modern toleration is thus through a kind of doctrinal triangulation, trying to determine how Leibniz was philosophically situated with regard to each of them and what they have come to represent, taking into account the similarities and differences in their respective theoretical models that both gather them and set them apart as members of same family. It is those basic similarities and differences between Locke, Bayle and Spinoza that I will sketch out in this section. In short, I will give a basic portrait—some would say a caricature, but I think it useful for the present purposes—of how these three philosophers have been constructed by contemporary intellectual historiography as the paradigmatic thinkers of early modern toleration without pretending in any way to provide an exhaustive account of their respective theories, or accounting for the philosophical and historical relations obtaining between them.¹⁶

3. Leibniz on civil and ecclesiastical toleration

For Leibniz, toleration was mainly construed as a necessary condition for church reunion. Hence, he noted already in March 1683 in a letter to Ernst von Hessen-Rheinfels: ‘I admit that the powers would have to first agree to mutual toleration in order to temper the spirits, before a reunion can be hoped for’ (A I.iv.352). Toleration was sometimes associated with Leibnizian core intellectual values such as charity, good intentions, and moderation.²⁷ But he also at times seemed to remain deliberately vague about his position on the topic, especially when writing to Catholic correspondents likely to speak of ‘toleration’ as a vice rather than a virtue: ‘I dare not myself say anything ascertained about toleration …. God knows what is right, as for me, I content myself with leaving the judgement to him, and I dare condemn only those who lack good will’ (to Paul Pelisson-Fontanier, 21 November (1 December) 1692, A I.viii.201).

He did, however, also have a more fine-grained conception of toleration, mainly inspired by the Bishop Molanus, one of his main interlocutors in a court-mandated project of reuniting the protestant churches between Hanover and Berlin that Leibniz orchestrated. It is a technical concept that is part of a three-stage model for reunion that Leibniz presented as follows in a 1697 letter to James Cresset, the English ambassador to the Berlin Court:

I note that this union can have different degrees which are (1) good public understanding; (2) ecclesiastical toleration; (3) agreement of opinions. The first and second degrees appear to me necessary, feasible, and sufficient. The first degree is necessary by political reasons for the conservation of the two parties. The second degree is necessary by the principle of Christian charity, and consequently it is more than just feasible. The third degree does not seem achievable, but is also not necessary. It would however be good if able theologians would work upon it at least in relation to certain points where I actually think that the disputes only arise on account of formulations and are not real. This conciliation of some controversies, albeit particular and imperfect, would already be of great use. Est aliquid prodire tenus, si non datur ultra [It is something to get this far, if we cannot go further]. But putting to one side the third degree, let us stick to the first and second for now.²⁸

This three-stage model shows up on several occasions.²⁹ In some writings, he formulates the distinction between civil understanding and ecclesiastical toleration as a distinction between civil and ecclesiastical toleration.³⁰

Civil toleration is a matter of securing public order within the state and assuring that pacts among states are respected. As favorable as Leibniz was to civil toleration, essential to public security and the good of mankind, still, as he noted to Jablonski, ‘toleration in the public exercise of protestant religions’ belongs among the ‘affairs that do not concern the very essence of religion, but rather exterior aspects mixed up with a host of secondary considerations, political and other’ (to Jablonski, 18 December 1707, in Jablonski and Leibniz 1899: 121). In short, civil toleration is a matter of public policy more than of public morality and religion. It can be established in a state by sovereign command and upheld by executive power.³¹

