FOM: Question grown from Friedman talks
Martin Davis
martin at eipye.com
Mon Feb 5 14:20:12 EST 2001
At 07:18 PM 2/3/01 -0500, Harvey Friedman wrote:
>I also stand by what I said in my previous FOM posting about the before the
>fact look and feel of indications that independence may be present - as in
>the situation with set theoretic problems like CH.
>
>However, I will say that if you allow natural adjustments to the
>literature, then all bets are off. That hedged belief is not irrational.
>But the literature taken literally - extremely unlikely.
Obviously, the intuition of someone who has made the kind of contributions
that Harvey has should not be lightly dismissed.
Nevertheless, this is how things have seemed to me: We know by G\"odel that
for any system of axioms for (say) set theory, there are Pi-0-1 sentences
independent of those axioms. We also know that there are significant open
questions of this form that have resisted strenuous efforts at their
resolution. Now, a priori, this may be because the right elementary tools
have not yet been found (as in the case of FLT for so many years), or it
may be because one is dealing with assertions that require methods going
beyond PA or even ZFC. How is one to decide? Does the fact that FLT
eventually succumbed to attack by elementary methods in any way imply that
the same will be true for, say, RH? If so, I don't see the reason.
One can imagine a completeness theorem. One would specify some criterion of
simplicity perhaps based on complexity of expression and then prove that
every true Pi-0-1 sentence that satisfies that criterion is provable in
ZFC. That would shut me up - especially if RH and Goldbach's conjecture met
the criterion. But absent such a theorem or at least some heuristic
evidence for such a theorem, I remain agnostic.
Martin
Martin Davis
Visiting Scholar UC Berkeley
Professor Emeritus, NYU
martin at eipye.com
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