
Why Roger Penrose thinks computers can't - justsee
http://www.friesian.com/penrose.htm
======
spot
Penrose and his book have been debunked.
<http://www.mth.kcl.ac.uk/~llandau/Homepage/Math/penrose.html>

~~~
justsee
'have been debunked' - quite an emotionally laden phrase to introduce what is
in fact an opposing view by another mathematician don't you think?

The hostility the Strong AI camp have for Penrose's views is fascinating - it
must be infuriating to have such a respected mathematician and physicist take
the time to write a few books refuting the reductionist approach. There
certainly seems to be no room for a contrarian around those parts!

Thanks for the link, but to state that it debunked anything does not seem to
be correct. It was an attempted refutation by a computationalist, and Penrose
answers these criticims in:
[http://web.archive.org/web/20080618195657/http://psyche.csse...](http://web.archive.org/web/20080618195657/http://psyche.csse.monash.edu.au/v2/psyche-2-23-penrose.html)

I'd recommend reading the section "4. The "Bare" Gödelian Case". Two
particularly relevant points!

"4.5 The many arguments that computationalists and other people have presented
for wriggling around Gödel's original argument have become known to me only
comparatively recently: perhaps we act and perceive according to an unknowable
algorithm; perhaps our mathematical understanding is intrinsically unsound;
perhaps we could know the algorithms according to which we understand
mathematics, but are incapable of knowing the actual roles that these
algorithms play. All right, these are logical possibilities. But are they
really plausible explanations?

4.6 For those who are wedded to computationalism, explanations of this nature
may indeed seem plausible. But why should we be wedded to computationalism? I
do not know why so many people seem to be. Yet, some apparently hold to such a
view with almost religious fervour. (Indeed, they may often resort to
unreasonable rudeness when they feel this position to be threatened!) Perhaps
computationalism can indeed explain the facts of human mentality - but perhaps
it cannot. It is a matter for dispassionate discussion, and certainly not for
abuse! "

~~~
spot
Did you see where he admits he's wrong? "these are logical possibilities". IE,
Penrose made a logical argument, and he didn't cover all the cases. Maybe this
one is clearer: <http://www.nytimes.com/books/97/04/27/nnp/17540.html>

------
ntoshev
"The question of whether a computer can think is no more interesting than the
question of whether a submarine can swim."

E. Dijkstra

~~~
hsmyers
So submarines with deformable surfaces and glider technology are what---
chopped liver?

------
davnola
He's a Platonist, so he believes in the existence of a real world that is
neither material nor mental.

His central claim that conscious acts are in some sense noncomputational is
prima facie false.

And his concrete solution to problem collects together several other very
difficult problems and essentially says, solve one, solve them all. (Great
news for his publishers btw.)

For those reasons, it's hard to take seriously because it's outrageously
speculative.

------
Symmetry
I was annoyed at how the article just blithely asserted that wavefunctions
collapse, as if that wasn't a matter of ongoing debate. In fact, Penrose is
remarkable among big name physicists for being sure that wavefrom collapse
occurs. <http://www.hedweb.com/manworld.htm#believes>

------
varjag
Patricia Smith Churchland has famously remarked about Penrose's theories that
"Pixie dust in the synapses is about as explanatorily powerful as quantum
coherence in the microtubules."

[http://en.wikipedia.org/wiki/Hard_problem_of_consciousness#S...](http://en.wikipedia.org/wiki/Hard_problem_of_consciousness#Scientific_attempts)

~~~
zephjc
Pretty much. Penrose, despite being generally brilliant, is not an expert in
neuroscience. QM explanations seem like hand waving or saying "we don't really
know, and since I know a lot about QM, that must be the reason". It's almost
avoiding investigation into the hard problems of neurobiology to find the
real, physical processes that bring about human cognition.

------
jacksoncarter
The argument that computers can't think derives from the idea that there are
noncomputational processes at work in the brain. Essentially, we don't know
how certain thoughts arrive in our mind. We can't create an algorithm to mimic
our chain-of-thought generator.

But that doesn't mean we can't create a computer that can have similar
noncomputational "thoughts".

