The progress of the Academy edition shows that Leibniz spent a lifetime dealing with theological questions. It also shows that his philosophy grew out of an attempt to resolve theological controversies and to defend the Christian world view against the danger of atheism. It is therefore not wrong to say that Leibniz referred to theology, its questions and solutions throughout his life. One of his central motives was to better justify these and to resolve their controversies through rational reflection: part of that rational love of God (amour éclairé) that is all-encompassing, since the world shares in the reason and goodness of God, which must be promoted everywhere.
If Leibniz's life can be interpreted as working through questions of the Christian religion, it is also worth asking to what extent Christian theology worked through his position in reverse. This history of reception is more than just a historiographical list of scholarly references. The transformation of Christian thought through Leibniz, the claim of the convergence of Christianity and reason and the ecumenical initiatives linked to this had to become a point of reference for theology itself, to which one had to position oneself. This positioning always took place in relation to what was known of Leibniz's thinking in the respective age. The following section outlines important stages in this history of reception, which continues to this day.
The sources known in the 18th century
Leibniz stood at the beginning of an epoch that led to a profound transformation of theology and a fundamental change in all living conditions, the Enlightenment. Defending theology against atheism, rationally rethinking the doctrines of faith and overcoming the division of denominations were intentions that the theology of the 18th century continued in variations. Often, Leibniz was not referred to directly, as very few of his ideas were published and known to posterity. For a long time, the popular philosophical Essais de théodicée (1710), its echoes in the correspondence with the English theologian and Newton confidant Samuel Clarke, first published in 1717, and the two editions of the Monadologie (1720 in German and 1721 in Latin translation) were the only published writings. However, elements of his thought were conveyed indirectly and in a new frame of reference via Wolff's philosophy. For a long time, his ecumenical endeavours to abolish the schism between the churches were only revealed in fragments in publications containing pieces of Leibniz's correspondence relevant to the topic. Essentially, this was his correspondence with Pellisson, Jablonski, Bossuet and Volume I of Louis Dutens' edition of Theologica. However, this was more an occasion for brief reminiscences; theodicy remained powerful. The connection between systematic theological considerations, philosophical positions and ecumenical proposals could not be grasped in this way.
Leibniz reception via theological Wolffianism
Through Christian Wolff (1679-1754), Leibniz's thinking initially gained great influence. It is of course a misconception that Wolff only organised and vulgarised Leibniz's thoughts, which can largely be traced back to the Halle-based pietist opponent of Wolff, Joachim Lange (1670-1744), in his "Notes" and then in his Modesta disquisitio (1724) on Wolff's German Metaphysics. Lange accused Wolff of having merely taken up and systematised Leibniz's ideas, in particular his doctrine of the monad and pre-stable harmony. Shortly afterwards, the title Metaphysica Leibniz-Wolffiana was coined, which was also adopted by Wolff supporters. Although Wolff defended himself as early as 1727 in his Monitum ad commentationem luculentam that only very little in his philosophy came from Leibniz ("paucissima sunt Leibnitii"), it was not only Kant who repeatedly spoke of the Leibniz-Wolff school.
Wolff certainly drew more than paucissima from Leibniz, explicitly or implicitly, especially with regard to the doctrine of God and the human soul. On the other hand, he did not adopt the doctrine of monads, especially with regard to the interpretation of corporeal substances. Although the doctrine of pre-stabilised harmony in relation to the body-soul problem is at least more plausible than that of Aristotle or Malebranche, Wolff did not adopt it through proof. Wolff was an eclectic and took up many of Leibniz's ideas, but sometimes placed them in the context of his own teachings and attempted to prove them at great expense or made them the starting point for syllogisms. Together with Leibniz, he advocated a "reasonable orthodoxy", according to which philosophy can prove the truth of natural theology, but can show with regard to the revealed mysteries that these do not contradict reason, so that the act of faith is not contradictory, even if not every truth of Christianity can be proven philosophically.
Even the early Wolff had theological followers, such as Georg Bernhard Bilfinger (1693-1750), who taught at the Faculty of Philosophy in Tübingen and had previously worked there as a castle preacher, among other things. He not only attempted to explain Wolff's philosophy, but also to prove that it was in line with the moral philosophy of the Confucians. In Tübingen, the theology professor Israel Gottlieb Canz (1690-1753) was also an early follower of Wolff, who published a work in Frankfurt in 1728 that summarised the most important chapters of Leibniz and Wolff's philosophy for theologians.
