an illustrated book of bad arguments by ali almossawi

7/16/2015 AnIllustratedBookofBadArguments

https://bookofbadarguments.com/?view=allpages 1/32



Thistinyprintservesnopurpose,buttomakethisbookseemlikeanactualbook.Inprintedbooks,oneusuallyseesalargeblockof tinyprintonthe firstorsecondpage followedbyterms like2013.AllRightsReserved.Soandso.PrintedintheUnitedStatesofAmerica.Thepublishermayalsoincludeprosetodeterwouldbepirates.Nopartofthisbookmaybeusedorreproducedinanymannerwhatsoeverwithoutwrittenpermission.Thatistypicallyfollowedbyalineortwoaboutthepublisher,followedbyasequenceofnumbers.

Formoreinformation,pleasecontactJasperCollinsPublishers,99StMarksPlNewYork,NY94105.1213141516LP/SSRH10987654321

Butseriously,allyouneedtoknowisthatthisworkissharedunderaCreativeCommonsBYNClicense,whichmeansthatyoucanfreelyshareandadaptitfornoncommercialusewithattribution.

Artdirection:AliAlmossawi,Illustration:AlejandroGiraldo.

Ilovethisillustratedbookofbadarguments.Aflawlesscompendiumofflaws.

Prof.AliceRoberts,Anatomist,PresenteroftheBBCsTheIncredibleHumanJourney

A wonderfully digestible summary of the pitfalls and techniques of argumentation. I can'tthink of a better way to be taught or reintroduced to these fundamental notions of logical

discourse.Adelightfullittlebook.

AaronKoblin,CreativeDirectoroftheDataArtsteamatGoogle



Thisbook isaimedatnewcomers to the fieldof logicalreasoning,particularly thosewho, toborrow a phrase fromPascal, are somade that they understand best through visuals.selected a small set of common errors in reasoning and visualized them using memorableillustrationsthataresupplementedwithlotsofexamples.Thehopeisthatthereaderwilllearnfromthesepagessomeofthemostcommonpitfallsinargumentsandbeabletoidentifyandavoidtheminpractice.



Theliteratureonlogicandlogicalfallaciesiswideandexhaustive.Thiswork'snoveltyisinitsuseofillustrationstodescribeasmallsetofcommonerrorsinreasoningthatplaguealotofourpresentdiscourse.

TheillustrationsarepartlyinspiredbyallegoriessuchasOrwell'sAnimalFarmthehumorousnonsenseofworkssuchasLewisCarroll'sstoriesandpoems.thereisn'tanarrativethattiesthemtogethertheyarediscretescenes,connectedonlythroughstyleandtheme,whichbetteraffordsadaptabilityandreuse.Eachfallacyhasjustonepageofexposition,andsothetersenessoftheproseisintentional.

Reading about things that one should not do is actually a useful learning experience.book,OnWriting,StephenKingwrites:Onelearnsmostclearlywhatnottodobyreadingbadprose.He describes his experience of reading a particularly terrible novel as, the literaryequivalent of a smallpox vaccination [King]. ThemathematicianGeorgePlya is quoted ashavingsaid ina lectureonteachingthesubject that inadditiontounderstanding itwell,onemustalsoknowhowtomisunderstandit[Plya].Thisworkprimarily talksaboutthingsthatoneshouldnotdoinarguments.

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Foralookattheconverse,seeT.EdwardDamer'sbookonfaultyreasoning.1



Many years ago, I spent part of my time writing software specifications using firstorderpredicate logic. It was an intriguing way of reasoning about invariants using discretemathematics rather than the usual notationEnglish. It brought precision where there waspotentialambiguityandrigorwheretherewassomehandwaving.

During the same time, I perused a few books on propositional logic, both modern andmedieval, one of which was Robert Gula'sA Handbook of Logical Fallacies. Gula's bookremindedmeofalistofheuristicsthatIhadscribbleddowninanotebookadecadeagoabouthowtoarguetheyweretheresultofseveralyearsofarguingwithstrangersinonlineforumsandhadthingslike,trynottomakegeneralclaimsaboutthings.Thatisobvioustomenow,buttoaschoolboy,itwasanexcitingrealization.

Itquicklybecameevidentthatformalizingone'sreasoningcouldleadtousefulbenefitssuchasclarity of thought and expression, objectivity and greater confidence. The ability to analyzeargumentsalsohelpedprovideayardstickforknowingwhentowithdrawfromdiscussionsthatwouldmostlikelybefutile.

Issues and events that affect our lives and the societies we live, such as civil liberties andpresidentialelections,usuallycausepeopletodebatepoliciesandbeliefs.Byobservingsomeofthat discourse, one gets the feeling that a noticeable amount of it suffers from the

absenceofgoodreasoning.Theaimofsomeofthewritingonlogicistohelponerealizethetoolsandparadigmsthataffordgoodreasoningandhenceleadtomoreconstructivedebates.

