It has been known for over two centuries that Gottfried Wilhelm Leibniz (1646-1716) spent many years endeavouring to unite the separate Christian denominations. His writings and correspondence are preserved in one of the most extensive scholarly estates in the world, but are still far from being fully catalogued. And with almost every 1,000 pages of the now 64 volumes of the Academy Edition, new insights into his work and thinking in all areas of his work are revealed.
In the last few decades, Leibniz the ecumenist has become increasingly visible to us and his profile has been sharpened by some surprising new insights. Almost half a century ago, the Pallotine Father Paul Eisenkopf had already drawn a picture in the spirit of Vatican II in his work Leibniz und die Einigung der Christenheit (Leibniz and the Unification of Christianity), Munich, Paderborn, Vienna 1975. Leibniz appears there as a committed follower of the great figures of humanism, such as Erasmus of Rotterdam or Philipp Melanchthon, who had opposed the division of Christianity in the 16th century.
Pioneer of ecumenism?
But can he even be called an ecumenist or even a pioneer of ecumenism? Apart from the fact that this term only came into use in the modern sense a good hundred years ago, some researchers also refuse to label him as such for another reason. For some, Leibniz's commitment was due to his duties as an advisor to the princes in whose service he also worked in this field. And these princes were mostly guided by their own dynastic interests when they advocated a rapprochement between opposing churches, be it between Lutherans and the Roman Catholic Church or when they wanted to bring about an intra-Protestant unification of Lutherans and Reformed. Others concede that Leibniz was also an irenicist out of personal conviction and that he was in favour of peace and reconciliation, but do not see him as an ecumenist. French Leibniz researcher Claire Rösler-LeVan, for example, argues that Leibniz's attempts at union differ fundamentally from the ecumenism of our time because the latter emerged from the autonomy that the religious had gained in relation to the political and, conversely, the political in relation to religion. So, one might ask, are the many thousands of pages in which Leibniz develops his proposals for Christian unity, propagates his method or deals in detail with the controversial issues in letters and expert opinions mere products of the commissioned work of a court servant, bound by time and interests? Or are they impressive and forward-looking testimonies to the commitment of an ecumenist in the modern sense? This question will be
will now be analysed, at least in an overview.
Starting points
As a member of a generation born during the Thirty Years' War, Leibniz had already been sensitised to the adversity of the church schism. His contemporaries had perceived it primarily as a battle between the two separate camps of Christianity in Central Europe. In his native city of Leipzig, Leibniz also experienced a Lutheranism that was characterised by rigid confessionalism. The latter believed itself to be in possession of the only inalienable truth of the Gospel, which had to be defended not only against other denominations, but also against the irenic-minded Lutheran theologians.
The latter endeavoured to reach an inter-confessional compromise with the Roman Church, and ultimately also with the Calvinists, in order to create greater unity, at least among the non-Roman churches, which would allow mutual admission or even joint celebration of the Lord's Supper. The young Leibniz thus sympathised with the Irenics, whose head and most important spirit was the well-known Helmstedt Lutheran theologian Georg Calixt. This university in Helmstedt formed the centre of an irenicism that found its fiercest opponent in the Lutheran theologians at the faculties in Leipzig and Wittenberg.
The fact that Leibniz's later commitment to church unity was not simply fuelled by his sympathy for irenicism, but had its roots in much more complex ideas, is shown by the path he took after being awarded a doctorate in both law at the age of 21 on the basis of an outstanding thesis. He turned down a professorship in law that was soon offered to him because he already harboured a life plan that we can certainly call ecumenical. Even in the young Leibniz, we come across indications of a very precise idea of how reconciliation between controversial positions would be possible.
Even for jurisprudence, his field of study, he called for the unification, in his language the conciliare or syncretizein, i.e. the reconciliation of the different justifications of law, by recourse to philosophy, not just any philosophy, but as the application of scientifically rigorous methodology in the Euclidean sense, i.e. the mathematical-logical linking of statements on the basis of clear definitions of concepts. Even as a young man, Leibniz considered the development of such a science of sciences to be necessary, a project that would later accompany him throughout his life as an endeavour towards a scientia generalis.
