Broca's Brain is one of Carl Sagan's typically variegated works, its scope ranging from the dangers of pseudoscience, to the societal impact of technology and artificial intelligence, to the exploration of the Solar System and our celestial neighborhood. It tosses aside trivial matters and delves into deepest questions of life in the cosmos: the evolution of the human species, the existence of extraterrestrial life and intelligence, the origin and fate of the universe. Sagan's characteristic talent for writing is well-developed in Broca's Brain, a talent that leaves even the most complicated concepts accessible to the newcomer.
Read more reviews on AmazonThere is a 55-page chapter in the book called "Venus and Dr. Velikovsky". Immanuel Velikovsky was an American who in the 1950s tried to argue that spectacular events in the Bible, such as the Crossing of the Red Sea, were caused by astronomical collisions and catastrophes. Velikovsky, understandably, stirred up a firestorm of criticism in his time, supposedly including calls by scientists for him to be silenced. What Sagan is doing in this chapter is demonstrating how the scientific process should work—i.e. through skepticism and critical analysis instead of personal attacks or censorship. As such the chapter is overkill, a 12-pointed critique, supported by technical appendices, of Velikovsky's ideas. Nonetheless, much about the workings of the Solar System can be extracted from this case study.
Perhaps the prevailing weakness of Broca's Brain is its disjointed nature. The chapters originate from lectures and essays published independently between 1974 and 1979. There is little that unifies the various chapters other than the author's wide-ranging interests, although Sagan does attempt to group the chapters into five categories. Having already been a successful author, it seems Sagan devised the book as a collection of his previous projects. He writes that debunking Velikovsky "took badly needed time" away from his own research. But this is his own research; this is what made Carl Sagan who he is. As such Broca's Brain is not one of his flagship works, but rather an essential addition for anyone who wants to absorb the full breadth of Sagan's knowledge.