Consciousness: a User's Guide
Authors: Mark Harper
Journal: Journal of the Royal Society of Medicine (2003)

In the introduction Zeman states that his aims are both modest and ambitious. Given the vast and difficult nature of the subject and his desire to produce a book that appeals to general and specialist reader alike, I think that his aims are wholly ambitious. However, as a neurologist who has come to his specialty via philosophy and the humanities, he has as good a chance as anybody in succeeding.

The clarity which pervades both the structure and the content of the book is apparent from the beginning. The preface sets out the underlying conundrum: ‘what happens in our brains is connected with what passes through our minds, but how exactly are the two related?’ Rather than using the book to convince us of his own pet theory, he sets out to ‘strike an equitable balance between the warring factions’ and the conflicting hypotheses. He quotes the great Sir William Osler's warning to a group of newly qualified doctors: ‘I must tell you that half of what you have been taught is wrong, and we don't know which half.’ Although the balance has probably improved in medicine, with consciousness we could still be some considerable way short of 50%.

The complexity of the subject is evident from the first chapter. For a start, consciousness has to be divided into ‘conscious’ as in ‘awake’ and ‘aware of’, and ‘consciousness’ as in ‘mind’. Furthermore, it cannot be considered in isolation from self-consciousness and conscience. Superficially ‘self-consciousness’ appears straightforward. However, it emerges as a diverse and fundamental concept encompassing ‘awkward’, ‘embarrassment-prone’, ‘self-detecting’, ‘self-recognising’, ‘self-knowing’ and ‘aware of awareness’. The dissection of this previously innocuous word and the mapping of the links between its different meanings is fascinating and thought-provoking. All ideas, particularly difficult ones, are best approached from first principles. This is effectively achieved through Zeman's foray into the etymology, definition and subsequent expansion of consciousness both as a word and as a concept. Our further understanding of the subject is then gradually built up by a wide-ranging but well-directed journey.

Evolution can be thought of as the etymology of existence; anatomy and embryology give important insights into higher functioning. ‘Consciousness’ might immediately be associated with being ‘awake’. But we also need to reflect on the structure and function of sleep in this context. The importance of vision in structuring our conscious view of the world is self-evident but there is also much to learn from consideration of ‘attention’ and ‘neglect’. The relevance and subtleties of these subjects are demonstrated with a wealth of clinical examples. Familial fatal insomnia is a topically relevant cousin of bovine spongiform encephalopathy. Zeman records the experience of a sufferer who was ‘frequently disturbed by vivid dreams, during which he would rise from his bed, stand and give a military salute. When he was awakened by his relatives he would report dreaming of attending a coronation’. At necropsy most of the damage induced by the prions was found in the thalamus and its links with the limbic system, thereby giving clues to the role of this part of the brain in control of conscious states. He reports other discrete neurological lesions that have given insights into the function of the brain and its parts—inability to distinguish colour, loss of depth perception, failure to recognize faces.

It is only after development of this solid foundation that theories of consciousness are considered. We are again presented with a comprehensive round-up of the philosophical and the scientific, illustrated by numerous analogies and incorporating such diverse elements as computers and ‘aliens’. At times I was worried that the book might turn out to be another Brief History of Time, seeming to make perfect sense but altogether forgotten five minutes later. There were several topics, notably the neuroanatomy, which I found myself glossing rapidly over; but the book is sufficiently well structured that at no point did I feel I had lost the thread of the argument.

There were areas that I thought under-emphasized. Zeman only touches on the quantum theory of consciousness. The possibility of super-positioned states based on microtubular anatomy and ‘sogel’ transformations in the brain offers a very attractive and plausible (if potentially utterly wrong) explanation for the vastly complex processing that might generate consciousness. It is a shame that ‘swarm intelligence’ is not mentioned. Models based on the way insects, such as ants, organize themselves into efficient and effective units have been successfully adapted to businesses. Although not ‘consciousness’ as such, this generation of quite complex behaviours from simple rules could offer useful insights. My final quibble is that, although ‘user's guide’ is a catchy subtitle, it implies an offer to enhance use of the appliance in question. I was slightly disappointed to find that, in these terms, it did not deliver.

Zeman illuminates his difficult and unwieldy subject with quotations from philosophy, fiction and four-year-olds. Consciousness: a User's Guide is not an easy read, but it is an elegant and clear distillation of the rich diversity of theories behind one of the greatest challenges for human understanding.