And there are already writings in which he wants to apply this science, one example being a writing by the 21-year-old against the atheists, whose views he saw as a serious threat to the res publica christiana. At the age of 22, he wrote an overview of all-encompassing evidence (Demonstrationum Catholicarum Conspectus). In just a few pages, it first names the prolegomena in which the "elements of true philosophy" should be developed: these are metaphysics, logic, mathematics, physics and practical philosophy. In the following two parts, he names the topics of natural theology, everything that can be recognised by reason, i.e. that can be understood by all rational people if they apply the scientific method claimed by Leibniz.
In the third part, he addresses the mysteries of the Christian faith, i.e. the contents of revelation that are not accessible to reason. For these, he projects the proof not of their truth, but of their possibility, i.e. that they do not contradict reason, which would prove them to be impossible and thus untrue. Finally, the fourth part is devoted to a double proof, namely the authority of the Catholic Church and the authority of Holy Scripture. And here the Lutheran Leibniz at least states the supremacy of the Roman Pope over the whole of Christendom, a supremacy that three decades later, going beyond the Reformation, he also explicitly sees as being based not only on human law, as was the case with Melanchthon, but on divine law.
A glance at the Academy edition, which has now reached the first decade of the 18th century in almost all its series, shows how Leibniz worked through the themes of this plan in the following decades, even if he always kept the plan as such a secret. It was drawn up in 1668 at the court in Mainz, probably in the expectation that the influential Prince Elector Johann Philipp Schönborn, who had an irenic outlook, would be able to present it to the Pope on his upcoming trip to Rome.
We owe our knowledge of the significance of this plan to two letters from the summer and autumn of 1679 to Duke Johann Friedrich of Hanover, in whose service Leibniz was now working. The prince, who had converted to Catholicism under the influence of Johann Christian Boineburg - who had brought Leibniz to the court in Mainz - had already got to know and appreciate Leibniz as a young scholar. We do not know whether Leibniz actually gave him the letters. In any case, it was once again a planned trip to Rome by an influential prince that triggered Leibniz's idea that the prince should communicate this plan to the Pope as something that came from himself. Leibniz now explains his plan in the letters.
It describes what the prerequisites for its realisation are: The actual ecclesiastical endeavour to achieve common clarity among Christians about the content of the Christian faith and the endeavour to integrate and subordinate Christians to the ecclesiastical hierarchy requires preparatory work, a foundation. He describes it entirely in terms of the prolegonema of his plan of 1668: the elements of true philosophy must be developed, a new logic, a metaphysics that points beyond the previous one and uses veritable concepts of God - namely the triune God -, of the soul, of the person, of substance and accident, and a physics that at least makes creation, the Flood and the bodily resurrection appear possible.
However, the Prolegomena also include the clarity required for the "foundation of true morality" of such concepts as law, justice, freedom, happiness and bliss. For Leibniz, the goal of true politics is nothing less than the "attainment of happiness" for all of humanity, indeed even icy bas, here on earth. And there is nothing that conforms to this goal as much as what he, Leibniz, has said about the indestructible and irresistible power of the divine sovereign over all external goods and the inner rule of God, as exercised through the Church and souls.
Nothing is more conducive to the common good than the authority of the universal Church, which forms the body of all Christians united by the bond of love, caritas. And therefore it must be the wish of every good person that the splendour of the Church be restored everywhere and that the spiritual authority of her true servants over the faithful be recognised a little more than is often the case in practice, especially among those who consider themselves to be the most Catholic.
As the few references to the starting points already show, we are not simply dealing with an irenic and certainly not with a court official simply carrying out the orders of his employer, but with a person who, from his youth, had focussed all his intellectual energy and life planning on the goal of uniting the divided Christendom in the universal Catholic Church. But it also became clear that this goal should serve an even higher purpose, namely the well-being and happiness of all mankind. And so his endeavours, which can probably be described as ecumenical, are also linked to the other project that spanned his life over four decades: The establishment of a European network of scientific societies, in other words what we now call academies of science.
