On page 197 Penrose divides scientific theories into three broad categories: SUPERB, USEFU

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On page 197 Penrose divides scientific theories into three broad categories: SUPERB, USEFUL, nad TENTATIVE. (Yes, he uses caps) The paragraph following this list reads: Into the SUPERB category must go all those I have been discussing in the paragraphs preceding this one [that is, relativity - both varieties - and quantum mechanics]. To qualify as SUPERB, I do not deem it necessary that the theory should apply without refutation to the phenomena of the world, but I do require that the range and accuracy with which it applies should, in some appropriate sense, be _phenomenal_. The way that I am using the term `superb', it is an extraordinary remarkable fact that there are any theories in this category at all! I am not aware of any basic theory in any other science which could properly enter this category. Perhaps the theory of natural selection, as proposed by Darwin and Wallace, comes closest, but it is still some way off. Anyone who wants to use Penrose as an example of someone "who reject[s] some aspect of evol[ution]" had better think again! Ken Smith =================================================== The following quote from the forward of _The Emperor's New Mind_ may refresh your memory as to the main purpose of the book: Penrose's book is the most powerful attack yet written on strong AI. Objections have been raised in past centuries to the reductionist claim that a mind is a machine operated by known laws of physics, but Penrose's offensive is more persuasive because it draws on information not available to earlier writers. --- Martin Gardner in the forward to _The Emperor's New Mind_ Indeed, the breadth of topics considered is truly amazing. In the last chapter titled "Where lies the physics of mind" he has a section dealing with natural selection in the context of his overall thrust stated above. He begins this section ... If we suppose that the action of the human brain, conscious or otherwise, is merely the acting out of some complicated algorithm, then we must ask how such an extraordinarily effective algorithm came about. The standard answer, of course, would be 'natural selection'. --- Roger Penrose, _The Emperor's New Mind_ He then goes on to summarize the basic ideas of natural selection as they would apply to algorithms giving Dawkins (_The Blind Watchmaker_) as a source for further reading. He continues ... Even according to my own viewpoint, there would have to be _some_ truth in this picture, since I envisage that much of the brain's action is indeed algorithmic, and - as the reader will have inferred from the above discussion - I am a strong believer in the power of natural selection. But I do not see how natural selection, in itself, can evolve algorithms which could have the kind of conscious judgements of the _validity_ of other algoritms that we seem to have. --- Roger Penrose, _The Emperor's New Mind_ He elaborates on this idea further and takes into consideration such arguments as "given enough time, ...", yet remains unconvinced that natural selection provides the complete answer to the question posed in his opening statement. Another quote that may illustrate his point more clearly ... Nevertheless, one still might imagine some kind of natural selection process being effective for producing _approximately_ valid algorithms. Personally, I find this very difficult to believe, however. Any selection process of this kind could act only on the _output_ of the algorithms and not directly on the ideas underlying the actions of the algoritms. This is not simply extremely inefficient; I believe that it would be totally unworkable. In the first place, it is not easy to ascertain what an algorithm actually is, simply by examining its output. (... deletion of example involving Turing machines ...) Moreover, the slightest 'mutation' (say a slight change in a Turing machine specification, or in its input tape) would tend to render it totally useless, and it is hard to see how actual _improvements_ in algorithms could arise in this random way. (Even _deliberate_ improvements are difficult without 'meanings' being available. ..... ) --- Roger Penrose, _The Emperor's New Mind_


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