Being+Logical+-+A+Guide+to+Good+Thinking

BEINGLOGICALBeingLogicalAGUIDEtoGOODTHINKINGD.Q.MclnernyRANDOMHOUSEi^MMlNEWYORKCopyright©2004byD.Q.MclnernyAllrightsreservedunderInternationalandPan-AmericanCopyrightConventions.PublishedintheUnitedStatesbyRandomHouse,animprintofTheRandomHousePublishingGroup,adivisionofRandomHouse,Inc.,NewYork,andsimultaneouslyinCanadabyRandomHouseofCanadaLimited,Toronto.RANDOMHOUSEandcolophonareregisteredtrademarksofRandomHouse,Inc.LIBRARYOFCONGRESSCATALOGING-IN-PUBLICATIONDATAMclnerny,D.Q.Beinglogical:aguidetogoodthinking/D.Q.Mclnerny.p.cm.Includesbibliographicalreferences.ISBN1-4000-6171-71.Logic.2.Reasoning.3.Thoughtandthinking.I.Title.BC71.M372004160—dc222003058779TextdesignbyMaryA.WirthPrintedintheUnitedStatesofAmericaonacid-freepaperRandomHousewebsiteaddress:—DR.SAMUELJOHNSONPrefaceLOGICISABOUTclearandeffectivethinking.Itisasci­enceandanart.Thisbookisintendedtointroducereaderstotherudimentsofthescienceaswellastothebasicskillsassociatedwiththeart.Weallknowpeoplewhoareverybrightbutwhodonotalwaysshinewhenitcomestobeinglogical.Theyhavetheabilitytothinklogically—thatis,clearlyandeffectively—butthatabilitydoesnothabituallymanifestitself.Thelike­lihoodisthatithasneverbeenproperlydeveloped,pointingtoadeficiencyintheireducation.Indeed,logicistheverybackboneofatrueeducation,andyetitisseldomtaughtassuchinAmericanschools.Tomymind,logicisthemissingpieceoftheAmericaneducationalsystem,thesub­jectthatinformseveryothersubjectfromEnglishtohistorytoscienceandmath.Somereaders,especiallyifthisbookrepresentstheirfirstseriousencounterwithlogic,mightreactskittishlytowhatappearstobeanoverlytechnicalvocabulary,ortothe1XXPrefacesymbolicnotationthatlogicmakesfrequentuseof.Don'tbescaredoffbyinitialimpressions.IhavemadeaconcertedefforttopresentwhatevertechnicalmattersIdealwithhere(whichinanyeventarenotallthattrying)inassimpleanduncomplicatedawayaspossible.Atthesametime,how­ever,Ihavetriedtoavoidlapsingintothesimplistic.Adumbed-downlogicisnotlogicatall.Otherreadersmightbeputoffbywhattheyperceivetobeanemphasisupontheobvious.Ido,infact,placeagooddealofstressontheobvi­ousinthisbook,andthatisquitedeliberate.Inlogic,asinlife,itistheobviousthatmostoftenbearsemphasizing,be­causeitsoeasilyescapesournotice.IfIhavebelaboredcer­tainpoints,andregularlyoptedfortheexplicitovertheimplicit,itisbecauseIadheretothetime-honoredpeda­gogicprinciplethatitisalwayssafesttoassumeaslittleaspossible.Logic,takenasawhole,isawide,deep,andwonder­fullyvariedfield,andIwouldbepleasedifmyreaders,asaresultoftheirencounterwiththislittlebook,weremovedtobecomemorefamiliarwithit.However,myaimhereisverymodest.Thisisneitheratreatiseinlogicaltheorynoratext­bookinlogic—thoughIwouldnotbedisappointedtolearnthatitprovesusefulintheclassroom.Mygoverningpur­posewastowriteapracticalguidebook,presentingthebasicprinciplesoflogicinawaythatisaccessibletothosewhoareencounteringthesubjectforthefirsttime.BeingLogicalseekstoproducepractitioners,nottheoreticians—peopleforwhomknowingtheprinciplesoflogicisintheserviceofbeinglogical.PrefacexiInthehopeofbetterservingthepracticalendsofthebook,Ihaveadoptedasomewhatinformalstyle,oftenad­dressingthereaderdirectly,and,inthemannerofatutororcoach,sometimesassumingadistinctivelydirectivetone.Itreatlogicinfivestages,representedbythefivepartsofthebook,eachsuccessivestagebuildingupontheonethatpre­cededit.PartOneispreparatory,anddealswiththeproperframeofmindthatmustbeestablishediflogicalthinkingistotakeplaceatall.InPartsTwoandThree,theheartofthebook,wepassintotherealmoflogicproper.PartTwoex­plainsthefoundationaltruthsthatgovernlogicalthinking,whilePartThreefocusesonargument—thepublicexpres­sionoflogicalthinking.InPartFour,Idiscussattitudesandframesofmindthatpromoteillogicalthinking.Finally,PartFiveconcentratesontheparticularsofillogicalthinking—thefallacies.Afinalword,ofadmirationandappreciation,forasparklinglittlebookcalledTheElementsofStyle,byWilliamStrunk,Jr.,andE.B.White,whichwastheinspirationforBeingLogical.WhatIhavemanagedtoaccomplishhereisnomatchfortheuniqueachievementofStrunkandWhite,butIhopethatBeingLogicalmighttosomedegreesucceedindoingforthecauseofgoodthinkingwhatTheElementsofStylehasdoneforthatofgoodwriting.Myearnestwishisthatthisbookmaysucceedinconvincingitsreadersoftheintrinsicimportanceoflogic—andthatitengenderinthemanappreciationforthepricelesssatisfactionwhichin­evitablyaccompaniesthehappystateofbeinglogical.ContentsPrefaceixPARTONE—PREPARINGTHEMINDFORLOGIC1/.BeAttentive32.GettheFactsStraight43.IdeasandtheObjectsofIdeas74.BeMindfuloftheOriginsofIdeas75.MatchIdeastoFacts96.MatchWordstoIdeas117.EffectiveCommunication128.AvoidVagueandAmbiguousLanguage169.AvoidEvasiveLanguage1810.Truth19PARTTWO—THEBASICPRINCIPLESOFLOGIC231.FirstPrinciples252.RealGrayAreas,ManufacturedGrayAreas303.There'sanExplanationforEverything,Eventually32X111X1VContents4.DonVStopShortintheSearchforCauses335.DistinguishAmongCauses356.De