Ecclesiastical toleration is a more complex matter. Leibniz sometimes defines ecclesiastical toleration as ‘not considering another doctrine as condemnable’ and ‘not mistaken’, as opposed to civil toleration which consists only in ‘leaving the other his freedom’ or upholding ‘civic peace’; it is a practical attitude, a ‘sincere disposition’ (Geschwinde Anmerckungen, before 12 February 1700, A IV.viii.363–64). In religious matters, such toleration is partly achieved by downplaying non-essential differences, leaving to one side what is traditionally described as ‘things indifferent’ (adiaphora)³² or at least by ascertaining that they pose no practical obstacle to reconciliation.³³ Importantly, Leibniz relates ecclesiastical toleration to the principle of charity. This principle stands absolutely central in his ethics, natural theology, political philosophy and universal jurisprudence. It is a basic component in his concept of justice (defined as caritas sapientis) and is associated with formal principles such as equity, reciprocity, geometrical proportionality, harmony, and the just mean (Lærke 2008[a]: 223–6). Charity is also a principle of controversy and negotiation that Leibniz associates with a procedure of constant and complex exchanges of perspective among opposing parties, an obligation of ‘putting ourselves in the other’s place’ (Analyse de Jean Domat, end 1695, Grua 648). The conception has its background in Leibniz’s reading of the so-called ‘golden rule’ from the Gospels, i.e., the rule according to which I should not do unto others, what I do not wish others do unto me: ‘The true meaning of the rule is that the right way to judge equitably is to adopt the viewpoint of the other [la place d’autrui].’³⁴ Leibniz’s controversialist conception of charity and the golden rule has been explored by a great number of commentators, including myself, in commentaries dedicated to Leibniz’s ‘art of controversies’, in Marcelo Dascal’s expression.³⁵ Leibniz’s best explanation of what such charity or moderation in controversy implies in practice is probably the following, largely self-explanatory passage from his Conversation du Marquis de Pianese et du Pere Emery Eremite, written around 1679–81:

[T]his is what gives rise to this diversity of opinion, everybody considering the objects from a certain side: only very few people have the patience to go all the way round the thing [faire le tour de la chose] until they are on the side of their opponent, that is to say, people who will examine the pros and cons with equal zeal and with the spirit of a disinterested judge in order to see to which side the balance must lean. (A VI.iv.2250, translated in Leibniz 2005: 173)

As for the third degree, complete agreement, as we have seen, Leibniz sometimes concedes that ‘it does not seem achievable, but is also not necessary.’He does, however, always maintain the concept, at a minimum as a kind of regulative idea providing an ideal horizon for ecclesiastical toleration.³⁶ The border between ‘union’ understood as an achievable goal and ‘union’ understood as a regulative idea is fluid and changes according to context. It is from this perspective that we must read the following clarification regarding the meaning and scope of ecclesiastical toleration that we find in the 1698 Tentamen expositionis irenicae trium potissimarum inter protestantes controversia:

Thus, since it is clear that the obstacles to a perfect agreement reduce to certain formulations and certain metaphysical positions, or at the most to a very limited number of controversies that concern neither the salutary faith nor practice, and which, for the rest, resemble those that frequently take place between members of the same church; and since it is clear, on the other hand, that what until now has been taken for a disagreement of the utmost importance will largely dissolve by means of such explications, once these [two points] have been admitted, nothing remains that would prevent reaching complete reunion and re-establishing an actual communion between the evangelicals and the reformed—and nothing can appear more salutary or more necessary for the Church of our time, since the virtual union or simple ecclesiastical toleration [virtualis unio sive simplex tolerantia Ecclesiastia], even though one abstains from anathema and accusations of heresy, still lets the schism and the hatred subsist, or at least the seeds of hatred [odiorum semina], and would, in the future, be exposed to constant recriminations, suspicions and conflicts. (A IV.vii.387/Jablonski and Leibniz 2013: 826–27)³⁷

Contrary to what is sometimes suggested, I do not think Leibniz’s talk of ‘complete reunion’ in this text is at odds with other texts where such complete reconciliation is presented as something out of reach.³⁸ The specific context of the Tentamen here plays a role: the text was part of Leibniz’s efforts to establish a reunion only among the protestant churches of Brandenburg (reformed or Calvinist) and Hanover (evangelical or Lutheran). And he was quite clear that, whenever he was speaking of complete reunion as an achievable goal, he was aiming only at a restricted one, limited to those protestant churches whose dogmatic divergences, according to him, could be resolved by simple analysis and explication of the terms of debate, in other words, by analytic resolution of pseudo-divergences.³⁹ In this respect, one cannot consider the Tentamen to teach a general lesson about Leibniz’s views on the prospects of religious reconciliation more broadly.

