GRE课件逻辑错误PART1

常见逻辑错误

及分析方法逻辑错误类型一览一，调查数据相关(evidence)二，因果关系类(assumption/conclusion)三，比较类比(evidence)四，改变范围类（evidence）五，对策的充分性与必要性(assumption/conclusion)六，其它一，调查数据相关(evidence)Problemsconcerningdata一，调查数据相关(evidence)1.有偏采样S2.不充分采样S3.实验对比4.百分比陷阱5.质疑权威S6.模棱两可S1.有偏采样SThebiased-samplefallacy根据最新研究显示，80%的日本男性觉得凤姐就是他们梦寐以求的妻子。所以。。。凤姐必定在中国男人中大受欢迎！ExampleInarecentsurveyconductedbyWallStreetWeekly,80%oftherespondentsindicatedtheirstrongdisapprovalofincreasedcapitalgainstaxes.Thissurveyclearlyshowsthatincreasedcapitalgainstaxeswillmeetwithstrongoppositionfromtheelectorate.基本错误模型比较---抽样中的对象和结论中的对象Sample------Conclusion

Theconclusionunjustifiablyreliesonthesurvey/poll/studythat_________.80%oftherespondentsindicatedtheirdisapprovalofincreasedcapitalgainstaxesHowever,therespondentsofthesurvey/investigation/pollaredifferentfromthetargetintheconclusioninnature,sothedatadrawnfromthesurveyareunrepresentativetosupportwhatthearguerclaims.ExercisesAccordingtoarecentsurvey,78%ofhighschoolstudentsshowtheirgreatinterestinextracurricularactivities.Therefore,theextracurricularactivitiesorganizedbythestudentunionmustbeverypopularwiththelocalcollegestudents.请注意：此类错误和调查的对象有关，和数据无关！2.不充分采样STheinsufficient-samplefallacyIusedtohave3boyfriendsandfoundthemtobeirresponsibleandrude.Itisobviousthatmenareevil.

Example1Accordingtoasurveyof500urbanresidents,theprevalenceofstressheadachesincreaseswitheducationallevel,sothatstressheadachesoccurmostoftenamongpeoplewithhigherdegreesinPalmTreeCity.MODEL关键：无对象总数假设合理性假设不合理性Thesamplemightbetoosmalltorepresentative点出错误的关键thestatisticscitedmaybemisleadingbecausethetotalnumberof___isnotspecified.Theurbanresidents假设合理性Forexample,if_____,thefactthat______providesstrongsupportfortheconclusion.Thecityhas800residents500ofthemreporttheirstressheadachesduetoincreasingeducationallevel假设不合理性Ontheotherhand,if_____,theconclusionismuchweakened.Thecityhas80000000residentsExample2Thecommonnotionthatworkersaregenerallyapatheticaboutmanagementissueisfalse,oratleastoutdated:arecentlypublishedsurveyindicatesthat79%ofthenearly1200workerswhorespondedtosurveyquestionnairesexpressedahighlevelofinterestinthetopicsofcorporaterestructuringandredesignofbenefitsprograms.请注意：此类错误和具体的数据有关，和百分比以及对象无关。3.实验对比

Test&ControlGroupFallacyWhethertestgroupandcontrolgroupareofthesamenature???基本错误模型TobesubjectiveTobeobjectiveThingsarewhattheyare.Becausewethinktheyare."Doctorshavelongsuspectedthatsecondaryinfectionsmaykeepsomepatientsfromhealingquicklyafterseveremusclestrain.Thishypothesishasnowbeenprovedbypreliminaryresultsofastudyoftwogroupsofpatients.Thefirstgroupofpatients,allbeingtreatedformuscleinjuriesbyDr.Newland,adoctorwhospecializesinsportsmedicine,tookantibioticsregularlythroughouttheirtreatment.Theirrecuperationtimewas,onaverage,40percentquickerthantypicallyexpected.

Patientsinthesecondgroup,allbeingtreatedbyDr.Alton,ageneralphysician,weregivensugarpills,althoughthepatientsbelievedtheyweretakingantibiotics.Theiraveragerecuperationtimewasnotsignificantlyreduced.Therefore,allpatientswhoarediagnosedwithmusclestrainwouldbewelladvisedtotakeantibioticsaspartoftheirtreatment."MODELExceptadoptingdifferentmedicines:Ageandhealth?Severityofthedisease?Othertherapiesexceptthemedicine?Backgroundsofthetwodoctors?Theresultofthestudycanonlybeprovedwhensomecriticalpreconditionshavebeenmet!提出第一种可能性Aboveall,itdoesnottakeintoaccountthepossibilitythat…Twogroupsofpatientshavedifferenthealthconditions.Supposethefirstgroupconsistsofonlyyoungpeoplebutthesecondgroupofoldones.What’smore,theargueralsofailstoruleoutthepossibilitythat_____Thetwodoctorsofdifferentbackgroundsmightadoptdifferenttherapiesandtreatment,whichmightequallyaffecttherecuperationtime.4.百分比陷阱