Johann Gustav Reinbeck (1683-1741), provost of St Peter's Church in Berlin and consistorial councillor, was also one of the leading early theological Wolffians, who sought to prove the truth of the Confessio Augustana as rational in nine volumes. In Jena, Jakob Carpov (1699-1768) built up his dogmatics in a Wolffian manner using the demonstrative-syllogistic "mathematical" method, having previously defended Wolff in Marburg against Lange's accusations. After Wolff's return to Halle, he gained more and more supporters among theologians, including Catholics. According to Karl Aner, the "full flowering of Wolff's philosophy" now began. Siegmund Jakob Baumgarten (1706-1757) was particularly influential in Halle, who, despite his pietistic background, adopted Wolff's demonstrative method and applied it to dogmatics and ethics.
Catholic theology in the 18th century was characterised by the major ecclesiastical orders. The Augustinian Hermits played a significant role in opening up to the new Wolffian philosophy and theology, inspired by the Roman Generalate of the Order. Augustinian Hermits such as Agnellus Kändler (1692-1745) and Gelasius Hieber (1671-1731) played a decisive role in the Bavarian academy movement, even if this academy, which later came to be known as the "Wolffian Lodge", did not come into being until 1759. The Benedictine monasteries and the Salzburg Benedictine University also became starting points for the reception of Leibniz and Wolff in the 18th century. In Salzburg, the later Ensdorf Abbot Anselm Desing (1699-1772) introduced the new philosophy by reforming the study regulations; the Benedictine Berthold Vogel (1708-1772) from Kremsmünster subsequently read the Philosophia scholastica by receiving Leibniz. The recipients of Leibniz-Wolff's philosophy in Austria were then the Jesuit Sigismund von Storchenau (1731-1798), in Munich the enlightened theatine Ferdinand Sterzinger (1721-1786), but above all but above all the Jesuit Benedikt Stattler (1728-1797), who was an outspoken supporter of Leibniz and Wolff at Ingolstadt University and adopted central philosophical theses from both; in his irenic-ecumenical works he advocated a rapprochement between the denominations. Stattler had enormous significance for the history of Catholic thought; the arguments of his "anti-Kant" long characterised the critical rejection of Kant's philosophy by most Catholics.
The Prague priest Bernhard Bolzano (1781-1848) with his enlightened, ethical understanding of religion, who was known as the "Bohemian Leibniz" but was removed from his chair in Prague in 1819/20 as a result, can be seen as an echo of this philosophical, anti-antian Leibnizianism in the Catholic sphere of thought in the 19th century. As a mathematician, logician, philosopher and theologian, he intensively studied Leibniz. In theological terms, the influence of Leibniz's monadology is particularly evident in his work Athanasia (1827), which takes up and further develops the proof of immortality from the simplicity of the monad; life after death also results from the infinite capacity for perfection of finite mental faculties.
The connection between sources, reception and Leibniz's image
The fact that only a few of Leibniz's writings were available in print and the temporary dominance of Christian Wolff implied three fundamental decisions for the theological reception of Leibniz.
a) A philosophical theology was received, which apologetically wanted to open up the space for a theology of revelation, for dogmatics, but which itself did not deal with the dogmatic loci. The fact that Leibniz spent his life thinking about the dogmas of this dogmatic theology, that he wanted to think them through and justify them better, remained unknown.
b) Theological Wolffianism was only able to assert its dominance in Protestant Germany for a short time. It has been called a "transitional theology". At the end of his life, Baumgarten had already devoted himself more to historical than rational proof, a tendency that his pupil Johann Salomo Semler was to continue more consistently. While Wolff still wanted to use reason to prove the possibility of revelatory truths that remained inaccessible secrets for reason, neology and rationalism found this unsatisfactory. The divine is rational and therefore rationally recognisable; the only thing that can be decisive for man's salvation is what he can recognise and act upon qua man. Consequently, Leibniz was soon seen as a pioneer of theological rationalism. The fact that he explicitly argued against the Socinians and the Deists receded into the background, although Lessing explicitly relied on Leibniz's anti-Socinian arguments.
c) Not only has the connection between theology and philosophy in Leibniz's work been insufficiently recognised, but also how closely his ecumenical endeavours were connected to his other thought, namely his theology and philosophy. For this reason, his union negotiations were only of historical interest, prompted by particular political circumstances.