The passage does, however, afford us crucial, additional lessons about the second degree in the three-stage reunion project, namely ecclesiastical toleration. Leibniz describes ecclesiastical toleration as a ‘virtual union’ as opposed to ‘actual union.’ The formulation suggests that it should be conceived as tending toward union without however itself being such a union: ecclesiastical tolerance is virtual union because it can lead to actual union.⁴⁰ This positive tendency, I think, must be explained in terms of the conception of charity that Leibniz associated with ecclesiastical toleration in the letter to Cresset or, more specifically, in terms of Leibniz’s procedural and controversialist conception of charity as an exercise in reciprocity. In exchanging with others, being charitable consists in putting oneself in the others’ place and consider the point under discussion from ‘all sides.’ In this dialectical context, then, charity does not prescribe that one discusses the matter at hand in a disinterested way, but rather that one discusses it while making an active effort to take into account in an equitable and balanced fashion all the different interests involved. Being ecclesiastically tolerant is honoring that Christian duty in ecclesiastical negotiation.

And yet, at the same time, from the passage in the Tentamen cited above, it appears that ecclesiastical toleration also envelops a necessary reference to ‘schism’ and, along with it, what Leibniz describes as ‘seeds of hatred.’ This is not because the practice of ecclesiastical toleration as such involves hatred, of course, but because ecclesiastical toleration, if seen as a goal in and of itself, as opposed to a means to reach a higher goal of actual unity, necessarily implies the affirmation that such differences in perspective subsist which are at the root of schism and hatred. Practicing ecclesiastical toleration, i.e. performing one’s Christian duty to put oneself in the others’ place, necessarily involves acknowledging that others occupy places—or theological positions—different from one’s own. Indeed, such differences are a necessary condition for the practice of ecclesiastical toleration because, in their absence, such toleration would have no object. The practice of ecclesiastical toleration requires disagreement. At the same time, however, such disagreements are ‘seeds of hatred.’ For, as long as they subsist, they remain potential reasons of violent conflict and schism. In other words, if ecclesiastical toleration is a virtual union in virtue of the active goal of complete agreement it pursues, it is also virtual schism by the situation of disagreement that it tacitly, or passively, acknowledges the existence of.

I think this double-sided notion reflects Leibniz’s most considered conception of toleration. It implies that ecclesiastical toleration, at the same time as it represents a crucial stage toward union, also represents a stage where sliding back into hatred and intolerance remains a constant and non-eliminable risk. On this point, Leibniz’s Tentamen echoes Molanus’ 1704 Unpartheyisches Urtheil, where the bishop denounced such back-sliding in less abstract terms, as a concrete problem to which the history of Protestantism had borne witness only too often:

[A]s good and Christian, laudable and useful as mutual tolerance [mutua tolerantia] and virtual union [virtualis unio] of protestants [Evangelischen] may appear in theory, yet it has invariably given rise to such bad effects in practice and in its application … that moderate, or even very moderate Lutherans [Evangelicis] who … consider the Calvinists [Reformierten] as brothers in Christ, have with good reason not approved such tolerance since the conditions of the Evangelical Church have always become worse for it, and each time at least a secret persecution and oppression has followed, and more than once public conversion and persecution of our [people].⁴¹