Since persuasion is a function of not only logic, but other things aswell, it is helpful to becognizant of those things.Rhetoric likely tops the list, andprecepts such as the principle ofparsimonycometomind,asdoconceptssuchastheburdenofproofandwhereitliesinterestedreadermaywishtorefertothewideliteratureonthetopic.

In closing, the rules of logic are not laws of the natural world nor do they constitute all ofhumanreasoning.AsMarvinMinskyasserts,ordinarycommonsensereasoningisdifficult toexplainintermsoflogicalprinciples,asareanalogies,adding,Logicnomoreexplainshowwethinkthangrammarexplainshowwespeak[Minsky].Logicdoesnotgeneratenewtruths,butallowsonetoverifytheconsistencyandcoherenceofexistingchainsofthought.forthatreasonthatitprovesaneffectivetoolfortheanalysisandcommunicationofideasandarguments.

A.A.,SanFrancisco,July2013

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Thefirstprincipleisthatyoumustnotfoolyourselfandyouaretheeasiestpersontofool.

RichardP.Feynman



Informal Fallacy Red Herring Argument from Consequences

ArgumentfromConsequencesArguingfromconsequencesisspeakingfororagainstthetruthofastatementbyappealingtothe consequences of accepting or rejecting it. Just because a proposition leads to someunfavorableresultdoesnotmeanthatitisfalse.Similarly,justbecauseapropositionhasgoodconsequencesdoesnotallofasuddenmakeittrue.AsDavidHackettFischerputsit,itdoesnotfollow,thataqualitywhichattachestoaneffectistransferabletothecause.

In the caseofgoodconsequences, anargumentmayappeal toanaudience'shopes,whichattimestaketheformofwishfulthinking.Inthecaseofbadconsequences,suchanargumentmayinstead appeal to an audience's fears. For example, takeDostoevsky's line, If God does notexist, theneverythingispermitted.Discussionsofobjectivemoralityaside, theappealtotheapparentgrimconsequencesofapurelymaterialisticworldsaysnothingaboutwhetherornottheantecedentistrue.

One should keep in mind that such arguments are fallacious only when they deal withpropositions with objective truth values, and not when they deal with decisions or policies[Curtis],suchasapoliticianopposingtheraisingoftaxesforfearthatitwilladverselyimpactthelivesofconstituents,forexample.

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Informal Fallacy Red Herring Straw Man

StrawManIntentionallycaricaturingaperson'sargumentwiththeaimofattackingthecaricatureratherthan the actual argument is what is meant by putting up a straw man. Misrepresenting,misquoting, misconstruing and oversimplifying are all means by which one commits thisfallacy. A strawman argument is usually one that ismore absurd than the actual argument,making itaneasier target toattackandpossibly luringaperson towardsdefending themoreridiculousargumentratherthantheoriginalone.

For example,Myopponent is trying to convince you thatwe evolved frommonkeyswhowereswingingfromtreesatrulyludicrousclaim.Thisisclearlyamisrepresentationofwhatevolutionarybiologyclaims,whichistheideathathumansandchimpanzeessharedacommonancestor severalmillionyearsago.Misrepresenting the idea ismucheasier than refuting theevidenceforit.

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Informal Fallacy Red Herring Genetic Fallacy Appeal to Irrelevant Authority

AppealtoIrrelevantAuthorityAnappealtoauthorityisanappealtoone'ssenseofmodesty[Engel],whichistosay,anappealto the feeling that others aremoreknowledgeable.The overwhelmingmajority of the thingsthat we believe in, such as atoms and the solar system, are on reliable authority, as are allhistorical statements, to paraphrase C. S. Lewis. One may reasonably appeal to pertinentauthority,asscientistsandacademicstypicallydo.Anargumentbecomesfallaciouswhentheappeal is to an authoritywho is not an expert on the issue at hand. A similar appeal worthnoting is theappeal tovagueauthority,wherean idea isattributed toavaguecollective.Forexample,ProfessorsinGermanyshowedsuchandsuchtobetrue.

A typeof appeal to irrelevant authority is theappeal to ancientwisdom,where something isassumed to be true just because it was believed to be true some time ago. For example,Astrology was practiced by technologically advanced civilizations such as the AncientChinese.Therefore,itmustbetrue.Onemightalsoappealtoancientwisdomtosupportthingsthatareidiosyncratic,orthatmaychangewithtime.Forexample,Peopleusedtosleepforninehoursanightmanycenturiesago,thereforeweneedtosleepforthatlongthesedaysaswell.Thereareallsortsofreasonsthatmayhavecausedpeopletosleepforlongerperiodsoftimeinthepast.Thefactthattheydidprovidesnoevidencefortheargument.

