Logic of Fiction and Logic in Computer Science.ppt

LogicofFictionandLogicinComputerScience ChayuntMathonDepartmentofPhilosophy ChulalongkornUniversityThailand Fictions FictionalDiscourseFictiveDiscourseMetafictiveDiscourseTransitiveDiscourse TheoriesofFictionOntologicalAnalysisFictive operatorAnalysisPretense Imagination andMakeBelieveAnalysis FictionalDiscourse WoodsandAlward 2004 thoughthatthebelowaspectsoffictionareaxiomofna vetheoriesoffictionalityorourpre theoreticintuitionsregardingfictions Referenceispossibletofictionalbeingseventhoughtheydonotexit A Somesentencesaboutfictionalbeingsandeventsaretrue B Someinferenceaboutfictionalbeingsandeventsarecorrect C Thesethreefactsarenamepossible inacentralway byvirtueofthecreativeauthorityofauthorsoffiction Indeed theprimaryandoriginatingcriterionoftruthforfictionalsentencesistheauthor ssayso D Thesethreefactsarenamepossible inacentralway byvirtueofthecreativeauthorityofauthorsoffiction Indeed theprimaryandoriginatingcriterionoftruthforfictionalsentencesistheauthor ssayso E Itispossibleforafictionaltruthtomakereferencetorealthings Forexample SherlockHolmeslivedinLondon istrueandreferstotheactualcapitalcityofEngland OntologicalView Thisviewbelievesthatsentencesoffictionalandnon fictionaldiscoursehavethesamelogicalform butadistinctrangeofentitiesserveasthesemanticvaluesoffictionalandnon fictionalexpressions Theexemplarsare Qusasi actualistMeinongeanaccountsofthereferentsoffictionalnames Parsons 1975 and 1980 and Routley 1979 andCf Castaneda 1979 and Zalta 1983 TheversionofParsons correlatedwitheachnon emptysetofpropertiesadistinct specificobject existentandnon existent Fictionalobjectsareasubclassoftheclassofnon existentobjects Theyaretheobjectscorrelatedwithsetsofthefollowingsort wherexisafictionalobject x theobjectcorrelatedwith p accordingtotherelevantbodyofliterature xhasp Anexampleofthisschemeis p accordingtotheConanDoylestories SherlockHomeshasp Theconsequenceofsuchtreatisthat fictionalobjectscanentertoasentenceorthelikeandmakeittohavetruth value true Fictive OperatorAnalysis Thisviewbelievesthatsentencesoffictionalandnon fictionaldiscoursehavedifferentlogicalform Thesentencesoffictionaldiscourseareanalyzedintermoftacitorexplicitfictiveoperator Eachoftheapproachdiffersininterpretationoffictiveoperator ButtheirgeneralschemeorlogicalformisItistrue in tthat Wheretisfictionaltextand isfictionalsentence Forexample Itistrue in the Holmes storiesthatSherlockHolmeswasadetective Theexemplarsare Possibleworldanalyses Plantinga 1974 and Kaplan 1973 and Gabriel 1979 and Lewis 1983 TheversionofLewis truththeoryofthefictionaldiscourseis Asentenceoftheform Itistrue in tthat istrueiff istrueateveryworldwheretistoldatknownfactratherthanfiction Forexample Itistrue in the Holmes storiesthatSherlockHolmeswasadetective istruejustincaseatallpossibleworldsinwhichtheHolmesstoriesaretoldasknownfact theoccupantoftheHolmes roleisdetective Fictionalworldanalyses Howell 1979 and Pavel 1986 and Woltersdorff 1980 Simply fictionalworldsareworldsoffiction buttheyneednotbeconsistent evenneednotbecomplete Suchanalysesinterpretfictiveoperatoras Itistrue in tthat is actually truejustincase istrueatallofthefictionalworldsdeterminedbyt Non referential substitutional quantificationalaccounts Woods 1974 TheversionofWoods truththeoryofthefictionaldiscourseis Asentenceoftheform Itistrue in tthat istruejustincaseeither 1 occursintor 2 canbederivedfromsentencesthatoccurintthroughrepeatedapplicationoffictional inferencerule Propositionalattitudeapproaches Curries 1990 Briefly Currieswouldmadethematefictiveclaim Itistrue in tthat tobeanalyzedas Thefictionalauthoroftbelievesthat Whereas believe istheattitudeandfictionalauthoristhesubjectoftheattitudeCuurieschoosesrespectively ImaginativeAnalyses Thisgroupofviewsisanalyzedintermofsomekindofimaginativeactivities Accordingtothiskindofanalyses storytellersdonotassertthesentencestheyutter nordoreadersbelievethesentencestheyencounter theyget involvedinthestory incertainway Authorialpretenseanalyses