Re: What should I say to the post-grads about Godel?
- From: Marshall <marshall.spight@xxxxxxxxx>
- Date: Mon, 16 Jun 2008 01:43:47 -0700 (PDT)
On Jun 15, 11:05 pm, Rupert <rupertmccal...@xxxxxxxxx> wrote:
On Jun 15, 9:41 pm, Marshall <marshall.spi...@xxxxxxxxx> wrote:
On Jun 15, 9:17 pm, Rupert <rupertmccal...@xxxxxxxxx> wrote:
This seems to be a good list of references discussing the issue of
what bearing Gödel's theorem has on the question of whether the mind
is a physical mechanism.
I just don't see how anyone sensible can entertain the question of
whether or not the mind is a physical mechanism. What things
in the universe are *not* physical mechanisms? Saying that
the mind might not be a physical mechanism is tantamount to
saying that it's magic, supernatural, etc. It is medieval thinking.
Consciousness--it's all in your head.
First of all, I myself am quite friendly to the idea that the mind is
a physical mechanism and indeed that a complete description of
physical reality would be a complete description of all of reality,
and I believe Roger Penrose is also quite friendly to these
propositions (although he also thinks that a computational model of
the mind is inadequate).
What to say of Penrose? He is by all accounts quite a physicist, and
yet, does he have any background that should lend any weight to
his arguments about the nature of the mind? I am not aware of any.
Also, we have the fact that his motivation is more easily attributed
to personal aesthetic feelings than by any deep crossover from
the realm of physics. Finally, we may consider that his conclusions
are ridiculous.
If the mind is not the result of computation, what is it the result
of?
There can be only two types of answer: 1) is to say that it is some
physical process that we are not yet aware of, and 2) is to say that
it is supernatural in nature. 2) is not worth refuting; we might as
well
just say consciousness comes from Santa Claus.
But 1 doesn't say anything interesting either, at least as far as the
possibility of artificial consciousness goes. As the saying goes,
if consciousness can be instantiated in three pounds of fatty meat,
it can be instantiated in other implementations as well.
We have the realm of Church-Turing. We have many
different approaches to computation: recursive functions, Turing
Machines, cellular automata, term rewriting, etc etc. They are
all equivalent. Almost any time we sit down to make up a
computational model, we notice two things right away: we
have to do almost nothing before we hit Turing-completeness,
and nothing anyone has ever been able to come up with gets
us past that. The most egregious example being the lambda
calculus. We have a programming language that has ... pretty
much nothing in it, just lambda abstraction of application, and
it's already computationally complete.
What we see is that computational completeness is a black
hole. In designing a computational system it is almost inescapable
and always impassible. The power of this black hole will have
been just as binding on the evolution of the mind as on anything else.
A further (abbreviated) argument: what can be accomplished with
simple computation is counterintuitively impressive as the size of
the training data increases. By itself this strikes me as a complete
explanation for how well humans do relative to computers in many
cognitive tasks.
However, I would also say that I am not sure
that you can say that this proposition has been established beyond all
reasonable doubt. I will elaborate on this more below.
I say, with respect, that I don't think you especially did. You
told me some things that Godel and Unger think, but you
didn't really give any arguments for why we might think
their conclusions have merit.
That is, unless you consider the fact that they concluded
so to be the argument.
We find the following quotation from the article by Feferman to which
I linked previously:
"What was Gödel's own view? Typically cautious, in the Gibbs lecture
he stated his conclusion from the second incompleteness theorem only
as a disjunction, despite his person conviction that mind is not
equivalent to a finite machine. Apparently the reason he did that is
because he did not feel he had a knock-down proof of the falsity of
the mechanist position. Rather, he put forward various arguments
against that position, including several communicated to Hao Wang and
first recounted in the latter's book, 'From Mathematics to Philosophy'
and then at greater length in 'A Logical Journey. From Gödel to
Philosophy.'"
So it would appear that Gödel believed that a computational model of
the mind is inadequate. I am not sure if he also entertained the idea
that the mind is not a physical mechanism, or that physical
determinism is false. If Jesse Hughes wants to look into Gödel's views
on these matters, the references given in the above quotation might be
a good place to start.
In any event, it seems conceivable that Gödel entertained the idea
that the mind is not a physical mechanism, and Gödel was perhaps a
sensible person. (Had a few strange ideas towards the end of his life
when he was unwell, admittedly).
There's also a chap called Peter Unger who works at New York
University who has recently come up with a book called "All the Power
in the World" where he tries to argue that the mind is not a physical
entity. Now, I understand that some people might not regard Peter
Unger as a sensible person, because he has tried in various works to
argue that no-one knows anything to be the case, that there are no
people and no composite physical objects, and that we have a moral
obligation to donate just about all of our disposable income to
organizations like Oxfam and UNICEF. Nevertheless, I find him to be an
interesting thinker and I think he occasionally comes up with
arguments that are worth considering, and, while I haven't had a
chance to look at "All the Power in the World" yet, I'm going to give
it my serious attention.
Perhaps strangely, I agree that no one knows anything, if we use
a sufficiently strict definition of "know." I also would claim that
distinct physical objects such as rocks and cars, and even people
are creations of the mind; the "truth" seems more to be that there
are only atoms in the universe, interacting. (And atoms are of
course made up of smaller particles...) However I don't find
disposing of these creations of the mind to be useful, at least
in the day-to-day, and certainly if we abandon the idea of distinct
people, we have no possible motivation to give to charity. Indeed,
the very concept of "moral obligation" disappears with the concepts
of composite physical objects; who could possibly be this so-called
"self" that is supposed to be "giving?" (God, I sounded like John
Jones there for a second.<shudder>) As I said: not so useful
day-to-day.
Anyway, goodnight all.
Marshall
.
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