In sum, a situation of ecclesiastical toleration is an essentially tense one because it includes, potentially or ‘virtually’ as Leibniz puts it, two opposing tendencies: an active tendency toward union and a passive tendency to slide back into violent schism. These contrary tendencies are embedded within the notion of ecclesiastical toleration itself on account of the admission of disagreement that explains the need for it. Consequently, the ideal horizon for the exercise of ecclesiastical toleration, i.e. the elimination of all hatred and schism by reason of charity, necessarily involves the dissolution of ecclesiastical toleration itself. On the ideal horizon of complete reunion, ecclesiastical toleration simply no longer has any object or application. For, at this endpoint, there is nothing more to tolerate to the extent that the charitable exchange of perspectives that defines the exercise of ecclesiastical toleration no longer has any discernible divergences that it can be applied to. I see myself in my neighbor as he sees himself in me, a situation Leibniz also sometimes identifies with piety understood as perfect justice or ‘universal benevolence.’

One could object that Leibniz’s argument regarding the ‘seeds of hatred’ subsisting in ecclesiastical toleration is bound to specific circumstances and that no general conclusions should be drawn from the Tentamen alone. However, remarks about toleration made in other contexts also suggest that, even in a situation of implemented toleration, the causes of ‘evil’ still remain (Promemoria zur Frage der Reunion der Kirchen, November 1687, A I.v.11, trans. in Leibniz 2005: 248). And this, I would suggest, is probably the most important reason why Leibniz’s notion of toleration is not comparable to the constitutive ideal that modernity has embraced. Not only is toleration, for Leibniz, not foundational as an ideal. It is also ambiguous: by seeking to mitigate from within the pernicious effects of schism and conflictual religious plurality it also, at the same time, acknowledges and allows for the existence of such schism and conflictual plurality. Consequently, toleration contains, as a kind of shadow within it, the very thing it is designed to counter, namely theological hatred. This is why, in a Promemoria zur Frage der Reunion der Kirchen from 1687, while stressing that it is ‘always necessary to begin’ with ‘the way of mutual toleration and civil peace’, Leibniz immediately goes on to stress that this only ‘mitigates evil rather than eliminating its cause, like physicians who begin their healing by the most pressing symptoms’ (Promemoria, A I.v.11, trans. in Leibniz 2005: 248). Practicing ecclesiastical toleration is always, at the same time as it is an exercise in charity, a tacit admission of the fact that the goal of piety is also the end of toleration. Unity simply eliminates the need for it.

4. Toleration and Freedom of Expression

Ever since Spinoza and his defense of the libertas philosophandi in chapter XX of the Tractatus Theologico-Politicus, freedom of expression has come to be seen as an essential component of a tolerant society. Conversely, a society of censorship is generally seen as intolerant. Toleration and censorship are considered, if not necessarily mutually exclusive in practice, then at least as expressing contrary attitudes: more of the one means less of the other, and vice versa. Did Leibniz subscribe to such direct proportionality between toleration and freedom of expression?⁴²

There certainly are passages going in that direction. Hence, writing to Bartholomew des Bosses concerning the persecutions of Jansenists in France, he noted: ‘Even if I do not approve of the main views of an author, I should like to have conceded to the learned … the freedom of philosophizing, which inspires competition and arouses intellects’ and warns that ‘it is extremely harmful that freedom of opinion be restrained from day to day within unnecessary limits’ (to Des Bosses, 21 July 1702, in Leibniz 2007: 93 and 95). He staunchly opposed the censorship of Galileo and clearly defended the right to freely conduct scientific research having no immediate implications for morality or religion: ‘I have no objections to refuting authors whose opinions are dangerous, but I do not know whether it is suitable to establish a sort of inquisition against them, when their false opinions have no influence on morality.’⁴³ Moreover, when it came to authors who did write things that could prove morally detrimental, he favored efficient refutation over repression: ‘I am thus of the opinion that one can and must respond to the objections put forward by libertines, atheists, infidels and heretics’ (to Jaquelot, 6 October 1706, Grua 66–67).’ And yet Leibniz also clearly believed that there were necessary limits to uphold: ‘[W]hen there is question of toleration, one should not condemn hastily, but still … one should not be negligent either when a doctrine is dangerous’;⁴⁴ ‘one has the right to take precautions against bad doctrines that influence the mores and the practice of piety’ (Nouveaux essais sur l’entendement humain, IV, xvi, § 4, A VI.vi.461). Hence, writing to Thomas Burnett in 1710, he insisted that ‘one is perfectly right to declare oneself against atheist and libertine books which are more dangerous than the Socinians and prevent their diffusion’ (to Burnett, [1710], GP III.319). He believed that it was the role of the governing political authorities to repress evidently dangerous publications through state control over the publishing business.⁴⁵

