Could a computer ever think? Be intelligent? Have a mind? Be creative? Be conscious? Or is there something special about humans that endows us with these wonderful properties but, being absent in current computers, dooms them to a dark and mindless existence?
Proponents of "strong artificial intelligence" (AI) claim that intelligence and consciousness arise somehow from the way in which a device computes--described by its set of rules, its algorithms . Thus consciousness can be evoked not only in biological brains but also in properly programmed computers, or, for that matter, in an astoundingly complex contraptions of gears and pulleys. The task, according to such proponents, is to ascertain the proper algorithms.
Not so, claims Roger Penrose, the distinguished mathematical physicist from Oxford University; the brain is uniquely suited to harness non-algorithmic aspects of the world, and thus can be conscious. As its title suggests, "The Emperor's New Mind" is Penrose's attack on strong AI; it is based on recent research on quantum mechanics, quantum gravity, black holes, cosmology, fractals, quasicrystals and more, all as they relate to the question of algorithmic processing.
His general argument builds on the ideas of philosopher Karl Popper. First, Kurt Goedel's celebrated theorem demonstrates that there are mathematical truths that are forever beyond proofs using merely the algorithms of mathematics itself--which is all that a standard computer could employ. Next, conscious beings seem to be able at times to recognize truths directly, apparently without deriving them by any algorithms. Thus, in his effort to understand consciousness, Penrose seeks properties of the physical world involving non-algorithmic behavior, aspects which biological brains might exploit. But are there any properties of the physical world such that their behavior can not be captured in a computer program?
For Penrose, astounding complexity of behavior and chaos such as the billowing dust from a volcano will not suffice, since this could in principle be simulated in a very large computer. Nor will quantum mechanics--the branch of physics typically treating very small or very fast processes such as the decay of a radioactive atom--suffice, despite its "magical" aspects such as the wave-particle duality, "collapse of the wave function," and so on. The problem here is that, as quantum mechanics is currently understood, random probabilities underlie all phenomena--hardly what Penrose would like in a being that has will, consciousness, intelligence and ethics.
Penrose's central hypothesis is that a current dilemma in physics--how to reconcile quantum mechanics with Einstein's relativity--may hold the clue. If a so-called "correct quantum theory of gravity" ever is devised, perhaps it will be non-algorithmic.
What could be more intriguing--a book that relates forefront physics research with the age-old philosophical question: "What is consciousness?"
But, frankly, the book is disappointing--and at times frustrating--despite the clarity of the writing and the manifestly interesting topic. Time and time again Penrose defers objections or alternate interpretations, breezing along with his line of thought; when he finally has to meet these objections--often quite late in the book--many of his "explanations" collapse.
Here is just one example. The crushing disappointment concerns his central hypothesis that the key to having a brain function non-algorithmically is to exploit phenomena of an as yet undiscovered "correct quantum gravity," for which standard quantum mechanics is but an approximation. He is forced to postulate special nerve cells in the brain-- as yet not recognized --that operate on fundamentally quantum gravitational processes in a manner as yet not even postulated . After about 100 pages related to such wild speculations, he then admits that the brain is too "hot" for the scheme to work anyway; the random motion of its components would swamp any quantum gravity effect. He concludes this analysis somewhat despondently: "Perhaps we are doomed to be computers after all!"
After Penrose paints himself into an unpleasant corner this way, he tries to paint a doorway out. It simply doesn't work. He turns in the last chapter away from his field of expertise--physics--and into territories where he is, frankly, an unreliable guide; for instance, psychology, cognitive science and the evolution of consciousness. Some of his analyses here are mere recapitulations of ideas presented elsewhere.
Conversely, there are issues that have preoccupied other thinkers on these subjects--most notably the importance of levels of description, and flexibility of response--that get only cursory treatment by Penrose.