FalseRatioFallacy小月月今年长胖了20%杜老师今年长胖了5%很明显，今年小月月长的肉比杜老师多多了。SMM---50DLS---10001050基本错误模型百分比无意义，没有基数：nobaseamount百分比陷阱往往企图用比率的变化来掩饰绝对数量的变化A的百分比比B高，说明A比B多好强A的百分比比B低，说明A比B少坏弱Accordingtoapollof200charitableorganizations,donationsofmoneytononprofitgroupsincreasedbynearly25percentlastyear,thoughnotallcharitiesgainedequally.Religiousgroupsgainedthemost(30percent),followedbyenvironmentalgroups(23percent),whereaseducationalinstitutionsexperiencedonlyaverysmallincreaseindonations(3percent).Thispollindicatesthatmorepeoplearewillingandabletogivemoneytocharitiesbutthatfundingforeducationisnotapriorityformostpeople.Thesedifferencesindonationratesmustresultfromtheperceptionthateducationalinstitutionsarelessinneedofdonationsthanareotherkindsofinstitutions.

MODEL假设百分比小的基数较大，则实际值较大假设百分比大的基数较小，则实际值较小结论被推翻引出分析Lackingmorespecificinformationaboutbaseamount,itisimpossibletoassessthereliabilityofthesurvey’sresults.假设并比较基数Supposethebaseamountof_____is_______,thenevenif______,_______.假设百分比小的对象基数可能很大However,itisquitelikelythatthebaseamountof___ismerely,andevenif____,______.假设百分比大的对象基数可能很小Therefore,theargumentisstronglyweakened.Supposethebaseamountofthefundofeducationinstitutionsis100milliondollars,thenevenifthereismerelya3%increase,itis3milliondollars.However,itisquitelikelythatthebaseamountofthefundofenvironmentalandreligiousgroupsismerely10thousandand20thousand,andevenifthereisa30%&23%increase,itissimply3thousandand4.6thousand.Therefore,theargumentisstronglyweakened.请注意：此类错误只和无基数的百分比有关系，和其它数据对象无关。5.质疑权威S

False-AuthorityFallacy调查的权威性值得质疑,何人,何时,何地进行,是否真正权威?

Theargumentusestheword______,butitfailstoprovidesufficientevidencetojustifytheauthorityoftheresearchersconductedtheresearch/theaccuracyoftheresearch.EXERCISES244650请注意：此类错误只和表示权威的词语有关系，和其它无关。6.模棱两可SThefallacyofequivocation论者用一些模糊的量词,如很多，更好，大量,绝大多数,最高等等来描述数量,这使得人们很难估计实际数量到底是多少.ExampleTheCumquatCafemadeamistakeinmovingtoanewlocation.Afteroneyearatthenewspot，itisdoingaboutthesamevolumeofbusinessasbefore，buttheownersoftheRoboWrenchplumbingsupplywholesaleoutletthattookoveritsoldlocationareapparentlydoingbetter：RoboWrenchisplanningtoopenastoreinaneighboringcity.Theword____inthestatementthat______istoovaguetobemeaningful.However,thearguerfailstoprovideasecondtermtoclarifytheblur.EXERCISE2388109二，因果关系类

(assumption/conclusion)CausalRelationship1.急于概括2.后此谬误3.因果倒置S1.急于概括

Hasty-GeneralizationFallacyAndytookMeibaoyuanfor2monthsandbecamemuchmoreslimthaneverbefore.Therefore,ifyouwanttoloseweight,takeMeibaoyuan.基本错误模型A----BConclusionExampleTheCumquatCafebeganadvertisingonourlocalradiostationthisyearandwasdelightedtoseeitsbusinessincreaseby10percentoverlastyear’stotals.Theirsuccessshowsyouhowyoucanuseradioadvertisingtomakeyourbusinessmoreprofitable.MODEL原因结果原因2原因3原因4复述原文的原因和结论Thearguerassumesthat_________.RadioadvertisingalonehascausedtheincreaseinbusinessattheComquatCafe.提出其它可能的原因Thisassumptionisquestionablebecauseitoverlooksanumberofotherfactors.Forexample,________TheComquatmighthavechangedownersorchefs.ItmighthavelaunchedcouponadcampaignItmighthavechangedorupdatedthemenu.Inthepast,thebodystylesofPatriotcarshavebeenold-fashioned,andourcarshavenotsoldaswellashaveourcompetitors'cars.Thus,weshoulddiscontinueouroldestmodelsandconcentrateinsteadonmanufacturingsportycars.Post-saleserviceHighfuelconsumptionEngineperformanceAutomotivetrimSecurityMarketingstrategiesPreviousexperiencehasshownthatourstoresaremostprofitableinareaswhereresidentsarehighlyconcernedwithleadinghealthylives.WeshouldthereforebuildournextnewstoreinPlainsville,whichhasmanysuchresidents.Plainsvillemerchantsreportthatsalesofrunningshoesandexerciseclothingareatall-timehighs.(88)Inthefirstplace,theargumentisbasedonafallacyofhastygeneralization.ThearguerassumesthatPlainvilleresidents’concernwithleadinghealthylives

hasgivenriseto

theboomingsaleofrunningshoesandexerciseclothing.