The interpretation of Leibniz's union endeavours
There were already attempts to grasp the inner connection between ecumenism, theology and philosophy in Leibniz's work in the 18th century, not least among Catholic recipients. The Bavarian academy movement also included the Pollingen Augustinian canon Eusebius Amort (1692-1775), a universal scholar who was deliberately eclectic in his philosophy and who not only took up Leibniz's philosophy, but also engaged with his ecumenical endeavours. The Tübingen theologian Christoph Matthäus Pfaff, as a Protestant theologian, denied the doctrinal differences between Lutherans and Reformed a relevance that divided the church. He was also aware of Leibniz's negotiations with Jablonski; nevertheless, his statements on Leibniz's union endeavours are rather negative. According to a statement from 1742, Leibniz was regarded by him as "an irreligionaire".
A later recourse to Leibniz's Catholic-Protestant negotiations was made by the former Benedictine Maximilian Prechtl (1757-1822) from the Upper Palatinate. He had studied with the Jesuits in Amberg, joined the Benedictines in Michelsfeld after their abolition and taught dogmatics and church history at the Amberg Lyceum until he was elected abbot of his home monastery at the beginning of 1800. After the secularisation, which was never fully overcome, he researched the history of his monastery as a private scholar and endeavoured to bring the two denominations closer together. Mutual enlightenment and an unprejudiced examination of reason made a reunion seem possible. His irenic-ecumenical hope and optimistic approach to the historical and philosophical examination of reason remained committed to the Catholic Enlightenment in defence of radical anti-Christian currents. In 1815, his work was published: "Friedens-Benehmen zwischen Bossuet, Leibnitz und Molan für die Wiedervereinigung der Katholiken und Protestanten. Historically and critically assessed". In addition to the aforementioned motives, the preface mentions another reason for discussing Leibniz's ecumenical plans: The hope of strengthening the German fatherland through religious reunification in the fight against "religious indifferentism". In terms of content, Prechtl sided with Bossuet: for him, it was "the great philosopher Leibniz" who brought political and self-serving calculations into the objective and rational understanding and therefore caused the failure. "Theology alone was not the subject", says Prechtl, "in which Leibniz possessed equal strength".
This split in the image of Leibniz between a systematic philosopher and a religious politician characterised the theological debate surrounding Leibniz's reunion efforts in the 19th century. This was initiated by a bang from the Catholic side. From 1821, the strictly anti-enlightenment and anti-Protestant journal "Der Katholik", which was orientated towards the Pope and the restorative Catholicism of France, was published in Mainz. In 1820, its editors, Andreas Räß and Nikolaus Weis, published the first edition and translation of Leibniz's Examen religionis christianae (then called Systema theologicum) in the German-speaking world, with a preface by the Jesuit Johann Lorenz Doller (1750-1820). It was based on a French edition for which the Superior General of St Sulpice, Jacques André Émery (1732-1811), had received a copy from Hanover. His erroneous, posthumously published edition served as a model for Räß and Weis. Leibniz was to be turned into a Catholic and convert - in line with the interests of the Mainzers - and the Systema had already been dubbed Leibniz's "religious testament" by the French editor. Doller's 122-page preface sought to prove this. His argumentation was clear: first he proved that the highly educated Leibniz stood on the ground of revealed religion from the very beginning and was neither an indifferentist nor an anti-Trinitarian, and therefore not a "neo-Protestant" afflicted by it. He then sought to define Leibniz's position ever more precisely by means of exclusion, ruling out the possibility that he was Reformed or Old Lutheran on the basis of his doctrine of the Lord's Supper and liberty. He was a Catholic at heart, as he wrote to Madame de Boinon in 1691. His ecclesiological views corresponded most closely to Catholic doctrine. As he no longer replied to Bossuet, he had agreed with him and was a convert, even if he had neglected to publicise his conversion out of love for his court. All this is proven by Leibniz's system of theology, which is genuine and a true apologia for the Catholic religion.