Hence, Leibniz recommended a regime of centralized and systematic censorship which, on the face of it, sits somewhat uneasily with the ‘freedom to think and to say what one thinks’ championed by Spinoza. This is not to say that Spinoza recommended ‘free speech’ as an individual right in the modern, liberalist sense. Spinoza’s philosophical notion of freedom as rational self-determination informs not only his ethics and politics but also his conception of the freedom of philosophizing, inviting use to avoid any such facile assimilation of his position to present-day conceptions.⁴⁶ For Spinoza, permitting free philosophizing was mostly about creating the best conditions for a public sphere wherein the rationality of the people could develop. He was not granting a general license to say—or even think!⁴⁷—anything whatsoever. He even cautioned that it would be ‘disastrous to grant it completely’ (G III.240/C II.345), excluding ‘deception, anger, hatred’ and any ‘intention to introduce something into the republic on the authority of [one’s] own decision’, presumably on the grounds that such speech and action does not qualify as free in any positive sense (G III.241/C II.346–47). Nonetheless, a significant contrast between Leibniz and Spinoza’s positions remains, in that the fundamental criterion behind Leibniz’s conception of censorship was not that of freedom in any sense, but rather that of moderation and charity in controversy. Hence, the only positions to be subjected to censorship were immoderate or extremist positions—including atheism, libertinism, enthusiasm, radical fideism—, and such positions as Leibniz saw as incapable or unwilling to ‘go all the way round the thing’, or adopt ‘the viewpoint of the other’ in order to judge equitably. Moreover, such immoderate doctrines should be subjected only to moderate censorship by suppressing writings while abstaining from persecuting the authors; by clamping down only on such dangerous opinions which gave rise to sects or movements; and—here echoing Bayle’s position—by taking into account that beliefs are not voluntary.⁴⁸

Leibniz’s conception of legitimate, moderate censorship has implications for his stance vis-à-vis another component of modern toleration, namely the admission of atheists. Those authors whose books Leibniz recommended be censored were principally those whom he labelled ‘libertines’ and ‘atheists.’ And yet we should not see in Leibniz someone who thought people should be muted on account of their religious beliefs, or lack thereof. Moreover, he did not reject Bayle’s argument in the Pensées diverses regarding the possibility of a virtuous atheist. In fact, in the Nouveaux essais, he appears to subscribe to it:

I know that excellent and well-intentioned men maintain that these theoretical opinions have less of an influence in practice than one might think, and I also know that there are people of excellent disposition whose opinions would never lead them to do anything unworthy of them. … and one can say that Epicurus and Spinoza, for example, have both led a perfectly exemplary life (Nouveaux essais, VI, x, §4, A VI.vi.462).

Leibniz did however differ from Bayle in thinking that an atheist could only be virtuous from habit or disposition, but not from a moral conscience grounded in right reason, thus making his virtue merely contingent, grounded in (personal) history and experience and not in rational principle: ‘an atheist can be a good man, morally speaking, by temperament, by habit or by some fortunate prejudice, but he cannot be so by a firm principle of right reason’ (to Mathurin Veyssière de la Croze, 2 December 1702, in Dutens V.484).

