Formallogicfallacy
Formallogicfallacyreferstothefallacyoflogicthatdoesnotfollowtherulesofformallogicreasoningforreasoning,deduction,andargumentation:
Negationoftheantecedentfallacy
Typicalform:"IfAisthenB;notA;thereforenotB."
Example:"Ifitisabird,thenitwilleventuallydie;manisnotabird;oldmanWillnotdie."Thisisamisuseofthebluntsyllogism.Thecorrectformofthebluntsyllogismshouldbe:"IfAisthenB;A;thereforeB."
Affirmingthefallacyofthesubsequentpart
Typicalform:"IfAisthenB;CisB;ThereforeCisA;"
Example:"Ifitisfrieddoughsticks,thenitisdelicious;breadisdelicious;thereforebreadisfrieddoughsticks."Thisisalsoamisuseofthebluntsyllogism.
Falsedilemma
Typicalform:"AorBorC;notA;thereforeB."
Thisisamisuseoftheselectivesyllogism.Theformoftheselectivesyllogism:"AorB;notA;thereforeB."Thecascadeisthisform:"P1orP2orP3...orPn;notP2andnotP3...andnotPn;ThereforeP1."InthewordsofHolmes:"Whenallotherpossibilitiesareeliminatedandoneisleft,itisthetruth,nomatterhowimpossibleitseems."
Thisfallacyiscalledafalsedilemma,becausesophistsoftenexpressinthisform:"supportsweetsorsupportsaltyfood;youdonotsupportsweets;thereforeyousupportsaltyfood."Sophistsdeliberatelyput"neutral"intheirexpressions.Thisoptiondisappears,creatingtheillusionofselectivesyllogism.Itisworthnotingthatsomepeopletendtoclassifyfalsedilemmaasthefallacyofinformallogic.
Thefallacyofinformallogic
Thefallacyofinformallogicisessentiallythefallacyofpremiseerrors.Thisreferstologicalfallaciescausedbyreasoning,deduction,andargumentationbasedonwrongpremises,suchasnotadmittingthattheobjectiveworldexistsindependentlyofconsciousness.
Foraninference,itmusthaveitspremiseandinferenceform.
Inthegeneralthinkingofhumanbeings,thepremiseisoftenunclear,andthewrongconclusionwillbedrawnduetosomewrongpremises.
Appealtoignorance
Thepremiseoferror:todeterminethatathingiscorrectonlybecauseithasnotbeenprovenwrong;ortoconcludethatathingiswrong,onlyBecauseithasnotbeenprovencorrect.
Forexample,thelogicofmanyconspiracytheoristsisthis:Youcannotfalsifymytheory,somytheoryiscorrect,andreligioustheoryisatypicalexample.
CircularArgument
Alsoknownas"expectedreason"and"beggingmagic".Thisistousehypothesistoprovethelogicalfallacyofthehypothesis.Thepremiseoftheerrorhereistheassumptionitself.
Typicalform:"IfPisthenQ,ifQisthenR,ifRisthenP;supposeP;thereforeP."
Example:"XXsaysthatGodexists"XX"isthewordofGod,so"XX"isdefinitelynotwrong;thereforeGodexists."
Ofcourse,whensophistryusescircularargument,theywillgoaroundabigcircle.Makesitlooksflawless.
Whenitcomestocircularargumentation,letmementionthecirculardefinitionbytheway.Arealexample,theacademiccirclesinthepast(nineteenthcentury)definedthekilogramas"themassofaliterofwateratstandardatmosphericpressure",whilethestandardatmosphericpressurewasdefinedas101325Pa,andthepressureunitPawasdefinedas"Newtonpersquaremeter”(N/(m^2)),andthedefinitionoftheunitofforceNewtonis“theforcethatcausesanobjectwithamassofonekilogramtoproduceanaccelerationofonemeterpersecondsquared”(kg·m/(s^2)),whichcreatesacirculardefinition.Later,inordertoavoidthecirculardefinition,thekilogramwaschangedtousethemassoftheinternationaloriginalkilogramtodefineit.
Thelandslidefallacy
Thepremiseoftheerroristhat"possibility"equals"inevitability"ormagnifiescertainrelatedfactors,whichwillnotleadtochangesinresults.
