语义学 Saeed教科书 的课件

12020/2/23MajorIssuesfordiscussionModel-TheoreticalSemanticsTranslatingEnglishintoaLogicalMetalanguageTheSemanticsoftheLogicalMetalanguageCheckingtheTruthValueofSentencesIntensionalityWordMeaning:MeaningPostulates22020/2/23IntroductionThislabelisusuallyusedforafamilyofdenotationaltheorieswhichuselogicinsemanticanalysis.Othernameswhichfocusonparticularaspectsorversionsofthisapproachinclude:truth-conditionalsemantics,model-theoreticsemantics,MontagueGrammar.Thereisinmyopinionnoimportanttheoreticaldifferencebetweennaturallanguagesandtheartificiallanguagesoflogicians:indeed,Iconsideritpossibletocomprehendthesyntaxandsemanticsofbothkindsoflanguagewithinasingle,naturalandmathematicallyprecisetheory(Montague1974:222,citedinCann1993:2)32020/2/23Reviewofthetwophilosophicalapproachestomeaning:RepresentationalTheory(概念论)---ForsemanticistslikeJackendoffsemanticsanalysisinvolvesdiscoveringtheconceptualstructurewhichunderlieslanguage.Forsuchlinguiststhesearchformeaningisthesearchformentalrepresentations.DenotationalTheory(外延论)---thereisadirectrelationbetweenlanguageandtherealityitrepresents.TheperspectiveofFormalSemanticsisthat:--Aprimaryfunctionoflanguageisthatitallowsustotalkabouttheworldaroundus,--Whencommunicating,weuselanguagetodescribe,ormodel,factsandsituations.--Understandingthemeaningofanutteranceisbeingabletomatchitwiththesituationitdescribes.Hencethesearchformeaning,isthesearchforhowthesymbolsoflanguagerelatetoreality.Formalsemanticistsemploythecorrespondencetheoryoftruth:i.e.anutteranceeitherdescribesasituation,andthereforetrueofthatsituation(asuccessfulmatchbetweentheutteranceandthesituation),ornot,inwhichcaseitisfalse(anunsuccessfulmatch).Therearenoalmostsornearlysinthisapproach42020/2/23AdvantagesofFormalSemantics1)Itenablessemanticiststoimporteconomy(precision)andformalityofthetraditionaldisciplineoflogicandthebenefitsofthelongstruggletoestablishmathematicsandlogiconcommonprinciples.Logic,asapotentialsemanticmetalanguage,hastheimportantadvantageofprecision.2)Itescapetheproblemofcircularity,i.e.whenweuseanothersetofsymbols,usu.,language,tointerpretEnglish,weneedtogivethatlanguageasemantics.Man[HUMAN][Adult][MALE].Theaimofadenotationalapproachistoseektoconnectlanguagetotheworld.3)(lessobvious)denotationalapproachesallowustoseemoreclearlytheconnectionbetweenhumanlanguagesandthesimplersignssystemsofotherprimateslikemonkeys,baboonsandchimpanzees,becauseitispossiblethatthestartingpointofhumanlanguageswasthebasicmatchingbetweenasymbolandentitiesintheecvironment.Disadvantages--highlytechnicalandformalizedapproach,steepimmersionintomathematicalformulae--againsthumanism,thestudyof‘subjectivity’--atendencytoformularize‘pragmaticstudies’,controversial52020/2/23Model-TheoreticalSemantics(模型-理论语义学)Muchoftheinvestigationoflogicandnaturallanguagesemanticshasbeenconductedbyphilosophers,logiciansandmathematicians,e.g.GottlobFrege(logicianandmathematician):predicatelogicAlfredTarski(logician):notionoftruthRichardMontague(logician):MontagueGrammarAmodel--aformalstructurerepresentinglinguisticallyrelevantaspectsofasituationModel-TheoreticalSemanticsBasedontheworkofA.Tarskiandothermodel-theoreticsemantics,aconceptofsemanticinterpretationinformal-logicallanguagesdevelopedbylogiciansforlogicalsemanticswhichpermitsconditionsof‘truth’and‘satifisfaction’tobedescribedrecursively(递归性的）.Animportantbasicprincipleisthestrictdistinctionbetweenan(formal)objectlanguage,tobesemanticallyinterpreted,andametalanguage,inwhichsemanticpredicateslike‘false’or‘true’areintroduced(objectlanguagevsmetalanguage)62020/2/23Threestages:ThesemanticanalysisofthisMontagueapproachconsistsofthreestages1)AtranslationfromanaturallanguagelikeEnglishintoalogicallanguage(anexpressioninauniversalmetalanguage)whosesyntaxandsemanticsareexplicitlydefined.Onesuchmetalanguageispredicatelogic.Propositionallogic2）Theestablishmentofamathematicalmodelofthesituationsthatthelanguagedescribes.3）Asetofproceduresforcheckingthemappingbetweentheexpressionsinthelogicallanguageandthemodeledsituations.Essentiallythesealgorithms(算法或规则系统）checkwhethertheexpressionsaretrueorfalseofthemodeledsituations.Eachofthesethreestagescanthrowlightuponthesemanticcapabilitiesofnaturallanguages.72020/2/23Stage1:Atranslationfromanaturallanguageintoalogicallanguagepredicatelogic(谓词逻辑)Formula:asubject–predicatestructureFirst:representthepredicatebyacapitalpredicateletter,isasleep:Asmokes:SSecond:representthesubjectargumentbyalowercaseletter(usuallychosenfromatotandcalledanindividualconstant)Mulliganisasleep:AmBillsmokes:Sbwecanusevariablesforthesubjectunidentified,lowercaseletters(w,x,y,z)xisasleep:Axysmokes:SyBillresemblesEddie:RbeLibbyadoresMorgan:Alm.82020/2/23FatimaprefersBilltoHenry:PfbhCarrick,whoisamillionaire,isasocialist:Mc∧ScEmileisacatthatdoesnotpurr:Ce∧-PeJeanadmiresRobert,whoisagangsterAjr∧Gr92020/2/23propositionallogic(命题逻辑).Peterdoesn’tsmoke–SpPetersmokesandKatedrinks.Sp∧DkIfBilldrinks,Jennygetsangry.Db→AjJaneadmiresRobertwhoisanastronautAjr∧Arwecanrepresentcomplexsentencescontainin