The relation between Bayle and Leibniz is further complicated by the fact that they did not entertain the same conception of atheism. For Bayle, Christian faith was inseparable from speculative truths of a revealed, ‘supernatural order’ (Bayle 1820: XV.310). Atheism was, for him, tied to the rejection of those truths. As for the basic practical principles of Christian faith, charity above all, they were ultimately grounded in right reason and common notions of moral conscience and not in religious faith. This is why he denied that those Christians ‘who do not live according to the principles of their religion … are all hidden atheists’ (Bayle 2007: § 139, 299), but affirmed that those who do live according to those principles can in fact very well be atheists. In fact, the ‘spirit of debauchery does not depend on the opinions one does or does not entertain regarding the nature of God, but on a certain corruption which stems from the body and which is strengthened every day by the pleasure one finds in such voluptuousness’ (Bayle 2007: § 144, 309).

For Leibniz, on the contrary, ‘atheism’ was not primarily defined by the denial of revealed, supernatural truths. Certainly, he did occasionally define atheism in terms of dogmatic assertions regarding the existence of God, providence, and the immortality of the soul: ‘An atheist is he who does not acknowledge a wise and powerful governor rewarding the good and punishing the evil after death. Consequently, he who denies the immortality of the soul is an atheist’ (Grua 740–41). However, such a person is reproachable exactly because ‘the doctrine of providence is useless if the immortality of soul is taken away’, for in this case ‘natural theology becomes vain, and is worth nothing against practical atheism’ (to Bierling, [undated], GP VII.511; my italics). For Leibniz, contrary to Bayle, libertinism and atheism were first of all practical categories, referring less to propositions and doctrines than to moral attitudes and patterns of behavior. Libertines and atheists were such people as posed a threat to the social fabric, hostile to public security and the best interests of mankind. Atheists and libertines were not just, in Leibniz’s terminology, people who proposed arguments against the revealed truths of Christian religion. They were people who, fearing no God, would ‘completely give in to their brutal passions and turn their mind to seducing and corrupting others’ (Nouveaux essais, IV, xvi, § 4, A VI.vi.462). By definition, they were, as Leibniz put it to Gottlieb Spitzel, ‘an evil from which to expect nothing less than universal anarchy and the overturning of society’ (to Gottlieb Spitzel, 10/20 February 1670, A II.ii.55).

Hence, if Leibniz embraced some form of state censorship, it was because he was deeply concerned by the way public opinion could be swayed and manipulated by unscrupulous practical atheists. In a text on public security from 1670, Leibniz thus warned of all the einreissenden Atheismus in Germany corrupting the youth and threatening morality and religion.⁴⁹ And when writing Arnauld in 1671, he expressed his concern that ‘impiety spreads everywhere’ and the fear that atheist opinions should ‘surreptitiously take over’ people’s minds’ (to Arnauld, November 1671, A II.i.277). Now, one of the primary problems with such atheist libertines—this ‘sect of all sects’, ‘the most dangerous sect of them all’ according to a 1683 letter to Seckendorf (A I.iii.572)—was that they represented a substantial threat to ecclesiastical toleration. Schism had given rise to mutual rejection among confessions. Atheist libertinism represented the logical endpoint of such recriminations to the extent that it represented their degeneration into a general rejection of religion altogether. Hence, in 1691, in De religionis pace, Leibniz described how ‘the greatest evils have risen from the disagreement among religions: hate and distrust, murderous wars, the rise of incredulity, horrible sects in England and Holland, libertine ways, and the whole contempt of religion’ (De religionis pace, circa 1691, A IV.iv.544). Atheism and libertinism were, in sum, the logical outcome of religious controversies when they cultivated the ‘seeds of hatred’ described by Leibniz in the Tentamen, i.e. when the participants in controversy seized upon the most pernicious aspects of religious plurality. Their rise to prominence was, in fact, the effect of generalized religious intolerance or the rejection of all religion. No wonder, then, that Leibniz stressed that ‘we should now put considerable more effort into combating atheism and deism than heresy’ (to Ernst von-Hessen Rheinfels, 4 (14) March 1685, Grua 196). In fact, combating atheism was, for him, no different than combating religious intolerance. Indeed, by Leibniz’s lights, there was something almost contradictory about calling for the toleration of atheists in the way Bayle did, to the extent that, on Leibniz’s definition of atheism at least, this amounted to promoting the toleration of intolerance.

