Readers of Descartes' Error will know that Damasio is an excellent writer as well as one of the most prominent neuroscientists of our time. They will not be disappointed in this new book, which is in a sense a sequel to the earlier work, though they should be warned that it requires reading with close attention—not surprisingly, in view of its subject matter. For this is a book about what is commonly reckoned to be one of the most intractable problems facing science today: how the brain gives rise to consciousness.
The great merit of the book is that the theory it describes is firmly based on modern knowledge of the nervous system, on which Damasio is an authority. He is also a clinician, and he illustrates his argument by means of some fascinating case studies in which people who suffered brain damage of various kinds exhibited selective deficits of different types of consciousness or psychological ability. An appendix provides further material of this kind, together with references for those who want to follow up Damasio's sources.
Damasio distinguishes three different kinds of self that we possess. First, there is the proto-self, which is an interconnected and temporarily coherent collection of neural patterns representing the state of the organism, moment by moment, at multiple levels of the brain. The proto-self is unconscious.
Next we have the core self, which is produced whenever an object of any kind modifies the proto-self. The core self does not change much throughout our lifetime, and we are conscious of it. Hence we can speak of core consciousness. What I found particularly interesting about this notion is that the core consciousness is supposed to continually regenerated in a series of pulses, which seemingly blend together to give a continuous 'stream of consciousnes'. Damasio connects his conception of core consciousness with the view expressed by a variety of earlier thinkers: Locke, Brentano, Kant, Freud, and William James.
Finally, there is the autobiographical self, which is based on memory and also on anticipations of the future, and which develops gradually throughout life. You must have a core self in order to acquire an autobiographical self, but the converse is not true; there are cases in which people lose their autobiographical self, temporarily or permanently, while maintaining their core consciousness. The autobiographical self permits the existence of a much richer form of consciousness, which Damasio calls extended consciousness.
As readers of Damasio's earlier book would expect, he attaches great importance to the role of emotion. The nomenclature is somewhat complex here. By 'emotion', Damasio does not mean a psychological state; instead he uses the term to refer to internal changes in body state (chemical, visceral, muscular) and also the accompanying changes in the nervous system. Emotions are thus not conscious. But when they are induced (for example, by the sight of an external object) they may give rise to 'feelings', which provide the stimulus for action: avoiding situations, seeking them out, as the case may be. A prolonged feeling state constitutes a mood.
Are feelings conscious? It seems that sometimes they are and sometimes they are not. Because we are conscious creatures, we tend to think that feelings must always be conscious, but Damasio thinks that an organism may "represent in neural and mental patterns" the state that we call a feeling without ever knowing that the feeling is taking place. I'm not clear about what he means by 'mental' here; but it isn't the same as 'conscious', because he goes on to say that we are not conscious of all our feelings. For example, we may suddenly find ourselves feeling anxious, or pleased, or relaxed, without knowing why; in such cases the physical state that gave rise to the feeling must have begun some time previously. But because we do sometimes know that we have a feeling, we have to speak of a third level of development, that of conscious knowledge of feeling. Damasio suggests that there was an evolutionary advantage to organisms that could have this knowledge.
Emotion, feeling, and consciousness of feeling are really arranged along a continuum, but for descriptive purposes it is convenient to separate them. Damasio also suggests that some non-human creatures that exhibit emotions but are unlikely to have our sort of consciousness may well have feelings, but without knowing that they have them. As he remarks, there is no word to name 'feelings that are not conscious' but perhaps there should be.
The lack of a suitable vocabulary to describe his ideas is indeed something of a problem for Damasio. He uses terms such as emotion and feeling in a different sense from the usual and this coining of terms is essential for his theory, but it's difficult to find succinct definitions of their meanings in the book. There is what is rather apologetically called 'A Glosssary of Sorts', but this doesn't provide the summary descriptions that might have made things easier for the reader.
As Damasio acknowledges at the outset, he may be criticized for not addressing the qualia problem (how the processes in our brain can produce the subjective experience of the blueness of the sky or the sound of a violin). He believes that this question can be approached scientifically and that his theory is a contribution to the solution. Views on this, the 'hard problem', as it has been called, are very varied, and not everyone would agree with him that it is soluble from a neurophysiological angle. But this does not affect the theory he advances, which is concerned with the nature of the self and how it originates, and on this he is profound and illuminating. It would be difficult to read this book and not find one's ideas about what constitutes a human being to be considerably enriched, perhaps even radically restructured.
We are fortunate to be living at a time when the scientific study of consciousness has once more become respectable and when philosophers are willing to take account of neuroscience and neuroscientists of philosophy. The most exciting activity is taking place today at the interface between these two disciplines, and Damasio's new book is an important contribution to the debate.
Buy from Amazon.com or Amazon.co.uk.