Leibniz and Kant were the most important figures in German philosophy from the late 17th to the early 19th century. This volume examines the relationships between their philosophies, illuminating fundamental questions of metaphysics, epistemology, and philosophical theology, and assessing Kant's understanding of his philosophical predecessor.

This essay examines arguments offered in support of the Principle of Sufficient Reason (PSR) by Leibniz and his followers as well as Hume's critique of the PSR. It is shown that Leibniz has a defensible argument for the PSR, whereas the arguments of his self-proclaimed followers are weak. Thus, Hume's challenge is met by Leibniz, by Wolff and Baumgarten not so much.

Gottfried Wilhelm Leibniz (1646–1716) was one of the great thinkers of the seventeenth and eighteenth centuries and is known as the last “universal genius”. He made deep and important contributions to the fields of metaphysics, epistemology, logic, philosophy of religion, as well as mathematics, physics, geology, jurisprudence, and history. Even the eighteenth century French atheist and materialist Denis Diderot, whose views could not have stood in greater opposition to those of Leibniz, could not help being awed by his achievement, writing (...) in his Encyclopedia, “Perhaps never has a man read as much, studied as much, meditated more, and written more than Leibniz… What he has composed on the world, God, nature, and the soul is of the most sublime eloquence. If his ideas had been expressed with the flair of Plato, the philosopher of Leipzig would cede nothing to the philosopher of Athens.” (Vol. 9, p. 379) Indeed, Diderot's mood was almost despairing in a remark from another piece, which also has a great deal of truth in it: “When one compares the talents one has with those of a Leibniz, one is tempted to throw away one's books and go die quietly in the dark of some forgotten corner.” More than a century later, Gottlob Frege, who fortunately did not cast his books away in despair, expressed similar admiration, declaring that “in his writings, Leibniz threw out such a profusion of seeds of ideas that in this respect he is virtually in a class of his own.” (“Boole's logical Calculus and the Concept script” in Posthumous Writings , p. 9) The aim of this entry is primarily to introduce Leibniz's life and summarize and explicate his views in the realms of metaphysics, epistemology, philosophical theology, and natural philosophy. (shrink)

This paper addresses D. C. Williams’s question, “How can Leibniz know that he is a member of the actual world and not merely a possible monad on the shelf of essence?” A variety of answers are considered. Ultimately, it is argued that no particular perception of a state of affairs in the world can warrant knowledge of one’s actuality, nor can the awareness of any property within oneself; rather, it is the nature of experience itself, with the flow of perceptions, (...) that guarantees our actuality. A consequence of this view is that no non-actual individuals can truly be said to experience their worlds, nor can they ask the question if they are actual or not. (shrink)

In the main article on Leibniz, it was claimed that Leibniz's philosophy can be seen as a reaction to the Cartesian theory of corporeal substance and the necessitarianism of Spinoza and Hobbes. This entry will address this second aspect of his philosophy. In the course of his writings, Leibniz developed an approach to questions of modality—necessity, possibility, contingency—that not only served an important function within his general metaphysics, epistemology, and philosophical theology but also has continuing interest today. Indeed, it has..

In a short piece written most likely in the 1690s and given the title by Loemker of “On Wisdom,” Leibniz says the following: “...we see that happiness, pleasure, love, perfection, being, power, freedom, harmony, order, and beauty are all tied to each other, a truth which is rightly perceived by few.”1 Why is this? That is, why or how are these concepts tied to each other? And, why have so few understood this relation? Historians of philosophy are familiar with the (...) fact that both Spinoza and Leibniz place strong emphasis on the notion of power in giving their accounts of the human passions. But, while many scholars have explicated the relation between power and the passions (especially in Spinoza’s philosophy), there has been considerably less attention given to the nature of perfection and its relation to both power and the passions.2 Consider the following passages from Spinoza and Leibniz in which these two thinkers seem to bring together the issue of perfection and passion. In Ethics IIIp11s, Spinoza says the following: We see, then, that the Mind can undergo great changes, and pass now to a greater, now to a lesser perfection. These passions, indeed, explain to us the affects of Joy and Sadness. By Joy, therefore, I shall understand in what follows that passion by which the Mind passes to a greater perfection. And by Sadness, that passion by which it passes to a lesser perfection. The affect of Joy which is related to the Mind and Body at once I call Pleasure or Cheerfulness, and that of Sadness, Pain or Melancholy.3 And, in the Monadology §49, Leibniz says this: “The creature is said to act externally insofar as it is perfect, and to be acted upon [patir] by another, insofar as it is imperfect.”4 In other words, for Spinoza, the primitive passions of joy and sadness are cases in which a being’s perfection is increasing or decreasing, while, for Leibniz, any passion, it would.. (shrink)

That Leibniz finds the philosophy of Spinoza horrifyingly wrong is obvious to anyone who reads Leibniz’s work; that Leibniz finds Spinozism so seductive that his own system is in danger of collapsing into it is less obvious but, I believe, equally true. The difference here is not so much between an exoteric and an esoteric philosophy suggested by Russell2 but between a thorough-going rationalism on the part of Spinoza and Leibniz’s “mitigated rationalism” – mitigated by the exigencies of his orthodox (...) Christianity. In other words, it is Leibniz’s traditional view of the nature of God and his creatures that leads him to abhor Spinoza’s vision, while his own commitment to a number of principles and ideas pushes him to rationalism. And if Kant is right that the mind naturally desires a system, then Leibniz ought to see the Spinozistic consequences of many of his philosophical principles. Of course, there is nothing new in saying that the God of Spinoza and the God of Leibniz are fundamentally different, but I believe that if we focus on Leibniz’s critique of Spinoza’s account of the nature of God and a constellation of related concepts, we can come to a deeper understanding of the thought of both philosophers. (shrink)

Beschäftigung mit der Philosophie, selbst wenn keine positiven Ergebnisse herauskommen (sondern ich ratlos bleibe), ist auf jeden Fall wohltätig. Es hat die Wirkung (dass „die Farbe heller“), d.h., dass die Realität deutlicher als solche erscheint. – Kurt Gödel..

