Of all the great philosophers, Leibniz is perhaps the most inaccessible and certainly one of the most difficult to teach. This is partly for textual reasons, there being no single great work upon which his reputation depends, but instead a vast number of texts that go to make up what is surely the messiest and most unsatisfying corpus of work in the philosophical canon apart from Wittgenstein's. In his lifetime, Leibniz published just one book, the Theodicy of 1710, a work that is generally regarded as inferior to the various articles he published in obscure learned journals such as the Journal des Savants and Acta Eruditorum. Better still, it is commonly held, are the books he left unpublished: the Discourse on Metaphysics, the New Essays on Human Understanding, the Principles of Nature and Grace and the Monadology. But best of all, it is claimed, are the essays he left in manuscript form and the arguments he developed in correspondence with contemporaries such as Antoine Arnauld, Nicholas Remond, and Samuel Clarke.
Faced with this plethora of more or less minor texts, every student of Leibniz's work who is not a dedicated specialist is forced to depend upon selected anthologies. For non-specialist English readers, the most popular and useful collection is probably Leibniz: Philosophical Writings, edited by G.H.R. Parkinson and published in 1973. But, frustratingly, the secondary literature on Leibniz, even that in English, very rarely refers to this collection, and what one finds instead are references to the seven-volume German edition edited by C.I. Gerhardt that was published in the 19th century and which only a dedicated Leibniz scholar would ever even look at. Thus, the dependence upon commentators for a knowledge and an understanding of Leibniz's work is possibly greater than for any of the other great philosophers.
The aim of the Cambridge Companion series, its publishers state, is to "dispel the intimidation that readers may feel when faced with the work of a difficult and challenging thinker". That, in Leibniz's case, readers are more likely to be faced with reports of and extracts from his work, only makes it more difficult and challenging and the need for such a companion all the greater. The appearance of this volume is, then, extremely welcome, the task it sets itself being one that needs urgently to be tackled. And, on the whole, it accomplishes its aims tolerably well. The 13 essays it contains - all by professional Leibniz scholars of international renown - provide a far-ranging and, for the most part, accessible introduction to the various aspects of Leibniz's work, concentrating in particular on his metaphysics, his logic, his philosophy of language, his philosophy of science and his moral philosophy.
If I have a complaint against the volume as a whole, it is that it is rather relentlessly the product of professional philosophers. Leibniz was engaged in such a variety of intellectual and cultural endeavours that there would have been plenty of scope for the inclusion of essays by people outside the profession. A mathematician, for example, might have discussed his invention of the calculus and his other notable contributions to mathematics; a linguist might have discussed his pioneering study of Chinese; a literary scholar might have analysed his portrayal as Dr Pangloss in Voltaire's Candide; a historian might have commented on his work as a diplomat, most notably his attempt to persuade the French to attack Egypt rather than Germany. All these - and there are many more such possibilities - might have broken up the unwitting uniformity of style that dogs the various essays in this collection even despite their great diversity of subject matter. In place of a literary discussion of the perception of Leibniz by Voltaire and others, for example, we get an essay by David Blumenfeld that attempts, with a dogged, not to say po-faced earnestness, to reconstruct Leibniz's argument that, despite appearances, this is indeed the "best of all possible worlds". The result is an article that would not look out of place in a volume of conference papers, the sort of thing that merely adds to the "intimidation" of non-specialists by the experts.
More useful to the general reader, one suspects, will be the three essays that seek to place Leibniz in his historical context. Roger Ariew's biographical essay is especially good, emphasising as it does the astonishing range of Leibniz's interests and the curious gap between his "official" work and his philosophy. Rejecting, at an early stage, an offer of a university post, Leibniz pursued a career in public service, first with the elector of Mainz and then with the court of Hanover. During the time that he wrote his great contributions to philosophy, he was officially employed on a history of the House of Brunswick, which remained unfinished (indeed, practically unstarted) at the time of his death, Leibniz having chosen with characteristic thoroughness to preface the work with an account of the origins of nations, languages, customs and opinions and even a geological study of the formation of the earth.
Stuart Brown's contribution, "The 17th-century intellectual background" is not so much an article as a miniature encyclopaedia, providing short and lucid paragraphs on the ideas and the philosophers that formed the background to Leibniz's work, including Descartes, Hobbes, Spinoza, Malebranche, etc. The level of detail is just right to serve as an invaluable reference source for undergraduates. Catherine Wilson's study of "The Reception of Leibniz in the 18th century" is more discursive. It is also rather more narrowly focused than its title might imply, concentrating almost exclusively on Leibniz's reception in Germany. "In France," she writes, in a remark that sums up the tone of the whole book, "there was little sustained interest in Leibniz among philosophers, as opposed to litterateurs."
At the heart of the book is a series of essays that take the reader through a detailed study of Leibniz's chief contributions to philosophy. Discussion of his notoriously confusing metaphysical theories is spread over two articles, Christia Mercer and R.C. Sleigh dealing with the early period up to the Discourse on Metaphysics and concentrating in particular on the development of his notion of "substance", and Donald Rutherford treating the late period, focusing on the "metaphysical fairy tale" (as Bertrand Russell once called it) of Leibniz's notorious theory of monadology. Russell's famous claim that everything - or, at least, most things - in Leibniz's apparently bizarre metaphysics was deducible from his logic is not dealt with in either paper, rather disappointingly, and neither, perhaps still more oddly, is it dealt with at any great length in G.H.R. Parkinson's article "Philosophy and logic", which contents itself with an attempt to explain, with little argument or defence, Leibniz's views on, for example, truth, contingency and necessity, possible worlds, and so on.
One of the most intriguing and suggestive of Leibniz's ideas - his conception of a "universal characteristic", a formal language in which all metaphysical and moral truths might be expressed with the rigour of mathematics - is dealt with at length by Donald Rutherford in his article "Philosophy and language". Leibniz's vision here is one in which his aspirations as a philosopher and his work as a diplomat most obviously come together, the "universal characteristic" being the means by which the passion of dispute might be altogether dissipated in favour of disinterested reason. "If controversies were to arise," he wrote, "there would be no more need of disputation between two philosophers than between two accountants. For it would suffice to take their pencils in their hands, to sit down to their slates, and to say to each other (with a friend as witness, if they liked): Let us calculate."
It takes a certain kind of personality to find this vision of the philosopher as accountant inspiring, and, whether one finds it appealing or revolting, it is, appropriately perhaps, the personality belonging to this "companion" to Leibniz.
Ray Monk, a biographer of Wittgenstein and of Russell, teaches philosophy at the University of Southampton.
The Cambridge Companion to Leibniz
Editor - Nicholas Jolley
ISBN - 0 521 36588 0 and 36769 7
Publisher - Cambridge University Press
Price - £40.00 and £12.95
Pages - 500