Penrose on the brain; book review (Introduction)

by David Turell , Friday, January 29, 2016, 15:09 (3223 days ago)

In this review by Stephen M. Barr we learn that the brain is much more than a computer and we still don't understand what that is:-http://www.leaderu.com/ftissues/ft9511/revessay.html-"In Shadows of the Mind, however, Penrose says, in effect, "Not so fast." The human mind cannot be a computer, if by "computer" one means the computer as currently conceived. There are, he argues, mathematically demonstrable limitations to the kinds of things computers can do, and these limitations are not shared by the human mind. Penrose, as a good materialist, has faith nonetheless that the human mind is nothing other than a machine. But it must be, he endeavors to show, a machine of a radically new and as yet inconceivable kind. -"There are two parts, then, to Penrose's argument, and two parts to his book. He argues negatively about what the mind cannot be. And he argues speculatively about what the mind might be. -"The first part of Penrose's argument was originally developed, as he admits, in essentially the same form over thirty years ago by another Oxford professor, John Lucas. The Lucas-Penrose argument rests, in turn, on a profound and epoch-making theorem in mathematical logic proven by Kurt Godel in 1930. It is generally recognized that this theorem is as fundamental and revolutionary in its implications as the discoveries of Newton, Einstein, and Heisenberg. -***-"As Penrose says: One might imagine that it would be possible to list all possible obvious steps of reasoning once and for all, so that from then on everything could be reduced to computation-i.e., the mere mechanical manipulation of these obvious steps. What Godel's argument shows is that this is not possible. There is no way of eliminating the need for new "obvious" understandings. Thus, mathematical reasoning cannot be reduced to blind computation. -***-"Mentalism is, Penrose thinks, "unscientific." One of the hallmarks of scientific explanation is that it leads to testable predictions. And some implications of mentalism are not only testable, but have to some extent already been borne out in spite of the fact that they strike the materialist as incredible. A mentalist prediction is that digital computers will never and can never reproduce human intellect, and Penrose claims (correctly, I think) to have proven this very point. -***-"Wigner concludes that while "solipsism may be logically consistent with present quantum mechanics, monism in the sense of materialism is not." Another great physicist, Sir Rudolph Peierls, asserts as an implication of quantum theory that "the premise that you can describe in terms of physics the whole function of a human being . . . including its knowledge and its consciousness is untenable. There is still something missing." -***-"Penrose's book is an exceedingly important one, but it will not be an easy one for those not technically inclined to follow. Much more accessible, though probably still difficult for most readers, is the brilliant essay of John Lucas that appeared in The Modeling of Mind: Computers and Intelligence. An even more satisfactory treatment, which puts these arguments into the context of a wider attack on materialism and defense of free will, is Lucas' book The Freedom of the Will (though this otherwise admirable book is sadly marred by a bizarrely heterodox chapter on God's foreknowledge).-"It must be admitted that while we have faith that the human mind is understandable, we do not in fact understand it. It is indeed a very profound mystery how spirit and matter are integrated into a single nature in man in such a way as to respect the accuracy and consistency of physical law. But a mystery is not something incomprehensible in itself. It is something uncomprehended by us. Doubtless, further research on the brain will much enlighten us about these issues. Whether it will succeed in dispelling the mystery entirely, only time will tell."-Comment: An extremely rich essay. Read it all.