If we look at Leibniz's metaphysics, then we can also understand his plan as co-operation in God's universal monarchy. This monarch is defined by Leibniz as the being who is rational, just and good in the highest perfection. Therefore, the goal of his monarchy can be nothing other than the perfection of the whole of humanity and the whole of creation, as it is achieved in the infinite, when God is all in all. God rules this monarchy with the help of the best spirits among the creatures, who as such are metaphysically necessarily imperfect (for otherwise they would be God himself), but who participate in the divine perfection, asymptotically approaching it like the whole of creation.
Thus Leibniz sees himself as a co-worker in the Republic of Spirits, and for Leibniz it is a strictly rational necessity that this goal be achieved, even if our necessarily imperfect and therefore clouded perception is not able to recognise the wisdom of the divine monarchy in every single event. Can this not be called ecumenical? What element of the modern ecumenical movement is not represented in Leibniz's ideas? This may be asked only in passing.
Leibniz's goal is ambitious, it is global, truly ecumenical, it is about the whole of humanity. But it should not be called visionary and certainly not utopian. After all, does Leibniz not take the vastness and greatness of the goal into account in a decidedly sober manner (always said under the conditions of his age) by recognising that the means he named were anything but easy or cheap to obtain? He knew that it was an enormous task that he did not see himself capable of solving alone. On the other hand, he knew that, endowed with a special genius, he could play a significant role in providing the means for humanity. Can one blame such a keen intellect that this genius did not remain hidden from him?
We count him among the leading scholars of his time; everywhere he could communicate on an equal footing with the leading minds of his time. But he was a mathematician and also a metaphysician, a physicist, politician, theologian, jurist, historian, technician and more; but he was not a mere polyhistor, he was rather all of these as an ecumenist and the areas mentioned were to a certain extent subsidiary. Heinrich Schepers (who edited the philosophical letters and writings for decades) concluded his article on Leibniz in the third edition of the encyclopaedia Religion in Geschichte und Gegenwart as early as 1960 with the sentence: "What characterises L's rationalism in general is that he became a mathematician for the sake of theology."
And Ursula Goldenbaum has documented this connection in her own way in several meticulously elaborated essays: Leibniz, she writes at one point, became a metaphysician, a mathematician - we can add a physicist - in the first place "because he wanted to make Christian theology of revelation compatible with modern science". And so, with a view to the sources mentioned, we can add that this created a prerequisite for the unity of Christians and thus in turn the prerequisite for achieving the decisive global goal, the well-being of all humanity.
In the following, I would like to give a few quick pointers as to how and to what extent these foundations or characteristics of Leibnizian ecumenism are actually recognisable in practical church union efforts.
Concretisations and directions
a.) All of Leibniz's initiatives and endeavours did not lead to any tangible rapprochement between the divided confessional parties. The history of his endeavours has, if one looks at the sober historical facts, remained a history of failure. But that is what links him to most irenicists and ecumenists. The other project just briefly alluded to, the founding of academies of science in Europe, also failed to succeed, with a few exceptions (in Berlin), although he came very close to realising it, for example in Saxony and Vienna. Leibniz's experiences of failure could not deter him from his plan; for higher than all historical experiences was reason, which in its strict application had led him to the truth of his metaphysics and thus to the insight into the wise reign of the universal monarch who rules rationally, benevolently and justly in the highest perfection, even if the realisation of the wisdom of many a development and many an adversity may have often remained hidden from him. "And it is enough that we know in general that God has chosen the best that the perfectio universi requires, even if it is impossible to grasp the specialities of it in this life".
For decades, the irenic-minded highest Hanoverian clergyman Gerhard Wolter Molanus was his comrade-in-arms both in negotiations with Catholic representatives and with the Reformed denomination. And in the spirit of that quote, we see Leibniz in his late correspondence with a now unwilling Molanus as the persistent fighter who stuck to his goal. In this case, it was about a communion of the Lord's Supper between Lutherans and Calvinists with the involvement of the Anglican Church, which was only achieved in the 1970s with the Leuenberg Agreement.
