Heidegger famously held two fundamental claims about Being and the Nothing. The first, known as the ‘ontological difference’, asserts that the Being of an entity is not itself an entity. The second, which we might call the ‘meontological difference’, claims that the Nothing is not an entity.

Both claims seem prima facie true. Consider the ontological difference first. We perceive all sorts of entities, but we never seem to perceive something like Being itself. For example, we can see the colours on the screen, hear sounds in our environment, feel sensations in our bodies, but within this rich experiential landscape, we don’t know where to direct our attention if we want to experience Being as such. This point was also famously made by Hume in his Treatise (Hume 1740 [Reference Hume, Norton and Mary2000], 1.2.6): we receive all sorts of impressions, but there is no ‘distinct impression’ of existence from which our idea of existence derives (‘existence’ and ‘Being’ are used interchangeably in this context). From these observations, one might conclude that the existence or Being of an entity is not itself an entity. As Heidegger puts it in On Time and Being:

And yet, somehow, we know that things exist. How is this possible if the Being of entities is not itself an entity? According to one interpretation of Heidegger, we know that entities exist because we know, contrastively, that the Nothing is not. As Heidegger puts it in What is Metaphysics?:

A similar view was also voiced around the same time by Max Scheler, who argued that in order to have a ‘clear perception of the immeasurable positivity of the fact there is something rather than nothing’, one must entertain the thought that there might have been nothing rather than something, in such a way that ‘the subsistence of every entity seems like a miraculous repeal of that possibility, an eternally astonishing roofing over the abyss of absolute nothingness’ (Scheler 2017 [Reference Scheler1917], p. 101).

In his recent book, Heidegger and the Contradiction of Being: An Analytic Interpretation of the Late Heidegger, Filippo Casati explores these fascinating and fundamental issues. He does so with admirable clarity and precision, allowing readers to grasp Heidegger’s views on Being and the Nothing as well as the contemporary interpretative and philosophical debates in the anglophone literature surrounding these issues. In the first part of the book, Casati guides us through a thicket of problems and paradoxes that challenge the Heideggerian position that Being is not an entity. In the second part, the author presents a way to resolve these paradoxes. Casati tackles many intricate and thought-provoking issues in this relatively short book (183 pages). But the heart of the book, which I will focus on here, is Casati’s exposition of two ways Heidegger’s view on Being and the Nothing leads to paradox – where Heidegger seems committed to the view that both Being and the Nothing are and are not entities – and his proposal to embrace these paradoxes as true contradictions.

Let’s first examine why Heidegger seems to be committed to paradox. The thesis of the ontological difference holds that the Being of an entity is not itself an entity. Now, according to a particular interpretation of Heidegger’s remarks on language and thought, Heidegger also held the following principle: if x is the subject matter of an assertion, then x is an entity. But it seems that Heidegger asserts many things about Being, chief among them the assertion of the ontological difference itself. Thus, it seems that Being can and cannot be the subject matter of an assertion, and that Being both is and is not an entity.

The second way of revealing a paradox about Being relies on two additional claims, which Casati and other interpreters attribute to Heidegger: first, that something x is an entity only if x has a reason, and second, that the reason for all entities is Being. But it seems that Being can be the reason for entities only if Being is itself an entity. Thus, we face a contradiction: in order to be the reason for all entities, Being must be an entity, yet, according to the ontological difference, Being is not an entity.

The same contradiction arises with respect to the Nothing. There are at least two ways to expose the paradoxical nature of the Nothing, both of which reflect the ways in which Casati illustrates the paradoxical nature of Being. The first has been familiar since antiquity: on the one hand, it seems that the Nothing is not an entity; yet, if we accept the principle that if x is the subject matter of an assertion, then x is an entity, then, since we assert many (true!) things about the Nothing – chief among them the meontological difference – it follows that the Nothing both is and is not an entity.

