An Unexpected Leibniz is Arising from His Unpublished Papers
A conversation with Lloyd Strickland, the Project Director and Editor of the Leibniz Philosophical Papers Project, a continuing manuscript-based English edition of Leibniz’s philosophical writings
By Primavera Fisogni
The Leibniz Philosophical Papers Project (LPPP) is probably one of the most challenging projects for contemporary philosophy. It addresses a major gap in early modern philosophy by expanding the limited body of Leibniz’s writings available in English. Published by Oxford University Press, its first three volumes (1677–1686) present 314 texts—over 200 translated for the first time—transcribed directly from original manuscripts (primarily in Hannover). Rekh Magazine asked the editor, Professor Lloyd Strickland, the Project Director and editor of the LPPP, to introduce readers to this work, which is going to throw a new light on Gottfried Wilhelm von Leibniz (July 1, 1646 – November 14, 1716).
The project is building on a centuries-long history of attempts to publish Leibniz, while your first three volumes were published by Oxford University Press in 2026. What prompted the creation of this particular English-language project, what was missing from existing editions, and why was a new editorial effort necessary?
If you go into a good university library and look for the writings of the major figures of early modern philosophy, you will find substantial English editions of Descartes, Spinoza, and Kant. With Leibniz, the situation is very different. For generations, English-speaking readers have largely had to rely on short anthologies, thematic selections, and collections of the best-known texts, but between them all these collections contain only a small fraction of Leibniz’s entire philosophical output. To date, no large-scale English-language edition rounding up Leibniz’s key philosophical papers is available, to the great detriment of English-language students and scholars. Putting this right was the fundamental motivation behind the Leibniz Philosophical Papers Project. The aim was not to focus merely on the same famous texts once again, but to enlarge the body of philosophical writings available in English. Consequently, the first three volumes of Leibniz’s Philosophical Papers published earlier this year focus on a whole decade — 1677 to 1686 — and try to recover something much closer to the breadth of Leibniz’s philosophical activity during those years. Between them, these three volumes contain 314 texts, of which 203 appear in English for the first time, and nearly a million words.
A central feature of this edition is that it returns directly to Leibniz’s manuscripts rather than simply relying on previously printed transcriptions. In the great majority of cases the manuscript has survived, and I have consulted it directly (and where the original manuscript has been lost, I have worked from the best surviving copy or transcription). This matters because earlier printed transcriptions, though often extremely useful, can contain misread words, omissions, and other errors that materially affect a translation. Working from the manuscripts also allows different drafts to be kept distinct instead of being merged into artificial hybrid texts (which has often happened with Leibniz’s famous “Discourse on Metaphysics”, for example), and makes it possible to preserve deletions and marginal additions that show Leibniz changing his mind as he writes.
So the Leibniz Philosophical Papers Project is not intended as a rival to the foundational German historical-critical edition (the Academy edition) which publishes Leibniz’s writings in their original languages of Latin, French, and German. It is instead doing something complementary: creating a much larger manuscript-based English corpus, while preserving enough of the evidence of composition to let readers encounter Leibniz not only as the author of polished finished works but as a thinker at work. The twin ambitions of the project are to make considerably more of Leibniz’s writings available in English, and to present them as accurately and clearly as possible.
Where are the manuscripts you are working from physically located? How dispersed is Leibniz's philosophical archive among libraries, archives and private or institutional collections? And how much of the surviving material has actually been digitised and made accessible to researchers?
The vast majority of Leibniz’s surviving manuscripts are housed in the Gottfried Wilhelm Leibniz Bibliothek (GWLB) in Hannover, with smaller numbers held by libraries and archives in Wolfenbüttel, Vienna, Paris, London, Copenhagen, and elsewhere. Most of the manuscripts I consulted for the first three volumes of Leibniz’s Philosophical Papers are held by the GWLB, with a few additional items in Vienna and Paris.
A large proportion of Leibniz’s manuscripts have now been digitised and made available online, which has certainly transformed the possibilities for research, though some still remain undigitised. But of course, digitisation is only the first step in any case, as putting an image of a manuscript online does not amount to editing it. Leibniz’s handwriting still has to be deciphered, the text established and dated, revisions and deletions interpreted, sources identified, and, in the case of this project, the result translated and annotated. So while digitisation has greatly improved access to the manuscripts, it hasn’t removed the need for painstaking editorial work.
