Article View: sci.logic
Article #597Re: recursive definitions and paradoxes
From: David Gudeman
Date: Mon, 23 Nov 1992 20:22
Date: Mon, 23 Nov 1992 20:22
66 lines
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3795 bytes
In article <By6EKn.E5B@unx.sas.com> Gary Merrill writes: ] ]What I wonder mostly is whether what you are trying to do hasn't been ]done before, and with substantially more precision that your ideas ]currently have. For a long time, I thought that my views on the paradoxes were the common solution to the problem. So I was somewhat surprised a while ago to discover that I was considered a crank for refering to this solution. Since I don't really have a crank personality (you know, the type that assumes that they are so brilliant that they can single handedly solve problems that have eluded a large community for centuries, and that everyone who doesn't see their solution is stupid), I spent the next two years searching the literature for a reference to this. The solution was so obvious to me that I was certain it had been proposed decades ago, but I never found a direct reference. There are some indirect references like "the lambda calculus avoids the equivalent of Russel's paradox for functions", but no one seems to have applied the work in this area back to set theory. It still would not surprise me at all to find a complete developement of these ideas elsewhere, what surprises me is that there is so much resistence to the idea. I stumbled across the idea by imagining what would happen if you tried to implement self-containing sets on a computer and then creating Russell's paradoxical set. The result would be a stack overflow due to unbounded recursion. I thought, "Oh, Russell's paradox is caused by an ill-founded recursive definition." End of query. I didn't bother to explore the situation any more until I first realized that this is an unusual view. Then I spent some time looking for where my assumptions were going wrong so that I didn't have to have it pointed out to me by someone else, but I never found any reason to change my opinion. Especially given that most of the other solutions are demonstrably wrong. That is why I brought the idea up in this newsgroup. I was hoping that someone would either provide the references I could not find, or would be able to provide some sort of argument against my solution. So far, I've seen neither one. This discussion of terminology, while it may be necessary for communication, is not enlightening. No one has responeded in a substantive way to my contention that I can express Russell's paradox _without_ resorting to a universal set. Or to my contention that I can express the liar's paradox _without_ refering to sentences in a language. Or to my contention that all of the paradoxes can be unified with one explanation. These are the interesting points. The definitions are just a vehicle. ]This appears to be the introduction of yet more unexplained notation ]in order to explain the previous set of unexplained notation. No, I explained the previous notation before I introduced this extension. I gave explicit rules for introducing definitions and for using them. What more do you want? ]I take it that you don't want a definition to, by itself, imply ]the existence of the thing defined. Actually I would, if there were some way to make sure this does not lead to an inconsistency. I tried to accomplish this with the axiom of definition, but as someone else has pointed out, this makes the definition eliminable. -- David Gudeman gudeman@cs.arizona.edu
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arc1-ca.pugleaf.net!sparky!uunet!zaphod.mps.ohio-state.edu!sdd.hp.com!cs.utexas.edu!asuvax!ncar!noao!arizona!gudemanShow Full Headers
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Path: arc1-ca.pugleaf.net!sparky!uunet!zaphod.mps.ohio-state.edu!sdd.hp.com!cs.utexas.edu!asuvax!ncar!noao!arizona!gudeman From: gudeman@cs.arizona.edu (David Gudeman) Newsgroups: sci.logic Subject: Re: recursive definitions and paradoxes Message-ID: <26974@optima.cs.arizona.edu> Date: 23 Nov 92 20:22:51 GMT Organization: U of Arizona CS Dept, Tucson Lines: 66