The second route into the paradoxical nature of the Nothing is tied to a specific interpretation of Heidegger’s view of the Nothing and its relation to Being. According to this reading, the Nothing, like Being, is the reason for all entities – ‘entities are entities if and only if they stand against the Nothing’ (Casati Reference Casati2022, p. 126). But the Nothing can be the reason for all entities only if it is itself something (rather than the Nothing!). Thus, it seems that the Nothing both is and is not an entity.

There are several ways out of these paradoxes. For example, I personally endorse both the ontological and the meontological differences, but I reject the claims about language and reason that give rise to the paradoxes – namely, the view that if x is the subject matter of an assertion, then x is an entity, and the view that x is an entity only if x has a reason, and that this reason is Being (and the Nothing). Casati’s book discusses in great detail these and other strategies for resisting the conclusion that Being and the Nothing are contradictory. Some of his discussions are particularly insightful and valuable to the philosophical community: for instance, to anyone interested in these topics, I would wholeheartedly recommend reading Chapter 3, ‘On a Very Destitute Matter’, where Casati offers a clearly argued presentation of the paradoxes about Being and possible ways to dissolve them. More broadly, the first three chapters of the book should be read by anyone seeking a compact, well-structured introduction to Heidegger’s views on Being and the contemporary debates surrounding them. These chapters could also be useful in teaching, as I believe Casati’s writing has a strong didactic quality, leading the reader step-by-step through the argument, making all relevant premises explicit and suggesting possible dialectical moves.

One of the goals of Casati’s book, brilliantly achieved in the first three chapters, is to introduce contemporary readers – especially those raised in the so-called analytic tradition and unfamiliar with (or even suspicious of) Heidegger’s work – to Heidegger’s philosophical reflections on Being. The second part of the book aims to offer a new interpretation of Heidegger’s later philosophy and a view of the nature of Being and the Nothing that embraces their contradictory nature. To articulate both his interpretation and his philosophical position, Casati draws on contemporary discussions of the metaphysical position known as ‘dialetheism’ – the view that some contradictions are true in the actual world.

In Chapter 4, Casati argues that Heidegger’s later philosophy can be interpreted through a dialetheist lens, meaning that Heidegger endorses the view that Being is genuinely contradictory. Although he does not offer direct arguments in this book for the truth of dialetheism, he contends that it is a philosophically viable view by appealing to contemporary defences of dialetheism and arguing that they can be extended to capture Heidegger’s perspective. While Chapters 1–4 are accessible to all readers, Chapters 5–6 are more technical and are likely to be of interest primarily to readers with a solid grounding in formal logic and a specific interest in dialetheism. Classical logic endorses the so-called Principle of Explosion: any arbitrary statement B is entailed by any arbitrary contradiction A and not A. But if Heidegger is committed to true contradictions about Being and the Nothing, then Heidegger’s theory is logically trivial, that is, every statement in it is true just because it follows from such contradictions. A dialetheist accommodates this objection by defending a paraconsistent logic that rejects the Principle of Explosion. In Chapter 5, Casati develops this move by appealing to an inconsistent mereological system that purports to capture Heidegger’s contradictory view of Being. In Chapter 6, he coherently extends this interpretation by articulating a formal system that captures the inconsistent dependence relation between entities and their reason, namely Being.

Casati’s book will likely elicit very different reactions from different audiences. Some Heidegger scholars may be critical of the dialetheist interpretation and may feel there is something odd, if not outright mistaken, in trying to capture Heidegger’s meditations on Being and the Nothing through the rigid and superficial frameworks of analytic thinking (recall Heidegger’s critique of ‘calculative thinking’ versus ‘meditative thinking’). Conversely, some contemporary analytic philosophers may welcome Casati’s contribution because it offers a clear and rigorous introduction to Heidegger’s otherwise obscure philosophical reflections. What is certain is that Casati’s book will become an essential reference – and for good reason – in the upcoming contemporary debate on Being, the Nothing, and the profound philosophical and existential quandaries that have surrounded these notions since antiquity.