In sum, then, Leibniz differed from the modern conception of toleration by maintaining, contrary to Locke, unity and the cancellation of difference as a regulative ideal that had to be on the horizon of toleration as a necessary guiding principle. He differed from Bayle in denying that atheists could be safely tolerated. In fact, suppressing and censoring atheism and libertinism was necessary to defend toleration as he understood it, namely as something conducive to future confessional conciliation. Moreover, against Bayle, he denied that the principles of right moral reason could be established independently of religion. Finally, Leibniz was less concerned with the suppression of individual liberties than with rise of forms of extremism, less concerned with defending individuals’ autonomy than with ascertaining their moderation in their exchanges with others. Consequently, he was at odds with Spinoza when denying that the relation between toleration and freedom of expression was directly proportional.

5. Conclusion

I have argued that Leibniz’s explicit conception of toleration was substantially different from the modern notion of toleration. In order to understand why, it is important to stress the constitutive features of the modern conception of toleration which cannot be reduced to simply an opposition to coercion of beliefs. The modern conception, I think, involves a deeper inclusive embrace of diversity, religious and otherwise, as a value in and by itself, intrinsically linked to an equally fundamental imperative of freedom of expression allowing such diversity to flourish publicly. I have argued, following numerous other commentators, how the philosophical genesis of this modern conception of toleration can be traced back to a constellation of writers including Locke, Bayle and Spinoza. I have also argued that Leibniz is not a star in that constellation. As a post-Reformation thinker of conciliation, be belonged to another, older tradition.

By pointing out these decidedly pre-modern features of Leibniz’s conception of toleration, I have in no way intended to pass a negative judgment on him or reduce his position to some backwards remnant of an outdated theological-political paradigm. Quite to the contrary: despite its shortcomings, I think there is much that is attractive in Leibniz’s conception, as I also think there are fundamental difficulties in the modern conception of toleration that we, today more than ever, have come to experience firsthand not only as troubling conceptual inconsistencies but also as political and societal problems that shape our very lives. There are of course aspects of Leibniz’s position where he, for contemporary sensibilities, does not go nearly far enough—after all, despite gestures toward the Chinese for example, his conciliatory efforts focus on the Christian Churches and are decidedly Eurocentric or even, in some instances, Germano-centric.⁵⁰ His alleged multiculturalism is shot through with orientalism to put it in contemporary terms.⁵¹ Indeed, large swaths of his discussions of China, for example, can be seen as a foil for discussing issues and doctrines that are, in the end of the day, European.⁵² The Muslim world is, by and large, depicted as a political enemy against whom to wage war.⁵³

Nonetheless, there are aspects of Leibniz’s conceptions from which we can acquire a better grasp of the difficulties that modern toleration faces, such as his insight regarding the embryonic hatred necessarily contained within the very practice of toleration, or the question mark he puts after the contention that diversity can be coherently embraced as a constitutive value. Do we not require at least some regulative ideal of unity? And if we do, what shape could that ideal take today, when the notion of a Christian Commonwealth or a minimal apostolic creed are no longer appropriate options? Finally, Leibniz’s take on censorship and licentious writing may contribute meaningfully, by way of provocation, to a necessary discussion of what relation, exactly, we should see between toleration and liberty of expression, if not an inherent one. Leibniz was deeply concerned, for example, that a completely unregulated press might very well go rogue and favor the rise of such devious libertine atheists—persons constrained by no moral principle—who, if victorious, would prove catastrophic for peace, public security and, indeed, toleration. It is a point that, today, we would be hard-pressed to deny.

Competing Interests

The author has no competing interests to declare.