Love is a Fallacy谬论ppt课件

LoveisaFallacy Whatisafallacy Afallacyistheuseofpoor orinvalidreasoningfortheconstructionofanargument Itisalsousedtoreferto anargumentwhichappearstobecorrectbutisnot Anargumentinlogicpresentsevidenceinsupportofsomethesisorconclusion Anargumenthastwocomponents aconclusionandcertainpremises Theconclusionissaidtobedrawnorinferredfromthepremises Anargumentisdeductivelyvalidwhenitspremisesprovideevidencefortheconclusion Anargumentthatfailstobeconclusivelydeducedisinvalid itissaidtobefallacious Argument LogicFallacies 1 DictoSimpliciter 绝对判断 2 HastyGeneralization 轻率归纳 3 PostHoc 错误因果 4 ContradictoryPremises 矛盾前提 1 DictoSimpliciter Polly Isaidgently theargumentisafallacy Exerciseisgoodisanunqualifiedgeneralization Forinstance ifyouhaveheartdisease exerciseisbad notgood Manypeopleareorderedbytheirdoctorsnottoexercise Youmustqualifythegeneralization Youmustsayexerciseisusuallygood orexerciseisgoodformostpeople OtherwiseyouhavecommittedaDictoSimpliciter Doyousee 1 DictoSimpliciter 绝对判断 DictoSimpliciterisanargumentbasedonanunqualifiedgeneralization Theargumentappliesageneralruletoaparticularcaseinwhichsomespecialcircumstancesmaketheruleinapplicable Examples Womenareonaveragenotasstrongasmenandlessabletoperformwellpolitically Therefore womencan tpulltheirweightingovernmentwork 虽然女性确实在政界担任较少工作 但这不意味着女性群体中所有的人都是这样 JapanesewagedawartoChinese whichhadnothingtodowithhumanitybuteverythingtodowithaggression ThereforeeveryJapaneseisguiltyandshouldbecondemned 虽然日本侵华的邪恶战争任历历在目 但并不是所有的日本人都有罪 都应该受到谴责 2 HastyGeneralization NextwetakeupafallacycalledHastyGeneralization Listencarefully Youcan tspeakFrench PeteyBurchcan tspeakFrench ImustthereforeconcludethatnobodyattheUniversityofMinnesotacanspeakFrench Really saidPolly amazed Nobody Ihidmyexasperation Polly it safallacy Thegeneralizationisreachedtoohastily Therearetoofewinstancetosupportsuchaconclusion 2 HastyGeneralization 轻率归纳 Hastygeneralizationisafallacyinwhichaconclusionisnotlogicallyjustifiedbysufficientorunbiasedevidence Ahastygeneralizationalwaysproceedsfromtheparticulartothegeneral HastyGeneralization Itspattern XistrueforA XistrueforB XistrueforC XistrueforD Therefore XistrueforE F G etc Example Mikefailedbiologyexam Janefailedbiologyexam Mariafailedbiologyexam Therefore Iconcludethatmoststudentswhotakebiologyexamwillfailit Analysis Inunderstandingandcharacterizinggeneralsituations alogiciancannotnormallyexamineeverysingleexample However theexamplesusedininductivereasoningshouldbetypicaloftheproblemorsituationathand MaybeMike Jane andMariaareexceptionallypoorstudents Maybetheyweresickandmissedtoomanylectures Ifalogicianwantstomakethecasethatmoststudentswillfailbiologyexam sheshould a getaverylargesample atleastonelargerthanthreeor b ifthatisn tpossible shewillneedtogooutofhiswaytoprovetothereaderthatherthreesamplesaresomehowrepresentativeofthenorm 3 PostHoc Listentothis Let snottakeBillonourpicnic Everytimewetakeitoutwithus itrains Iknowsomebodyjustlikethat sheexclaimed Agirlbackhome EulaBecker hernameis Itneverfails Everysingletimewetakeheronapicnic Polly Isaidsharply it safallacy EulaBeckerdoesn tcausetherain Shehasnoconnectionwiththerain YouareguiltyofPostHocifyoublameEulaBecker 3 PostHoc 错误因果 PostHocisafallacyinwhichoneeventissaidtobethecauseofalatereventsimplybecauseitoccurredearlier PostHocisafallacywiththefollowingform 1 AoccursbeforeB 2 ThereforeAisthecauseofB Examples Joanisscratchedbyacatwhilevisitingherfriend Twodayslatershecomesdownwithafever Joanconcludesthatthecat sscratchmustbethecauseofherillness Mostyoungcriminalswatchviolentmoviesbeforetheycommittheircrimes obviously violentmoviesleadtojuveniledelinquency 甲事情发生在乙事情之前 这并不代表着先发生的甲事情就是后发生的乙事情的原因 4 ContradictoryPremises IfGodcandoanything canHemakeastonesoheavythatHewon tbeabletoliftit Ofcourse sherepliedpromptly ButifHecandoanything Hecanliftthestone Ipointedout Yeah shesaidthoughtfully Well thenIguessHecan tmakethestone ButHecandoanything Iremindedher Shescratchedherpretty emptyhead I mallconfused sheadmitted Ofcourseyouare Becausewhenthepremisesofanargumentcontradicteachother therecanbenoargument Ifthereisanirresistibleforce therecanbenoimmovableobject Ifthereisanimmovableobject therecanbenoirresistibleforce Getit 4 ContradictoryPremises 矛盾前提 ContradictoryPremisesisanargumentthatdrawsaconclusionfrominconsistentorincompatiblepremises Essentially apropositioniscontradictorywhenitassertsanddeniesthesamething Sometimesitisdifficulttodistinguishbetweenrealandapparentincompatiblepremises Let slookattheexamplebelow Afathersaidtohisson youcantrustnoone Analysis Thefatherwhoistryingtoconvincehischildthatnooneshouldbetrustedisobviouslymakinganexceptionofhimself Ifhereallyweremakingincompatibleclaims sinceyoushouldtrustnoone andyoushouldtrustme norationalconclusioncouldorshouldbedrawnbythechild However theincompatiblepremisesareonlyapparent thefatherhascarelesslyoverstatedthefirstpremise Ifhehadsaid Don ttrustmostpeople or Trustveryfewpeople or Don ttrustanyoneexceptme hewouldhavehadnotroubleavoidingthecontradiction THANKS