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《A Concise Introduction to Logic》由會員上傳分享，免費在線閱讀，更多相關內(nèi)容在學術論文-天天文庫。
1、11BasicConcepts1.1Arguments,Premises,andConclusionsLogicmaybede?nedastheorganizedbodyofknowledge,orscience,thatevaluatesarguments.Allofusencounterargumentsinourday-to-dayexperience.Wereadtheminbooksandnewspapers,hearthemontelevision,andformulatethemwhencommunicat-ingwithfriendsa
2、ndassociates.Theaimoflogicistodevelopasystemofmethodsandprinciplesthatwemayuseascriteriaforevaluatingtheargumentsofothersandasguidesinconstructingargumentsofourown.Amongthebene?tstobeexpectedfromthestudyoflogicisanincreaseincon?dencethatwearemakingsensewhenwecriticizetheargument
3、sofothersandwhenweadvanceargumentsofourown.Anargument,asitoccursinlogic,isagroupofstatements,oneormoreofwhich(thepremises)areclaimedtoprovidesupportfor,orreasonstobelieve,oneoftheothers(theconclusion).Allargumentsmaybeplacedinoneoftwobasicgroups:thoseinwhichthepremisesreallydosu
4、pporttheconclusionandthoseinwhichtheydonot,eventhoughtheyareclaimedto.Theformeraresaidtobegoodarguments(atleasttothatextent),thelatterbadarguments.Thepurposeoflogic,asthesciencethatevaluatesarguments,isthustodevelopmethodsandtechniquesthatallowustodistinguishgoodargumentsfrombad
5、.Asisapparentfromtheabovede?nition,theterm‘‘a(chǎn)rgument’’hasaveryspeci?cmean-inginlogic.Itdoesnotmean,forexample,amereverbal?ght,asonemighthavewithone’sparent,spouse,orfriend.Letusexaminethefeaturesofthisde?nitioningreaterdetail.Firstofall,anargumentisagroupofstatements.Astatementi
6、sasentencethatiseithertrueorfalse—inotherwords,typicallyadeclarativesentenceorasentencecom-ponentthatcouldstandasadeclarativesentence.Thefollowingsentencesarestatements:Aluminumisattackedbyhydrochloricacid.BroccoliisagoodsourceofvitaminA.ArgentinaislocatedinNorthAmerica.Napoleon
7、prevailedatWaterloo.RembrandtwasapainterandShelleywasapoet.The?rsttwostatementsaretrue,thesecondtwofalse.Thelastoneexpressestwostatements,bothofwhicharetrue.Truthandfalsityarecalledthetwopossibletruth112BasicConceptsvaluesofastatement.Thus,thetruthvalueofthe?rsttwostatementsistr
8、ue,thetruthvalueofthesecondtwoisfalse,andthetru
