The Evolution of Consciousness: Euan Macphail New York:  Oxford University Press, 1998,  256 pages, $75.00.

I tend to be partial to the musings of iconoclasts, and suspicious of well-accepted assumptions that haven't been thoroughly shaken out. So I find myself naturally receptive to Euan Macphail's predilection to challenge what most psychologists and biologists take for granted with respect to species' differences of brain size, intelligence, and cognition. In his 1982 book Brain and Intelligence in Vertebrates, Macphail took on the century-long dogma that species with larger brains, or larger relative brain sizes (aka encephalized species) are also more intelligent. Though he perhaps didn't win large numbers of converts to his view that brain size is essentially irrelevant and that species as different as goldfish and chimpanzees are about equally intelligent, he did deal a devastating blow to the complacent assumption that it wasn't necessary to actually test this hypothesis by comparing the learning capacities of different species. When he compared reports of the associative learning studies in different species (with different size brains) he found remarkably subtle if any difference in acquisition rates and complexity of learning, even at the extremes of brain size. Whatever the actual relationship, he concluded, the hypothesis of a simple quantitative correlation was disconfirmed. It isn't a surprise, then, to find Macphail's third book investigating comparative cognition to come down on a similarly unpopular and counterintuitive side of the comparative consciousness issue. Are animals conscious? Is there a sort of scala naturae of consciousness? How could we discover or disprove animal consciousness? Could there by any adaptive value to consciousness? Is human consciousness unique or different? Could machines be conscious? Macphail trains his skeptical eye on each of these currently fashionable and oft debated questions with predictable results, both for the questions and for the author.

Along the way to making his major point that the comparative behavioral evide