Theassumptionisquestionablebecausethearguerfailstoruleoutotherpossibilities.Forexample,Plainsvilleresidentspreferwearingsportswearsimplyduetothereasonoftheweathercondition.What’smore,sportswearmightbemorecomfortableandlessexpensivecomparedtoothertypeofclothing.请注意：此类错误只和因果关系有关（原因—结论），和其它无关2.后此谬误The“Afterthis,therefore”fallacy一下雨，动车就追尾了。所以，再下雨，所有动车都会追尾的！作者的推断是建立在一个错误的逻辑关系上的而这个逻辑关系就是作者基于时间先后所错误得出的因果关系。因此，我们这里要驳斥这种关系！基本错误模型INCIDENT1INCIDENT2PASTPRESENTCAUSALThesequenceoftime

标志词：afterthissincethenwhenagoExampleAfteropeningthenewswimmingpoolearlylastsummer,TakeHeartsawa12percentincreaseintheuseofthecenterbymembers.

（错误的因果关系）Therefore,inordertoincreasethenumberofourmembers,weshouldcontinuetoaddnewrecreationalfacilitiesinsubsequentyears:forexample,amultipurposegameroom,atenniscourt,andaminiaturegolfcourse.（作者的推断）点出逻辑关系Thearguerassumesthat___caused_____.TheopeningofthenewswimmingpoolTheincreaseintheuseofthecenter提出其它可能性Thecausalclaimbasedonthecorrelationisprematureunlessthearguercanruleoutotherfactors.Forexample,______otherfitnesscentersmightgobankruptatthattimeItmightbeextremelyhotatthattime,somorepeoplethanevercometothecentertoswim.EXERCISE1297Irecommendthisseminarbecauseitislikelytobeawiseinvestment,giventhattheautomobileracingindustryrecentlyreportedthattheperformanceofitsmaintenancecrewsimprovedmarkedlyaftertheircrewshadattendedtheseminar.First,thearguercommitsafallacyofposthoc,ergopropterhoc.Heunfairlyassumesthattheseminarhascausedthemarkedimprovementof

theperformanceofthemaintenancecrews.Thecausalclaimbasedonthecorrelationisprematureunlessthearguercanruleoutotherfactors.Forexample,thecrewsmayhaveworkedharder.Moreover,thetechnologyofinspectingandmaintainingmayhavebeendeveloped.Inaddition,theinspectionrequirementsmaybemorestringent.请注意：“后此谬误”是“急于概括”的变体，也包含有因果关系。但是这个错误中必需包含时间上的前后关系。3.因果倒置SThefallacyofconfusingthecauseandtheeffect经过调查：杜老师每天都喝2斤酒，他的酒量十分了得。因此，如果要增长你的酒量，每天最好都来2斤。每天2斤------------------酒量大事实上，天生酒量就大，才能喝二斤。基本错误模型A---BCONCLUSIONB---AOfthosewhoresponded,themenwhoreportedthattheyengagedinvigorousoutdoorexercisenearlyeverydaylivedlongerthanthemenwhoreportedthattheyexercisedmildlyonlyonceortwiceaweek.Giventheclearlinkthatthisstudyestablishesbetweenlongevityandexercise,doctorsshouldnotrecommendmoderateexercisetotheirpatientsbutshouldinsteadencouragevigorousoutdoorexerciseonadailybasis.Thearguerassumesthat____causes_____.However,itislikelythatjustbecause_____,______.Thearguerassumesthatvigorousexercisescausetheirlongevity.However,itislikelythatjustbecauseofagoodphysicalcondition,theytakevigorousexercises.三，比较类比(evidence)AnalogyandComparison1.错误类比S2.同等谬误1.错误类比S

ThefallacyoffaultyanalogyAndyandFurongSisterbothexcelatdancing.SinceFurongisawoman,itislikelythatAndyisawomantoo.基本错误模型对象A对象B交集CONCLUSIONExampleTheCumquatCafemadeamistakeinmovingtoanewlocation.Afteroneyearatthenewspot，itisdoingaboutthesamevolumeofbusinessasbefore，buttheownersoftheRoboWrenchplumbingsupplywholesaleoutletthattookoveritsoldlocationareapparentlydoingbetter：RoboWrenchisplanningtoopenastoreinaneighboringcity.Aretheysimilarenough?点出文中的类比关系Theargumentrestsonfaultyanalogybetween____and____.CumquatCafeRoboWrench点出类比关系中的同和异Althoughtheybothhavethesimilaritythat____,wecannotneglecttheessentialdifferencethat____tomakethecomparisonnonsense.TheyusedtochoosethesamespotTheyareengagedindifferentbusiness2.同等谬误TheAllThingsAreEqualFallacy杜老师去年赢得了超级女声第一名.

