WB, Zeno 2008-09-21

1 of 1 people found the following review helpful:

it's more than 8 years since I read TENM. The other day I found it fallen on the floor and decided to write a review about it, although I remember it hazily. I was dismayed to see it has 11 1 star revs, against only 23 5 star ones. How is it possible?

I think neg revs misinterpreted the book's intent: here [I hope] we're not in the middle of a religious war, as with string versus loop, or Darwin versus ID, or Sokal versus God knows what (by the way, I'm with Sokal). What Penrose set out to do, IMHO, was to amuse himself a little, and (why not?) also earn some money and get his name away from twistors and spin networks and tiling, and into the public's awareness; and by the way, propound some of his pet hypothesis and beliefs. But all among rational people. I was stunned by the virulence of some neg revs, as if he were rejecting naturalism (and even if so, what?). It seems that civilised discourse is definitely over.

So in my view the book is to be taken first of all as an opportunity to explore a first-rate mind, and what an enjoyment that is! I've NEVER seen Turing machines, Goedel method of converting letter strings into numerical ones, etc., better explained outside a classroom, when a prof had to clarify things for bumbling students.

As for his theses, well ... I concur with him about the implications of Goedel's theorem. I think his critics miss the point he's trying to make. Let's be reasonable: nobody can prove anything one way or the other, but to assert, as one neg rev does, that SUBJECTIVE vision is algorithmical ... well, again! What meager evidence we have (humble introspection) would seem to point the other way. As Eddington once said "if you see a salvo of rockets soaring upwards, it doesn't disprove the existence of gravity, but certainly is no evidence for it". I think the onus of proof lies with those who assert mind processes ARE algorithmical. Another neg rev says math is a closed system; well, if so, please explain to me the REASON for the connection between Riemann's zeta and prime numbers. Ah, we don't have the whole picture of the building's architecture yet? Well, neither do we of the (Uni/Multi)verse, another closed system, and this last one with some connection to reality, whatever THAT means. It depends on whether we're Platonists (as Penrose elsewhere acknowledges himself to be) or Formalists -and perhaps here one also should lump the Intuitionists?-.

As for the tubules and the -shotgun- marriage between quantum "theory" and gravity, they are two different things. I think the TUBULE HYPOTHESIS is a falsifiable suggestion (I wonder why Penrose mentioned it at all), hasn't any theory-like status, and anyhow doesn't purport to explain purely MENTAL phenomena: it's as far from it as any physical theory that eschews dualism. So I don't think it has anything to do with the AI discussion. Anybody wanting to criticize it is welcome (though not on the ground that hook -or flat- worms also have tubules: are they free-floating in a vacuum, or inside some cell of the worms?).

As regards the UNTENABILITY OF QUANTUM "THEORY" with its many dualities and dialetheisms -wavicles, wavefunction propagation versus collapse, acausality, nonlocality- I concur with Penrose that it is a phenomenally successful collection of recipes in search for an explanation, not a true theory (that's why I put the scare quotes around it) and should be reformulated, as should have been Newton's because of its nonlocality. In TENM he seeks to do it in an very incomplete and somewhat unorthodox way, but obviously doesn't put forward a theory to that effect in the book, so take it only as an amiable proposal! Even so, I think this is more of a philosophical question (should theories be based on entities understandable to human minds shaped by evolution, if only, pace Mach, by analogy and metaphorically, as for example the 4-dimensional continuum?; or should they be accepted even if they deny basic notions about "reality" such as non-contradiction and causality?) than a scientific one, and so must have as many answers as there are reviewers.

By the way, delving a little more into the AI problem: I think neither Penrose nor the reviewers here mention self-referentiality, which I would think should be considered the hallmark of (self)consciousness, on which naive -but honestly toiled- set theory foundered, and which would seem difficult to implement algorithmically. Why is that?
Another reviewer, and not book-oriented question: what results are emerging NOW fron research into computerised evolutionary algorithms?

To summarise this rambling half non-review: when readind Penrose (and especially "TENM" and "The Road to Reality: A Complete Guide to the Laws of the Universe") I had the warm feeling I was in the company of a trusted, non-abrasive old friend with whom one might -respecfully, because he knows so much more than you do- disagree, but to whom it is always sage to listen and to pay attention to. And for this, TENM gets my five stars.

Pinner Blinn 2007-09-12

4 of 5 people found the following review helpful:

I was compelled to write as I came by on the way to buying Dr. Penrose's more recent book ("Road to Reality") and was appalled that Amazon features 2 out of 3 negative views on the first page, including one which dismisses the "Emperor's new mind" as "rubbish". Surely the book is controversial in certain quarters, but the vehemence of much of the criticism can only make me wonder why some people are so defensive about it.

I have to admit I have not reread this book since my original reading around 1990, so take my remarks at some discount on that basis. But I will tell you that this book remains influential in my choice of what I read and how I evaluate things even to this day. It has indeed changed my life.

Dr. Penrose's premise is that a computer simulation of a brain will not achieve the equivalent of human consciousness. I don't wish to enter the fray of arguing points. Dr. Penrose is a mathematical and scientific genius, a deep thinker on the nature of reality, and he can do his own counterpoint. Read this book with an open mind, and even if you disagree with some of his arguments, you will take much away with you.

