- Review of Graham Priest, One: Being an Investigation into the Unity of Reality and of its Parts, including the Singular Object which is Nothingness, Oxford University Press, 2014, 272 pp., ISBN 9780199688258
- Since the beginning of Western thought, philosophers have been interested in problems of the one and the many. For example, how can two or more parts be unified together to constitute one object? Considering this question, Parmenides and Plato cast doubt on the notion of parthood. Indeed, they offer some arguments according to which the notion of parthood leads to contradiction. How should we evaluate such arguments? If we turn our eyes to the Eastern tradition, we find that Buddhists have considered the one and the many from a different perspective. According to them, the one is the many and the many is the one. How does this claim make sense? One is the ambitious attempt to answer these and other questions concerning the metaphysics of the one and the many, using formal materials like paraconsistent logic, world semantics, mereology, non-well-founded set theory and so on.
- This book consists of three parts.
- Part I (“Unity”)1 examines the problem of unity2 – how are two or more objects unified into one object? – and develops a theory of unity3 on the basis of what he calls gluons4. According to Priest, a gluon for an object is one of its parts and, as its name suggests, glues all parts of it together. Discussing Frege’s account of the proposition unity5 and his puzzle about the concept horse,
- Chapter 1 explicates the paradoxical nature of gluons: a gluon is an object but not an object. Arguing that gluons are essentially contradictory, Priest’s gluon theory is a clear instance of dialetheism, which he has developed and argued for over the years.
- After establishing the foundation of gluon theory in Chapter 2 (discussed in some details later), Priest presents some applications of it.
- In Chapter 3, the author develops a novel theory of universals and their instances on the basis of his gluon theory.
- Chapter 4 is about two extreme entities, that is, everything (the totality of all objects) and nothing (the absence of all objects).
- Finally, Chapter 5 examines cases of the non-transitivity of identity, more generally, cases of the failure of substitutivity of identicals, which are essential in gluon theory.
- In Part II (“Plato’s Trajectory”), Priest untangles some riddles which have kept philosophers busy since Plato such as
He also gives an original interpretation of the Parmenides of Plato.
- Mereological wholes (Chapter 6),
- Falsity (Chapter 9),
- Perception (Chapter 10.1) and
- Intentionality (Chapter 10.5).
- First of all, Priest summarizes, discusses and criticizes the position of Parmenides presented in On Nature.
- Secondly, he examines the Plato’s Sophist specifying the meaning of ‘being one’ into two different meanings (‘being one’ or ‘being the sum of parts’ and ‘being a true unity’6 or ‘the unity itself’).
- Finally, Priest provides a dialetheistic interpretation of Plato’s Parmenides suggesting that “by the end of the dialogue, the contradictory nature of the One is defended, and the dialogue ends” (p. 138).
- In Part III (“Buddhist Themes”), Priest links his metaphysics to the well-known Buddhist claim that all is one, through a clear-cut interpretation (including exposition on the basis of formal theories like graph-theory and non-well-founded set theory) of the Buddhist notion of interpenetration and emptiness. The view in the Huayan tradition that all things interpenetrate with – ontologically depends on – all things is defended, in particular, by showing that such a holistic interdependence relation does not lead to any vicious regress (Chapters 11 and 12). The paradox of ineffability (the effability of the ineffables) and some ethical consequences of the theory are also discussed from the viewpoint of Buddhist philosophy (Chapters 13, 14 and 15).
- From this first overview, it is easy to see that the number of topics covered in the book is surely impressive. The generality of the theory is, too. Ambitiously enough, Priest is presenting his gluon theory as a general theory of unity7: it is not intended to apply only to the unity8 of some particular kinds of objects (for example, propositions or complex physical objects), but to the unity9 of objects in general. In this sense, this book is about what it is to be an object. That’s why gluon theory perfectly fits the definition of metaphysics given by Adrian W. Moore, according to whom “metaphysics is the most general attempt of making sense of things”. Gluon theory then is exactly that general attempt to make sense of things.
- Most of the concepts are expressed with remarkable clarity. The arguments are always well-structured and the overall reading of the book is enjoyable. For example, we expect that most readers of this review are not familiar with Buddhist philosophy. Don’t worry. Readers will find very clear exposition of Buddhist concepts in this book and thus understand how Buddhist ideas make sense. Readers will be also happy to find Priest strengthening his metaphysical claims by exploiting some formal tools which we have previously mentioned. There are specific paragraphs and appendixes to clarify the formal apparatus used. In this way, the readers who are not familiar with formal approaches can enjoy the metaphysical arguments without being overwhelmed by any formalism. In this book Priest develops his theory on the basis of what he has already defended in his previous works, like paraconsistency, dialetheism and noneism (a version of Meinongianism). Relying on these works, One doesn’t give detailed defense of these theories. But it is a laudable feature of this book that it presents an accessible introduction to both the formal and metaphysical aspects of them and thus it does not require any strong background in them. In this sense, the book is self-contained.
- In what follows, we will give a closer look at the core ideas of the three parts.
- Why did Priest adopt this terminology when “gluon” is the name of the mediator of the strong nuclear force? See Wikipedia: Gluon.
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