Deductive Reasoning Examples

Deductive reasoning is a type of deduction used in science and in life. It is when you take two true statements, or premises, to form a conclusion. For example, ... HomeExamples DeductiveReasoningExamples DeductiveReasoningExamples Somewouldarguedeductivereasoningisanimportantlifeskill.Itallowsyoutotakeinformationfromtwoormorestatementsanddrawalogicallysoundconclusion.Deductivereasoningmovesfromgeneralitiestospecificconclusions.Perhapsthebiggeststipulationisthatthestatementsuponwhichtheconclusionisdrawnneedtobetrue. Ifthey'reaccurate,thentheconclusionstandstobesoundandaccurate.Let'sexploresomedeductivereasoningexamples.Seeifyouwould'vedrawnthesameconclusionsyourself. Advertisement WhatIsDeductiveReasoning?Deductivereasoningisatypeofdeductionusedinscienceandinlife.Itiswhenyoutaketwotruestatements,orpremises,toformaconclusion.Forexample,AisequaltoB.BisalsoequaltoC.Giventhosetwostatements,youcanconcludeAisequaltoCusingdeductivereasoning. Now,let’slookatareal-lifeexample. Alldolphinsaremammals.Allmammalshavekidneys. Usingdeductivereasoning,youcanconcludethatalldolphinshavekidneys.Remember,forthistowork,bothstatementsmustbetrue.Okay,nowthatyouhaveagoodgrasponit,tryafewexamples.ExamplesofDeductiveReasoningEverydaylifeoftentestsourpowersofdeductivereasoning.Didyoueverwonderwhenyou'dneedwhatyoulearnedinalgebraclass? Well,ifnothingelse,thoselessonsweremeanttostretchourpowersofdeductivereasoning.Remember,ifa=bandb=c,thena=c.Let'sfleshthatoutwithaddedexamples: Allnumbersendingin0or5aredivisibleby5.Thenumber35endswitha5,soitmustbedivisibleby5.Allbirdshavefeathers.Allrobinsarebirds.Therefore,robinshavefeathers.It'sdangeroustodriveonicystreets.Thestreetsareicynow,soitwouldbedangeroustodriveonthestreets.Allcatshaveakeensenseofsmell.Fluffyisacat,soFluffyhasakeensenseofsmell.Cactiareplants,andallplantsperformphotosynthesis.Therefore,cactiperformphotosynthesis.Redmeathasironinit,andbeefisredmeat.Therefore,beefhasironinit.Acuteanglesarelessthan90degrees.Thisangleis40degrees,soitmustbeanacuteangle.Allnoblegasesarestable.Heliumisanoblegas,soheliumisstable.Elephantshavecellsintheirbodies,andallcellshaveDNA.Therefore,elephantshaveDNA.Allhorseshavemanes.TheArabianisahorse;therefore,Arabianshavemanes. Advertisement InvalidDeductiveReasoningWhenitcomestodeductivereasoning,youcanovergeneralize.Inthesecases,evenwithtwosolidandtruepremises,deductivereasoninggoeswrong.Hereareafewexamplesofjustthat: Allswansarewhite.Janeiswhite.Therefore,Janeisaswan.Allfarmerslikeburgers.Jethrolikeschickenwings.Therefore,Jethroisnotafarmer.Allactorsarehandsome.TomCruiseishandsome.Therefore,TomCruiseisanactor. Ineachoftheseexamples,thepremisesmayverywellbetrue,buttheconclusionsmakeinvalidassumptions.Intheseexamples,a+bdoesnotnecessarilyequalc.Rather,"c"isanovergeneralization. Let'staketheTomCruiseexample.JustbecauseTomCruiseishandsome,doesthatmeanhemustbeanactor?Who'stosayallelectriciansorwritersaren'tpretty,too?DeductiveReasoningvs.InductiveReasoningInductivereasoningisakintodeductivereasoning.Themaindifferenceisthat,withinductivereasoning,thepremisesprovidesomeevidenceforthevalidityoftheconclusion,butnotall. Withdeductivereasoning,theconclusionisnecessarilytrueifthepremisesaretrue.Withinductivereasoning,theconclusionmightbetrue,andithassomesupport,butitmaynonethelessbefalse.However,youreducatedguesscanbecomeahypothesisyoucouldconsiderfleshingoutthroughresearchandanabundanceofoutsidesources.ExamplesofInductiveReasoningLet'stakealookatafewexamplesofinductivereasoning.Afterweexaminetheinductivereasoning,we'llflipitandseewhatitlookslikeintheformofdeductivereasoning. InductiveReasoning:ThefirstlipstickIpulledfrommybagisred.ThesecondlipstickIpulledfrommybagisred.Therefore,allthelipsticksinmybagarered.DeductiveReasoning:ThefirstlipstickIpulledfrommybagisred.Alllipsticksinmybagarered.Therefore,thesecondlipstickIpullfrommybagwillbered,too. InductiveReasoning:MymotherisIrish.Shehasblondhair.Therefore,everyonefromIrelandhasblondhair.DeductiveReasoning:MymotherisIrish.EveryonefromIrelandhasblondhair.Therefore,mymotherhasblondhair.InductiveReasoning:Mostofoursnowstormscomefromthenorth.It'sstartingtosnow.Thissnowstormmustbecomingfromthenorth.DeductiveReasoning:Allofoursnowstormscomefromthenorth.It'sstartingtosnow.Therefore,thestormiscomingfromthenorth.InductiveReasoning:Maximilianisashelterdog.Heishappy.Allshelterdogsarehappy.DeductiveReasoning:Maximillianisashelterdog.Allshelterdogsarehappy.Therefore,heishappy. Noticehoweachexampleofdeductivereasoningismoresound(assumingthefirsttwopremisesaretrue)?Ineachinstance,theinductivereasoningmaybetrue.But,they'relackingenoughevidencetobeuniversallytrue.Furthersamplingswouldberequired. Advertisement OtherTypesofReasoningDeductiveandinductivereasoningaren’ttheonlytypeofreasoning.Youmightalsocomeacrossabductivereasoning,backwardinduction,andcriticalthinking.Let’slookatwhatthesetypesofreasoningare: Abductivereasoningiswhenyoutakeasetofobservationsanduseatheorytoexplainthem.Thisisverysimilartohowdoctorsworkonpatientsbytakingsymptomstomakeadiagnosis.Backwardinductionlooksattheendresultandconsidersthedifferentdecisionsthatleadtothatconclusion.It’susedbyartificialintelligencetowingames.Criticalthinkingusesanalysisandevidencetomakeaninformeddecision.It’suseddailytomakedecisionsandtoanalyzedecisionsinscience,literature,etc.Don'tLeaveRoomforAssumptionsIfyouproceedwithfactsandevidence,yourdeductiveorinductivereasoningcanquicklyturnintoanassumption.Andthat'swhatwetypicallytrytoavoidinlife.Ahypothesis,however,isaniceplacetostart.Thisisanideathatcanbemoldedintofactualityandfollowthelinesofdeductivereasoning. Thatmightbearoadworthconsideringifyou'reevertaskedwithwritinganargumentativeessay.Ofcourse,thegoalisnottogetintoanargumentbut,rather,takeapositionandpresentevidenceinsupportofyourclaim.Formore,enjoytheseargumentativeessayexamples. JenniferBetts StaffWriter 7thgrade8thgrade9thgrade10thgrade11thgrade12thgrademiddleschoolhighschoolcollegeRelatedArticlesExamplesofLogic:4MainTypesofReasoningInsimplewords,logicis“thestudyofcorrectreasoning,especiallyregardingmakinginferences.”Logicbeganasaphilosophicaltermandisnowusedinotherdisciplineslikemathandcomputerscience.Whilethedefinitionsoundssimpleenough,understandinglogicisalittlemorecomplex.Uselogicexamplestohelpyoulearntouselogicproperly.ExamplesofInductiveReasoningTheterminductivereasoningreferstoreasoningthattakesspecificinformationandmakesabroadergeneralizationthat'sconsideredprobablewhilestillremainingopentothefactthattheconclusionmaynotbe100%guaranteed.