Here's my take. "Consciousness" is pretty central to the whole enterprise of scientific endeavor, as well as how each of us understands our place in the world. Consciousness, as modeled by psychological and AI researchers, has a lot to say about the biological/physical systems that underpin what is happening in our heads, but one has to wonder about claims that consciousness is now completely understood. To this end, Dr. Penrose takes us on a fascinating journey to the frontiers of scientific knowledge, at scales both large and small. This is entirely relevant to the central theme. Science can only talk about what we can measure, and there are limits to what we can now measure. Our current picture of reality is not as complete as some people would have us believe.

So read Penrose. Read Stephen Jay Gould. Read Raymond Smullyan. Read about the Banach-Tarski theorem. Read about Fermat's last theorem. Read great literature. Keep an open mind. Peace!

Randall McCutcheon 2007-09-07

4 of 4 people found the following review helpful:

This book is a real mess, and although I am giving it five stars, I don't really recommend anyone read anything like all of it. In fact, most of it isn't about the problems with strong AI at all. Mostly, it's a general, populist book about modern physics and mathematics. That can be an interesting read too, but probably Penrose isn't the person to be writing such a thing. He uses way too many exclamation points and I suspect he also tends to think he knows more than he really does. For example, it is clear by his one use of the word "ergodic" that he thinks it means something like "single orbits of a measurable set spread out and fill the whole space". That's mixing, not ergodicity. Lots of ergodic transformations do nothing of the kind, like for example irrational rotations of the circle. I only know this because I'm an ergodic theorist; I do tend to wonder how many other things I would catch Penrose speaking as if he knew more about them than he does, if only I knew more about them than I do.

So why does this book get five stars? Mostly because it has no good competitors. Daniel Dennett, for example, wrote a book called "Consciousness Explained." In it, he didn't even try to explain consciousness. Which is not to say he didn't write a terrific book. He did. It's wonderful. But when it comes to consciousness, Dennett just punts and doesn't seem to realize this is what he is doing (hence the ludicrously inappropriate title). This is why Searle thinks cognitive scientists come out, on analysis, "too stupid for words" (Dennett's phrase, speculating on what Searle thinks--if you haven't read these two guys' reviews of each others books, you really are missing some top-flight entertainment). As scientists, that's not really fair, but as philosophers of consciousness, it's probably pretty apt. Unfortunately Searle, marvelously adept at diagnosing the deficiencies of others, is ill-equipped to give a positive account. Penrose on the other hand at least gives us an inkling of what a positive account might look like. He does this mostly in the last chapter of the book, which is all I think anybody really needs to read (read the chapter on quantum theory too, if you don't remember anything about it).

Is Penrose right? I think, in broad outline, probably so. I do think consciousness has some power to choose at quantum branching points. I think this because I believe in the causal closure of the physical, I believe in the efficacy of consciousness, I don't believe that consciousness is physical, and I don't believe in overdetermination. You can only rectify these beliefs (as far as I can tell), by booting causal closure upstairs into the many-worlds arena and letting consciousness slide around in this ultra-high-dimensional plane with some measure of latitude. It's also the only way I can imagine that consciousness could have evolved in the first place (given that the strong AI premise that consciousness is automatically, miraculously generated by the execution of an algorithm really is too stupid for words).

I'm sure I'm one of hundreds of people who took quantum mechanics as an undergraduate and immediately formed these opinions; I am happy to defer to Penrose as to the details of how it might work. Are these details worked out in full, or even correctable in principle? Probably not. But almost surely it's not for being too crazy; the truth of the matter about consciousness is probably much, much crazier than even Penrose can imagine. Indeed, probably too crazy to be of any practical use to congnitive science now (maybe ever). So you're still going to have good reason to read your Daniel Dennett.

Oh, right. Penrose thinks the quagmire of consciousness has a lot to do with computability, tilings, entropy and Godel incompleteness. It doesn't (though the aperiodic tilings make for a good analogy involving unusual crystals). Those are just things Penrose knows a lot about, and paranoids think that all the things they know about are related.

WilliamRich 2007-03-19

4 of 5 people found the following review helpful:

Jeez, twelve bucks and one hell of a good read! Stick your neck out and find out for YOURSELF if the book is any good. I'm suspicious that Penrose is being persecuted for theist tendencies.

John S. Allen 2006-11-21

4 of 8 people found the following review helpful:

I skimmed over the equations, and still found the exposition clear enough, with one significant exception. At one point, Penrose describes how an event in the Andromeda galaxy would already have occurred for a person on Earth walking toward the galaxy and not for another at the same spot walking away. the implication is that information would arrive at the same place at significantly different times for people walking in different directions. Penrose is assuming simultaneity of the events on our planet and in the Andromeda galaxy -- after several pages of discussion of how relativity excludes it!

Penrose soon returns to form though, stating that neither person would perceive the event until information about it arrived at the speed of light, millions of years later. Even if people could live that long, they would have to keep walking away from one another to perceive the event at very different times. That would be not be possible on our little round planet.

This is the one place where Penrose's discussion of modern physics lost me for a little while. Otherwise, I found it compelling. In particular, his explanation that Newtonian physics is deterministic stuck with me.

The discussion of mind at the end of the book is inconclusive and speculative, as it must yet be. The mechanical structure of living beings reflects Newtonian physics -- for example, the leg must be strong enough to support the body. Digestion can be explained in terms of chemistry, the nervous system uses electrical conduction, the reception of light by the eye is a quantum phenomenon. But then, there is the mind. Though the uncertainty in quantum physics allows of free will, it does not explain that, or consciousness. Evolution takes advantage of physical phenomena not yet understood -- after all, none were understood until very recently. The question of consciousness and that of the structure of the universe converge. Thought-provoking, indeed!