Book Review: The Emperor's New Mind, by Roger Penrose

The Emperor's New Mind is ostensibly a response to proponents of strong AI and a vehicle for eminent mathematical physicist Roger Penrose to lay out his perspective on the physics underlying consciousness. While that part of the tome is interesting, what is most valuable is the first three quarters of the book, in which Penrose explains key issues in theoretical computer science, the philosophy of mathematics, logic, and a great deal of physics. Curious minds looking for clear introductions to subjects such as the Church-Turing thesis and computability, Mathematical Platonism, Godel's incompleteness theorems, classical or modern physics, and basic neurobiology would be hard pressed to find better reading than the relevant chapters contained in this book.

Penrose does return, in the last chapter or so, to the question of whether machines can think, or dually, whether our minds operate algorithmically. He answers this question negatively, using fairly plausible arguments incorporating computability theory and Godel's incompleteness theorem. He then proceeds to lay out very speculative ideas concerning the nature of consciousness and how we might eventually come to understand the phenomenon physically. Penrose believes that the a more complete explanation of consciousness will only come with a theory he calls "Correct Quantum Gravity". True to his scientific training, Penrose very clearly states when he is speculating, but the conclusion of the book is nevertheless weakened by such whimsical trains of thought. One almost gets the impression that Penrose is simply smart enough to draw whatever conclusions he desires. But that keen intellect is exactly what saves the last chapter, as even the less organized thoughts make for thought-provoking fare, and illustrate how relatively the relatively disparate fields covered in earlier chapters can be brought to bear in novel ways. While the reader will likely remain skeptical of his conclusions, the journey through Penrose's ideas is the true genius of this book.