People must choose, when a computer need not choose. What I mean is, a
computer _can_ shut down. A human mind cannot -- and continue to live. When a
computer "observes" -- so to speak -- stimuli it cannot handle or are beyond
its capacity, it does not make random choices about what to do now. We do not
trust randomness. Sometimes, however, humans have no option but randomness.
This is why in a crowd of 100 each one will react differently to the same
stimulus. If it suddenly gets very cold, some will shiver, some will leave,
some will get up and jump around.

In most cases, Computer systems aren't even allowed to accept input that isn't
known to be valid. Minds have to all the time.

When you begin to predict the future and that's largely what the human mind is
-- a future prediction machine, then it becomes even more complex. It requires
memory. Concoctions from memory or assumptions. We don't let computers assume.

In many ways, we are holding computers back. Because we are afraid. We are
afraid of what they will decide for us. We are afraid of random. We need
control. We haven't subjected computers to survival of the fittest.

If we did, then by the law of large numbers, eventually, like I suppose is
true with many humans, one will survive that we can't explain how. We won't
know how that computer made all the right decisions the whole time.

We don't know how to program computers to accept _any_ input. White is the
maximum color. Black is the darkest. But computers could see much darker than
black and much brighter than white. How can we control something like that? We
can't. We won't be able to. It will see and know thinks we can't imagine.

It's silly to think computers can't.

~~~
Symmetry
"People must choose, when a computer need not choose." Perhaps I'm not
understanding something, but that seems to be obviously false. A human always
has the option of being unsure in the face of non-computable statements like
"You can't know that this sentence is true" or such.

~~~
jacksoncarter
Imagine a dataset where the inputs are to be in a range from 1-100, but for
some reason unknown to the programmers when the program was written, there is
a value of 4,000.

In the real world, a human must decide what to do with that 4,000. A computer
would crash or throw an error or something like that even though the data may
actually be valid.

------
waveman
This is a classic Dunning-Kruger situation. Penrose is out of domain of
expertise here. He has not bothered to study the theory of mind (eg see the
lack of relevant references in his book).

His arguments do not stack up, as extensively documented elsewhere.

This is not the first time that a famous physicist/mathematician has got it
drastically. Neils Bohr was an animist - he believed along with many people at
the time that there was some magic hidden essence to life that went beyond
material things. When told about the discovery of DNA he said "Yes, but where
is the _life_?".

~~~
gruseom
Personally my sympathies are with Penrose and Bohr.

------
ugh
Check out the awesome Gödel CAPTCHA (linked from the article):
<http://www.scottaaronson.com/writings/captcha.html>

Yay! No more spam.

------
joubert
_Thus, Penrose notes, they are true because of their meaning, not because of
their syntax relation to an axiomatic system. This reinforces the thesis of
Jerrold Katz, that syntactic simples are not semantic simples, and so some
truths will depend on semantic contents that cannot be exhaustively expressed
as syntax_

If this were true, would it mean that there are aspects in physics which are
_not_ mere abstractions of math?

------
mark_l_watson
I bought and read "The Emperor's New Mind" in the early 90s, mostly for
"knowing your enemy." I have slowly but surely come to mostly agree with
Penrose: I think there is something magical and "quantum mechanical" about
brain consciousness (including animals).

I believe in eventual real AI, but I would guess that it will not be on
current computer hardware.

~~~
ugh
Why is quantum physics magical? Or is that not what you wanted to say?

As far as I know we have a pretty clear understanding of quantum physics.

~~~
mark_l_watson
I only have a BS in Physics (UCSB) so this may be rough: about 10 years ago I
went to a Quantum Mechanics and Consciousness conference and the gist is that
there is a quantum effect that is required consciousness. My dad taught
physics at Berkeley and his friend from Berkeley Henry Stapp presented an
interesting paper on this theory. The philosopher David Chalmers was also
there and he talked about the difficult question of consciousness: why did
evolution favor the development of consciousness and qualia (an inner mental
life)?

~~~
Symmetry
There are several obvious explanations like that we evolved conciousness in
order to be able to explain ourselves to other humans. But I thought Chalmers
believe that the physical world was "causally closed" and that therefore a
purely material feedback process like evolution couldn't select for qualia?

------
danbmil99
because he's wrong and confused

