Julian Jaynes, a Princeton University psychologist who died recently at the age of 77, is famous, or notorious, depending on your point of view, for one book only: this one. It was first published in 1976 and I originally read it then; it impressed me, rather against my will, but I put it aside as being almost certainly wildly and completely wrong. I went back to it recently and found that it produced a different impression now from what it had done nearly a quarter of a century ago. Many critics then thought that Jaynes was deluded or a crank, and at that time I tended to agree with them, but now I'm not so sure. Nor am I alone in this opinion; the philosopher Daniel Dennett, for example, takes Jaynes seriously and has written in complimentary terms about his book. And Richard Dawkins has recently written as follows:
[Jayne's book] is as strange as its title suggests. It is one of those books that is either complete rubbish or a work of consummate genius, nothing in between! Probably the former, but I'm hedging my bets.
Jaynes's central, and thoroughly outrageous, idea is that consciousness is a recent development; indeed, it began as recently as 3,000 years ago. Before that time human mentality was characterized by auditory and sometimes visual hallucinations, in which people heard the voices of the gods speaking to them and telling them what to do. Only when this process became internalized and recognized as coming from within individuals' own minds did truly modern consciousness begin. Jaynes illustrates this by means of Homer's Iliad, in which the participants continually receive orders and advice from various deities. This, according to Jaynes, is no mere literary trope but is an accurate description of how people really experienced the world at the time.
The book develops this idea at length in its first section, in which Jaynes maintains that the mind of preconscious people was split functionally into two (the 'bicameral mind'), probably as a result of a dissociation between the left and right hemispheres of the brain. The second part examines the historical evidence, with particular reference to the development of consciousness in Greece and Mesopotamia and in the Old Testament. The third section relates all these ideas to the modern world and discusses poetry, music, prophecy, hypnosis, and schizophrenia. (A sequel, to be called The Consequences of Consciousness, was supposed to be published in 1984, but I am not sure that it ever appeared.)
Whether one agrees with Jaynes or not, there is no denying that his book is eminently readable. He writes elegantly and clearly and one always knows what he is getting at. The first two chapters offer one of the best summaries of the problem of consciousness and the attempts that have been made to solve it that I have seen. And throughout the book Jaynes displays an impressive grasp of the historical aspects of his subject as well as of the state of neurophysiological science as it existed at the time he was writing. In other words, he was a polymath, and his book is correspondingly rich in facts and ideas. Naturally, much more is known about the brain today than was the case a quarter of a century ago, and even then it was possible for specialists to object to this or that fact that he cites. However, all this is rather unimportant; what really matters is the question: was he right? Did humanity really undergo a radical shift in consciousness at some time in the past, or did consciousness simply develop, more or less smoothly, from its origins in our anthropoid forebears? The real importance of Jaynes's book is that it asks this question, and answers that there was indeed a shift.
Most psychologists and archaeologists who have ventured to speculate on these matters have been gradualists, and have been unwilling to countenance the possibility of sudden shifts. But perhaps the intellectual climate is beginning to change. For example, Nicholas Humphrey, in a recent paper (Cave Art, Autism, and the Evolution of the Human Mind, in Journal of Consciousness Studies, 1999, vol. 6, pp. 116-143) has suggested that the resemblance between the cave paintings of the Upper Palaeolithic and the drawings of certain autistic children, such as 'Nadia', may indicate a radical shift in consciousness as having occurred between about 11,000 and 5,000 years ago. This is a little earlier than the time of the shift proposed by Jaynes but not all that much earlier. So perhaps Jaynes's main fault was that he was too much in advance of the thought of his day.
One problem with a theory such as Jaynes's is that it is very difficult to test. We can probably never really know what the consciousness of people in Mycenean times or earlier was like. However, this doesn't mean that the attempt isn't worth making. I'd say that Jaynes's book should certainly be read by anyone with an interest in the way in which the human mind has evolved and developed. Whether you finally agree with Jaynes or not, you will almost certainly find that your own mind has been altered in some way by the experience.