CMENZEL@TAMLSR.BITNET (08/04/88)
Date: Sat, 30 Jul 88 18:09 EDT From: CMENZEL%TAMLSR.BITNET@MITVMA.MIT.EDU Subject: Self-reference and the Liar To: ailist@ai.ai.mit.edu X-Original-To: ailist@ai.ai.mit.edu, CMENZEL In AIList vol. 8 no. 29 Bruce Nevin provides the following analysis of the liar paradox arising from the sentence "This sentence is false": > The syntactic nexus of this and related paradoxes is that there is no > referent for the deictic phrase "this sentence" at the time when it is > uttered, nor even any basis for believing that the utterance in progress > will in fact be a sentence when (or if!) it does end. A sentence cannot > be legitimately referred to qua sentence until it is a sentence, that > is, until it is ended. Therefore, it cannot contain a legitimate > reference to itself qua sentence. There are type-token problems here, but never mind. If what Nevin says is right, then there is something semantically improper in general about referring to the sentence one is uttering; note there is nothing about the liar per se that appears in his analysis. If so, however, then there is something semantically improper about an utterance of "This sentence is in English", or again, "This sentence is grammatically well-formed." But both are wholly unproblematically, aren't they? Wouldn't any English speaker know what they meant? It won't do to trash respectable utterances like this to solve a puzzle. Nevin's analysis gets whatever plausibility it has by focusing on *English utterances*, playing on the fact that, in the utterance of a self-referential sentence, the term allegedly referring to the sentence being uttered has no proper referent at the time of the term's utterance, since the sentence yet isn't all the way of the speaker's mouth. But, first, it's just an accident that noun phrases usually come first in English sentences; if they came last, then an utterance of the liar or one of the other self-referential sentences above would be an utterance of a complete sentence at the time of the utterance of the term referring to it, and hence the term would have a referent after all. Surely a good solution to the liar can't depend on anything so contingent as word order in English. Second, the liar paradox arises just as robustly for inscriptions, where the ephemeral character of utterances has no part. About these, though, Nevin's analysis has nothing to say. A proper solution must handle both cases. Recommended reading: R. L. Martin, {\it Recent Essays on Truth and the Liar Paradox}, Oxford, 1984. J. Barwise and J. Etchemendy, {\it The Liar: An Essay on Truth and Circularity}, Oxford, 1987. ---Chris Menzel Dept. of Philosophy/Knowledge Based Systems Lab Texas A&M University BITNET: cmenzel@tamlsr ARPANET: chris.menzel@lsr.tamu.edu
bwk@MITRE-BEDFORD.ARPA (Barry W. Kort) (08/07/88)
Path: linus!mbunix!bwk From: Barry W. Kort <bwk@mitre-bedford.ARPA> Newsgroups: comp.ai.digest Subject: Re: Self-reference and the Liar Summary: Can someone advise me on the advisability of this advice? Date: Fri, 5 Aug 88 17:33 EDT References: <19880803191843.7.NICK@HOWARD-JOHNSONS.LCS.MIT.EDU> Sender: news@linus.UUCP Reply-To: Kort <bwk@mbunix> Organization: Neurotic Netware, Dendrite Faults, NV Lines: 11 While we are having fun with self-referential sentences, perhaps we can have a go at this one: My advice to you is: Take no advice from me, including this piece. (At least the self referential part comes at the end, so that the listener has the whole sentence before parsing the deictic phrase, "this piece".) --Barry Kort