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Informal Fallacy Ambiguity Equivocation2

EquivocationEquivocationexploitstheambiguityoflanguagebychangingthemeaningofawordduringthecourseofanargumentandusingthedifferentmeaningstosupportsomeconclusion.Awordwhosemeaning ismaintained throughoutanargument isdescribedasbeingusedunivocally.Considerthefollowingargument:Howcanyoubeagainstfaithwhenwetakeleapsoffaithall the time,with friendsandpotential spousesand investments?Here, themeaning of thewordfaithisshiftedfromaspiritualbeliefinacreatortoariskyundertaking.

Acommoninvocationofthisfallacyhappensindiscussionsofscienceandreligion,wherethewordwhymaybeusedinequivocalways.Inonecontext,itmaybeusedasawordthatseekscause,whichasithappensisthemaindriverofscience,andinanotheritmaybeusedasawordthatseekspurposeanddealswithmoralsandgaps,whichsciencemaywellnothaveanswersto.Forexample,onemayargue:Sciencecannottelluswhythingshappen.Whydoweexist?Whybemoral?Thus,weneedsomeothersourcetotelluswhythingshappen.

TheillustrationisbasedonanexchangebetweenAliceandtheWhiteQueeninLewisCarroll'sThroughtheLookingGlass.2

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Informal Fallacy Unwarranted Assumption False Dilemma3

FalseDilemmaAfalsedilemmaisanargumentthatpresentsasetoftwopossiblecategoriesandassumesthateverythinginthescopeofthatwhichisbeingdiscussedmustbeanelementofthatset.Ifoneofthose categories is rejected, then one has to accept the other. For example, In the war onfanaticism,therearenosidelinesyouareeitherwithusorwiththefanatics.Inreality,thereisathirdoption,onecouldverywellbeneutralandafourthoption,onemaybeagainstbothandevenafifthoption,onemayempathizewithelementsofboth.

InTheStrangestMan,itismentionedthatphysicistErnestRutherfordoncetoldhiscolleagueNielsBohraparableaboutamanwhoboughtaparrotfromastoreonlytoreturnitbecauseitdidn't talk.After several suchvisits, the storemanager eventually says: Oh, that's right!Youwantedaparrotthattalks.Pleaseforgiveme.Igaveyoutheparrotthatthinks.Now clearly,Rutherfordwasusing theparable to illustrate the genius of the silentDirac, thoughone canimaginehowsomeonemightusesuchalineofreasoningtosuggestthatapersoniseithersilentandathinkerortalkativeandanimbecile.

This fallacymayalsobe referred toas the fallacyof theexcludedmiddle, theblackandwhitefallacyorafalsedichotomy.3

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Informal Fallacy Causal Fallacy Not a Cause for a Cause

NotaCauseforaCauseThefallacyassumesacauseforaneventwherethereisnoevidencethatoneexists.Twoeventsmayoccuroneafter theotheror togetherbecause theyare correlated,byaccidentordue tosome other unknown event one cannot conclude that they are causally connected withoutevidence. The recent earthquake was due to people disobeying the king is not a goodargument.

Thefallacyhastwospecifictypes:afterthis,thereforebecauseofthisandwiththis,thereforebecauseofthis.Withtheformer,becauseaneventprecedesanother,itissaidtohavecausedit.Withthelatter,becauseaneventhappensatthesametimeasanother,itissaidtohavecausedit.Invariousdisciplines,thisisreferredtoasconfusingcorrelationwithcausation.

HereisanexampleparaphrasedfromcomedianStewartLee:Ican'tsaythatbecausein1976IdidadrawingofarobotandthenStarWarscameout,thentheymusthavecopiedtheideafromme.HereisanotheronethatIrecentlysawinanonlineforum:Theattackertookdowntherailwaycompany'swebsiteandwhenIcheckedthescheduleofarrivingtrains,whatdoyouknow,theywerealldelayed!What theposter failedtorealize is that those trainsrarelyarriveontime,andsowithoutanykindofscientificcontrol,theinferenceisunfounded.

4

As it turns out, eating chocolate and winning a Nobel Prize have been shown to be highlycorrelated,perhapsraisingthehopesofmanyachocolateeater.4

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Informal Fallacy Red Herring Emotional Appeal Appeal to Fear

AppealtoFearThefallacyplaysonthefearsofanaudiencebyimaginingascaryfuturethatwouldbeoftheirmaking if some proposition were accepted. Rather than provide evidence to show that aconclusionfollowsfromasetofpremisses,whichmayprovidealegitimatecauseforfear,suchargumentsrelyonrhetoric,threatsoroutrightlies.Forexample,Iaskallemployees tovoteformychosencandidateintheupcomingelections.Iftheothercandidatewins,hewillraisetaxesandmanyofyouwillloseyourjobs.