Naturally, this claim by the ultramontane Catholics was met with resolute opposition in the Protestant camp; the intention of Leibniz was completely misjudged by the Catholics, according to the Königsberg Kant successor Wilhelm Traugott Krug (1770-1842) and the Göttingen philosopher Gottlob Ernst Schulze (1761-1833), whose Aenesidemus once prompted Fichte to justify Kant's results more deeply against sceptical doubts. The first edition of the Realencyclopädie für protestantische Theologie und Kirche also rejected all attempts to appropriate him for the Catholic Church.
Aloys Pichler's interpretation of Leibniz
The Munich church historian Ignaz Döllinger, who wanted to historically refute Protestantism because of what he saw as its negative consequences for the moral, ethical and free personality, was also initially close to conservative, anti-enlightenment ultramontanism. From the 1860s onwards, however, he became increasingly critical of the papacy, which had distorted the church constitution into a papal system of rule since the Middle Ages. As Rector of Munich University in its 400th anniversary year in 1872, he developed a programme for the reunification of the denominations. He also referred to Leibniz: The latter had been the most outstanding man in Germany at the time, "as perceptive as he was versatile and of immeasurable knowledge". He rejected the theory that Leibniz was secretly a Catholic. The Systema was written as a document in order to empathise with others and present their position as acceptably as possible. In fact, no Protestant had ever been as favourably disposed towards the papacy as Leibniz.
In Döllinger's circle, his pupil Aloys Pichler (1833-1874) produced a complete account of Leibniz's theology. He received his doctorate in Munich in 1857 and had been a private lecturer since 1863. He was one of Döllinger's most talented students, who was fully committed to Döllinger's programme of overcoming confessional divisions through historical research. His polemical writings against the ultramontane papacy were placed on the index of banned books. In 1869, he was appointed by the Russian government to St. Petersburg, where he was able to devote his life entirely to his studies of church history. In 1871, however, he was sentenced to life imprisonment in Siberia for book theft; pardoned in 1874 on the intercession of the Bavarian Prince Regent, he died a few weeks later, aged just 40. In 1869/70, a complete account of Leibniz's theology appeared on over 1,100 pages. Leibniz was to be removed from the shadow of Wolff and rationalism, as he was an unabridged Christian thinker. After a general introduction, Pichler dealt with his theology of God and creation, then anthropology, ecclesiology and the doctrine of the sacraments and eschatology. Only from here did he illuminate the reunion negotiations between Leibniz and Bossuet, identifying with Leibniz's position throughout the work. This knowledgeable work is characterised by its close proximity to the sources, even if central categories from the party struggles of Pichler's time repeatedly appear, in which Leibniz is placed, especially in opposition to ultramontanism. For him, Leibniz was a true Christian who stood above all particular confessionalism and was thus able to lay the intellectual foundation for a reunion of Christians, even if he failed due to the egoism and power politics of his contemporaries. In the course of his life, the historian became more prominent in him than the philosopher: His historical studies alienated him to some extent from Catholicism, to which he had been philosophically close. The Systema theologicum was a product of Leibniz's first phase, even if embedding it in his other thinking clearly shows that he was not a crypto-Catholic even then. His most important principle was that only that which the Church had always believed as such could be an essential doctrine of faith, binding on all Christians by divine right. Although simple biblical faith sometimes required a scientific reformulation and defence if it was disputed, something could never be established as a salvation-decisive church doctrine where freedom had prevailed in the early church.
The image of Leibniz in Protestant theological historiography
In the history of Protestant theology in the 19th century, Leibniz, interpreted through the lens of Wolffianism, usually served as a negative foil in contrast to theological rationalism. Friedrich Schleiermacher was critical of Leibniz from the very beginning; theodicy was at the centre of his rejection, as it subjected God to the laws of reason and made him the author of evil. Instead of starting with the Christian-pious consciousness, it was wrongly purely speculative: it was merely "a product of speculation". These accusations were to dominate the view of Protestant theology in the following period. In revivalist and confessional Protestantism, the accusation of heterodoxy was added: According to Friedrich August Tholuck, his doctrine of the "best of all possible worlds" signified a rationalist falsification of the consciousness of sin and salvation, as it "excluded not only sin but also revelation. It has the consequence of the sentence "Whatever is, is right". Julius Müller (1801-1878), a dogmatist from Marburg and later from Halle, was also accused of falsifying the Christian doctrine of sin and redemption.