Leibniz died in 1716, yet your project describes a substantial body of philosophical material that remains unpublished or only partially edited (after 1690). Is the problem primarily the sheer quantity of manuscripts, their handwriting and physical condition, the complexity of reconstructing drafts, the lack of specialists, the history of Leibniz scholarship—or a combination of these factors?
I would say it’s very likely a combination of all these things. The most obvious problem is simply the quantity of material Leibniz left behind: about 100,000 sheets. Not all of these concern philosophy, of course, as he wrote on many other subjects: mathematics, history, politics, languages, poetry, etc. The thousands of sheets containing his philosophical writings include polished works as well as drafts, fragments, reading notes, marginalia, discarded beginnings, and sheets on which several quite different pieces of work may appear together. Much of this material was never intended for publication. Editing a corpus like that is inevitably a very slow process.
In addition, Leibniz’s handwriting can be extremely challenging, particularly in hurried drafts where he appears to be thinking faster than he could write, leading him to cross words out, insert alternatives above the line, and add material in the margins. He also sometimes returned to a manuscript at a later stage. As a result, a text that fills only a page or two may require a considerable amount of work before one can confidently say what Leibniz wrote and in what order he wrote it.
Dating and reconstructing the texts can be just as difficult, as he left many manuscripts without a title or a date. Sometimes the date can be narrowed down by evidence such as watermarks, his references to books or events, or the development of a particular argument. In other cases, there may be several drafts whose relationship has to be established before the text can properly be understood.
There is also a question of expertise. Working on this material requires a combination of palaeography, languages, textual scholarship, intellectual history, and philosophy. It is not enough just to decipher the words, as one also has to understand what Leibniz is arguing, what sources he is responding to, and sometimes why a seemingly minor alteration matters philosophically.
The publication involves recovering texts, establishing reliable readings and translating them, while preserving drafts, deletions, marginalia, corrections and variants. Can you take us through the forensic process?
Earlier this year I made a series of short videos in which I document all of these things. The full playlist is here: https://www.youtube.com/playlist?list=PLOZ9zM6XIrg5Din4cMrjEoxdwJz3Om48Y
See especially the videos on Dating, Capturing, Deciphering, Reconstructing, Unearthing, Reassembling, and Deleting.
All of those videos concern the work done on the 3 volumes of Leibniz’s Philosophical Papers 1677—1686, which were published earlier this year. Rather than repeat what is said in those videos, I’ll give a different example, this one from the two volumes of Leibniz’s Philosophical Papers: Reading Notes and Reviews 1675–1715 that are currently in preparation:
This is part of a long manuscript on metaphysics. In a marginal note written on the right-hand side of the page, Leibniz states that there are two supreme principles governing our knowledge: (1) the principle of contradiction, which holds that anything containing a contradiction is false, and the principle of sufficient reason, which asserts that there is a sufficient reason why things, truths, or events are thus and not otherwise.
When the manuscript was transcribed in the 1970s, the note was made to end with the words Ex principio contradictionis oritur, which the editor took to mean: “It arises from the principle of contradiction”, where “it” refers back to the principle of sufficient reason.
As the editor noted, that creates a genuine philosophical puzzle, because Leibniz normally treats the principle of contradiction and the principle of sufficient reason as distinct fundamental principles, and nowhere else does he say that the latter can be derived from the former. The editor therefore took the passage seriously as evidence that Leibniz had, at least briefly, entertained just such a possibility.
But when one returns to the manuscript, the puzzle disappears. Leibniz did not stop at Ex principio contradictionis oritur. He continued with one further word: logica — “logic” — and then crossed that word out. What he had actually written was:
Ex principio contradictionis oritur logica.
“From the principle of contradiction arises logic”.
That deleted word is crucial, because it reveals that Leibniz was thinking not that the principle of sufficient reason arises from the principle of contradiction, but that logic does. And a few lines later, in the main body of the manuscript, he expresses essentially the same idea again, describing logic as “the science which uses only the principle of contradiction”.
So here, a single crossed-out word changes the philosophical meaning of the passage. Once we know Leibniz continued the sentence with logica before crossing it out and apparently abandoning the marginal note altogether, there is no need to suppose that he momentarily entertained the idea that one of his two great principles was derived from the other. What looked like an exceptional and puzzling philosophical position was simply an artefact of an incomplete transcription.