Here is another example, drawn from the novel, The Trial: You should give me all yourvaluables before the police get here. Theywill end up putting them in the storeroomandthingstendtogetlostinthestoreroom.Here,althoughtheargumentismorelikelyathreat,albeit a subtle one, an attempt is made at reasoning. Blatant threats or orders that do notattempttoprovideevidenceshouldnotbeconfusedwiththisfallacy,eveniftheyexploitone'ssenseoffear[Engel].

Anappealtofearmayproceedtodescribeasetofterrifyingeventsthatwouldoccurasaresultofacceptingaproposition,whichhasnoclearcausallinks,makingitreminiscentofaslipperyslope.Itmayalsoprovideoneandonlyonealternativetothepropositionbeingattacked,thatoftheattacker,inwhichcaseitwouldbereminiscentofafalsedilemma.

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Informal Fallacy Weak Analogy Unrepresentative Sample Hasty Generalization

HastyGeneralizationThisfallacy iscommittedwhenonegeneralizesfromasamplethat iseithertoosmallortoospecialtoberepresentativeofapopulation.Forexample,askingtenpeopleonthestreetwhattheythinkof thepresident'splantoreducethedeficitcan innowaybesaidtorepresentthesentimentoftheentirenation.

Although convenient, hasty generalizations can lead to costly and catastrophic results. Forinstance, itmay be argued that the engineering assumptions that led to the explosion of theAriane5duringitsfirstlaunchweretheresultofahastygeneralization:thesetoftestcasesthatwereusedfortheAriane4controllerwerenotbroadenoughtocoverthenecessarysetofusecases in the Ariane 5's controller. Signing off on such decisions typically comes down toengineers'andmanagers'abilitytoargue,hencetherelevanceofthisandsimilarexamplestoourdiscussionoflogicalfallacies.

HereisanotherexamplefromAlice'sAdventuresinWonderlandwhereAliceinfersthatsincesheisfloatinginabodyofwater,arailwaystation,andhencehelp,mustbecloseby:Alicehadbeentotheseasideonceinherlife,andhadcometothegeneralconclusion,thatwhereveryougo toon theEnglishcoastyou findanumberofbathingmachines in the sea, somechildrendigging in the sand with wooden spades, then a row of lodging houses, and behind them arailwaystation.[Carroll]

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Informal Fallacy Fallacy of Missing Data Appeal to Ignorance5

AppealtoIgnoranceSuchanargumentassumesapropositiontobetruesimplybecausethereisnoevidenceprovingthatitisnot.Hence,absenceofevidenceistakentomeanevidenceofabsence.Anexample,duetoCarlSagan:ThereisnocompellingevidencethatUFOsarenotvisitingtheEarththereforeUFOsexist.Similarly,whenwedidnotknowhowthepyramidswerebuilt,someconcludedthat,unlessprovenotherwise,theymusthavethereforebeenbuiltbyasupernaturalpower.Theburdenofproofalwayslieswiththepersonmakingaclaim.

Moreover,andasseveralothershaveputit,onemustaskwhatismorelikelyandwhatislesslikelybasedonevidencefrompastobservations.Isitmorelikelythatanobjectflyingthroughspace is amanmade artifact or a natural phenomenon, or is itmore likely that it is aliensvisitingfromanotherplanet?Sincewehavefrequentlyobservedtheformerandneverthelatter,it is thereforemorereasonable toconcludethatUFOsareunlikely tobealiensvisiting fromouterspace.

Aspecificformoftheappealtoignoranceistheargumentfrompersonalincredulity,whereaperson'sinabilitytoimaginesomethingleadstoabeliefthattheargumentbeingpresentedisfalse.Forexample,It is impossibleto imaginethatweactually landedamanonthemoon,therefore it never happened. Responses of this sort are sometimes wittily countered with,That'swhyyou'renotaphysicist.

TheillustrationisinspiredbyNeildeGrasseTyson'sresponsetoanaudiencemember'squestiononUFOs:youtu.be/NSJElZwEI8o.5

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Informal Fallacy Ambiguity Equivocation Redefinition No True Scotsman

NoTrueScotsmanAgeneralclaimmaysometimesbemadeaboutacategoryofthings.Whenfacedwithevidencechallenging that claim, rather than accepting or rejecting the evidence, such an argumentcountersthechallengebyarbitrarilyredefiningthecriteriaformembershipintothatcategory.