今年，杜老师是应该还会得第一.基本错误模型假设事件发生的条件和背景不随着时间和地点的变化而改变。

过去=将来A地=B地不同时间/不同地点-----产生同样结果那有人会问:它和错误类比有什么区别？区别很简单，请看以下陈述小明去年得了三好学生，因此今年他还会得莫非这里的共同点是，去年和今年---他都是他自己？Sevenyearsago,homeownersinnearbyBrookvillecommunityadoptedasetofrestrictionsonhowthecommunity’syardsshouldbelandscapedandwhatcolorstheexteriorsofhomesshouldbepainted.Sincethen,averagepropertyvalueshavetripledinBrookville.InordertoraisepropertyvaluesinDeerhavenAcres,weshouldadoptourownsetofrestrictionsonlandscapingandhousepainting.MODEL同等推断

不成立原因1不成立原因2不成立原因3提出文章中的同等推断Thearguerclaimsthat_____because______.ThearguerclaimsthatDeerhavenAcresshouldadoptrestrictionsonlandscapingandhousingpaintingbecausethenearbyBrookvilleadoptedthem7yearsagoandtheirpropertyvaluestripled.指出这个推断是有问题的Thisisanunwarrantedassumptionbecausethingsrarelyremainthesamefromplacetoplace/overextendedperiodsoftime.指出推断不成立的可能性Importantfactorscannotbedeniedforas_______Brookville’sraiseinpropertyvaluesmightresultfortourism,foreigninvestmentorevenfoameconomy.ItislikelythatinBrookvillethelandscapingandhousepaintingisindisorderedcondition,neitherisDeerhavenAcres.结尾Allthesefactorsmentionedabovecanservetoweakenthearguer’claim.四，改变范围类（evidence）Changingscope1.整体推个体S2.偷换概念1.整体推个体SThegeneraldoesn’tequalaspecificfallacy根据统计和调查，全国的男同胞都会娶女人为妻。因此，杜老师也会娶女人。整体情况不等于个体情况，因为可能存在exception.MayorBrownwasrecentlyre-electedbyaclearmajorityof52percentofMonroetown‘svoters.Herre-election,however,doesnotshowthatmostpeopleinourtownfavoredMayorBrown’sproposalfortaxreductionoverthatofheropponent,Mr.Greene,whoproposedraisingtaxestoimproveeducation.Thisisclearlybecausevotersnationwidetendtore-electpeoplealreadyinoffice,regardlessofcandidates'proposals.提出文中的关系Theauthorunfairlyassumesthatthenationwidetendencyappliesspecificallyto_______TheauthorunfairlyassumesthatthenationwidetendencyappliesspecificallytoMonroetownresidents.指出和整体存在差异的可能性Lackingevidencethat个体reflectthisgeneraltendency,itisentirelypossiblethat与整体相反可能性./thetrendof_____mightbejusttheoppositeLackingevidencethatMonreotownresidents

reflectthisgeneraltendency,itisentirelypossiblethattheyvotestrictlywithfullconsideration./thetrendofMonreotownmightbejusttheoppositeEXERCISE1742.偷换概念Afallacyofinconsistentconnotationandextension什么是好男人？为了成为一个“好男人”，杜老师决定坚持增发减肥挣钱基本错误模型比较题目中所出现的概念和其定义是否是能够匹配的。这个概念是否存在其它更合理的定义？

好男人？头发长，苗条，有钱senseofresponsibilityrational概念定义ExampleInMegalopolis,thenumberoflawschoolgraduateswhowenttoworkforlarge,corporatefirmsdeclinedby15percentoverthelastthreeyears,whereasanincreasingnumberofgraduatestookjobsatsmall,generalpracticefirms.Eventhoughlargefirmsusuallyoffermuchhighersalaries,lawschoolgraduatesarechoosingtoworkforthesmallerfirmsmostlikelybecausetheyexperiencegreaterjobsatisfactionatsmallerfirms.Inasurveyoffirst-yearstudentsataleadinglawschool,mostagreedwiththestatementthatearningahighsalarywaslessimportanttothemthanjobsatisfaction.Thisfindingsuggeststhatt