This is precisely why the manuscripts themselves matter, and why deletions matter. A word that an editor might easily regard as dispensable because Leibniz crossed it out can preserve the evidence needed to reconstruct what he was thinking as he wrote. In this case, recovering one deleted word does not merely improve the text: it resolves a philosophical puzzle.
In the two volumes of reading notes and reviews now in preparation, you have identified 23 manuscripts that have never been published in their original language and another five that were only partially published. What kinds of material do these texts contain, and what might they add to our understanding of Leibniz?
The 23 manuscripts in Reading Notes and Reviews 1675—1715 that have never previously been published in their original language, together with the five that have appeared only in part, already show something of the extraordinary range of the material. They concern metaphysics, epistemology, logic, natural philosophy, theology, language, and a number of other subjects.
But the importance of the two volumes is not confined to those 28 items. The complete collection contains 76 writings extending across roughly forty years of Leibniz’s career, and it gives us access to a side of him that is much less familiar than the author of polished philosophical works: Leibniz as reader. In these writings we see him encountering books and arguments, identifying what interests him, objecting, correcting, testing possibilities, and sometimes developing ideas of his own in direct response to what he has read. We see Leibniz engaging with familiar figures such as Descartes, Malebranche, Locke, and Bayle, but also Epictetus, Sextus Empiricus, and Maimonides, as well as topics such as the Kabbalah, Jewish philosophy, Chinese philosophy, and Indian religion.
It’s worth noting here that even in the case of the texts have been previously appeared in print, publication does not necessarily mean that they have been available in a satisfactory form. In fact, many have not. Many of the items that have appeared before are available in old or unreliable transcriptions, and when I return to the surviving manuscripts I often find these transcriptions contain misread words, omissions, or other errors: we saw an example of this in my answer to the previous question. So part of the task is not simply to publish new material, but to recover more reliable texts of material that scholars may think they already possess.
Some of the material in the texts of these two volumes appears nowhere else in Leibniz’s surviving writings. One text records Leibniz’s reaction to emerging racial categories; another shows that his commitment to the doctrine of complete concepts persisted well into the 1700s. Another contains an important anecdote concerning Spinoza’s reaction to the murder of the de Witt brothers, a reaction that Leibniz witnessed firsthand; this can now be presented on a more accurate textual basis than has previously been available.
Some of the material also throws new light on the genesis of the Theodicy, Leibniz’s major book published in 1710. The book closes with a famous allegory in which Theodorus is shown different possible worlds and comes to understand why divine wisdom selects the one it does despite the evils it contains. An unpublished manuscript that will be included in the two volumes of Reading Notes and Reviews 1675—1715 contains a precursor to this allegory, where Leibniz asks us to imagine Prometheus being taken into Jupiter’s cabinet and shown not different possible worlds but different possible lineages or sequences of human beings. In one, he sees Eteocles and his brother killing one another, together with “a thousand other evils”; yet the laws of divine wisdom nevertheless oblige Prometheus to choose that one. To the best of my knowledge, this earlier Prometheus version has so far gone unnoticed.
This is just one reason why these reading notes are so valuable: they preserve stages in the formation of ideas that later emerge in much better-known works. They give us something close to a running record of Leibniz thinking in response to other thinkers.
How many researchers are currently involved in the Project, how are their roles divided, and what specialist skills are required? Is this fundamentally the work of a philosopher, a historian, a philologist, a palaeographer, a translator—or all of them?
The principal editorial work is currently carried out by one person: me. The Project has an Advisory Board of five senior scholars who can provide occasional scholarly advice, and of course I consult other specialists when needed, but the selection of texts, manuscript work, transcription, translation, annotation, dating, introductions, and preparation of the volumes are all my responsibility.
So the answer to the second part of the question is really: all of them. Working with Leibniz’s manuscripts requires skills that would normally be associated with several different disciplines. Palaeography is needed to establish what Leibniz wrote; Latin, French, and German are needed to understand and translate it; textual scholarship is required to distinguish drafts and reconstruct revisions; intellectual history is needed to identify the books, people, and controversies that are discussed; and philosophy is indispensable for understanding what is actually at stake in the arguments.