Forexample,onemaypositthatprogrammersarecreatureswithnosocialskills.If someonecomesalongandrepudiates thatclaimbysaying,ButJohnisaprogrammer,andhe isnotsocially awkward at all, it may provoke the response, Yes, but John isn't a trueprogrammer.Here,itisnotclearwhattheattributesofaprogrammerare,noristhecategoryofprogrammersasclearlydefinedasthecategoryof,say,peoplewithblueeyes.Theambiguityallowsthestubbornmindtoredefinethingsatwill.

ThefallacywascoinedbyAntonyFlewinhisbookThinkingaboutThinking.There,hegivesthe following example:Hamish is reading thenewspaper and comes across a story about anEnglishmanwhohascommittedaheinouscrime,towhichhereactsbysaying,NoScotsmanwould do such a thing. The next day, he comes across a story about a Scotsman who hascommittedanevenworsecrimeinsteadofamendinghisclaimaboutScotsmen,hereactsbysaying,NotrueScotsmanwoulddosuchathing.

6

Whenanattackermaliciouslyredefinesacategory,knowingwell thatbydoingso,heorsheisintentionallymisrepresentingit,theattackbecomesreminiscentofthestrawmanfallacy.6

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Informal Fallacy Red Herring Genetic Fallacy

GeneticFallacyAnargument'soriginsortheoriginsofthepersonmakingithavenoeffectwhatsoeverontheargument's validity. A genetic fallacy is committed when an argument is either devalued ordefendedsolelybecauseofitshistory.AsT.EdwardDamerpointsout,whenoneisemotionallyattachedtoanidea'sorigins,itisnotalwayseasytodisregardtheformerwhenevaluatingthelatter.

Consider the following argument,Of course he supports theunionworkers on strike he isafterallfromthesamevillage.Here,ratherthanevaluatingtheargumentbasedonitsmerits,itisdismissedbecausethepersonhappenstocomefromthesamevillageastheprotesters.Thatpiece of information is then used to infer that the person's argument is thereforeworthless.Hereisanotherexample:Asmenandwomenlivinginthe21stcentury,wecannotcontinuetoholdtheseBronzeAgebeliefs.Whynot,onemayask.ArewetodismissallideasthatoriginatedintheBronzeAgesimplybecausetheycameaboutinthattimeperiod?

Conversely,onemayalsoinvokethegeneticfallacyinapositivesense,bysaying,forexample,Jack'sviewsonartcannotbecontestedhecomesfromalonglineofeminentartists.Here,theevidenceusedfortheinferenceisaslackingasinthepreviousexamples.

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Informal Fallacy Red Herring Guilt by Association

GuiltbyAssociationGuiltbyassociationisdiscreditinganargumentforproposinganideathat issharedbysomesociallydemonizedindividualorgroup.Forexample,Myopponentiscallingforahealthcaresystemthatwouldresemblethatofsocialistcountries.Clearly,thatwouldbeunacceptable.Whether or not the proposed healthcare system resembles that of socialist countries has nobearingwhatsoeveronwhetheritisgoodorbaditisacompletenonsequitur.

Anothertypeofargument,whichhasbeenrepeatedadnauseaminsomesocieties,isthis:Wecannotletwomendrivecarsbecausepeopleingodlesscountrieslettheirwomendrivecars.Essentially, what this and previous examples try to argue is that some group of people isabsolutelyandcategoricallybad.Hence,sharingevenasingleattributewithsaidgroupwouldmakeoneamemberof it,whichwould thenbestowononeall theevilsassociatedwith thatgroup.

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Formal Fallacy Propositional Fallacy Affirming the Consequent

AffirmingtheConsequentOneofseveralvalidformsofargumentisknownasmodusponens(themodeofaffirmingbyaffirming)andtakesthefollowingform:IfAthenC,AhenceC.Moreformally:

AC,AC.

Here,wehavethreepropositions:twopremissesandaconclusion.A iscalled theantecedentandCtheconsequent.Forexample,Ifwaterisboilingatsealevel,thenitstemperatureisatleast100C.Thisglassofwaterisboilingatsealevelhenceitstemperatureisatleast100C.Suchanargumentisvalidinadditiontobeingsound.

Affirmingtheconsequentisaformalfallacythattakesthefollowingform:IfAthenC,ChenceA.

Theerroritmakesisinassumingthatiftheconsequentistrue,thentheantecedentmustalsobetrue,whichinrealityneednotbethecase.Forexample,Peoplewhogotouniversityaremore successful in life. John is successful hencehemust havegone touniversity. Clearly,John'ssuccesscouldbearesultofschooling,butitcouldalsobearesultofhisupbringing,orperhapshiseagernesstoovercomedifficultcircumstances.Moregenerally,onecannotsaythatbecause schooling implies success, that if one is successful, then one must have receivedschooling.

