建构第一人称信念逻辑的一致性难题fly的第三人称单数
slay什么意思中文StudiesinLogic,V ol2,No.2(2009):30-52
aplusPit:1674—3202(2009)一02—0030—23 TheDifficultiesofConstructingaConsistent
First—personDoxasticLogic
ThomasBenda
InstituteofPhilosophyofMind,Y angMingUniversity
*************.tw
Abstract.Thestudyofdoxastictheoriesisinterestingbecautherebyaformajtheoryof enitieswithoutclearexistenceandidentityconditionscanbeestablished.Plausiblefornlal systemswhichhavebeenpropod,however,turnouttobeinconsistentduetoavariantofthe famousKnower'sParadox.InthisPaDer,aforlllalsystemformodelingfirst—personbeliefis constructed.BelieffromaninnerperspectiveiStaken.sonobeliefagentjsconsidered.andit isarguedthatbeliefbackgroundsaretobeaddedthatplaymantic.epistemicandpragmatic r61es.Theconstructedsystemisaconrvativeextensionofstandardfirst—orderlogic.which
mwx什么意思usquotation,Itsaxiomsandrulesarecomparativelyweak.indeedtooweakcObeadequate. yetitisshownthattheyresultagaininaninconsistency.Hencethatnodefinabletofbeliefsis found.Exploringremediesto1ifttheinconsistencyrevealsthatintheprentdoxastictheory. andpossiblyinanyotherfirst—persondoxastictheory.eachtofbeliefsthatisfiniteand definableisincompleteinthenthatjtdoesnotcoverbeliefsweactuallyhave.
1.Outlineofalogicofbeliefs
1.1Motiveandscope
Itissaidthatlogicisabouttruthandinference.Weaimtoknowunderwhich conditionspropositionsaretrueandhowwecaninferfromtruepropositionsfurther truepropositions.Thuslogicconcernsourreasoning.Reasoning,inturn,isamental activity,whichisconcernedwiththetaskofgettingmeaningsandthusinferences
becau you live
correct.Henceitemsnottobeoutofplacetomodelourreasoningbyanintentional
logic,inthesimplestca,byalogicofbelief.
0newouldbuildsuchalogicofbeliefonafoundationofclassicallogic.The threatofcircularityofsuchanapproa
chmaybedeflectedbymaintainingthatthere isanimmutableclassica1bivalentcoreof1ogicwhichisadequateforhowwethink ofsimpleformalentities.Everythingbeyondthatisbestcapturedbyanintentional
1ogicwhichreflectsourwayofreasoning. Arelatedmotiveforttingupalogicofbeliefsisthefollowing.Accordingto manyscholars,ifweknowthemeaningofastatement.wehavethewherewithalto iudgeonitstruth.Intheworldofmathematics,meaningssimplycoincidewithrefer- encesandare—at1eastthoughttobe.clear.PathologicalcaslikethefamousLiarare Received2008—06.22RevisionReceived2008.10—2O
slideunlockThomasBenda/TheDifficultiesofConstructingaConsistentFirst—personDoxasticLogic3l
usuallyignored.Classicalbivalentlogicisanadequatetoolforthoclear—cutcas. Still,ourdailyreasoningisrifewithambiguitiesofmeaningand,conquently,of truthconditions.Non—formalentitiesareindeterminate.Theyaremadedeterminate onlybyconventionswhichworkwellinpractice,butareadhocinnature.Muchwork hasbeendoneintheareasoflogicandphilosophyoflanguagetoclarifytheworkings ofalogicoftalkingaboutn
on—formalentities.Inthelightofthementa1characterof reasoning,apossible,ifnotwidelyadopted,approachistotakeaninternalistposition whichviewsnon—specifically.asobjects ofbelief.Non.forma1entitiesarethereforeplausiblybesttreatedbyalogicofbelief, moreprecily,ofbelieffromaninnerperspective,whichwebrieflyandcatchilycall first—personbelief.morning是什么意思
Themeritsofsuchanapproachwill
thelogicoffirst—personbeliefcertainlyiskrater
notbediscusdhere.Afterall,studying
aworthysubjectonitsown.Theprent
topicisratherthefollowing:Giventhatwefindalogicoffirst.personbeliefuful,
howcanitbeconstructedinthefaceofknowntechnicaldifhculties?Along—term desideratumisalogicoffirst—personbeliefwhichisadequate—inaninforma1n. lyasking.canweformalizefirst—personbelief, suchthatthereisadefinabletofbeliefswhicharerelatedtoeachotherinaroughly rationalwayandmoreorle
sscoverwhatisntialtoourmentalnature? Accordingly.theprentscopewillroughlybeasfollows.Wearenotconcerned desiresandfears.Beliefin turnwillberestrictedtobeliefthatispropositional,thatpresupposlanguage.As alreadystated.weconsiderbelieffromaninnerperspectiveratherthanbyanobjec—riveaccountofexternallyvisiblepersonalattitudes.Thus.actsofbeliefasrtionfall outsidetheprentscope.Inthesamevein,physicallimitationsofabeliever'sbrain shallplaynor61e,sinceweareconcernedwithlogicratherthanphysicalsituations. Wetakebeliefsasgivenanddonotconsiderhowtheycomeaboutorarerevid. Erroneousbeliefispermittedandtheproblemhowerroneousbeliefmergeisnot dealtwithsincetruthvaluesofntences"Ibelievethat…"areconsideredrather thentruthvaluesofrespectivethat—claus.Also,wedonotexplicitlydealwiththe admittedlyinterestingproblemofdegreesofbelief. Hencewearenotgoingtodiscusstokensofbeliefasrtionsorformations ofbeliefoccurrencesinthemind,whonatureisunclearanyway,butbeliefsas typeswhichcontributetocharacterizingamind.Oursubjectwillbeaphysically idealizedpropositionalattitudeof-inprivate—intellectuallyhonestbelieffromafirst—personperspective.W
eassumethatsuchfirst—personbeliefexists.Again,theprent topicisnottodiscussthevalidityofthisclaim,buttolookathowweareableto formalizeitssubject.