In practice, these skills are not neatly separable. A difficult word in a manuscript may be decipherable only once you understand the philosophical argument in which it occurs; conversely, what looks like an important philosophical claim may disappear once the manuscript has been read correctly, as I noted in my answer to question 4. Translation comes only after those problems have been resolved.
That combination of skills has taken a long time to acquire. I have been working on Leibniz and early modern philosophy for more than twenty-five years, and a good deal of what makes the Project possible is the cumulative knowledge that comes from having spent that long reading his manuscripts, following his terminology, and becoming familiar with the intellectual world in which he worked.
Gottfried Wilhelm von Leibniz (July 1, 1646 – November 14, 1716) Why have 59 of the 76 texts in the next two volumes never previously appeared in a complete English translation? And could the newly translated material significantly broaden the picture of what Leibniz was actually interested in?
I suspect there is no single reason why so much of this material has never appeared in English. Part of the explanation probably lies in the way Leibniz has traditionally been edited and translated. English-language collections have understandably tended to concentrate on his best-known philosophical writings: finished essays, major correspondence, and texts in which he states or defends his signature doctrines. Reading notes and book reviews are a rather different category, as they can be fragmentary, highly dependent on the work being discussed, and sometimes difficult to appreciate without reconstructing quite a lot of context. As a result, where they have appeared in English-language collections, it has usually been as isolated pieces rather than as a substantial body of material in their own right.
There are also practical reasons. Some of the texts have never been published at all in their original language; others survive in editions or transcriptions that are difficult to use or unreliable; and many require a good deal of editorial work before translation can even begin. A reading note may make little sense until one has identified the book Leibniz was reading, located the precise passage to which he is responding, established a reliable text of Leibniz’s remarks, and reconstructed enough of the surrounding argument to understand what is at stake. So translating this material is often inseparable from editing it.
As to the second question, I would be wary of saying that the texts in these volumes will radically broaden our picture of what Leibniz was interested in, as scholars already know that his interests were extraordinarily wide, but the volumes certainly will provide a much fuller picture. They bring together 76 texts extending across forty years of Leibniz’s career, and because these texts are arranged chronologically, they allow readers to see not simply what interested him, but how particular interests and engagements persisted, changed, or resurfaced over time. In some cases we can watch him return repeatedly to the same author or work, reconsidering arguments years later. The result is not so much a new map of Leibniz’s intellectual world as a map with a lot more of the detail filled in. So the principal gain is not that we suddenly discover an entirely different Leibniz entertaining an entirely different philosophy, but that the Leibniz we already partly know becomes more densely documented, more historically situated, and hence more complete. Leibniz himself once used an image which seems very appropriate here. He suggested that if a beautiful painting were partly covered, we would be in no position to judge its full beauty from the fragment we can see. He applied the comparison to the universe: because we see only a tiny part of the whole, our perspective on it is necessarily limited. Something similar is true of Leibniz’s own philosophy: if we can read only a fraction of what he wrote, we should not be surprised if our picture of his thought is partial as well. The more of the canvas that is uncovered, the better our chances of understanding not simply individual doctrines, but the relations between them, their development over time, and the extraordinary range of questions with which he was engaged.
The Project plan asks for £75,000 to fund twelve months of full-time research and editorial work, while stating that existing Emergent Ventures support ends in May 2027. What exactly does the £75,000 pay for? How many researchers’ salaries or working months does it cover, and why can’t the project continue on the basis of Oxford University Press publication revenue, university funding or existing institutional resources?
The simplest way of putting it is that the £75,000 secures twelve months of protected, full-time research time for one senior editor and translator. It is not the budget for a team of researchers, nor is it a publication cost. It allows me to spend a year doing the work itself: locating and deciphering manuscripts, establishing texts, translating them, identifying sources, writing annotations and introductions, and preparing further volumes of the edition. Based on the work completed so far, I typically produce around 6,000–8,000 words a week of edited, translated, and annotated text, the pace varying according to the difficulty of the material. Since a substantial volume of the edition is around 300,000 words, a year of protected full-time research is, in practical terms, roughly what is needed to produce another volume. Work of this kind would normally be undertaken by someone holding a salaried university or research position, with the associated institutional support and employer costs. I no longer hold such a post, so there is no university salary underwriting the time I spend on the Project.
- Oxford University Press is the publisher of the edition, not its research funder. Scholarly editions of this kind are produced for a specialist academic market, and unfortunately royalties from them do not come close to covering the cost of the years of research needed to produce them. That is true of academic publishing generally: the fact that a university press is willing to publish a work does not mean that it is financing the research behind it.