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Informal Fallacy Red Herring Genetic Fallacy Ad Hominem Appeal to Hypocrisy

AppealtoHypocrisyAlsoknownbyitsLatinname,tuquoque,meaningyoutoo, the fallacy involves counteringacharge with a charge, rather than addressing the issue being raised, with the intention ofdiverting attention away from the original argument. For example, John says, This man iswrongbecausehehasnointegrityjustaskhimwhyhewasfiredfromhislastjob,towhichJackreplies,Howaboutwe talkabout the fatbonusyou tookhome lastyeardespitehalfyourcompanybeingdownsized.Theappealtohypocrisymayalsobeinvokedwhenapersonattacks another because what he or she is arguing for conflicts with his or her past actions[Engel].

OnanepisodeofthetopicalBritishTVshow,HaveIGotNewsForYou,apanelistobjectedtoaprotest inLondonagainstcorporategreedbecauseof theprotesters'apparenthypocrisy,bypointingoutthatwhiletheyappeartobeagainstcapitalism,theycontinuetousesmartphonesandbuycoffee.Thatexcerptisavailablehere:youtu.be/8WvAkhWXNI.

Here is another example from Jason Reitman's movie, Thank You for Smoking (FoxSearchlightPictures,2005),whereatuquoqueladenexchangeisendedbythesmoothtalkingtobacco lobbyistNickNaylor: I'm just tickled by the idea of the gentleman fromVermontcallingmeahypocritewhenthissameman,inoneday,heldapressconferencewherehecalledfortheAmericantobaccofieldstobeslashedandburned,thenhejumpedonaprivatejetandflewdown toFarmAidwherehe rodea tractoronstageashebemoaned thedownfallof theAmericanfarmer.

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Informal Fallacy Not a Cause for a Cause Slippery Slope

SlipperySlopeA slippery slope attempts to discredit a proposition by arguing that its acceptance willundoubtedlyleadtoasequenceofevents,oneormoreofwhichareundesirable.Thoughitmaybe the case that the sequence of events may happen, each transition occurring with someprobability, this type of argument assumes that all transitions are inevitable, all the whileprovidingnoevidenceinsupportofthat.Thefallacyplaysonthefearsofanaudienceandisrelated to a number of other fallacies, such as the appeal to fear, the false dilemmaand theargumentfromconsequences.

Forexample,Weshouldn'tallowpeopleuncontrolledaccess to theInternet.Thenext thingyou know, they will be frequenting pornographic websites and, soon enough our entiremoral fabricwill disintegrateandwewill be reduced to animals.As is glaringly clear, noevidence is given, other than unfounded conjecture, that Internet access implies thedisintegration of a society's moral fabric, while also presupposing certain things abouttheconduct.

7

Theslipperyslopefallacydescribedhereisofacausaltype.7

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Informal Fallacy Red Herring Appeal to the Bandwagon

AppealtotheBandwagonAlsoknownastheappealtothepeople,suchanargumentusesthefactthatasizablenumberofpeople,orperhapsevenamajority,believeinsomethingasevidencethatitmustthereforebetrue.Someoftheargumentsthathaveimpededthewidespreadacceptanceofpioneeringideasareofthistype.Galileo,forexample,facedridiculefromhiscontemporariesforhissupportofthe Copernican model. More recently, Barry Marshall had to take the extreme measure ofdosinghimselfinordertoconvincethescientificcommunitythatpepticulcersmaybecausedbythebacteriumH.pylori,atheorythatwas,initially,widelydismissed.

Luringpeopleintoacceptingthatwhichispopularisamethodfrequentlyusedinadvertisingand politics. For example, All the cool kids use this hair gel be one of them. Althoughbecomingacoolkidisanenticingoffer, itdoesnothingtosupporttheimperativethatoneshould buy the advertised product. Politicians frequently use similar rhetoric to addmomentumtotheircampaignsandinfluencevoters.

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Informal Fallacy Red Herring Genetic Fallacy Ad Hominem8

AdHominemAnadhominemargumentisonethatattacksaperson'scharacterratherthanwhatheorsheissayingwiththeintentionofdivertingthediscussionanddiscreditingtheperson'sargument.Forexample,You'renotahistorianwhydon'tyousticktoyourownfield.Here,whetherornotthe person is a historian has no impact on themerit of their argument and does nothing tostrengthentheattacker'sposition.

This typeof personal attack is referred to as abusive adhominem.A second type, known ascircumstantial ad hominem, is any argument that attacks a person for cynical reasons, bymakingajudgmentabouttheirintentions.Forexample,Youdon'treallycareaboutloweringcrimeinthecity,you justwantpeople tovote foryou.Therearesituationswhereonemaylegitimatelybringintoquestionaperson'scharacterandintegrity,suchasduringatestimony.