For Tholuck, Leibniz was seen as a pioneer of rationalism, whereas for Ferdinand Christian Baur he was seen as the stage of a higher synthesis of faith and knowledge. From this perspective, liberal cultural Protestant theology was able to honour him and interpret him as a historical prerequisite for its own thinking. For Adolf von Harnack, Leibniz's theological achievement lay in his break with the Augustinian view of man and its doctrine of sin and grace, which he replaced with a joyful optimism. According to Ernst Troeltsch, Leibniz played a key role in the development of the modern form of Christianity, having introduced a new idea of God into theology that was compatible with modern science. The core of his philosophy of religion was mysticism, the inner presence of the gospel in the subject. Heinrich Hoffmann
(1874-1951), a student of both, published a monograph on Leibniz's philosophy of religion at the beginning of the 20th century. Despite the realisation that Leibniz had worked on numerous theological problems, the view that his importance lay in paving the way for rationalism remained dominant: "To summarise, it can be said that Leibniz's religious-philosophical outlook was essentially deistic, but that this basic scheme was crossed by a number of other tendencies. [. . .] There can be no doubt that the vital elements of Leibniz's view of religion lay on the side of what he called natural theology."
It was also the image of Leibniz as a pioneer of rationalism that led to criticism by the Lutheran Renaissance and dialectical theology at the beginning of the 20th century; according to Karl Holl and Werner Elert, Leibniz misjudged the sinful brokenness of man. In his great history of theology, Emanuel Hirsch interpreted Leibniz's theology as a shift in Reformation Christianity towards a piety that was nourished by the "universal view of rational-ethical character", even if Luther's Reformation religion of faith and conscience was still at work in it. Finally, for Karl Barth, Leibniz - as respectfully as he wrote about him - was the prototype of an improper mediation of faith in reason and Christ, a monistic optimism to which the revealing God had said no.
The long shadow of reception history: outlook into the 20th century
The stages of the Leibniz recourse in Christian theology were characterised by the external conditions of reception: the fragmentary knowledge of his work and the influential mediation of his thought by Christian Wolff. The result was that natural, i.e. philosophical theology, was at the centre of the reception. Leibniz was seen as a thinker of the theorem of sufficient reason, the monad and pre-stabilised harmony and of metaphysical optimism. As such, he was influential - in the form of Wolffianism - but was soon regarded as a precursor of rationalism, which he had rejected in itself. The theology of the 19th century therefore either saw him as a (mere) precursor of its own cultural Protestant thinking or rejected him as a pioneer of a rationalist falsification of Christianity.
The communication of Leibniz's thinking on theodicy and through Wolff resulted in a one-sidedness: Leibniz's defence against deism, Socinianism and rationalism was only insufficiently recognised; his reflections on material theology, on dogmatics, were almost unknown; the connection between his philosophical and theological thinking and his ecumenical efforts were not grasped. This is one of the reasons why the modern ecumenical movement in the 20th century initially managed without any significant knowledge of Leibniz's thoughts. Aloys Pichler's complete account of his theology remained the exception; due to Döllinger's break with the Catholic Church at Vatican I and Pichler's tragic fate, it too was unable to exert any great influence.
Only recently has the Academy edition and, in conjunction with it, Leibniz research brought to light the wealth of Leibniz's theological reflections and texts. The realisation of how closely philosophy, theology and ecumenism, as well as other areas of knowledge, are linked in Leibniz's work has since shaped Leibniz research and also our conference. A new, more in-depth reception of his thought in Christian theology has also begun to emerge, particularly in the work of the emeritus Erlangen systematician Walter Sparn. Nevertheless, a broader reception of his thought is still pending, which claims to ward off naturalism, rationalism and atheism, to preserve the mysteries of Christianity and to rethink them in a rational way, thus contributing to peace, unity and progress among Christians
and all of humanity.