Sophistswhousetheslipperyslopefallacyoftenusealongseriesofcascadinginferences.Manyoftheseinferencesareonlyprobabilistic(orevenanegligiblysmallprobability),andthesophistrydeliberatelysaidthatitisinevitable,soonethingcanfinally"reason"toalmostunrelatedresults..
Example:Xiaohongopposesgaymarriagebecauseshethinksthatifweallowgaymarriage,thensomepeoplewillwanttomarryatableorchair.Xiaohongcommittedthefallacyofslipperyslope.
Various"upgradesontheline"alsooftenusetheslipperyslopefallacy.
Takingpartialgeneralizations
Thepremiseoftheerroris:acertainpropertyofanindividualisauniversalpropertyofthegroupcontainingtheindividual.
Example:"ADutchisaliar,soallDutchareliars."
Example:"Oneofmytheoriesiscorrect,soallofmyThetheoriesarecorrect."
Clusterfallacy
Alsoknownastotalbias,thisisacommonmistakewhenanalyzingstatisticaldata.Thepremiseoftheerroristhatthefallacybelievesthatfromtheuniversalnatureofthegroup,itcanbeinferredthatanyindividualinthegroupmusthavethisnature.
Example:"Saudisaregenerallyrich,soeverySaudiisrich."
Example:"ThepercapitaincomeoftheUnitedStatesishigherthanthatofChina,soanyAmericanIncomeishigherthanthatofanyChinese."
Appealtoanalogy
Analogyissuitableforelaboration,explanationandconjecture.
Thecorrectpremiseisthattwothingswithacertain"commonality"thatmakesense,havecommonalityatthelevelofargumentation.
Generallyspeaking,peoplethinkthatonlytwothingswhosecommonalityisnot"largeenough"atthelevelthatneedstobedemonstrated,ortwothingswhosecommonalityliesoutsidethelevelthatneedstobeargued,canbedemonstratedbyanalogy.Itisaninvalidargument.
Example:"Dogsandhumansarebothmammals,andeatinghumanfleshisagainstmorals,soeatingdogmeatisagainstmorals."(Thecommonalitybetweenhumansanddogsisinbiology.Notinhumanmorality.)
Infact,fromarigorouslogicalpointofview,theso-called"sufficientlylargecommonality"isactuallyimpossibletomeasure,andtheresultsobtainedarenotlogicallyinevitable.Sinceitisnotinevitable,italsolosesthebasicmeaningoflogicandargumentation.Logicallyspeaking,onlywhenthetwoarecompletelyequalcananinferencesimilartotheanalogyargumentbemade.Fromitspremise,thisargumentismeaningless.
Appealtothepublic
Alsoknownas"bandfloats",itisalogicalfallacythatusesherdeffecttodemonstrate.Toputitbluntly,appealingtothepublicisonlyapersuasivemethod,notanargumentationmethod.Truthhasnothingtodowiththeamountofsupport.
Thetypicalformisalsothepremiseoftheerror:"Everyoneislikethis,sothismustnotbewrong."
Example:"Therearemanysmokers,sosmokingisnotharmfultoyourhealth.”
Appealtosubjectiveemotion
Thisisactuallythemostcommonfallacyofinformallogic.
Inthefallacyofappealingtosubjectiveemotions,itisoftenpresupposedthat"themotivatedbehaviorisappropriate"isthefalsepremise.Infact,thecriteriaforjudgingtheappropriatenessofbehaviorareoftenbasedonsomecomprehensiverationalresults.Foraperson,motivationcanalsobedividedintolargeandsmall,foramotivatedbehavior,thereisalsoarationalwayornot.Whetherabehaviorisappropriateornotisnotonlyjudgedbytheperson.
Oneofitscommonapplicationsis"Aslongasitisrighttopraisethemotherland",thisisoftenusedasthewrongpremiseofthetheoryofculturalhegemony.
Whenapersonlovessomething,heoftenthinksitisbeautifulorevenperfect,andmaypraiseit.Thisisapurelyemotionalimpulse.Ifapersonistrulypatriotic,thegreatermotivationshouldbetodosomethingthatisgoodforthecountry,anditshouldberationallyconsideredwhatkindofbehaviorisgoodforthecountry,soastoavoidsomeuselessorharmfulactionsanddosomethingreallyuseful.thing.