TheillustrationisinspiredbyadiscussiononUsenetseveralyearsagoinwhichanoverzealousandstubbornprogrammerwasaparticipant.8

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Informal Fallacy Begging the Question Fallacy Circular Reasoning

CircularReasoningCircularreasoningisoneoffourtypesofargumentsknownasbeggingthequestion,[Damer]whereoneimplicitlyorexplicitlyassumestheconclusioninoneormoreofthepremisses.Incircular reasoning, a conclusion is either blatantly used as a premiss, or more often, it isrewordedtoappearasthoughitisadifferentpropositionwheninfactitisnot.For example,You'reutterlywrongbecauseyou'renotmakingany sense.Here, the two propositions areoneandthesamesincebeingwrongandnotmakinganysense,inthiscontext,meanthesamething.Theargumentissimplystating,Becauseofxthereforex,whichismeaningless.

Acircularargumentmayattimesrelyonunstatedpremisses,whichcanmakeitmoredifficulttodetect.HereisanexamplefromtheAustralianTVseries,PleaseLikeMe,whereoneofthecharacterscondemnstheother,anonbeliever, tohell, towhichheresponds,[That]doesn'tmakeanysense.It'slikeahippiethreateningtopunchyouinyouraura.Inthisexample,theunstated premiss is that there exists aGodwho sends a subset of people to hell.Hence, thepremissThereexistsaGodwhosendsnonbelieverstohellisusedtosupporttheconclusionThereexistsaGodwhosendsnonbelieverstohell.

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Informal Fallacy Unwarranted Assumption Composition and Division

CompositionandDivisionCompositionisinferringthatawholemusthaveaparticularattributebecauseitspartshappentohave thatattribute. Ifeverysheep ina flockhasamother, itdoesnot then followthat theflockhasamother,toparaphrasePeterMillican.Hereisanotherexample:Eachmoduleinthissoftwaresystemhasbeensubjectedtoasetofunittestsandhaspassedthemall.Therefore,whenthemodulesareintegrated,thesoftwaresystemwillnotviolateanyoftheinvariantsverifiedbythoseunittests.Therealityisthattheintegrationofindividualpartsintroducesnewcomplexitiestoasystemduetodependenciesthatmayinturnintroduceadditionalavenuesforpotentialfailure.

Division, conversely, is inferring that a partmust have some attribute because the whole towhichitbelongshappenstohavethatattribute.Forexample,Ourteamisunbeatable.Anyofourplayerswouldbeabletotakeonaplayerfromanyotherteamandoutshinehim.Whileitmaybetruethattheteamasawholeisunbeatable,onecannotusethatasevidencetoinferthateachofitsplayersisthusunbeatable.Ateam'ssuccessisclearlynotalwaysthesumoftheindividualskillsofitsplayers.

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Many years ago, I heard a professor introduce deductive arguments using a wonderfulmetaphor,describingthemaswatertightpipeswheretruthgoesinoneendandtruthcomesouttheotherend.Asithappens,thatwastheinspirationforthisbook'scover.endof thisbook, Ihope thatyou leavenotonlywithabetterappreciationof thebenefitsofwatertight arguments in validatingandexpandingknowledge,but alsoof the complexitiesofinductive argumentswhere probabilities come into play.With such arguments in particular,criticalthinkingprovesanindispensabletool.Ihopethatyoualsoleavewitharealizationofthedangersofflimsyargumentsandhowcommonplacetheyareinoureverydaylives.

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Proposition:Astatementthatiseithertrueorfalse,butnotboth.Forexample,largestcityinMassachusetts.

Premiss:Apropositionthatprovidessupporttoanargument'sconclusion.haveoneormorepremisses.Alsospelledpremise.

Argument:Asetofpropositionsaimedatpersuadingthroughreasoning.subsetofpropositions,calledpremisses,providessupportforsomeotherpropositioncalledtheconclusion.

Deductiveargument:Anargumentinwhichifthepremissesaretrue,thentheconclusionmustbetrue.Theconclusion issaid to followwith logicalnecessity fromthepremisses.example,Allmenaremortal.Socratesisaman.Therefore,Socrates ismortalargumentisintendedtobevalid,butofcoursemightnotbe.

Inductiveargument:Anargumentinwhichifthepremissesaretrue,thenitisprobablethatthe conclusion will also be true. The conclusion therefore does not follow with logicalnecessityfromthepremisses,butratherwithprobability.Forexample,thespeedoflightinavacuum,itis310 m/s.Therefore,thespeedoflightinavacuumisauniversalconstant.Inductiveargumentsusuallyproceedfromspecificinstancestothegeneral.

