Gerald M. EdelmanA Universe of Consciousness: How Matter Becomes Imagination

I've come to this book as someone who has been reading about consciousness and the mind-body problem since encountering Descartes and Locke in his university days. Hi-lights along the way have been Dennett's Consciousness Explained (Penguin Science) (not) and Chalmers' The Conscious Mind: In Search of a Fundamental Theory (Philosophy of Mind Series). After reading several recent philosophy titles, including Kim's The Philosophy of Mind (Dimensions of Philosophy), I was getting the strong impression that the Philosopher's were getting bogged down, with no real progress to show for quite some time now.Edelman and Tononi are writing from the leading edge of neuroanatomy, and present a fascinating and extremely readable account of the architecture of the human brain and indeed monkey and cat brains, which are now being mapped out in very great detail. For this account alone the book gets its five stars. The bulk of the book then builds on this to present a theory of what consciousness, considered as a process, is from a neurological perspective. In brief, the brains of higher mammals who enjoy primary consciousness, that is the conscious experience of their sensory modalities and a range of emotional states, are mostly made up of the cortex and the thalamus. These areas implement hundreds or thousands of tiny modules, all with very specific functions like, identifying colours and lines, orientations and so on. If we now imagine there to be a cloud of such modules and then imagine that each module is connected by a mesh of fibres to some, possibly many of the other modules, we have the essence of the model. It is evidently the case then that when we are awake or dreaming in REM sleep, i.e. experiencing consciousness, the modules are all working away at their allotted tasks, but there is also a vast amount of bi-directional traffic on their mesh of interconnections. However, when we are in deep NREM sleep, or in seizures such as epilepsy, where consciousness is absent, then the modules are all still active but the traffic on the interconnections is absent. The authors are saying then that whatever consciousness is, it is the traffic on these interconnections that distinguishes conscious from unconscious mental states in the brain's physical operation. The system defined by the model operates such that no overall process is in charge but behaviour emerges from the interaction between the dumb modules according to rules not yet understood.The authors work this model and a lot of additional detail up into a theory which they call they Dynamic Core Hypothesis, the first big result of which is that consciousness cannot be identified with particular neurones, types of neurones or areas of the brain. Consciousness arises from the constantly shifting pattern of activation between the many modules along what they call the re-entrant connections between them. When the pattern switches off, or slows down below a certain rate, then so does consciousness. This to me was all fresh knowledge and magnificent stuff.The latter part of the book includes speculations on the evolution of consciousness, including what they call the secondary or higher consciousness which only humans enjoy. This would plausibly seem to have arisen first with language as external signalling to peers, followed by the internalisation of language, a talking to oneself that eventually evolves into thought. This in turn gives rise eventually to the discovery or invention of logic and mathematics. They stress that there was no 'logic', in the formal sense, going on anywhere in the universe until thought arose. This is part of their strongly held position that the brain IS NOT a computer.Here we arrive at the nub of the book. Part of the theory they present is the Theory of Neural Group Selection (TNGS) which is based on observations of the development, over time, of axons and dendrites down in the neurones in response to patterns of stimuli. While TNGS presents the way neurones operate and what the brain needs to be doing as a whole, it doesn't really have much to say about how the changes going on in the neurones are doing what they need to do. Eventually in the book we are at a stage where they declare that the brain is not a computer in the strict sense of not being a Turing machine, but is rather a Selectional system. They make much of the contrast between Turing machines (based on logic) and Selectional systems. However, and I admit I may have missed something here, the workings of Selectional systems, as presented, are not described clearly enough to say whether what they do could or could not be carried out by a Turing machine. To claim that any information processing system IS NOT a Turing machine, I would have thought, requires a formal mathematical description and proof. What does the Selectional system do that a Turing machine cannot? Can a Selectional system tackle classes of problem that are non-computable by Turing machines? Such questions seem to be unanswered.Nonetheless a fascinating read. The first seventy pages or so were very easy going but once we got into the nitty-gritty it became a demanding book, requiring the kind of slow methodical approach that a proper philosophy text demands. I have seen Edelman criticised that his style includes a lot of repetition of terms and definitions. I actually think that this is appropriate because he is trying to be as unambiguous as possible about concepts that are notoriously slippery.A very fine book and it will be a while before I go back to reading a Philosophy of Mind text. Hopefully, when I do the philosophers will have found something new to say.

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Having been pretty much a devotee of "airy-fairy" philosophical explanations of memory, learning, consciousness and psychopathology, I picked up this book with some hesitation. However, it seems that Edelman and Tonio are really onto something. Something so profound that it may be that all future mental health and education theories use it as the new paradigm that unites or dismisses previous explanations.However, it does open the way for more airy fairy philosophical debates about, if forward movement is merely a concept made of linked neuronal maps, what the external world is really like. Or if it is at all. Anyway, great thought provoking and very satisfying book.