The Principle of Identity of Indiscernibles is the thesis that, necessarily, no two (concrete) objects differ only numerically. This is the weakest version of the Principle of Identity of Indiscernibles. Gonzalo Rodriguez-Pereyra argues that there is no trivial version of the Principle of Identity of Indiscernibles, since what is usually known as the trivial version of the principle is consistent with objects differing only numerically. He provides two positive arguments for the Principle: one based on broadly Humean considerations excluding a certain kind of necessary connection between distinct objects, and the other based on ideas about what grounds the having of certain properties by objects. This book also presents two new arguments against restricted versions of the principle according to which, necessarily, no two objects can be purely qualitatively indiscernible or intrinsically purely qualitatively indiscernible. It is further argued that one of the arguments for the weakest version of the principle can be extended to abstract objects. The conclusion is drawn that, necessarily, there are no objects, whether abstract or concrete, that differ only numerically.

Examines the place and role of the identity of indisernibles, which rules out numerically distinct but perfectly similar things, in Leibniz's philosophy.

In Spinoza’s Argument for Substance Monism: Why There Is Only One Thing, Christopher Martin provides an interpretation and defense of this argument, using speculative metaphysics as a method to show how the key terms and concepts are employed and fit together. Specifically, Martin argues that (i) Spinoza’s understanding of substance and attribute departs only slightly from dominant historic notions; (ii) his definition of God in terms of attributes instead of perfections is quite helpful and (mostly) compatible with more traditional definitions; and (iii) Spinoza’s pairing of causal and conceptual relations is more intuitive than we think. Martin also shows how these essences function as causes and explains why, with Spinoza’s understanding of emanation and conceptual independence, any substance must have every attribute. These features of Spinoza’s argument explain and defend his ultimate claim that God/Nature is the only substantial being in existence. This book demonstrates how approachable and compelling Spinoza’s argument is and illustrates the practice and potential of speculative metaphysics for specialists and non-specialists alike.

Gonzalo Rodriguez-Pereyra presents an original study of the place and role of the Identity of Indiscernibles in Leibniz's philosophy. The Principle of the Identity of Indiscernibles rules out numerically distinct but perfectly similar things; Leibniz derived it from more basic principles and used it to establish important philosophical theses. Rodriguez-Pereyra aims to establish what Leibniz meant by the Principle of Identity of Indiscernibles, what his arguments for and from it were, and to assess those arguments and Leibniz's claims about the Principle of Identity of Indiscernibles. He argues that Leibniz had a very strong version of the principle, according to which no possibilia (whether or not they belong to the same possible world) are intrinsically perfectly similar, where this excludes things that differ in magnitude alone. The book discusses Leibniz's arguments for the Identity of Indiscernibles in the Meditation on the Principle of the Individual, the Discourse on Metaphysics, Notationes Generales, Primary Truths, the letter to Casati of 1689, the correspondence with Clarke, as well as the use of the Identity of Indiscernibles in Leibniz's arguments against the Cartesian conception of the material world, atoms, absolute space and time, the Lockean conception of the mind as a tabula rasa, and freedom of indifference. Rodriguez-Pereyra argues that the Identity of Indiscernibles was a central but inessential principle of Leibniz's philosophy.

Philosophical questions regarding both the existence and nature of properties are ubiquitous in ordinary life, the sciences, and philosophical theorising. In philosophy, it is one of the oldest topics discussed in various intellectual traditions – East and West – reaching back to Plato and Aristotle. Today, in the analytic tradition, properties continue to be a core area of study and research. The Routledge Handbook of Properties is an outstanding reference source to this perennial topic and is the first major volume of its kind. It contains forty specially commissioned chapters written by an international team of expert contributors, and is divided into nine clear parts: Methodology and Metaontology Distinctions Realism about Universals Nominalism Trope Theory Properties in Causation, Time, and Modality Properties in Science Properties in Language and Mind Properties in the Normative Realm, the Social World, and Aesthetics The Routledge Handbook of Properties is essential reading for anyone studying and researching metaphysics, metametaphysics, and ontology, and will also be of interest to those in closely related areas such as philosophy of science, philosophy of language, philosophy of mind, ethics, and aesthetics.

Georg Lukács wrote that "there is autonomy and 'autonomy.' The one is a moment of life itself, the elevation of its richness and contradictory unity; the other is a rigidification, a barren self-seclusion, a self-imposed banishment from the dynamic overall connection." Though Lukács' concern was with the conditions for the possibility of art, his distinction also serves as an apt description of the way that Hegel and Hegelians have contrasted their own interpretations of self-determination with that of Kant. But it has always been difficult to see how elevation is possible without seclusion, or how rigidification can be avoided without making the boundaries of the self so malleable that its autonomy looks like a mere cover for the power of external forces. Yeomans explores Hegel's own attempts to grapple with this problem against the background of Kant's attempts, in his theory of virtue, to understand the way that morally autonomous agents can be robust individuals with qualitatively different projects, personal relations, and commitments that are nonetheless infused with a value that demands respect. In a reading that disentangles a number of different threads in Kant's approach, Yeomans shows how Hegel reweaves these threads around the central notions of talent and interest to produce a tapestry of self-determination. Yeomans argues that the result is a striking pluralism that identifies three qualitatively distinct forms of agency or accountability and sees each of these forms of agency as being embodied in different social groups in different ways. But there is nonetheless a dynamic unity to the forms because they can all be understood as practical attempts to solve the problem of autonomy, and each is thus worthy of respect even from the perspective of other solutions. "Everyone recognizes the importance of Hegel's critique of Kantian morality as empty, but until now there has not been a fully worked out presentation of how Hegel's views in his discussion of Sittlichkeit actually provide the missing content. Yeomans has finally provided us with a reconstruction of Hegel's mature position that makes good on all the promissory notes that Hegel (and his commentators) gives in his famous descriptions of his alternative to Kantian ethics. Yeomans offers a compelling account of Hegel's view of individuality, societal differentiation and its roots in Kantian and Fichtean moral theory. The book will be a major contribution to the scholarship on Hegel's practical philosophy."-Dean Moyar, Associate Professor of Philosophy, Johns Hopkins University "Yeomans' book is a subtle, detailed and original explication of some key ideas having to do with how Hegel's general philosophy of action (or theory of the nature of agency) relates to his social and political philosophy. It is attentive to Hegel's texts, and it ties its discussions into all the relevant contemporary themes in philosophy. It is very ambitious in its attempt to make Hegel's theory into a real competitor to other views that are currently in wide play in the philosophical world. It will very likely become one of the key texts in the secondary literature on Hegel."-Terry Pinkard, University Professor of Philosophy, Georgetown University

Is analytic metaphysics the kind of metaphysics that contemporary analytic philosophers study? One of the aims of this special issue of the Studia Leibnitiana is to demonstrate that it would be misleading to think so. The reason is simply that some important past metaphysicians also adopted an analytic style and G. W. Leibniz is surely one of them. His analysis on the notion of identity and individuality, on the difference between artifacts and biological entities are pieces of analytic metaphysics. The other aim of the volume is to show that there is a close semantic connection between the concepts of individual, mind and body in Leibniz. The book tried to demonstrate it from both an analytical and a historical point of view. .