Trusting in divine goodness and wisdom does not mean devoutly waiting, but constant vigilance with regard to favourable political constellations. Leibniz speaks of "conjunctures"; he saw one such conjuncture in 1685, for example, during the reign of Pope Innocent XI, whom he called a "Pape traitable" (an affable pope). And there were rational theologians under a committed prince: "I think it would be good to profit from this boom." He expressed similar sentiments in 1668, 1679, 1706 and even in November 1716, the month of his death.
b.) Leibniz gives the same answer to the question of the causes of church schisms as Augustine or the aforementioned theologians of the Reformation period: church schisms are not primarily caused by theological differences, by doctrinal and confessional differences, but by a lack of love. However, this caritas is now a central concept that Leibniz works through in the first decades of his philosophical and political work and which he ultimately incorporates into the definition of justice as the caritas of the wise and of universal benevolence, based on antiquity, Plato, Cicero, Augustine and the book of golden virtue (1647) by the Jesuit priest Friedrich Spee. This is his demand for the union negotiations: We must negotiate not with an amour mercenaire, not in the greedy insistence of a merchant's soul on self-interest, but in an amour non mercenaire, as one might say in modern terms, in the manner of a dialogue or discourse free of domination, oriented not only to one's own good but also to the good of the respective counterpart. For negotiations, this means refraining from trying to force unity by asserting one's own position as the only true one at the expense of that of the other party and asserting one's own position against the other side in every respect.
Then, as now, it was the concept of the church that stood in the way of a union between Protestants and Catholics with regard to the reunion negotiations. Contrary to some statements in older literature, Leibniz did not have a spiritual concept of church; the love that he saw as the decisive element was the love of God, which he defined as the love of divine perfections. Unfortunately, there is not enough space here to analyse the consequences of this. In any case, love of God and love of neighbour did not mean, as with the great pseudo-areopagite Dionysius or with the Quietists of Leibniz's time and especially with François Fénélon, giving up or the willingness to deny and completely abandon one's own self - this was already forbidden by Leibniz's metaphysics of substance - but rather the joy in the happiness of others.
His concept ruled out an amorphisation of the churches in the sense of a dissolution of fixed juridically determined hierarchical structures. The church is res publica, is a persona civilis in the sense of Roman law. Paul Eisenkopf has already pointed out that for Leibniz, the formation of a new, third party could not be the solution to the controversies of two parties. Instead, Leibniz endeavoured to formulate his own truth in a way that did justice to the truth in the position of his opponent. "Everything that is true agrees with what is true". This sentence from Aristotle's Nicomachean Ethics had already motivated the equalising theologians of the Reformation period, above all Martin Bucer.
Leibniz tried to realise this in a new way, using his extensive knowledge of the history of dogma and confessional studies. A famous example is the Examen religionis christianae (Examination of the Christian Religion), later known as the Theological System, which he wrote in the important year 1686, like the Discourse on Metaphysics. In it, he wrote down how a Catholic theologian could express the truth of his faith, which he considered indispensable, in such a way that his Protestant opponent would find his concerns taken into account without either party having to give up the essence of their confession. This has often been misunderstood as crypto-Catholicism. Leibniz remained a Lutheran or, as he put it, a member of the Augsburg Confession in order to avoid using the term linked to a person. According to what has just been said, a conversion would not be conclusive either. Thus we have the statement from him: "If I had been born a Catholic, I would have remained a Catholic all my life".
c.) Much of what has just been said is methodologically in line with irenicism, represented in Leibniz's time above all by the aforementioned Georg Calixt, his pupil Molanus, the Scotsman John Dury and not least by the Berlin court preacher and bishop of the Moravian Church Daniel Ernst Jablonski, and in certain respects also by Johann Amos Comenius. And yet Leibniz's irenic impulse had a different basis and ultimately led to a singular position among the irenics of his time, as well as in the history of ecclesiastical unity endeavours in general.
