[( Shadows of the Mind: A Search for the Missing Science of Consciousness )] [by: Roger Penrose] [Oct-1995] Paperback – 3 Oct 1995
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Shadows of the Mind By the author of "The Emperor's New Mind", this is an exploration of what modern physics has to tell us about the mind, and a visionary description of what a new physics might look like. It is also a speculation on the biological process that makes consciousness what it is. Full description
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The philosopher Wittgenstein once asked a friend, "How was it that people thought the Sun orbited the Earth for so long"? His friend said, "Because it looked that way". Wittgenstein responded, "What would it look like if the Earth orbited the sun"?
Being locked in illusion himself, Wittgenstein knew the answer was impossible.
Even scientists believe that the sun orbits the Earth but they pretend that they don't.
Kurt Godel, one of the few people who could terrify the brightest minds of the 20th century, wondered why people can be so illogical in believing that the brain produces consciousness. We are locked into this illusion. The illusion is a moving Sun, a Sun set and a sun rise. The illusion is a part of who we are. And the way our language and stories are based on the moving sun, the same can be said for idea the that the brain produces consciousness.
We talk about with this, we feel it, we even tell the kids they will die forever when their brain ages and dies. We tell little kids that dreams are inside their head. We tell them that their brain makes mind like a computer makes software (contradiction intended). We even tell kids that death is annihilation because we are so sure of our illusions. Most of us can't do tensor equations but we convince the kids about illusion. We point, "Look at the sunset". All illusion.
The illusion is solid. The way there is no way out of the illusion of the Sun orbiting the Earth, there is no way out of the illusion of a local mind in the box.
Before the sceptic retorts that brain science gives results. The same can be said for ptolemaic astronomy. Ptolemaic astronomy can predict eclipses. The top minds of the day were convinced, both mathematically and by observation, that Plotemy was correct. This went on for centuries. The hard problem of astronomy was there for all the see, but it was never to be answered. Only when Capernicus came along did the hard problem of astronomy disappear. There wasn't a problem in astronomy, rather, the problem came with the fixtures and fittings, as it where. The system of Plotemy was thrown out and the problem vanished.
There is a hard problem of consciousness. But if we are locked in illusion, we'll never know the answer. I suspect that most people go about their day, doing commerce, playing games and happily living as they've always done without even suspecting there is a hard problem of consciousness because there isn't. The hard problem is in the imagination of the brain scientist who is locked in a ptolemaic jail.
Intuition tells me that I am more than what the brain scientists tell me. Brain science tells me that I am an illusion. Between these banks my life flows.
A little copernican revolution is inside us all!
So there is a subtle argument needed to continue to show that despite this, humans will come out on top. If you are interested in this kind of subtlety after reading ENM then this is the book for you.
In effect Penrose is right at the heart of the Mind-Machine debate in this book. I give an overview of this debate as follows:
We need to find a scientific theory of the Mind. So we can examine what kind of cognitive or thinking device it might be, recognising that it also thinks about Mathematics. For that we need a model of cognition sufficiently general: the Turing Machine model is available and generally considered to be that model - there are no obvious rivals. So one can focus on whether the Turing Machine model could really be a model for the Human Mathematical Mind. If the answer is "yes" we would conclude also: Robots could have Minds.
Penrose draws the conclusion about mathematical reasoning that:
G: "Human mathematicians are not using a knowably sound algorithm in order to ascertain mathematical truth".
This statement isn't quite the statement that the Mind is not a Turing Machine (algorithm here), and some critics have attempted to expose the gaps. In this book Penrose discusses several lines of argument to close the gap. A possible rebuttal might be: "could mathematicians just be using unsound algorithms" - the faulty machine argument. This is very close to questions in the foundations of mathematics itself - after all is this suggesting that mathematics itself is fundamentally unsound? If so where is that unsoundness? So Penrose comes round to the conclusion step by step and through 100 odd pages, that the statement G above implies that indeed the Mind is not a Turing Machine.
This latter conclusion however introduces another problem: if the Mind is not a Turing Machine / algorithm then what sort of (scientific) model exists for it? At the end of the book Penrose examines a generalisation of the Turing Machine model (called Oracle Machines and also due to Alan Turing) and determines that a statement similar to G also applies to that model class as well. Thus the story is left incomplete and I would be tempted to say that somewhere a model M exists of which we can deduce:
"Human mathematicians are using M to ascertain mathematical truth"
However Shadows of the Mind ends without a discovery of that model M. So maybe the answer lies in studying Quantum properties, or in other aspects of these obscure machine models? If you want to be able to study this question further Shadows needs to be studied (and "studied" is the word)!
Penrose's argument that conscious thought is not based on computation as we understand it is sound. Whether this can be strictly ascertained from Godel's theorem is still open to question I think.
However his overall conclusion that when we think, we may be using quantum mechanical counterfactuals to take us beyond the limits of computation, is an intriguing possibility.
I would recommend this book strongly to anyone with a reasonably high level of scientific education. Its hard work to read because the questions he asks are so deep and his approach to answering them is so exhaustively rigorous.
Penrose is not an evangelist like Richard Dawkins so his writing style is not as engaging to a popular audience. Nevertheless it is worth ploughing through this book to at least be rewarded in the end with the firm belief that one is definitely not merely a computer controlled robot!
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