Searl 1975 TheversionofSearl struththeoryofthefictionaldiscourseis Authorsdonotassertsentencestheyutter theypretendtodoso andpartofthispretenseinvolvespretendingtorefertorealindividuals inthecaseofthesentencescontainfictionalnames Inthismanner authorscreatefictionalcharactersandevents Whencriticsorreaderssaythat theyreallyrefertothefictionalentityin theydosobecauseofthesharedpretense Reader appreciatormake believeanalyses Walton 1990 AccordingtotheversionofWalton gamesofmake believearerule governedactivities Suchrulesprescribethatparticularpropositionsbeimagined Thesearethefictionaltruthsofthegame Apropinagameofmake believeisanobjectthat invirtueoftherulesofthegame generatesfictionaltruths Hereishistheory Asentenceoftheform Itistrue in tthatS istrueifffictiontissuchthatonewhoengagesinpretenseofkindKinagameauthorizedforitmakesitfictionalofherselfthatshespeakstrulyForexample itistrue in TheHoundoftheBaskervillesthatHolmeswasadetective hastobeparaphrasedas TheHoundoftheBaskervillesissuchthatonewhoengagesinpretenseofkindKinagameauthorizedforittomakesitfictionalofherselfthatshespeakstruly NatureofFictions Afictionisamade upstory Scholes Robert 1991 ElementofLiterature There snoone right waytoreadapieceoffiction Therearemanygoodways Thisdoesnotmeanthatanyone sreadingofapieceoffictionisequaltoanyoneelse s Therearebetterandworsereading dependingonhowwellreaderscanattunethemselvestothestory onhowcarefullytheyhavelookedatthelanguage becomeawareofthetone understoodthetheme noticepatternsofimagery and ingeneral becomequiteandreallylistenedtoaseparatehumanbeing Butgivenequalattentionandsensitivitytoastory therearemanylegitimateapproaches Clayton JohnJ 2000 TheHeathIntroductiontoFiction StructureofFormallogicalSystem Grammar formalLanguage symbolsDeductiveApparatus axiom s RulesofInference ProofTheorySemantics Interpretationsofformallanguage HistoricalsematicsapproachofLogicofFiction We intuitively canvaluateametafictivepropositiontobeTRUEDenyingtheObjectualInterpretationofClassicalLogic onlyFALSEvaluecanbegivenforametafictiveproposition TherelevantsemanticsisordinaryModel TheoreticAmetafictivepropositioncanbeTRUEbecauseofanaspectofCorrespondenceTheoryofTruth thestorysaysoortheauthorsayso HistoricalsystematicapproachtotheLogicofFiction Woods John 1974 TheLogicofFiction PhilosophicalSoundingofDeviantLogic Nossum Rolf 2003 AContextualApproachtotheLogicofFiction LNAI2680 Woods JohnandPeterAlward 2004 TheLogicofFiction InGabbay D M ed HandbookofPhilosophicalLogic LogicofFictionvs logicsincomputerscience Logicincomputerscience topicswherelogicisappliedtocomputerscienceandartificialintelligence logichasimportantroleinsomeareaofcomputerscienceingeneralandAIinparticular Unconcernedlogics BooleanLogic FuzzyLogic QuantumLogic etc Concernedlogics CommonSenseLogicism includingnarrativeunderstanding AI JohnMcCarthy TheDefaultbasedlogics kindsofNonmonotonicLogics BeliefRevision AI Closed worldreasoning Databaseofcomputerscience RationalPlanning Woods JohnandPeterAlward 2004 TheLogicofFiction TaketheordinaryModel TheoreticSemantics YetInProofTheory proposed1 default Reiter 1980 Makinson 1993 asGenericproposition ThedefaultthatHolmeshasaskinisderivedfromthegenericpropositionthathumanshaveskins Holmesisahuman 2 Implicatures Grice 1989 Levinson 2000 asspeaker scommonknowledge Monotonic NonmonotonicLogics MonotonicLogic Aristotelianlogic Classicallogic dealonlywithpatternsofinferencethatholdwithoutexception NonmonotonicLogics Itisreasonabletoignoreoutlandishpossibilities Defaultbasedlogic Toignoreoutlandishpossibilitiesistohavedefault s ManipulatesomeDefaultRule forexampleGeneralform Inthepresenceof A1 An andintheabsenceof B1 Bn concludeC Normaldefaultform Generalform Inthepresenceof A1 An andintheabsenceof C concludeC Recall Clayton JohnJ 2000 TheHeathIntroductiontoFiction There snoone right waytoreadapieceoffiction Therearemanygoodways Thisdoesnotmeanthatanyone sreadingofapieceoffictionisequaltoanyoneelse s Therearebetterandworsereading dependingonhowwellreadersca