This is illustrated here by just one example from the initial phase of the intra-Protestant negotiations that began between Brandenburg and Hanover in 1697/98, not least in order to strengthen the weight of the non-Catholic electors in the empire, which had been weakened by the conversion of the Saxon elector. For Leibniz, love as the driving force of reconciliation is not simply understood in the sense of the paraenesis of 1 John, but as the love of divine perfection it is benevolentia universalis, universal goodwill. It is the realisation of the demand made by Leibniz in the Discours de Métaphysique: Morality must be bound to metaphysics, it is not acceptable "to see God only as a principle and as the cause of all substances and beings, but one must see him as the chief of all persons or intelligent substances, as the absolute monarch of the most perfect republic, such as that of the universe, composed of all spirits together".
The perfection of God's goodness is also an expression of the perfection of reason. God governs the universe as a rational being. This means that love of God, charity, universal benevolence and justice always correspond to the best possible use of reason. And this brings us to the last point, which in my opinion most clearly characterises Leibniz's ecumenical method.
The negotiations began in 1697 with an extensive expert report by Daniel Ernst Jablonski. Like other great irenicists, he examines the doctrinal differences between the religious parties according to their potential for consensus, establishes a consensus on the substance of most points, which is merely covered up verbally, and endeavours to find a "middle road" for the factual differences, which could be followed by both parties. For the rest, the unresolvable differences, mutual tolerance should be granted and thus a provisional union made possible.
Leibniz saw no real basis for church unity in this method, and his experiences with the religious dialogues of the 16th and 17th centuries proved him right. Leibniz did not see the doctrinal differences as being rooted in the theological, but rather in the philosophical pre-understanding that determined the theologians' thinking. Theological judgements arose from sometimes minor philosophical errors, which made the confessional statements of the other side appear heretical and catapulted the other side out of the community of those who had the right Christian faith.
Thus Leibniz's Uniongutachten, including his reply to Jablonski, contain broad statements that can also be found in his metaphysical writings and correspond methodologically to what he had already regarded as necessary for the clarification of the concepts and for the conclusiveness of the proofs as a young scholar and advisor.
Jablonski then told Leibniz about the resistance that Leibniz's opinions had met with among the Reformed in Brandenburg, who resisted having to accept a supposedly new philosophy. Leibniz also failed at this point. In 1817, when the administrative union of Lutherans and Calvinists finally came about in Prussia, Leibniz and Jablonski's attempt at union was at least respectfully commemorated.
The ecumenist
Leibniz's path to church union is truly ecumenical insofar as the common bond of the true Catholic Church is, for him, love in the sense of a benevolence that aims at the whole of humanity and finds its foundation in participation in the universal rule of God, who is rational, just and good in the highest perfection. His ecumenical endeavours are thus characterised by a great continuity right up to the last weeks of his life and by a far-reaching consistency of his actions in concrete situations, in the conjunctures, as he called them, and with what remained the basis of his work throughout his life. What sets him apart from the irenics of his time is the ecumenical breadth not only of his thinking, but also of his initiatives and proposals.
All available knowledge about the oikumene (the basic meaning of this Greek term is "the whole inhabited world") was included in his thinking, for decades he maintained contact with China and Russia, and his proposals on Islam, known as the Egyptian Plan, but his view of other countries, India and the cultures of the Near East, the countries of the so-called barbarians, also had an ecumenical background. He recognised the great importance of mutual exchange and a mutual mission between China and Europe, "that light should be kindled by light". In the last decade of his life, the plan for a world council under the aegis of Peter the Great, i.e. including the Orthodox Church of the East and the churches in the Middle East today, appears in his correspondence.
Thanks to his long experience and extensive global knowledge, he is aware of the provisos that would have to be considered in such a project with regard to the Roman Church, Anglicanism and also the Sultan. Certainly, many of his ideas reflect the horizon of expectations of the early Enlightenment, in some
However, he was far ahead of his time in terms of his ideas, such as his idea of a world council or a mutual mission between China and Europe.
