**From:** Lee Corbin (*lcorbin@rawbw.com*)

**Date:** Thu Jun 26 2008 - 23:04:51 MDT

**Next message:**Lee Corbin: "Re: [sl4] Evolutionary Explanation: Why It Wants Out"**Previous message:**Lee Corbin: "Re: [sl4] Evolutionary Explanation: Why It Wants Out"**In reply to:**Stuart Armstrong: "Re: [sl4] Re: More silly but friendly ideas"**Next in thread:**John K Clark: "Re: [sl4] Re: More silly but friendly ideas"**Reply:**John K Clark: "Re: [sl4] Re: More silly but friendly ideas"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ] [ attachment ]

Stuart writes

*>> As I said before, using Gödel and Turing and making an entirely
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*>> reasonable analogy between axioms and goals we can conclude that there
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*>> are some things a fixed goal mind can never accomplish, and we can
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*>> predict that we can NOT predict just what all those imposable tasks are.
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*>
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*> Godel and Turing are overused in analogies (the class of statements
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*> they deal with is a narrow one). But I don't see at all analogy
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*> between goals and axioms....
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Oh, thank you very much! Gödel's theorem has by now, I estimate

overtaken Einstein's relativity theories in incidence of flagrant misuse.

People need to keep in mind at least these three things:

1) The Gödel Incompleteness theorem of 1931 applies *only* to

(a) theories that have a certain amount of built-in arithmetic

(b) theories that are first order, in the sense that only finitary

reasoning may be used. (For example, Gentzen proved

in 1936 using transfinite numerals that arithmetic is consistent

http://en.wikipedia.org/wiki/Gentzen's_consistency_proof ,

and it's doubtful that first order is even strong enough to

capture the famous sentence "critics admire only one

another"---you need second order logic for that and

for much more in order to formalize our ordinary thinking,

if even second order is sufficient)

2) That for all we know the following systems are both complete

and consistent: (i) The Bible (ii) Shakespeare's Understanding

Of Human Nature (iii) Ayn Rand's Axioms for Everything.

3) In 1930, Gödel proved his *Completeness* theorem, showing

that first order logic (without that axiomatized arithmetical

component!) is both sound (anything you prove really is true)

and complete (if it's true, you can prove it).

So it is just hideously wrong to throw Gödel's theorem around as

in the sentence you quoted. In his marvelous, rather challenging

though entirely elementary, and very thorough little book "Gödel's

Theorem: An Incomplete Guide to Its Use and Abuse", Torkel

Franzen even demolishes Penrose's and Chaitin's loose positions.

*> Random example of a fixed goal institution: a bank (or a company)
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*> dedicated, with single mindness, only to maximising legal profits.
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*> I've never heard it said that its single goal creates any godel-type
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*> problems. What would they be like?
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Great example.

Lee

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