I am currently approaching the halfway mark of Metzinger's majestic opus, with progress between ten and twenty pages a day. As such, this review might be amended upon my completion of the book.
I have no doubt that this book is a millennial achievement, that will still be influencing thinkers for decades or more to come. It represents the 'ne plus ultra' of current thinking in consciousness studies, and I suspect that future progress must proceed with this work providing a new, deeper and broader foundation. Unfortunately it is not remotely a book for beginners, and I have created the listmania list 'How to realise that you are no-one', giving what I think would constitute the minimum background required for a realistic attempt at reading it. To a large extent Metzinger is describing the phenomenal world that we are all intimately familiar with, but he disassembles that world with the most meticulous precision, and re-presents it to us within the context of a carefully prepared systematic theoretical framework. The result is like watching the assembly of a huge building or jumbo jet. We are shown that consciousness, as the central core of mental processing in humans and higher animals, is not a raw undifferentiated process, but an exquisitely intricate structure that manages to integrate a huge array of disparate functional requirements into an optimally flexible and adaptive whole. To some extent the book is like an updating of Husserl's Phenomenology for the computer age, and with a determinately physicalist agenda. However, into this framework Metzinger manages to synthesise many of the key ideas that the mind sciences have generated in their renaissance of the last three decades. Along the way I have finally managed to clarify what some philosophers of mind have been trying to impart when talking of 'representationalist' theories of consciousness, and am gratified to see that it means what I, as a software designer, thought it should have meant in the first place. Metzinger's theory is a representationalist theory insofar as it shows the mind-brain as conspiring, through consciousness, to present the animal with a model of the world with itself and all its behavioural potentials actually integrated into that model, so seamlessly, that the animal mistakes the model for the world itself. We do not know that we are inhabiting a virtual reality, and the self at its centre is as virtual as the rest of it.
The bottom line is, at least in terms of what I have read so far, that Metzinger has explicated every aspect of phenomenal consciousness except the central enigma of raw consciousness; that is the logically coherent notion of an abstract, non-self-or-temporally-centered consciousness that 'experiences' a continuum of data points as an integrated whole. This is not to devalue Metzinger's achievement. His work provides the basis for many years of empirical research in cognitive-neuroscience and related fields. At the very least, Metzinger's analysis should eliminate once and for all the tendency of less subtle thinkers to claim a solution to the problem of consciousness when only providing solutions to simpler cognitive problems such as those of thought or language. It may yet prove that Dennett was right and there is no such thing as consciousness, in the raw, as such (I'm gradually coming round to the eliminativist perspective). It may just be that when an information processing system does all the stuff that Metzinger has so laboriously outlined, as implemented by a corresponding or related architecture, then what we experience as consciousness is just there as a surface feature of the processes involved, of the causational flux as it were. Consciousness would not then be a thing, an object or substance, and thus would be without physical ontological status. Like the 'picture' on a TV, having no independent existence over and above the pattern of flashing lights generated by the hardware substrate.
The adventure continues...