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Review of Penrose, The Emperor's New Mind - Pg 2
Review of The Emperor's New Mind Concerning Computers, Minds, and the Laws of Physics.The Times Literary Supplement. Oxford University Press
Finally, then, what does all this have to do with minds and brains? He returns to the topics of the early chapters, and resumes the argument that mathematical insight (in particular) is non-algorithmic. Here is where consciousness comes in. The function of consciousness, in Penrose's view, is to leapfrog the limits of (practical) computability by conjuring up appropriate judgments in circumstances in which "enough information is in principle available for the relevant judgment to be made, but the process of formulating the appropriate judgment, by extracting what is needed from the morass of data, may be something for which no clear algorithmic process exists--or even where there is one, it may not be a practical one." (p.412) The way a "quantum computer" would achieve this apparent magic would be by being a sort of super-parallel computer, using superposition of computational states to perform a near-instantaneous global search through an otherwise untraversable space of possibilities, with the solution being output by the collapse of the wavefunction. This would not be old-fashioned Cartesian dualism, but radically new-fashioned (revolutionized) materialism. Several features of what is currently known or believed about connectivity of neural nets in the human brain suggest to him that the brain could in principle be such a quantum computer.
One of the defining doctrines of strong AI is the possibility in principle of teleportation--transporting a person from A to B by transmitting a complete, atom-for-atom description of the person's body (and brain) and using the description to construct a duplicate at the destination. Is teleportation murder-and-artifice or a means of transportation? Popular science fiction has for years softened us up for the latter vision, but Penrose is among those who find this idea simply incredible, and one of the cardinal virtues of the quantum computer idea, in his eyes, is that it would rule out perfect duplication of the total quantum state of a brain on what he argues are relatively secure quantum-physical principles.
Where, though, would Penrose have quantum physics draw the line? In principle, could a geranium in a pot be teleported? (When as a child I first heard of "sending flowers by wire" I assumed that they were teleported, and was deeply disappointed to learn the truth.) We already teleport documents (by FAX) and CADCAM (computer-aided-design/computer-aided-manufacture) would readily permit us to teleport automobile parts. Is it all living things, or only all complicated living things, or only all human brains that quantum mechanics would prevent from being thus teleported? Are we the only things in the universe that require quantum computers for their persisting identity? For those who share Penrose's suspicion about human teleportation, this is one of the comforting implications of his theory, but the price to be paid (in terms of revision of the Cathedral of Science) is high. Among the likely casualties, according to a tentative and impressionistic argument of Penrose, will be the standard neo-Darwinian theory of evolution by natural selection. He does not see how algorithms for mathematical judgment could evolve, and "To my way of thinking, there is still something mysterious about evolution, with its apparent 'groping' towards some future purpose. Things at least seem to organize themselves somewhat better than they 'ought' to, just on the basis of blind-chance evolution and natural selection." (p.416) Creationists are not alone in harboring deep misgivings about the standard view; there are biologists who dare to wonder about the one leap of faith still required by the standard view: has there really been enough time for evolution to do all the designing by blind methods? Penrose shares those doubts, but provides no new argument to support them.
Might Penrose be right about all this? I suppose he might; he is an extraordinarily inventive and undogmatic thinker with an awesome mastery of many fields. If anyone could make such a discovery, it would have to be someone like Penrose. But whether he is right or not, his strenuous efforts to combat strong AI by unsettling the Cathedral of Science show, more clearly than any of the manifestos for the other side, that strong AI is a straightforward implication of orthodoxy. We cannot simply add a new wing to the Cathedral, enshrining an alternative theory of the mind; if strong AI is mistaken, the whole structure of science must be rebuilt from the ground up. This will inevitably lead some readers to reason as follows: If an opponent as brilliant and dedicated as Penrose discovers he has to go to such lengths to build a presentable case against strong AI, and can come up with nothing stronger than a speculative suggestion about quantum gravity, strong AI must be more secure than I had thought!