luvluv

Interesting review of his book on the mind here:

http://www.leaderu.com/ftissues/ft95.../revessay.html

Just wondering what you guys think, particularly you monists.

Philosoft

Seems Penrose's idea hinges on statements like this:Not having read the book, I can't be sure, but I wonder if Penrose has considered a quantum interpretation. I suspect the simplest machines might not work strictly computationally.

The Lone Ranger

I've read a little of Penrose's writings, and have been completely unimpressed. Granted, I don't understand the physics or mathematics as well as he does, but his whole argument from Godel's Incompleteness Theorem seems like a sophisticated Argument from Ignorance to me.

"I don't see how the brain could be anything other than an organic computer, and I don't see how it could be possible to build a computational device that does what the human brain does. Therefore, it will never be possible to build a machine that can do what the human brain does." That seems to be his argument, as I understand it.

Even if it's not possible to design a machine that does all that the human brain can do, including creative thought -- and that's a very big "if" -- it doesn't follow that such a machine can't be built. After all, natural selection built one (actually several billion) out of meat; certainly, there's not the slightest evidence that there's anything at all non-material about the makeup and functioning of the human brain.

Given sufficient time and resources, I don't see why it wouldn't be possible to build an evolving system that might ultimately prove to be capable of everything that supposedly makes the human brain unique, and then some. Indeed, we already design computer programs that "evolve" through random mutations in the code and retention of any mutation which improves the program's function. Some of these programs rapidly evolve capabilities that the original programmers never dreamed they'd be capable of, or such is my understanding.

***

One of Penrose's arguments is that quantum-level processes are a significant component of the functioning of the human brain. I find this argument completely unconvincing, since he claims that these quantum phenomena are occurring within the microtubules that make up the cytoskeleton of neurons. But microtubules are orders of magnitude larger than the scale at which quantum-level events are normally observed.

Some attempts have been made to detect changes in microtubule structure that might be due to quantum fluctuations, but no evidence whatsoever has been found, last I heard. The "quantum computer" hypothesis has no evidence whatsoever to support it, as far as I can tell, and sounds to me like nothing so much as wishful thinking.

Some people just don't want to believe that the functioning of the human brain is subject to the same physical/chemical laws that govern everything else.

Cheers,

Michael

Shake

Well, I don't know if I'm a monist or not, but here's my $0.02.

First, for any who are interested, I would recommend reading Godel, Escher, Bach: An Eternal Golden Braid by Douglas Hofstadter. The latter part of this work tackles precisely the problem of brain vs. mind. He builds up to it with an analysis of formal systems, including Godels' work which proved that no sufficiently powerful formal system is consistent. He provides a rather convincing (to me) argument that no machine will ever fully realize the potential of the human mind. He further argues that if such a 'computer' were actually constructed, it would not be capable of lightning fast computations (ala Commander Data of ST:TNG), but would be bogged down by sensations, other thoughts, etc.

Anyway, Hofstadter makes the points better than my paraphrasing, so I must again recommend his book to all. It's long, but a very good read! :notworthy

Wyz_sub10

Well, you have my respect for actually getting through it. I agree it is fantastic, but I've nibbled on it for about a year and I've barely made a dent in it.

What edition do you have? The book itself is genius, but the forward is the most tedious piece of rambling fodder I have ever read.

Shake

I've got the (relatively) new 20th anniversary edition! I found that once I had some time, I made very short work of it, never mind the size of it.

Corey Hammer

Based on the review...

A) Three words...argumentum ad verecundium-appeal to authority. He's a mathematician, not a researcher in cognitive neuroscience.

B) Two more words: Straw Man: The computer is a metaphor; not how the brain is thought to work. Computer models of mental functions are made just like model planes are made to test drag and lift in wind tunnels.

It falls apart from there. From what I read of the review, it's probably on the same par as the book from the Danish statistician on the environment.

[Editted to add...]

I just want to add that computer literally means something that computes. Penrose takes an absurdly narrow view of the word to mean things that have microchips and RAM in them. Basically, he's relying commonly-used definition that exist in the public lexicon and not in the field itself. I find that extremely disingenuous and poor science if not outright deception.

Corey Hammer

A monist is someone that thinks (correctly, I might add) that brain = mind.

[Added]

Conversely a dualist is someone who (falsely) believes that brain and mind are separate.

luvluv

Well, Lone Ranger, to be fair, the article does mention that Penrose thinks that such computers are possible but would be based on laws of physics we haven't discovered yet. I think all he is saying with this book is that such computers will probably be built one day, but "don't hold your breath."

Clutch

I agree with Michael. I thought The Emperor's New Mind, for example, was in many ways a great book. It has these lucid and accessible treatments of all sorts of technical themes. It's just that the overall argument is: Put all this in a pot, stir it, and voila! Computers can't have minds! (Unless they're quantum computers.)

More precisely, the argument seems to be: We don't understand consciousness. We don't understand the quantum. Therefore, the quantum explains consciousness.

Penrose is obviously a smart guy, but he seems to have fallen victim to something one of my colleagues calls "philosopause" -- the change of life that elder statesmen in physics undergo when they decide to Explain It All. Anyhow, I saw him lecture last year. He stuck to physics, addressing a lay/general university audience, and was absolutely brilliant.