According to Metzinger's Self-Model Theory of Subjectivity, there are no such things as selves in the world, but only conscious self-models. And, they are not things, but processes.

The framework of Metzinger's approach is naturalistic, representationalistic, and teleofunctionalistic. He distinguishes between three types of mental and phenomenal content: representational, presentational, and simulational. Mental representation is a three-place relationship between a representandum (a part of reality), a representatum (its internal depiction) and an information-processing system. Metzinger emphasizes the processual character of representations. Representata are time-slices of a process, they are not objects. As a successor to the concept of qualia, Metzinger defines “presentational” as nonconceptual content, cognitively unavailable. Presentations carry the signal aspect of representations. They never occur alone, but only integrated into a representational whole. Simulations are virtual representational processes, forming models of possible worlds. In contrast to representations, simulations have no presentational content. The stimulus correlation of representations works as an existence assumption, a “flagging of the dangerous present”. Insofar as this is true, the brain can be seen as an ontological engine.

One of the most interesting characteristics of phenomenal, conscious content is its transparency: the representational character of representations is not available to the subject of experience. The subject looks through those representations onto a modeled reality which does not appear as modeled, but simply as real. We have a systemic blind spot; we cannot experience the constructive character of our phenomenal reality. We don't experience it as what it is: a virtual reality. The unit through which this virtual reality is given to us is our “Global Phenomenal Model of Reality”. And this unit is a process. It is a dynamical multimodal map of reality.

In the second half of his book, Metzinger discusses the conditions of the constitution of a self-model and of a subject-centered perspective on phenomenal reality. Two theoretical entities are postulated (and thereby added to the transparent Global Phenomenal Model of Reality): the “Phenomenal Self-Model” (PSM) and the “Phenomenal Model of the Intentionality Relation” (PMIR). The PSM is a conscious model of the organism for itself, a model globally available to the system. In fact, there is no self, but only a self-representational process and its temporal states. A reification of the self would mean to commit a phenomenological fallacy. But, because of the transparency of self-representation, human beings are driven to commit this fallacy. It is the result of the functioning of the brain as an ontological engine, which leads to our “naive-realistic self-misunderstanding”. The PMIR is the conscious model of the “arrow of intentionality”: a model of the system as actually interacting with the world, a model of the subject-object relation, a subject-world link, a representation of the interaction between the transparent Global Phenomenal Model of Reality and the PSM. The PMIR forms the basis of the perspectivalness of human consciousness.

As a reality test for his conceptual instruments, Metzinger uses deviant self-models: anosognosias, identity disorders, hallucinated selves, multiple selves, and lucid dreams. With regard to out-of-body experiences, he formulates a very interesting hypothesis; he suggests that they are the origin of our proto-concept of mind, of the traditional concept of a soul, and, consequently, of ontological dualism. Lucid dreams are globally opaque simulations: their virtuality is experienced as virtual. They are probably the only case of an almost complete neutralization of transparency. Given the existence of such opaque dream states, it follows, to ask, if there exists the possibility of a lucid waking state. But, in such a state the opacity of the reality model would necessarily lead to a derealization of phenomenal experience. And, the opacity of the self-model would lead to a loss of phenomenal selfhood and of the subject of experience. So, the view from nowhere is fundamentally unreportable; subject and reality would have dissolved.

In the concluding chapter, Metzinger offers three metaphors for his Self-Model Theory of Subjectivity: (1) “The neurophenomenological caveman”—a modified version of Plato's metaphor: The cave in which we live our conscious life is formed by our Global Phenomenal Model of Reality. But, this cave is empty. What we see as our own shadow on the walls of the cave is a form of computational reflection. The conscious self is not a thing, but a shaded surface; it is no object, but a process of shading. What makes us neurophenomenological cavemen, is the transparency of the PSM. (2) “The little red arrow”—our phenomenal experience is like a dynamical, multidimensional map of the world. The phenomenal self is the little red arrow on this map, indicating: You are here! But, this map is a single-user map, changing in every moment. (3) “The total flight simulator”—our phenomenal first-person experience works like a flight simulator which simulates not only the aircraft and its surroundings, but also the pilot.

One of Metzinger's asides is concerned with artificial subjectivity. Subjectivity means capacity to suffer. Suffering starts, according to his evaluation, on the level of phenomenal self-models. And, artificial subjectivity might dramatically increase the amount of suffering in the world. The implications with regard to biological consciousness are close. In Metzinger's opinion, biological evolution is a process that has created an expanding ocean of suffering and confusion out of nothing comparable. So, the final question is: How can we emancipate from evolution? Could there be consciousness without suffering?

So, “being no-one” means, no such things as selves exist in the world. There are only the temporal contents of transparent PSMs. What we called “the self” in the past doesn't exist. There is no essence, but only a complex self-representational process. But, although subjects don't exist, they are sentient, endowed with the capacity to suffer. Not even being no-one protects us from misfortune, harm, and sorrow.

Metzinger's book is a convincing philosophical exposition and a well-structured compendium. Within some passages, one can have the impression that it is loaded with rather too much information and with a sometimes highly complex terminology. But, that impression fades away at a closer look. Being No One offers a lot of very interesting and often surprising reflections, integrated into a well-organized, but almost merciless analytical structure. It is at the same time a book which is in complete accordance with the standards of analytical philosophy and a treasure chest that in every corner of its analytical labyrinth surprises the reader with highly interesting insights. It is, without any doubt, a milestone of modern philosophy of mind.