- From: Henry Story <henry.story@bblfish.net>
- Date: Fri, 15 Apr 2005 10:49:34 +0200
- To: "Bill Kent" <billkent@bkent.net>
- Cc: 'SWIG' <semantic-web@w3.org>
On 14 Apr 2005, at 22:51, Bill Kent wrote:
> Hi-
>
> I don't know if this dialog is still going on, but I never did get any
> response to my email of 2/10/05, which is appended at the very end.
>
> In the meantime, I've run across an interesting passage in an article
> by Jim
> Holt entitled "Time Bandits", about Einstein and Godel, in the
> February 28,
> 2005 issue of The New Yorker. On page 83, he writes:
>
> <beginning of quote>
>
> It had been an article of faith that, armed with logic, mathematicians
> could
> in principle resolve any conundrum at all-that in mathematics, as it
> had
> been famously declared, there was no ignorabimus. Godel's theorems
> seemed to
> have shattered this ideal of complete knowledge.
>
> That was not the way Godel saw it. He believed he had shown that
> mathematics
> has a robust reality that transcends any system of logic. But logic,
> he was
> convinced, is not the only route to knowledge of this reality; we also
> have
> something like an extrasensory perception of it, which he called
> "mathematical intuition." It is this faculty of intuition that allows
> us to
> see, for example, that the formula saying "I am not provable" must be
> true,
> even though it defies proof within the system where it lives. Some
> thinkers
> (like the physicist Roger Penrose) have taken this theme further,
> maintaining that Godel's incompleteness theorems have profound
> implications
> for the nature of the human mind. Our mental powers, it is argued, must
> outstrip those of any computer, since a computer is just a logical
> system
> running on hardware, and our minds can arrive at truths that are
> beyond the
> reach of a logical system.
>
> <end of quote>
I can't answer this point in a short time, though it is a very
interesting
one, and would be more appropriately discussed on a philosophy forum. A
more
elaborate answer would involve the following points:
- restrictions have been placed on more recent formal systems that
have
taken Gödel's work into account
- Even though Logic can't solve all problems, that does not mean that
it
is not an excellent tool to solve a huge number of them
- fuzzy logics and modal logics need not be thought of as different
logics
but can well be seen as specialization of logics to certain domains
of
discourse. See David Lewis' "Counterfactuals" where he shows how
modal
logic can be expressed in simple first order logical terms. You
just need
to add quantification over possible worlds, introduce the notion of
possible
world similarity, and cross world identity. He also shows how to
deal with
problems of fuzziness in language, by defining the notion of a
mathematically
precise language and then defining natural languages as sets of
sets of such
languages. You can use that trick to deal with a huge range of
fuzziness issues.
- logic does not deny intuition in the least. Good
logicians/philosophers are
constantly calling upon our intuitions on various conceptual
issues. Their
aim is to help refine our concepts which at a certain level may
seem contradictory
in order to create more powerful conceptual structures. Not unlike
Einstein
reworking our notions of space time, thereby opening up worlds of
possibilities
unimaginable before.
- the logic of emotions has been a major preoccupation of analytical
philosophers
in the 1990ies. You may find it odd that emotions have a structure
or logic but
think about the following example:
you are walking down a dark alley. You hear some footsteps at a
certain distance
behind you, and you are worried. The steps get faster and you,
not being a
martial arts expert, feel defenseless and fearful. Suddenly a
voice shouts out
"coucou" and you realize it is your brother. The fear
disappears, and you turn around
with a smile.
This story illustrates very well how your knowledge about the
environment and your skills
shape your emotions. A martial arts expert would not have had fear
as he would have felt
comfortable that even at the last moment he would have been able to
turn the situation
to his advantage. He may even have been able to hear better the non
aggressive nature
of the steps.
The terms "would" "could" "knowledge" "skill" are all analyzable
using
modal logic. Understanding the nature of thought, its relation to
logic, and intuition
are all very important elements in correctly understanding the
behavior of people around
you.
>>>>>>
[snip]
>>>>>> Just a point of clarification about identity. (I thought the
>>>>>> example
>>>>>> is fun enough that it may be of interest)
>>>>>>
>>>>>> As we all know Madonna is a material girl, and she lives in a
>>>>>> material [snip]
>
> My curiosity has been aroused. What came after the [snip]?
Please check the semweb archive. [1] I have proposed a simple solution
[2]
and will provide a N3 formalization when I get time to do so. The trick
is simple to read up on mereology [3] and translate the mereological
rules into
N3.
In any case the madonna problem has some very good solutions.
>
> Thank you all for keeping me in the loop.
>
> Bill
>
>
> BTW: The Help Wanted notice on my web site is still open.
[1] http://lists.w3.org/Archives/Public/semantic-web/2005Feb/0062
[2] http://lists.w3.org/Archives/Public/semantic-web/2005Feb/0073
[3] http://plato.stanford.edu/entries/mereology/
Received on Monday, 18 April 2005 09:00:40 UTC