I actually don't reject the theory that accounts of Gods appearing and speaking to people could be actual mental processes, guided by culture. I find this more believable than it is all fiction or lies (or that Gods have physical existence outside the human mind). But I do reject the bicameral hypothesis that we either have Gods speaking or we have consciousness, and that shift happened a particular point in time around the eight century.
I just finished reading the book. In it, he doesn't state that it happened at once everywhere. There was one passage that implied that the Aztecs were still mostly bicameral (or were in the immediate period after the bicameral breakdown) when the Spanish arrived in the 16th Century.
Also, the breakdown is not instantaneous, but happens over time. Once it starts, you get religion and oracles (the Oracle at Delphi for example) as the populous attempts to hear the gods' voices for direction. Oracles lasted for about a millennium after the initial breakdown in Greece, and over time, the gods' voices were head less and less.
He also states that modern remnants of the bicameral mind exist in hypnosis and schizophrenia (but in the case of hypnosis, how it works is very culturally dependent).
Surely the hypothesis has be to rejected in all its specificity but what new hypothesis can be proposed in the negation of the previous one? Could it be that the shift happened but not in the precise time or not all at once or the shift manifested in a more individualistic manner instead of a collective manner? Precisely in Lacanian psychoanalysis the symbolic consciousness (language) emerges as the reaction to an external traumatic encounter with the chaotic impossibility of the real. The hypothesis of bicameral mind may not have much scientific value but isn't it interesting to coincide so much with structuralism?