Anotherformofappealingtosubjectiveemotionsis"empathy",suchas"Ifyouaretheparentofthevictim,wouldyoustillthinkthatitiswrongtosentenceYaoJiaxintodeath?"Isitsentencedhere?Thestandardofthedeathpenaltyshouldnotbedeterminedbythesubjectiveemotionsofthevictim’sparents.
Anothervariantofitis"thesameforyou",suchas"IfyousitinFangBinxing'sposition,youwillalso'buildawall',soFangBinxingisrighttobuildawall."Inthesameway,thestandardforjudgingrightorwronghereshouldnotbedeterminedbythesubjectiveemotionofthepersonsittinginthisposition.
Thereisalsoalogicalfallacythatusesthecompassionoftheaudiencetodemonstrate.Thisismoreameansofpropaganda.
Typicalform:"BecauseAisverypitiful,sowhatAdidisnotwrong."
Example:"BecauseXiaoZhang'sfamilyisverypoor,soXiaoZhangengravedfakeofficialseals.Thereisnothingwrongwithmedicalexpenses."
Similarly,thestandardforjudgingrightorwronghereshouldnotbedeterminedbyXiaoZhang’ssubjectiveemotions,andotherrationalmeanscanalsobeusedtoachieveitsgoals.
AppealtoAuthority
Youusethepointofviewofanauthorityfigure/organizationtoreplaceapowerfulargument.
Toproveapointofview,itisnotenoughtoextractotherpeople’spointsofview.Atleastonemustknowtheauthoritativepointofviewmentioned.Becauseauthorityfigures/organizationscanalsomakemistakes,itisimpossibletounconditionallyassumerationality.Ofcourse,theopinionofanauthorityfigure/organizationmayberight,soitisnotjustbecausetheotherpartyhasusedthefallacyofappealingtoauthoritytoconcludethatthispointofviewisdefinitelywrong.
Example:"Thetheoryofevolutioniscorrect,becauseawell-knownsingersupportsthetheoryofevolution."
Irrelevantfallacy
Alsoknownasdistortingthetopic,evadingthetopic,andchangingthetopic.Conceptorredherring.Itisafallacythatdistortstheobjectofargumentandshiftsthefocusofdiscussion.Sophistsoftenusethistofishintroubledwaters.Infact,thebasistoprovethestolenthesiscanprovethewrongpremiseoftheoriginalthesis.
Therearemanytypicalformsofthisfallacy,butonlyoneisgivenbelow.
Oneofthetypicalforms:"IfAthenB,ifCthenD;BecauseC,soB."(BandDareoftenveryconfusing,sosophistscanusethistochangetheirposts.)
Example:"Ifyouliketoeat'RedFuji',youliketoeatapples;ifyouliketodrink'MasterKongAppleJuice',youliketodrinkapplejuice;youliketodrink'MasterKongAppleJuice',Soyouliketoeatapples.
Personalattacksarealsoanirrelevantfallacy.Attackingtheopponent’spersonality,motivation,attitude,status,class,situation,etc.cannotbeusedtoproveyourownarguments.
>Example:"Youareanemployeeofanoilcompany,ofcourseyouhavetoclaimthatglobalwarmingisfake"
The"scarecrow"thatoftenappearsindebatesisalsoafallacy.
TheFallacyofThisLater
Alsoknownaspost-eventattribution,falsecausation.Thepremiseoftheerroris:justbecauseeventAhappenedbeforeeventB,itcanbeconcludedthateventAisthecauseofeventB.
Example:"Abutterflyflappeditswingsatnineo'clock,andatyphoongeneratedinthePacificatteno'clock,sothebutterflyflappeditswingswasthecauseofthetyphoon."
Therearealsosomesophistrymethodsforinvalidproofstousethe"obscuremethod"intheproofprocesstohideacertainwrongpremiseanddrawthewrongconclusion.
Example:Proof1isthegreatest"Assumethatthelargestpositiveintegerisnot1,buta,witha>1;a>1>0,andaispositive,soa*a>aisobtainedfroma>1;Buta*aisstillapositiveinteger,butthereisnopositiveintegergreaterthana,whichiscontradictory;therefore,thelargestpositiveintegeris1."(Leaveittoyoutofindoutthe"obscuremethod".)
Logicalfallacyisagreatenemyofdebate,butagoodfriendofsophistry.Aslongaswedefendourbrainwithlogicalthinking,wecanletLogicalfallaciesandsophistshavenowheretohide,thuscreatingaworldofrationaldebate.