32StudiesinLogic,V o1.2,No.2(2009)
1.2Formalizingfirst-personbelief
Wefirstnoteanobviousdistinction.Merebeliefsaredifferentfromknowledge inthattheydonotimplytruthnorneedjustification.Therefore,adoxasticlogic, incontrasttoanepistemiclogic.candowithouttheoremswhichstatethatbeliefof anypropositionimpliesthatpropositiontohold.Later,ananalogueoftheKnower's
paradoxwillprentdifficultiesforobtainingaconsistentdoxasticlogic,butwewill becarefulnottoconflatebeliefandknowledge.
Commonly,beliefsareformalizedasthird—personbeliefs,thatis,asbinaryrela. tionsbetweenbeliefagentsandbeliefcontents.Boththeiroccurrenceandtheirrelata aregiveninapubliclanguage.Objectiveconditionsandparameters,liketimestamps ofbeliefsareoftenincorporatedinformaltreatmentsofbeliefs.Thereby.beliefin—stanceslookformallysimil
artospeechacts,Itwould,however,beaconfusionto equateascriptionsofsuchbeliefinstancestobeliefreports,whicharenotourprent subject.V erbalbeliefasrtionsmaygrammaticallyuthefirstperson.However. thefirstpersonthereisnomorethananindexthatisresolvedaccordingtocontext andinfactviewedfromoutside.Evenbeliefinstancesthemlvesarenotourcon—cern.Assaidabove.theprentemphasisisOilbeliefsratherthanspatiotemporal beliefinstances,or,inananalogytocommonmetaphysicalterms,onbelieftypes ratherthanbelieftokens. Beliefsarementalstatesandthusnaturallyareheldfromafirst—personper- spective.Bydefinition,first—personstatesarenotcommunicable,soanyattemptto understandbeliefsscientificallywillbetakenfromanouter,third—personperspective. Indeed,thefirst—personperspectivelooksinscrutable,evenmysterious,mainlydueto theproblemsofqualiaandofcontentacquisition,simplyspeaking,theproblemof howsomecodingactuallyhasmeaning.Makingthefirst—personperspectivethepoint ofviewforinvestigatingthemindriskssteeringawayfromreasonable.scientificdis, cour.Intentionalmenta1statesofprentinterest,however.allowforanobjective. communicablediscussion,sincequaliaarenottouchedandtheacquisitionofcontent istakenforgranted.Atthesametime,forthepurpoofformalization,weoughtto beawareofdifferencesbetw
eeninner.first—personandouter.third—personperspec—tivesofintentiona1mentalstatesandtakethemintoaccount.guidedbythefoilowing briefc0nsideratiOns.
notionofbeliefsastypesratherthantokens.Infallibility—fromaninnerperspective—offirst—personbeliefswarrantsourdisregardfortheircorrectness.WewilImerely ,prop0sitiona11y,inconsistentbeliefsandnotadmitinconsistent backgrounds,whicharetobeintroducedbelow.Furthermorefirst—personbeliefsare notcompleteinthenthat.givenacertainbeliefcontent.beliefofeitheritor itsnegationareatheoremoftheirformalization.Afteral1.weareinpracticeoften ThomasBenda/TheDifficultiesofConstructingaConsistentFirst—personDoxasticLogic33 enoughagnosticaboutaquestionwithoutfeelingadeficiencyindoingso.
sonorSecondly.first—personbeliefisladenwithadifficultyofitsown.Whilethird—personbeliefjsviewedfromoutsideanditsincompletenessisnaturallyassumed. first—personbeliefpurportstogiveacompletesubjectivepictureoftheworld,so, tobeadequate.ithastoencompas
stheentirediscursivementalworldofourfirst—personbeliever.Thissoundstrivialandtautologica1.butinfactwillpoamajor challenge,aswillbecomeapparentfurtherbelow.
Thenagain,returningtoprivacyoffirst—personbelief,itsformalizationissim—Dlerthanaformalizationofthird.personbelief.Wlefirstlookatthird—personbeliefs. Theyaretakentobepropositionsandthereforeusuallyformalizedasntences,simi—lartocommonspeech.Y etmanyobiectsmentionedinbeliefs.1ikeintentionalobjects ingeneral,arenotdere,thatis.theirexistenceandextensionalityarenotassured.A commonexampleforpossible1ackofexistenceareobiectsoftheverb"tolookfor".
awel1.wornexamplefor1ackofextensionalityaretheMorningStarandtheEvening Star.TheusualwaytoremoveexistencepresuppOsitiOnsandrequirementsofexten. sionalityofmentionedobjectsistoenclothentencesinwhichtheyarementioned inquotes.Accordingly,beliefsintheprentlogicalsystemwillbequotedntences. Statementsofbeliefswillthenhaveapredicateastheirmainsymbolratherthana ntentionaloperator.Placesofthebeliefpredicatearedere,sincetheyarelanguage expresslons.
Merequotingofbeliefcontents,ofcour,doesnotresolvetheproblemoffind—ingandproperlyapplyingexistenceandidentityconditionsofmentionedobjects.At
addictive