Inscience,oneusuallyproceedsinductivelyfromdatatolawstotheories,henceinductionisthefoundation ofmuch of science. Induction is typically taken tomean testing a proposition on asample,eitherbecauseitwouldbeimpracticalorimpossibletodootherwise.

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Logicalfallacy:Anerrorinreasoningthatresultsinaninvalidargument.Errorsarestrictlytodowiththereasoningusedtotransitionfromonepropositiontothenext,ratherthanwiththefacts.Putdifferently,an invalidargument foran issuedoesnotnecessarilymeanthat theissueisunreasonable.Logicalfallaciesareviolationsofoneormoreoftheprinciplesthatmakea good argument such as good structure, consistency, clarity, order, relevance andcompleteness.

Formalfallacy:Alogicalfallacywhoseformdoesnotconformtothegrammarandrulesofinferenceofalogicalcalculus.Theargument'svaliditycanbedeterminedjustbyanalyzingitsabstractstructurewithoutneedingtoevaluateitscontent.

Informalfallacy:Alogicalfallacythatisduetoitscontentandcontextratherthanitsform.Theerrorinreasoningoughttobeacommonlyinvokedonefortheargumenttobeconsideredaninformalfallacy.

Validity:Adeductiveargumentisvalidifitsconclusionlogicallyfollowsfromitspremisses.Otherwise, it issaidtobe invalid.Thedescriptorsvalid and invalid applyonly toargumentsandnottopropositions.

Soundness:Adeductiveargumentissoundifitisvalidanditspremissesaretrue.thoseconditionsdoesnothold,thentheargumentisunsound.Truthisdeterminedbylookingatwhether theargument'spremissesandconclusionsare inaccordancewith facts in therealworld.

Strength:Aninductiveargumentisstrongifinthecasethatitspremissesaretrue,thenitishighlyprobablethatitsconclusionisalsotrue.Otherwise,ifitisimprobablethatitsconclusionistrue,thenitissaidtobeweak.Inductiveargumentsarenottruthpreservingitisneverthecasethatatrueconclusionmustfollowfromtruepremisses.

Cogency:Aninductiveargumentiscogentifitisstrongandthepremissesareactuallytruethatis,inaccordancewithfacts.Otherwise,itissaidtobeuncogent.

Falsifiability: An attribute of a proposition or argument that allows it to be refuted, ordisproved, through observation or experiment. For example, the proposition,green, may be refuted by pointing to a leaf that is not green. Falsifiability is a sign of anargument'sstrength,ratherthanofitsweakness.

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[Aristotle]Aristotle,OnSophisticalRefutations,translatedbyW.A.Pickard,http://classics.mit.edu/Aristotle/sophist_refut.html

[Avicenna]Avicenna,TreatiseonLogic,translatedbyFarhangZabeeh,1971.

[Carroll]LewisCarroll,Alice'sAdventuresinWonderland,2008,http://www.gutenberg.org/files/11/11h/11h.htm

[Curtis]GaryN.Curtis,FallacyFiles,http://fallacyfiles.org

[Damer]T.EdwardDamer,AttackingFaultyReasoning:APracticalGuidetoFallacyFreeArguments(6thed),2005.

[Engel]S.MorrisEngel,WithGoodReason:AnIntroductiontoInformalFallacies,1999.

[Farmelo]GrahamFarmelo,TheStrangestMan:TheHiddenLifeofPaulDirac,MysticoftheAtom,2011.

[Fieser]JamesFieser,InternetEncyclopediaofPhilosophy,http://www.iep.utm.edu

[Firestein]StuartFirestein,Ignorance:HowitDrivesScience,2012.




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[Fischer]DavidHackettFischer,Historians'Fallacies:TowardaLogicofHistoricalThought,1970.

[Gula]RobertJ.Gula,Nonsense:AHandbookofLogicalFallacies,2002.

[Hamblin]C.L.Hamblin,Fallacies,1970.

[King]StephenKing,OnWriting,2000.

[Minsky]MarvinMinsky,TheSocietyofMind,1988.

[Plya]GeorgePlya,HowtoSolveIt:ANewAspectofMathematicalMethod,2004.

[Russell]BertrandRussell,TheProblemsofPhilosophy,1912,http://ditext.com/russell/russell.html

[Sagan]CarlSagan,TheDemonHauntedWorld:ScienceasaCandleintheDark,1995.

[Simanek]DonaldE.Simanek,UsesandMisusesofLogic,2002,http://www.lhup.edu/~dsimanek/philosop/logic.htm

[Smith]PeterSmith,AnIntroductiontoFormalLogic,2003.


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