Logos(英语修辞与写作lecture 4)

Logos:LogicalAppeals.Logosappealstopatterns,conventions,andmodesofreasoningthattheaudiencefindsconvincingandpersuasive(CovinoandJolliffe17).Inmakingdecisionsaboutthebestwaytouselogos,thewritermustanswerthreequestions:Whatdowebelieve,think,orfeelincommon?Arethepremises,orevidence,fortheargumentjustandappropriate?andDoestheproperconclusionfollowfromtheassumptionsofthepremisesandwhatwouldpreventtheaudiencefromacceptingtheconclusion?(CovinoandJolliffe17).Inanynonviolentcampaigntherearefourbasicsteps:1)Collectionofthefactstodeterminewhetherinjusticesarealive.2)Negotiation.3)Self-purificationand4)Directaction.WehavegonethroughallofthesestepsinBirmingham.Therecanbenogainsayingofthefactthatracialinjusticeengulfsthiscommunity.BirminghamisprobablythemostthoroughlysegregatedcityintheUnitedStates.Itsuglyrecordofpolicebrutalityisknownineverysectionofthiscountry.ItsunjusttreatmentofNegroesinthecourtsisanotoriousreality.TherehavebeenmoreunsolvedbombingsofNegrohomesandchurchesinBirminghamthananycityinthisnation.Thesearethehard,brutalandunbelievablefacts.Onthebasisoftheseconditions,Negroleaderssoughttonegotiatewiththecityfathers.Butthepoliticalleadersconsistentlyrefusedtoengageingoodfaithnegotiation.MartinLutherKing,Jr.'sLetterfromBirminghamJail.Therearetwogeneralwaysofreasoning,ofgeneratingalogicalappeal:induction(归纳)anddeduction（推理）.Inductionisthemethodofreasoningfromaparttoawhole,fromparticularstogenerals,orfromtheindividualtotheuniversal.Deduction,theinversetoinduction,isthemethodofreasoningfromgeneralstoparticularsandisthemostcommonformofreasoninginargument.Withdeductivelogic,theconclusionisanecessaryconsequenceofthepremises,basedonrulespertainingtovalidarguments.Themostcommontypeofdeductivelogicisasyllogism【逻】推论式,三段论(法),whichrepresentsdeductivereasoninginapatternconsistingof:amajorpremise,aminorpremise,andaconclusion.ThehypotheticalsyllogismMajorpremise:IfP,thenQIfP,thenQMinorpremise:PNotQConclusion:ThereforeQThereforenotPExample:Ifthelinesofapoemdonotrhyme,thepoemmaybecalledblankverse;asthispoemisrhymeless,youmaycallitblankverse.Theeither-orsyllogismMajorpremise:EitherAorB(notboth)EitherAorBMinorpremise:ANotAConclusion:ThereforenotBThereforeBExample:Wecouldhavedriventhereortakenataxi.Unfortunatelyourcarbrokedownthatday,andsowewenttherebytaxi.ThecategoricalsyllogismMajorpremise:AllM’sareP’sMinorpremise:SisanMConclusion:ThereforeSisaPExample:Allmenaremortalcreatures.Socratesisaman.Therefore,Socratesisamortalcreature.Withinductivelogic,comingtoavalidconclusionisabitmoretricky:theconclusionisonlymoreorlessprobableonthebasisofthepremisesandoftennotpossibletobeproventrueabsolutely.Example:Everyraveninarandomsampleof3200ravensisblack.Thisstronglysupportsthehypothesisthatallravensareblack.SyllogismsandEnthymemes:TheProcessesofLogosAsyllogismisthemostcommontypeofdeductivelogic.Aristotlethoughtofitasthemaininstrumentforreachingscientificconclusions.anenthymeme,ontheotherhand,istherhetoricalequivalentofthesyllogism(Corbett73).Infact,Aristotlehimselfdefinedanenthymemeasarhetoricalsyllogism,sayingthatenthymemeistorhetoricassyllogismistologic(CovinoandJolliffe20).enthymeme[逻]省略三段论法Anenthymemeisthechiefwaythatlogicalargumentsarebuilt.Mostofthetimeanenthymemeisidentifiablebywordssuchasbecause,since,for,therefore,so,thus,andhence,whichsignaleithertheconclusionorthesupportforanargument.E.g.Pitbullsshouldbeillegalbecausetheyaredangerousanimals.Oneofthewaystotestthevalidityofsuchaclaim,istobreakitdownintowhatisknownasasyllogism[逻]三段论法,whichproceedsfrommajorpremisetominorpremisetoclaim:Majorpremise:DangerousanimalsshouldbeillegalMinorpremise:PitbullsaredangerousanimalsConclusion:PitbullsshouldbeillegalAnenthymemeattemptstousetheaudience'scommon-sensebeliefstopersuadethem(Crowley156).Example1.Johnwillsurelyfailhiscalculusexam,becausehehasn'tstudied.Example2.Wherethereissmoke,thereisfire.Now,whatisthedifferencebetweenthetwo?Howdoesonedeterminewhetheralawisjustorunjust?Ajustlawisaman-madecodethatsquareswiththemorallaworthelawofGod.Anunjustlawisacodethatisoutofharmonywiththemorallaw.ToputitinthetermsofSt.ThomasAquinas:Anunjustlawisalawthatisnotrootedineternallawandnaturallaw.Anylawthatupliftshumanpersonalityisjust.Anylawthatdegradeshumanpersonalityisunjust.Allsegregationstatutesareunjustbecausesegregationdistortsthesoulanddamagesthepersonality.Itgivesthesegregatorafalsesenseofsuperiorityandthesegregatedafalsesenseofinferiority.(tobecontinued)Anexampleofeffectiveuseoflogicalappeal---MartinLutherKing,Jr.“LetterfromBirminghamJail”Segregation,tousetheterminologyoftheJewishphilosopherMartinBuber,substitutesanI-itrelationshipforanI-thourelationshipandendsuprelegatingpersonstothestatusofthings.Hencesegregationisnotonlypolitically,economicallyandsociologicallyunsound,itismorallywrongandsinful.PaulTillichhassaidthatsinisseparation.Isnotsegregationanexistentialexpressionofman'stragicseparation,hisawfulestrangement,histerriblesinfulness?ThusitisthatIcanurgementoobeythe1954decisionoftheSupremeCourt[whichoutlawssegregationinthepublics