Kant’s Thinker is an excellent and important addition to the literature. In it, Patricia Kitcher aims at arriving at a comprehensive understanding of Kant’s theory of the cognitive subject. To this end, she analyzes a central component of the most notoriously difficult part of the Critique of Pure Reason, the theory of the unity of apperception in the chapter on the Transcendental Deduction of the Categories. In Kitcher’s view, the ultimate payoff of such a study is that Kant’s theory can (...) “provide a ‘new’ source of illumination for current attempts to understand the nature of cognition and the mind” (3). This may be so. But the main value of the book will likely be for Kant scholars, who will appreciate the depth .. (shrink)

According to the standard view of his metaphysics, Leibniz endorses idealism: the thesis that the world is made up solely of minds or monads and their perceptual and appetitive states. Recently,this view has been challenged by some scholars, who argue that Leibniz can be seen as admitting corporeal substances, that is, animals or embodied souls, into his ontology, and that, therefore, it is false to attribute a strict idealism to him. Subtler accounts suggest that Leibniz begins his philosophical career as (...) an advocate of (some form of) the modern ‘mechanical’ philosophy and ends his career as an idealist, raising the issue when and why Leibniz adopts his monadological metaphysics. This article argues that, given a constellation of metaphysical, logical, and theological views, Leibniz is committed to the ontological primacy of mind or form even in his ‘middle years’. (shrink)

One of the more interesting topics debated by Leibniz and Locke and one that has received comparatively little critical commentary is the nature of essences and the classification of the natural world.1 This topic, moreover, is of tremendous importance, occupying a position at the intersection of the metaphysics of individual beings, modality, epistemology, and philosophy of language. And, while it goes back to Plato, who wondered if we could cut nature at its joints, as Nicholas Jolley has pointed out, the (...) debate between Leibniz and Locke has very clear similarities to the topic that has dominated the philosophy of language from the 1970s on: namely, the challenge mounted by Kripke, Kaplan, Putnam, and others against Russellian and Fregean descriptivist accounts of meaning. Yet, this topic is also, as Jolley writes, one of the “most elusive” in the debate between Leibniz and Locke.2 The purpose of this paper is to examine in detail Leibniz’s critique of Locke’s distinction between real and nominal essences. In doing so, I hope to show certain virtues in Leibniz’s account of metaphysics and philosophy of language that usually escape notice. While I wish to provide a general account of Leibniz’s disagreement with Locke, I also plan to focus on the nature of species and natural kinds. In my opinion, those who have treated this topic have not paid sufficient attention to Leibniz’s claims that “Essence is fundamentally nothing but the possibility of the thing under consideration” and “essences are everlasting because they only concern. (shrink)

In his Between Two Worlds: A Reading of Descartes’s Meditations, John Carriero presents a sustained and sensitive interpretation of this seminal work of modern philosophy. The two worlds of the title are the worlds of Scholastic philosophy on the one side, and of the mechanical philosophy on the other, and it is Carriero’s argument that the Meditations are most helpfully understood against the background of Thomistic Scholasticism. In particular, Carriero shows that there is a deep difference between St. Thomas and (...) Descartes, first, concerning philosophical theology and the nature and possibility of our cognition of the divine essence, and second, concerning the nature of human cognition. What Carriero is ultimately trying to argue against is a picture of Descartes according to which he is fundamentally engaged in an anti-skeptical project and at the same time responsible for a crass and superficial form of dualism.While the book is organized simply, with one chapter devoted to each of the Descartes’s six Meditations, it is philosophically very rich and will reward careful study. Indeed, it is rare for a book to be devoted to such a close reading of a single text at this high level. Certainly, there are many “Introductions” for undergraduates, but few works written for advanced graduate students and professional philosophers cover a text so closely and so subtly. Carriero’s book demonstrates the virtues of this kind of text-immanent. (shrink)

This paper addresses D. C. Williams’s question, “How can Leibniz know that he is a member of the actual world and not merely a possible monad on the shelf of essence?” A variety of answers are considered. Ultimately, it is argued that no particular perception of a state of affairs in the world can warrant knowledge of one’s actuality, nor can the awareness of any property within oneself; rather, it is the nature of experience itself, with the flow of perceptions, (...) that guarantees our actuality. A consequence of this view is that no non-actual individuals can truly be said to experience their worlds, nor can they ask the question if they are actual or not. (shrink)

In this paper, the author examines Leibniz inconsistent treatments of the existence predicate in his formulations of the ontological argument and elsewhere. It is shown that, contrary to expectations, Leibniz at times adumbrates insights often attributed to Kant and Frege.

Contrary to most interpretations of the transcendental deduction that take it to depend upon the ideas of personal identity, the “ownership” of mental states, or the ontological unity of the mind, the author argues that Kant’s principal concern is to show how the objective reality of a complex representation is consistent with the spontaneity of the mind. The short answer to this question is that objective reality is consistent with spontaneity precisely because the categories are universal and necessary. Ultimately, as (...) Dickerson emphasizes—and this is the novel claim of the book—the problem addressed within the B-deduction ought to be seen as the representationalist parallel to the semantic question of what it is to understand a complex sign or the question of the unity of a proposition. (shrink)