- The current Emergent Ventures grant supports a defined programme of manuscript research, translation and public-facing work through May 2027 but does not provide continuing support after that point. The £75,000 target is therefore about securing the next uninterrupted year of work.
- Ultimately, the scarce resource here is time: concentrated time from someone with the specialist skills needed to turn difficult manuscript material into texts that other scholars can actually read and use.
What work would stop after May 2027 without new funding? Which manuscripts or volumes would be delayed, and how much time would ultimately be lost?
I’d like to start by clarifying that the two volumes of Reading Notes and Reviews 1675—1715 now in preparation will be completed before the present period of support ends, so the question is not whether those particular books will suddenly be abandoned in June 2027, because by then they will be in press anyway. The new funding is about what happens next. Without further support, what becomes difficult to sustain is continuous full-time work on the subsequent stages of the Leibniz Philosophical Papers Project, as I would have to devote a substantial proportion of my time to other paid work, and manuscript research, translation, and editing would consequently have to be fitted around it. That matters because this kind of work benefits enormously from continuity: if I am working through a group of related manuscripts, for example, I am simultaneously carrying in my head their terminology, handwriting, sources, chronology, and relationships to one another. Breaking that work into occasional days or snatched hours does not make it impossible, but it does make it considerably slower.
If funding does not emerge, what would be affected is not the quality of the work (that is, it would not lead me to lower the editorial standard or omit difficult material) but the timetable for further volumes: without substantial time to dedicate to them, they would take longer to prepare, and manuscripts that could otherwise be transcribed, translated, and published in the next few years would remain inaccessible for longer. I can’t give a precise figure for the delay, because that would depend on how much other paid work I needed to undertake, but the difference is essentially between being able to treat the Project as a full-time research programme and having to continue it intermittently alongside other work.
Are the documents being published also available online? Are they (or at least some of them) freely accessible to scholars around the world?
There are several different questions here. Many of the underlying manuscript images are freely available online through the libraries that hold them, particularly the Gottfried Wilhelm Leibniz Bibliothek in Hannover. But, as I mentioned earlier, access to an image of a manuscript is not the same thing as access to an edited and translated text.
The Leibniz Philosophical Papers volumes themselves are published by Oxford University Press and are available through the normal channels for scholarly books and electronic editions, including institutional library access. They are not currently open access. However, I have made hundreds of English translations of Leibniz freely available online (see https://www/leibniz-translations.com) as well as a lot of public-facing material (see https://leibnizpapers.org), but the Oxford University Press edition itself remains a conventional academic publication.
With that said, my longer term hope is that the Project will acquire a substantial open digital dimension. One possibility would be a separate project to convert the published volumes into a structured and searchable digital corpus, preserving the texts and their scholarly data in a form designed for long-term use rather than simply reproducing pages from printed books. But that would require funding in its own right and would also require agreement with Oxford University Press over the reuse of the published material. Full open-access publication through a major academic publisher is expensive, so it is not something I can simply add to a project of this scale without additional resources. My ideal long-term outcome would be to have both things: scholarly volumes held in libraries, and a sustainable digital resource that makes as much of the material as possible searchable and widely accessible. But the latter would need to be built as a properly funded project rather than improvised.
Who Lloyd Strickland
Lloyd Strickland is Project Director and Editor of the Leibniz Philosophical Papers Project, a continuing manuscript-based English edition of Leibniz’s philosophical writings. Formerly Professor of Philosophy and Intellectual History at Manchester Metropolitan University, he has worked on Leibniz and early modern philosophy for more than twenty-five years. The first three volumes of Leibniz’s Philosophical Papers were published by Oxford University Press in 2026. His wider publication record includes more than 100 scholarly works and 15 books and edited volumes, among them Leibniz on Binary: The Birth of Computer Arithmetic (MIT Press, 2022, with Harry Lewis), Leibniz’s Key Philosophical Writings: A Guide (Oxford University Press, 2020, with Paul Lodge), Leibniz's Legacy and Impact (Routledge, 2019, with Julia Weckend), and Leibniz’s Monadology (Edinburgh University Press, 2014). He has received support from the British Academy, Gerda Henkel Stiftung, and Emergent Ventures.
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