Article View: sci.logic
Article #1039Re: Why Some Sentences Lack Truth Values
From: R. Srinivasan
Date: Sun, 25 May 2008 07:44
Date: Sun, 25 May 2008 07:44
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5308 bytes
On May 20, 1:16 am, MoeBlee <jazzm...@hotmail.com> wrote: > On May 17, 8:08 am, "R. Srinivasan" <sradh...@in.ibm.com> wrote: > > > The basic philosophical ideas behind NAFL can be understood without > > delving into details. > > That's not adequate when NAFL is being used in a technical sense to > comment on details in other systems. > > > a NAFL theory cannot > > be defined as a mathematical object. > > Then I'm not very interested in NAFL. > > > You can only make the definition > > precise enough to be able to work within NAFL theories. There are > > solid reasons for this requirement. One of these is that Godel's > > incompleteness theorems cannot go through in NAFL, > > NAFL or NAFL theories are not even not just a formal theories, not a > theories even as ones not formally axiomatized; not theories, as you > say, as mathematical objects. Saying that incompleteness doesn't go > through for NAFL is like saying incompleteness doesn't go through for > my grandmother's diary. > As I said in a parallel post, patently false and there is no need whatsoever to formalize the notion of a NAFL theory as a mathematical object. E.g consider the NAFL version of Peano Arithmetic, call this NPA. It is true that NPA has infinitely many axioms, which may be generated by some rule. Here is a proposition about NPA: NPA is consistent if and only if its axioms are pairwise consistent (1) Now (1) will go through in NAFL, but not in classical logic. To see that (1) is true, we only need to know the rules by which the infinitely many axioms of NPA are generated. There is no need to formulate NPA as a mathematical object. That is your misconception. And as I noted earlier, note that no theorem of NPA will ever appeal to all of its axioms (the "coding" that enables Godel's incompleteness theorems to go through in classical PA is not permitted in NPA). (1) is metatheoretical statement *about* NPA and cannot be formalized within NPA. Take a simple analogy. Let us consider rational numbers of the form 1/ n, n=1, 2, .... We know that if we continue computing the numbers 1/n for n=1, 2, 3, ..., we will always find 1/n > 0 and we will never ever find an n for which 1/n is less than or equal to 0. To see that this assertion is true, one doesn't need to postulate the existence of the set of all rational numbers of the form 1/n. There is no commitment that our "checking" will ever be "completable". But still we know that if we continue to check, we are always going to find 1/n > 0. That very fact also guarantees that the process of computing these numbers one by one will never ever be "complete". It is a classical misconception that "all" natural numbers can be "exhausted" via the process of computing them one by one. NAFL computability theory does not accept that; any such computation will have to use infinite parallelism rather than a step-by-step procedure. The notion of consistency of a NAFL theory (say NPA) must be considered in some similar sense. If we continue to check the axioms of NPA pairwise, we will never ever find a pair that is inconsistent. This statement makes sense without any need whatsoever to formulate a NAFL theory as an object. In the distant future, when NAFL computability theory is fully developed, one might consider the possiblity of demonstrating the consistency of NPA by (an infinitely parallel) computation using NAFL principles (similar to quantum computation in some non-standard setting). Regards, RS
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X-Google-Thread: 10cc56,aa4b149b167b8a82 X-Google-Thread: 10ecd1,aa4b149b167b8a82 X-Google-Attributes: gid10cc56,gid10ecd1,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII Path: arc1-ca.pugleaf.net!g2news1.google.com!postnews.google.com!g16g2000pri.googlegroups.com!not-for-mail From: "R. Srinivasan" <sradhakr@in.ibm.com> Newsgroups: sci.logic,fa.analytic-philosophy Subject: Re: Why Some Sentences Lack Truth Values Date: Sun, 25 May 2008 00:44:36 -0700 (PDT) Organization: http://groups.google.com Lines: 72 Message-ID: <a42e85a9-0663-43d4-bee4-9e5ca622680f@g16g2000pri.googlegroups.com> References: <026f9bc3-c984-42e0-b4d0-8a109f4a36b4@k10g2000prm.googlegroups.com> <51aaf6a5-b6f6-49c2-8a4e-edfa4623b17a@i36g2000prf.googlegroups.com> <slrng2ou8a.8c4.cmenzel@philebus.tamu.edu> <167fb5fc-2bec-4a2b-bc61-803d48d9bb48@j33g2000pri.googlegroups.com> <f3c50e25-a16e-4125-b438-36127193a4dd@w1g2000prd.googlegroups.com> <179cef7d-fa73-4c01-a92a-0592a729ea7e@b5g2000pri.googlegroups.com> <b35ba30e-a2bf-40b2-b5b5-90a8773f3166@b5g2000pri.googlegroups.com> NNTP-Posting-Host: 221.128.233.176 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Trace: posting.google.com 1211701476 24945 127.0.0.1 (25 May 2008 07:44:36 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Sun, 25 May 2008 07:44:36 +0000 (UTC) Complaints-To: groups-abuse@google.com Injection-Info: g16g2000pri.googlegroups.com; posting-host=221.128.233.176; posting-account=ur107QkAAAAh8RGzP83dbOXW0aXSoPPQ User-Agent: G2/1.0 X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506; InfoPath.1),gzip(gfe),gzip(gfe)