CONSCIOUSNESS. A USER'S GUIDE * Adam Zeman * 2003. London: Yale University Press * Price 18.95. * ISBN 0-300-09280-6 * WIDER THAN THE SKY. THE PHENOMENAL GIFT OF CONSCIOUSNESS * Gerald M. Edelman * 2004. London: Allen Lane * Price 15.99. * ISBN 0-713-997-338 * THE QUEST FOR CONSCIOUSNESS. A NEUROBIOLOGICAL APPROACH * Christof Koch * 2004. Englewood: Roberts and

Abstract

That there is an intimate relationship between our consciousness and the functioning of our brains was not a novel idea even when Hippocrates famously asserted that ‘from the brain, and from the brain only, arise our pleasures, joys, laughter and jests, as well as our sorrows, pains, grief and tears’ (quoted in Spillane, 1981). The evidence—from everyday observations such as the effect of a bump on the head to the most sophisticated neuroscientific experiments—seems overwhelmingly to support the belief that the quantity, distribution and spatio-temporal patterns of neural activity in the brain are somehow connected with the level and content of consciousness. So much is clear. More opaque is the precise nature of the connexion. There are different ways of interpreting the broad correlation between neural activity and consciousness. Nowadays, by far the most common view is that experiences are identical to the relevant activity. Unfortunately, this theory—which philosophers have examined in minute detail in many thousands of articles since U. T. Place first advanced a modern formulation in 1956 (Place, 1956; Borst, 1970)—is not at all straightforward. It has at least two major variants. According to the first, neural activity simply is conscious experience—end of story. Unfortunately, nerve impulses do not seem like experiences, such as awareness of yellow or of pain; and the least one might expect is that something should seem like itself. This has prompted the suggestion that neural activity and conscious experiences are two different aspects of what are, essentially, the same event. This interpretation, often called ‘property dualism’, to contrast it with the ‘substance dualism’ of traditional Cartesian thought, is very popular with both philosophers and neuroscientists. For example, John Searle, one of the most prominent philosophers of consciousness, has advanced the dual aspect theory but tried to make it more palatable as …